projects/ldc: druntime/src/common/core/thread.d comparison

comparison druntime/src/common/core/thread.d @ 1458:e0b2d67cfe7c

Added druntime (this should be removed once it works).

author	Robert Clipsham <robert@octarineparrot.com>
date	Tue, 02 Jun 2009 17:43:06 +0100
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equal deleted inserted replaced

-:7b218ec1044f
+:e0b2d67cfe7c
+/**
+* The thread module provides support for thread creation and management.
+*
+* Copyright: Copyright Sean Kelly 2005 - 2009.
+* License:   <a href="http://www.boost.org/LICENSE_1_0.txt>Boost License 1.0</a>.
+* Authors:   Sean Kelly
+*
+*          Copyright Sean Kelly 2005 - 2009.
+* Distributed under the Boost Software License, Version 1.0.
+*    (See accompanying file LICENSE_1_0.txt or copy at
+*          http://www.boost.org/LICENSE_1_0.txt)
+*/
+module core.thread;
+// this should be true for most architectures
+version = StackGrowsDown;
+///////////////////////////////////////////////////////////////////////////////
+// Thread and Fiber Exceptions
+///////////////////////////////////////////////////////////////////////////////
+/**
+* Base class for thread exceptions.
+*/
+class ThreadException : Exception
+{
+this( string msg )
+{
+super( msg );
+}
+}
+/**
+* Base class for fiber exceptions.
+*/
+class FiberException : Exception
+{
+this( string msg )
+{
+super( msg );
+}
+}
+private
+{
+//
+// exposed by compiler runtime
+//
+extern (C) void* rt_stackBottom();
+extern (C) void* rt_stackTop();
+void* getStackBottom()
+{
+return rt_stackBottom();
+}
+void* getStackTop()
+{
+version( D_InlineAsm_X86 )
+{
+asm
+{
+naked;
+mov EAX, ESP;
+ret;
+}
+}
+else
+{
+return rt_stackTop();
+}
+}
+}
+///////////////////////////////////////////////////////////////////////////////
+// Thread Entry Point and Signal Handlers
+///////////////////////////////////////////////////////////////////////////////
+version( Windows )
+{
+private
+{
+import core.stdc.stdint : uintptr_t; // for _beginthreadex decl below
+import core.sys.windows.windows;
+const DWORD TLS_OUT_OF_INDEXES  = 0xFFFFFFFF;
+extern (Windows) alias uint function(void*) btex_fptr;
+extern (C) uintptr_t _beginthreadex(void*, uint, btex_fptr, void*, uint, uint*);
+version( DigitalMars )
+{
+// NOTE: The memory between the addresses of _tlsstart and _tlsend
+//       is the storage for thread-local data in D 2.0.  Both of
+//       these are defined in dm\src\win32\tlsseg.asm by DMC.
+extern (C)
+{
+extern __thread int _tlsstart;
+extern __thread int _tlsend;
+}
+}
+else
+{
+__gshared int   _tlsstart;
+alias _tlsstart _tlsend;
+}
+//
+// entry point for Windows threads
+//
+extern (Windows) uint thread_entryPoint( void* arg )
+{
+Thread  obj = cast(Thread) arg;
+assert( obj );
+scope( exit ) Thread.remove( obj );
+assert( obj.m_curr is &obj.m_main );
+obj.m_main.bstack = getStackBottom();
+obj.m_main.tstack = obj.m_main.bstack;
+Thread.add( &obj.m_main );
+Thread.setThis( obj );
+void* pstart = cast(void*) &_tlsstart;
+void* pend   = cast(void*) &_tlsend;
+obj.m_tls = pstart[0 .. pend - pstart];
+// NOTE: No GC allocations may occur until the stack pointers have
+//       been set and Thread.getThis returns a valid reference to
+//       this thread object (this latter condition is not strictly
+//       necessary on Windows but it should be followed for the
+//       sake of consistency).
+// TODO: Consider putting an auto exception object here (using
+//       alloca) forOutOfMemoryError plus something to track
+//       whether an exception is in-flight?
+try
+{
+obj.run();
+}
+catch( Object o )
+{
+obj.m_unhandled = o;
+}
+return 0;
+}
+//
+// copy of the same-named function in phobos.std.thread--it uses the
+// Windows naming convention to be consistent with GetCurrentThreadId
+//
+HANDLE GetCurrentThreadHandle()
+{
+const uint DUPLICATE_SAME_ACCESS = 0x00000002;
+HANDLE curr = GetCurrentThread(),
+proc = GetCurrentProcess(),
+hndl;
+DuplicateHandle( proc, curr, proc, &hndl, 0, TRUE, DUPLICATE_SAME_ACCESS );
+return hndl;
+}
+}
+}
+else version( Posix )
+{
+private
+{
+import core.sys.posix.semaphore;
+import core.sys.posix.pthread;
+import core.sys.posix.signal;
+import core.sys.posix.time;
+import core.stdc.errno;
+extern (C) int getErrno();
+version( OSX )
+{
+import core.sys.osx.mach.thread_act;
+extern (C) mach_port_t pthread_mach_thread_np(pthread_t);
+}
+version( GNU )
+{
+import gcc.builtins;
+}
+version( DigitalMars )
+{
+version( linux )
+{
+extern (C)
+{
+extern __thread int _tlsstart;
+extern __thread int _tlsend;
+}
+}
+else
+{
+__gshared int   _tlsstart;
+alias _tlsstart _tlsend;
+}
+}
+else
+{
+__gshared int   _tlsstart;
+alias _tlsstart _tlsend;
+}
+//
+// entry point for POSIX threads
+//
+extern (C) void* thread_entryPoint( void* arg )
+{
+Thread  obj = cast(Thread) arg;
+assert( obj );
+scope( exit )
+{
+// NOTE: isRunning should be set to false after the thread is
+//       removed or a double-removal could occur between this
+//       function and thread_suspendAll.
+Thread.remove( obj );
+obj.m_isRunning = false;
+}
+static extern (C) void thread_cleanupHandler( void* arg )
+{
+Thread  obj = cast(Thread) arg;
+assert( obj );
+// NOTE: If the thread terminated abnormally, just set it as
+//       not running and let thread_suspendAll remove it from
+//       the thread list.  This is safer and is consistent
+//       with the Windows thread code.
+obj.m_isRunning = false;
+}
+// NOTE: Using void to skip the initialization here relies on
+//       knowledge of how pthread_cleanup is implemented.  It may
+//       not be appropriate for all platforms.  However, it does
+//       avoid the need to link the pthread module.  If any
+//       implementation actually requires default initialization
+//       then pthread_cleanup should be restructured to maintain
+//       the current lack of a link dependency.
+version( linux )
+{
+pthread_cleanup cleanup = void;
+cleanup.push( &thread_cleanupHandler, cast(void*) obj );
+}
+else version( OSX )
+{
+pthread_cleanup cleanup = void;
+cleanup.push( &thread_cleanupHandler, cast(void*) obj );
+}
+else
+{
+pthread_cleanup_push( &thread_cleanupHandler, cast(void*) obj );
+}
+// NOTE: For some reason this does not always work for threads.
+//obj.m_main.bstack = getStackBottom();
+version( D_InlineAsm_X86 )
+{
+static void* getBasePtr()
+{
+asm
+{
+naked;
+mov EAX, EBP;
+ret;
+}
+}
+obj.m_main.bstack = getBasePtr();
+}
+else version( StackGrowsDown )
+obj.m_main.bstack = &obj + 1;
+else
+obj.m_main.bstack = &obj;
+obj.m_main.tstack = obj.m_main.bstack;
+assert( obj.m_curr == &obj.m_main );
+Thread.add( &obj.m_main );
+Thread.setThis( obj );
+void* pstart = cast(void*) &_tlsstart;
+void* pend   = cast(void*) &_tlsend;
+obj.m_tls = pstart[0 .. pend - pstart];
+// NOTE: No GC allocations may occur until the stack pointers have
+//       been set and Thread.getThis returns a valid reference to
+//       this thread object (this latter condition is not strictly
+//       necessary on Windows but it should be followed for the
+//       sake of consistency).
+// TODO: Consider putting an auto exception object here (using
+//       alloca) forOutOfMemoryError plus something to track
+//       whether an exception is in-flight?
+try
+{
+obj.run();
+}
+catch( Object o )
+{
+obj.m_unhandled = o;
+}
+return null;
+}
+//
+// used to track the number of suspended threads
+//
+__gshared sem_t   suspendCount;
+extern (C) void thread_suspendHandler( int sig )
+in
+{
+assert( sig == SIGUSR1 );
+}
+body
+{
+	    version( LDC)
+{
+version(X86)
+{
+uint eax,ecx,edx,ebx,ebp,esi,edi;
+asm
+{
+mov eax[EBP], EAX      ;
+mov ecx[EBP], ECX      ;
+mov edx[EBP], EDX      ;
+mov ebx[EBP], EBX      ;
+mov ebp[EBP], EBP      ;
+mov esi[EBP], ESI      ;
+mov edi[EBP], EDI      ;
+}
+}
+else version (X86_64)
+{
+ulong rax,rbx,rcx,rdx,rbp,rsi,rdi,rsp,r8,r9,r10,r11,r12,r13,r14,r15;
+asm
+{
+movq rax[RBP], RAX        ;
+movq rbx[RBP], RBX        ;
+movq rcx[RBP], RCX        ;
+movq rdx[RBP], RDX        ;
+movq rbp[RBP], RBP        ;
+movq rsi[RBP], RSI        ;
+movq rdi[RBP], RDI        ;
+movq rsp[RBP], RSP        ;
+movq  r8[RBP], R8         ;
+movq  r9[RBP], R9         ;
+movq r10[RBP], R10        ;
+movq r11[RBP], R11        ;
+movq r12[RBP], R12        ;
+movq r13[RBP], R13        ;
+movq r14[RBP], R14        ;
+movq r15[RBP], R15        ;
+}
+}
+else
+{
+static assert( false, "Architecture not supported." );
+}
+} else version( D_InlineAsm_X86 )
+{
+asm
+{
+pushad;
+}
+}
+else version( GNU )
+{
+__builtin_unwind_init();
+}
+else
+{
+static assert( false, "Architecture not supported." );
+}
+// NOTE: Since registers are being pushed and popped from the
+//       stack, any other stack data used by this function should
+//       be gone before the stack cleanup code is called below.
+{
+Thread  obj = Thread.getThis();
+// NOTE: The thread reference returned by getThis is set within
+//       the thread startup code, so it is possible that this
+//       handler may be called before the reference is set.  In
+//       this case it is safe to simply suspend and not worry
+//       about the stack pointers as the thread will not have
+//       any references to GC-managed data.
+if( obj && !obj.m_lock )
+{
+obj.m_curr.tstack = getStackTop();
+}
+sigset_t    sigres = void;
+int         status;
+status = sigfillset( &sigres );
+assert( status == 0 );
+status = sigdelset( &sigres, SIGUSR2 );
+assert( status == 0 );
+status = sem_post( &suspendCount );
+assert( status == 0 );
+sigsuspend( &sigres );
+if( obj && !obj.m_lock )
+{
+obj.m_curr.tstack = obj.m_curr.bstack;
+}
+}
+	    version( LDC ){}
+	    else version( D_InlineAsm_X86 )
+{
+asm
+{
+popad;
+}
+}
+else version( GNU )
+{
+// registers will be popped automatically
+}
+else
+{
+static assert( false, "Architecture not supported." );
+}
+}
+extern (C) void thread_resumeHandler( int sig )
+in
+{
+assert( sig == SIGUSR2 );
+}
+body
+{
+}
+}
+}
+else
+{
+// NOTE: This is the only place threading versions are checked.  If a new
+//       version is added, the module code will need to be searched for
+//       places where version-specific code may be required.  This can be
+//       easily accomlished by searching for 'Windows' or 'Posix'.
+static assert( false, "Unknown threading implementation." );
+}
+///////////////////////////////////////////////////////////////////////////////
+// Thread
+///////////////////////////////////////////////////////////////////////////////
+/**
+* This class encapsulates all threading functionality for the D
+* programming language.  As thread manipulation is a required facility
+* for garbage collection, all user threads should derive from this
+* class, and instances of this class should never be explicitly deleted.
+* A new thread may be created using either derivation or composition, as
+* in the following example.
+*
+* Example:
+* ----------------------------------------------------------------------------
+*
+* class DerivedThread : Thread
+* {
+*     this()
+*     {
+*         super( &run );
+*     }
+*
+* private :
+*     void run()
+*     {
+*         printf( "Derived thread running.\n" );
+*     }
+* }
+*
+* void threadFunc()
+* {
+*     printf( "Composed thread running.\n" );
+* }
+*
+* // create instances of each type
+* Thread derived = new DerivedThread();
+* Thread composed = new Thread( &threadFunc );
+*
+* // start both threads
+* derived.start();
+* composed.start();
+*
+* ----------------------------------------------------------------------------
+*/
+class Thread
+{
+///////////////////////////////////////////////////////////////////////////
+// Initialization
+///////////////////////////////////////////////////////////////////////////
+/**
+* Initializes a thread object which is associated with a static
+* D function.
+*
+* Params:
+*  fn = The thread function.
+*  sz = The stack size for this thread.
+*
+* In:
+*  fn must not be null.
+*/
+this( void function() fn, size_t sz = 0 )
+in
+{
+assert( fn );
+}
+body
+{
+m_fn   = fn;
+m_sz   = sz;
+m_call = Call.FN;
+m_curr = &m_main;
+}
+/**
+* Initializes a thread object which is associated with a dynamic
+* D function.
+*
+* Params:
+*  dg = The thread function.
+*  sz = The stack size for this thread.
+*
+* In:
+*  dg must not be null.
+*/
+this( void delegate() dg, size_t sz = 0 )
+in
+{
+assert( dg );
+}
+body
+{
+m_dg   = dg;
+m_sz   = sz;
+m_call = Call.DG;
+m_curr = &m_main;
+}
+/**
+* Cleans up any remaining resources used by this object.
+*/
+~this()
+{
+if( m_addr == m_addr.init )
+{
+return;
+}
+version( Windows )
+{
+m_addr = m_addr.init;
+CloseHandle( m_hndl );
+m_hndl = m_hndl.init;
+}
+else version( Posix )
+{
+pthread_detach( m_addr );
+m_addr = m_addr.init;
+}
+version( OSX )
+{
+m_tmach = m_tmach.init;
+}
+}
+///////////////////////////////////////////////////////////////////////////
+// General Actions
+///////////////////////////////////////////////////////////////////////////
+/**
+* Starts the thread and invokes the function or delegate passed upon
+* construction.
+*
+* In:
+*  This routine may only be called once per thread instance.
+*
+* Throws:
+*  ThreadException if the thread fails to start.
+*/
+final void start()
+in
+{
+assert( !next && !prev );
+}
+body
+{
+auto wasThreaded  = multiThreadedFlag;
+multiThreadedFlag = true;
+scope( failure )
+{
+if( !wasThreaded )
+multiThreadedFlag = false;
+}
+version( Windows ) {} else
+version( Posix )
+{
+pthread_attr_t  attr;
+if( pthread_attr_init( &attr ) )
+throw new ThreadException( "Error initializing thread attributes" );
+if( m_sz && pthread_attr_setstacksize( &attr, m_sz ) )
+throw new ThreadException( "Error initializing thread stack size" );
+if( pthread_attr_setdetachstate( &attr, PTHREAD_CREATE_JOINABLE ) )
+throw new ThreadException( "Error setting thread joinable" );
+}
+// NOTE: This operation needs to be synchronized to avoid a race
+//       condition with the GC.  Without this lock, the thread
+//       could start and allocate memory before being added to
+//       the global thread list, preventing it from being scanned
+//       and causing memory to be collected that is still in use.
+synchronized( slock )
+{
+version( Windows )
+{
+m_hndl = cast(HANDLE) _beginthreadex( null, m_sz, &thread_entryPoint, cast(void*) this, 0, &m_addr );
+if( cast(size_t) m_hndl == 0 )
+throw new ThreadException( "Error creating thread" );
+}
+else version( Posix )
+{
+m_isRunning = true;
+scope( failure ) m_isRunning = false;
+if( pthread_create( &m_addr, &attr, &thread_entryPoint, cast(void*) this ) != 0 )
+throw new ThreadException( "Error creating thread" );
+}
+version( OSX )
+{
+m_tmach = pthread_mach_thread_np( m_addr );
+if( m_tmach == m_tmach.init )
+throw new ThreadException( "Error creating thread" );
+}
+add( this );
+}
+}
+/**
+* Waits for this thread to complete.  If the thread terminated as the
+* result of an unhandled exception, this exception will be rethrown.
+*
+* Params:
+*  rethrow = Rethrow any unhandled exception which may have caused this
+*            thread to terminate.
+*
+* Throws:
+*  ThreadException if the operation fails.
+*  Any exception not handled by the joined thread.
+*
+* Returns:
+*  Any exception not handled by this thread if rethrow = false, null
+*  otherwise.
+*/
+final Object join( bool rethrow = true )
+{
+version( Windows )
+{
+if( WaitForSingleObject( m_hndl, INFINITE ) != WAIT_OBJECT_0 )
+throw new ThreadException( "Unable to join thread" );
+// NOTE: m_addr must be cleared before m_hndl is closed to avoid
+//       a race condition with isRunning.  The operation is labeled
+//       volatile to prevent compiler reordering.
+volatile m_addr = m_addr.init;
+CloseHandle( m_hndl );
+m_hndl = m_hndl.init;
+}
+else version( Posix )
+{
+if( pthread_join( m_addr, null ) != 0 )
+throw new ThreadException( "Unable to join thread" );
+// NOTE: pthread_join acts as a substitute for pthread_detach,
+//       which is normally called by the dtor.  Setting m_addr
+//       to zero ensures that pthread_detach will not be called
+//       on object destruction.
+volatile m_addr = m_addr.init;
+}
+if( m_unhandled )
+{
+if( rethrow )
+throw m_unhandled;
+return m_unhandled;
+}
+return null;
+}
+///////////////////////////////////////////////////////////////////////////
+// General Properties
+///////////////////////////////////////////////////////////////////////////
+/**
+* Gets the user-readable label for this thread.
+*
+* Returns:
+*  The name of this thread.
+*/
+final char[] name()
+{
+synchronized( this )
+{
+return m_name;
+}
+}
+/**
+* Sets the user-readable label for this thread.
+*
+* Params:
+*  val = The new name of this thread.
+*/
+final void name( char[] val )
+{
+synchronized( this )
+{
+m_name = val.dup;
+}
+}
+/**
+* Gets the daemon status for this thread.  While the runtime will wait for
+* all normal threads to complete before tearing down the process, daemon
+* threads are effectively ignored and thus will not prevent the process
+* from terminating.  In effect, daemon threads will be terminated
+* automatically by the OS when the process exits.
+*
+* Returns:
+*  true if this is a daemon thread.
+*/
+final bool isDaemon()
+{
+synchronized( this )
+{
+return m_isDaemon;
+}
+}
+/**
+* Sets the daemon status for this thread.  While the runtime will wait for
+* all normal threads to complete before tearing down the process, daemon
+* threads are effectively ignored and thus will not prevent the process
+* from terminating.  In effect, daemon threads will be terminated
+* automatically by the OS when the process exits.
+*
+* Params:
+*  val = The new daemon status for this thread.
+*/
+final void isDaemon( bool val )
+{
+synchronized( this )
+{
+m_isDaemon = val;
+}
+}
+/**
+* Tests whether this thread is running.
+*
+* Returns:
+*  true if the thread is running, false if not.
+*/
+final bool isRunning()
+{
+if( m_addr == m_addr.init )
+{
+return false;
+}
+version( Windows )
+{
+uint ecode = 0;
+GetExitCodeThread( m_hndl, &ecode );
+return ecode == STILL_ACTIVE;
+}
+else version( Posix )
+{
+// NOTE: It should be safe to access this value without
+//       memory barriers because word-tearing and such
+//       really isn't an issue for boolean values.
+return m_isRunning;
+}
+}
+///////////////////////////////////////////////////////////////////////////
+// Thread Priority Actions
+///////////////////////////////////////////////////////////////////////////
+/**
+* The minimum scheduling priority that may be set for a thread.  On
+* systems where multiple scheduling policies are defined, this value
+* represents the minimum valid priority for the scheduling policy of
+* the process.
+*/
+static const int PRIORITY_MIN;
+/**
+* The maximum scheduling priority that may be set for a thread.  On
+* systems where multiple scheduling policies are defined, this value
+* represents the minimum valid priority for the scheduling policy of
+* the process.
+*/
+static const int PRIORITY_MAX;
+/**
+* Gets the scheduling priority for the associated thread.
+*
+* Returns:
+*  The scheduling priority of this thread.
+*/
+final int priority()
+{
+version( Windows )
+{
+return GetThreadPriority( m_hndl );
+}
+else version( Posix )
+{
+int         policy;
+sched_param param;
+if( pthread_getschedparam( m_addr, &policy, &param ) )
+throw new ThreadException( "Unable to get thread priority" );
+return param.sched_priority;
+}
+}
+/**
+* Sets the scheduling priority for the associated thread.
+*
+* Params:
+*  val = The new scheduling priority of this thread.
+*/
+final void priority( int val )
+{
+version( Windows )
+{
+if( !SetThreadPriority( m_hndl, val ) )
+throw new ThreadException( "Unable to set thread priority" );
+}
+else version( Posix )
+{
+// NOTE: pthread_setschedprio is not implemented on linux, so use
+//       the more complicated get/set sequence below.
+//if( pthread_setschedprio( m_addr, val ) )
+//    throw new ThreadException( "Unable to set thread priority" );
+int         policy;
+sched_param param;
+if( pthread_getschedparam( m_addr, &policy, &param ) )
+throw new ThreadException( "Unable to set thread priority" );
+param.sched_priority = val;
+if( pthread_setschedparam( m_addr, policy, &param ) )
+throw new ThreadException( "Unable to set thread priority" );
+}
+}
+///////////////////////////////////////////////////////////////////////////
+// Actions on Calling Thread
+///////////////////////////////////////////////////////////////////////////
+/**
+* Suspends the calling thread for at least the supplied period.  This may
+* result in multiple OS calls if period is greater than the maximum sleep
+* duration supported by the operating system.
+*
+* Params:
+*  period = The minimum duration the calling thread should be suspended,
+*           in 100 nanosecond intervals.
+*
+* In:
+*  period must be non-negative.
+*
+* Example:
+* ------------------------------------------------------------------------
+*
+* Thread.sleep( 500_000 );    // sleep for 50 milliseconds
+* Thread.sleep( 50_000_000 ); // sleep for 5 seconds
+*
+* ------------------------------------------------------------------------
+*/
+static void sleep( long period )
+in
+{
+assert( period >= 0 );
+}
+body
+{
+version( Windows )
+{
+enum : uint
+{
+TICKS_PER_MILLI  = 10_000,
+MAX_SLEEP_MILLIS = uint.max - 1
+}
+// NOTE: In instances where all other threads in the process have a
+//       lower priority than the current thread, the current thread
+//       will not yield with a sleep time of zero.  However, unlike
+//       yield(), the user is not asking for a yield to occur but
+//       only for execution to suspend for the requested interval.
+//       Therefore, expected performance may not be met if a yield
+//       is forced upon the user.
+period /= TICKS_PER_MILLI;
+while( period > MAX_SLEEP_MILLIS )
+{
+Sleep( MAX_SLEEP_MILLIS );
+period -= MAX_SLEEP_MILLIS;
+}
+Sleep( cast(uint) period );
+}
+else version( Posix )
+{
+timespec tin  = void;
+timespec tout = void;
+enum : uint
+{
+NANOS_PER_TICK   = 100,
+TICKS_PER_SECOND = 10_000_000,
+}
+enum : typeof(period)
+{
+MAX_SLEEP_TICKS = cast(typeof(period)) tin.tv_sec.max * TICKS_PER_SECOND
+}
+do
+{
+if( period > MAX_SLEEP_TICKS )
+{
+tin.tv_sec = tin.tv_sec.max;
+tin.tv_nsec = 0;
+}
+else
+{
+tin.tv_sec = cast(typeof(tin.tv_sec)) (period / TICKS_PER_SECOND);
+tin.tv_nsec = cast(typeof(tin.tv_nsec)) (period % TICKS_PER_SECOND) * NANOS_PER_TICK;
+}
+while( true )
+{
+if( !nanosleep( &tin, &tout ) )
+return;
+if( getErrno() != EINTR )
+throw new ThreadException( "Unable to sleep for the specified duration" );
+tin = tout;
+}
+period -= (cast(typeof(period)) tin.tv_sec) * TICKS_PER_SECOND;
+period -= (cast(typeof(period)) tin.tv_nsec) / NANOS_PER_TICK;
+} while( period > 0 );
+}
+}
+/**
+* Forces a context switch to occur away from the calling thread.
+*/
+static void yield()
+{
+version( Windows )
+{
+// NOTE: Sleep(1) is necessary because Sleep(0) does not give
+//       lower priority threads any timeslice, so looping on
+//       Sleep(0) could be resource-intensive in some cases.
+Sleep( 1 );
+}
+else version( Posix )
+{
+sched_yield();
+}
+}
+///////////////////////////////////////////////////////////////////////////
+// Thread Accessors
+///////////////////////////////////////////////////////////////////////////
+/**
+* Provides a reference to the calling thread.
+*
+* Returns:
+*  The thread object representing the calling thread.  The result of
+*  deleting this object is undefined.
+*/
+static Thread getThis()
+{
+// NOTE: This function may not be called until thread_init has
+//       completed.  See thread_suspendAll for more information
+//       on why this might occur.
+version( Windows )
+{
+return cast(Thread) TlsGetValue( sm_this );
+}
+else version( Posix )
+{
+return cast(Thread) pthread_getspecific( sm_this );
+}
+}
+/**
+* Provides a list of all threads currently being tracked by the system.
+*
+* Returns:
+*  An array containing references to all threads currently being
+*  tracked by the system.  The result of deleting any contained
+*  objects is undefined.
+*/
+static Thread[] getAll()
+{
+synchronized( slock )
+{
+size_t   pos = 0;
+Thread[] buf = new Thread[sm_tlen];
+foreach( Thread t; Thread )
+{
+buf[pos++] = t;
+}
+return buf;
+}
+}
+/**
+* Operates on all threads currently being tracked by the system.  The
+* result of deleting any Thread object is undefined.
+*
+* Params:
+*  dg = The supplied code as a delegate.
+*
+* Returns:
+*  Zero if all elemented are visited, nonzero if not.
+*/
+static int opApply( int delegate( inout Thread ) dg )
+{
+synchronized( slock )
+{
+int ret = 0;
+for( Thread t = sm_tbeg; t; t = t.next )
+{
+ret = dg( t );
+if( ret )
+break;
+}
+return ret;
+}
+}
+///////////////////////////////////////////////////////////////////////////
+// Local Storage Actions
+///////////////////////////////////////////////////////////////////////////
+/**
+* Indicates the number of local storage pointers available at program
+* startup.  It is recommended that this number be at least 64.
+*/
+static const uint LOCAL_MAX = 64;
+/**
+* Reserves a local storage pointer for use and initializes this location
+* to null for all running threads.
+*
+* Returns:
+*  A key representing the array offset of this memory location.
+*/
+static uint createLocal()
+{
+synchronized( slock )
+{
+foreach( uint key, inout bool set; sm_local )
+{
+if( !set )
+{
+//foreach( Thread t; sm_tbeg ) Bug in GDC 0.24 SVN (r139)
+for( Thread t = sm_tbeg; t; t = t.next )
+{
+t.m_local[key] = null;
+}
+set = true;
+return key;
+}
+}
+throw new ThreadException( "No more local storage slots available" );
+}
+}
+/**
+* Marks the supplied key as available and sets the associated location
+* to null for all running threads.  It is assumed that any key passed
+* to this function is valid.  The result of calling this function for
+* a key which is still in use is undefined.
+*
+* Params:
+*  key = The key to delete.
+*/
+static void deleteLocal( uint key )
+{
+synchronized( slock )
+{
+sm_local[key] = false;
+// foreach( Thread t; sm_tbeg ) Bug in GDC 0.24 SVN (r139)
+for( Thread t = sm_tbeg; t; t = t.next )
+{
+t.m_local[key] = null;
+}
+}
+}
+/**
+* Loads the value stored at key within a thread-local static array.  It is
+* assumed that any key passed to this function is valid.
+*
+* Params:
+*  key = The location which holds the desired data.
+*
+* Returns:
+*  The data associated with the supplied key.
+*/
+static void* getLocal( uint key )
+{
+return getThis().m_local[key];
+}
+/**
+* Stores the supplied value at key within a thread-local static array.  It
+* is assumed that any key passed to this function is valid.
+*
+* Params:
+*  key = The location to store the supplied data.
+*  val = The data to store.
+*
+* Returns:
+*  A copy of the data which has just been stored.
+*/
+static void* setLocal( uint key, void* val )
+{
+return getThis().m_local[key] = val;
+}
+///////////////////////////////////////////////////////////////////////////
+// Static Initalizer
+///////////////////////////////////////////////////////////////////////////
+/**
+* This initializer is used to set thread constants.  All functional
+* initialization occurs within thread_init().
+*/
+static this()
+{
+version( Windows )
+{
+PRIORITY_MIN = -15;
+PRIORITY_MAX =  15;
+}
+else version( Posix )
+{
+int         policy;
+sched_param param;
+pthread_t   self = pthread_self();
+int status = pthread_getschedparam( self, &policy, &param );
+assert( status == 0 );
+PRIORITY_MIN = sched_get_priority_min( policy );
+assert( PRIORITY_MIN != -1 );
+PRIORITY_MAX = sched_get_priority_max( policy );
+assert( PRIORITY_MAX != -1 );
+}
+}
+private:
+//
+// Initializes a thread object which has no associated executable function.
+// This is used for the main thread initialized in thread_init().
+//
+this()
+{
+m_call = Call.NO;
+m_curr = &m_main;
+void* pstart = cast(void*) &_tlsstart;
+void* pend   = cast(void*) &_tlsend;
+m_tls = pstart[0 .. pend - pstart];
+}
+//
+// Thread entry point.  Invokes the function or delegate passed on
+// construction (if any).
+//
+final void run()
+{
+switch( m_call )
+{
+case Call.FN:
+m_fn();
+break;
+case Call.DG:
+m_dg();
+break;
+default:
+break;
+}
+}
+private:
+//
+// The type of routine passed on thread construction.
+//
+enum Call
+{
+NO,
+FN,
+DG
+}
+//
+// Standard types
+//
+version( Windows )
+{
+alias uint TLSKey;
+alias uint ThreadAddr;
+}
+else version( Posix )
+{
+alias pthread_key_t TLSKey;
+alias pthread_t     ThreadAddr;
+}
+//
+// Local storage
+//
+__gshared bool[LOCAL_MAX]  sm_local;
+__gshared TLSKey           sm_this;
+void*[LOCAL_MAX]        m_local;
+//
+// Standard thread data
+//
+version( Windows )
+{
+HANDLE          m_hndl;
+}
+else version( OSX )
+{
+mach_port_t     m_tmach;
+}
+ThreadAddr          m_addr;
+Call                m_call;
+char[]              m_name;
+union
+{
+void function() m_fn;
+void delegate() m_dg;
+}
+size_t              m_sz;
+version( Posix )
+{
+bool            m_isRunning;
+}
+bool                m_isDaemon;
+Object              m_unhandled;
+private:
+///////////////////////////////////////////////////////////////////////////
+// Storage of Active Thread
+///////////////////////////////////////////////////////////////////////////
+//
+// Sets a thread-local reference to the current thread object.
+//
+static void setThis( Thread t )
+{
+version( Windows )
+{
+TlsSetValue( sm_this, cast(void*) t );
+}
+else version( Posix )
+{
+pthread_setspecific( sm_this, cast(void*) t );
+}
+}
+private:
+///////////////////////////////////////////////////////////////////////////
+// Thread Context and GC Scanning Support
+///////////////////////////////////////////////////////////////////////////
+final void pushContext( Context* c )
+in
+{
+assert( !c.within );
+}
+body
+{
+c.within = m_curr;
+m_curr = c;
+}
+final void popContext()
+in
+{
+assert( m_curr && m_curr.within );
+}
+body
+{
+Context* c = m_curr;
+m_curr = c.within;
+c.within = null;
+}
+final Context* topContext()
+in
+{
+assert( m_curr );
+}
+body
+{
+return m_curr;
+}
+static struct Context
+{
+void*           bstack,
+tstack;
+Context*        within;
+Context*        next,
+prev;
+}
+Context             m_main;
+Context*            m_curr;
+bool                m_lock;
+void[]              m_tls;  // spans implicit thread local storage
+version( Windows )
+{
+version( X86 )
+{
+uint[8]         m_reg; // edi,esi,ebp,esp,ebx,edx,ecx,eax
+}
+else version( X86_64 )
+{
+ulong[16]       m_reg; // rdi,rsi,rbp,rsp,rbx,rdx,rcx,rax
+// r8,r9,r10,r11,r12,r13,r14,r15
+}
+else
+{
+static assert( "Architecture not supported." );
+}
+}
+else version( OSX )
+{
+version( X86 )
+{
+uint[8]         m_reg; // edi,esi,ebp,esp,ebx,edx,ecx,eax
+}
+else version( X86_64 )
+{
+ulong[16]       m_reg; // rdi,rsi,rbp,rsp,rbx,rdx,rcx,rax
+// r8,r9,r10,r11,r12,r13,r14,r15
+}
+else
+{
+static assert( "Architecture not supported." );
+}
+}
+private:
+///////////////////////////////////////////////////////////////////////////
+// GC Scanning Support
+///////////////////////////////////////////////////////////////////////////
+// NOTE: The GC scanning process works like so:
+//
+//          1. Suspend all threads.
+//          2. Scan the stacks of all suspended threads for roots.
+//          3. Resume all threads.
+//
+//       Step 1 and 3 require a list of all threads in the system, while
+//       step 2 requires a list of all thread stacks (each represented by
+//       a Context struct).  Traditionally, there was one stack per thread
+//       and the Context structs were not necessary.  However, Fibers have
+//       changed things so that each thread has its own 'main' stack plus
+//       an arbitrary number of nested stacks (normally referenced via
+//       m_curr).  Also, there may be 'free-floating' stacks in the system,
+//       which are Fibers that are not currently executing on any specific
+//       thread but are still being processed and still contain valid
+//       roots.
+//
+//       To support all of this, the Context struct has been created to
+//       represent a stack range, and a global list of Context structs has
+//       been added to enable scanning of these stack ranges.  The lifetime
+//       (and presence in the Context list) of a thread's 'main' stack will
+//       be equivalent to the thread's lifetime.  So the Ccontext will be
+//       added to the list on thread entry, and removed from the list on
+//       thread exit (which is essentially the same as the presence of a
+//       Thread object in its own global list).  The lifetime of a Fiber's
+//       context, however, will be tied to the lifetime of the Fiber object
+//       itself, and Fibers are expected to add/remove their Context struct
+//       on construction/deletion.
+//
+// All use of the global lists should synchronize on this lock.
+//
+static Object slock()
+{
+return Thread.classinfo;
+}
+__gshared
+{
+	Context*     sm_cbeg;
+	size_t       sm_clen;
+	Thread       sm_tbeg;
+	size_t       sm_tlen;
+}
+//
+// Used for ordering threads in the global thread list.
+//
+Thread              prev;
+Thread              next;
+///////////////////////////////////////////////////////////////////////////
+// Global Context List Operations
+///////////////////////////////////////////////////////////////////////////
+//
+// Add a context to the global context list.
+//
+static void add( Context* c )
+in
+{
+assert( c );
+assert( !c.next && !c.prev );
+}
+body
+{
+synchronized( slock )
+{
+if( sm_cbeg )
+{
+c.next = sm_cbeg;
+sm_cbeg.prev = c;
+}
+sm_cbeg = c;
+++sm_clen;
+}
+}
+//
+// Remove a context from the global context list.
+//
+static void remove( Context* c )
+in
+{
+assert( c );
+assert( c.next || c.prev );
+}
+body
+{
+synchronized( slock )
+{
+if( c.prev )
+c.prev.next = c.next;
+if( c.next )
+c.next.prev = c.prev;
+if( sm_cbeg == c )
+sm_cbeg = c.next;
+--sm_clen;
+}
+// NOTE: Don't null out c.next or c.prev because opApply currently
+//       follows c.next after removing a node.  This could be easily
+//       addressed by simply returning the next node from this
+//       function, however, a context should never be re-added to the
+//       list anyway and having next and prev be non-null is a good way
+//       to ensure that.
+}
+///////////////////////////////////////////////////////////////////////////
+// Global Thread List Operations
+///////////////////////////////////////////////////////////////////////////
+//
+// Add a thread to the global thread list.
+//
+static void add( Thread t )
+in
+{
+assert( t );
+assert( !t.next && !t.prev );
+assert( t.isRunning );
+}
+body
+{
+synchronized( slock )
+{
+if( sm_tbeg )
+{
+t.next = sm_tbeg;
+sm_tbeg.prev = t;
+}
+sm_tbeg = t;
+++sm_tlen;
+}
+}
+//
+// Remove a thread from the global thread list.
+//
+static void remove( Thread t )
+in
+{
+assert( t );
+assert( t.next || t.prev );
+version( Windows )
+{
+// NOTE: This doesn't work for Posix as m_isRunning must be set to
+//       false after the thread is removed during normal execution.
+assert( !t.isRunning );
+}
+}
+body
+{
+synchronized( slock )
+{
+// NOTE: When a thread is removed from the global thread list its
+//       main context is invalid and should be removed as well.
+//       It is possible that t.m_curr could reference more
+//       than just the main context if the thread exited abnormally
+//       (if it was terminated), but we must assume that the user
+//       retains a reference to them and that they may be re-used
+//       elsewhere.  Therefore, it is the responsibility of any
+//       object that creates contexts to clean them up properly
+//       when it is done with them.
+remove( &t.m_main );
+if( t.prev )
+t.prev.next = t.next;
+if( t.next )
+t.next.prev = t.prev;
+if( sm_tbeg == t )
+sm_tbeg = t.next;
+--sm_tlen;
+}
+// NOTE: Don't null out t.next or t.prev because opApply currently
+//       follows t.next after removing a node.  This could be easily
+//       addressed by simply returning the next node from this
+//       function, however, a thread should never be re-added to the
+//       list anyway and having next and prev be non-null is a good way
+//       to ensure that.
+}
+}
+///////////////////////////////////////////////////////////////////////////////
+// GC Support Routines
+///////////////////////////////////////////////////////////////////////////////
+/**
+* Initializes the thread module.  This function must be called by the
+* garbage collector on startup and before any other thread routines
+* are called.
+*/
+extern (C) void thread_init()
+{
+// NOTE: If thread_init itself performs any allocations then the thread
+//       routines reserved for garbage collector use may be called while
+//       thread_init is being processed.  However, since no memory should
+//       exist to be scanned at this point, it is sufficient for these
+//       functions to detect the condition and return immediately.
+version( Windows )
+{
+Thread.sm_this = TlsAlloc();
+assert( Thread.sm_this != TLS_OUT_OF_INDEXES );
+}
+else version( Posix )
+{
+int         status;
+sigaction_t sigusr1 = void;
+sigaction_t sigusr2 = void;
+// This is a quick way to zero-initialize the structs without using
+// memset or creating a link dependency on their static initializer.
+(cast(byte*) &sigusr1)[0 .. sigaction_t.sizeof] = 0;
+(cast(byte*) &sigusr2)[0 .. sigaction_t.sizeof] = 0;
+// NOTE: SA_RESTART indicates that system calls should restart if they
+//       are interrupted by a signal, but this is not available on all
+//       Posix systems, even those that support multithreading.
+static if( is( typeof( SA_RESTART ) ) )
+sigusr1.sa_flags = SA_RESTART;
+else
+sigusr1.sa_flags   = 0;
+sigusr1.sa_handler = &thread_suspendHandler;
+// NOTE: We want to ignore all signals while in this handler, so fill
+//       sa_mask to indicate this.
+status = sigfillset( &sigusr1.sa_mask );
+assert( status == 0 );
+// NOTE: Since SIGUSR2 should only be issued for threads within the
+//       suspend handler, we don't want this signal to trigger a
+//       restart.
+sigusr2.sa_flags   = 0;
+sigusr2.sa_handler = &thread_resumeHandler;
+// NOTE: We want to ignore all signals while in this handler, so fill
+//       sa_mask to indicate this.
+status = sigfillset( &sigusr2.sa_mask );
+assert( status == 0 );
+status = sigaction( SIGUSR1, &sigusr1, null );
+assert( status == 0 );
+status = sigaction( SIGUSR2, &sigusr2, null );
+assert( status == 0 );
+status = sem_init( &suspendCount, 0, 0 );
+assert( status == 0 );
+status = pthread_key_create( &Thread.sm_this, null );
+assert( status == 0 );
+}
+thread_attachThis();
+}
+/**
+* Registers the calling thread for use with the D Runtime.  If this routine
+* is called for a thread which is already registered, the result is undefined.
+*/
+extern (C) void thread_attachThis()
+{
+version( Windows )
+{
+Thread          thisThread  = new Thread();
+Thread.Context* thisContext = &thisThread.m_main;
+assert( thisContext == thisThread.m_curr );
+thisThread.m_addr  = GetCurrentThreadId();
+thisThread.m_hndl  = GetCurrentThreadHandle();
+thisContext.bstack = getStackBottom();
+thisContext.tstack = thisContext.bstack;
+thisThread.m_isDaemon = true;
+Thread.setThis( thisThread );
+}
+else version( Posix )
+{
+Thread          thisThread  = new Thread();
+Thread.Context* thisContext = thisThread.m_curr;
+assert( thisContext == &thisThread.m_main );
+thisThread.m_addr  = pthread_self();
+thisContext.bstack = getStackBottom();
+thisContext.tstack = thisContext.bstack;
+thisThread.m_isRunning = true;
+thisThread.m_isDaemon  = true;
+Thread.setThis( thisThread );
+}
+version( OSX )
+{
+thisThread.m_tmach = pthread_mach_thread_np( thisThread.m_addr );
+assert( thisThread.m_tmach != thisThread.m_tmach.init );
+}
+Thread.add( thisThread );
+Thread.add( thisContext );
+}
+/**
+* Deregisters the calling thread from use with the runtime.  If this routine
+* is called for a thread which is already registered, the result is undefined.
+*/
+extern (C) void thread_detachThis()
+{
+Thread.remove( Thread.getThis() );
+}
+/**
+* Joins all non-daemon threads that are currently running.  This is done by
+* performing successive scans through the thread list until a scan consists
+* of only daemon threads.
+*/
+extern (C) void thread_joinAll()
+{
+while( true )
+{
+Thread nonDaemon = null;
+foreach( t; Thread )
+{
+if( !t.isDaemon )
+{
+nonDaemon = t;
+break;
+}
+}
+if( nonDaemon is null )
+return;
+nonDaemon.join();
+}
+}
+/**
+* Performs intermediate shutdown of the thread module.
+*/
+static ~this()
+{
+// NOTE: The functionality related to garbage collection must be minimally
+//       operable after this dtor completes.  Therefore, only minimal
+//       cleanup may occur.
+for( Thread t = Thread.sm_tbeg; t; t = t.next )
+{
+if( !t.isRunning )
+Thread.remove( t );
+}
+}
+// Used for needLock below
+private __gshared bool multiThreadedFlag = false;
+/**
+* This function is used to determine whether the the process is
+* multi-threaded.  Optimizations may only be performed on this
+* value if the programmer can guarantee that no path from the
+* enclosed code will start a thread.
+*
+* Returns:
+*  True if Thread.start() has been called in this process.
+*/
+extern (C) bool thread_needLock()
+{
+return multiThreadedFlag;
+}
+// Used for suspendAll/resumeAll below
+private __gshared uint suspendDepth = 0;
+/**
+* Suspend all threads but the calling thread for "stop the world" garbage
+* collection runs.  This function may be called multiple times, and must
+* be followed by a matching number of calls to thread_resumeAll before
+* processing is resumed.
+*
+* Throws:
+*  ThreadException if the suspend operation fails for a running thread.
+*/
+extern (C) void thread_suspendAll()
+{
+/**
+* Suspend the specified thread and load stack and register information for
+* use by thread_scanAll.  If the supplied thread is the calling thread,
+* stack and register information will be loaded but the thread will not
+* be suspended.  If the suspend operation fails and the thread is not
+* running then it will be removed from the global thread list, otherwise
+* an exception will be thrown.
+*
+* Params:
+*  t = The thread to suspend.
+*
+* Throws:
+*  ThreadException if the suspend operation fails for a running thread.
+*/
+void suspend( Thread t )
+{
+version( Windows )
+{
+if( t.m_addr != GetCurrentThreadId() && SuspendThread( t.m_hndl ) == 0xFFFFFFFF )
+{
+if( !t.isRunning )
+{
+Thread.remove( t );
+return;
+}
+throw new ThreadException( "Unable to suspend thread" );
+}
+CONTEXT context = void;
+context.ContextFlags = CONTEXT_INTEGER | CONTEXT_CONTROL;
+if( !GetThreadContext( t.m_hndl, &context ) )
+throw new ThreadException( "Unable to load thread context" );
+version( X86 )
+{
+if( !t.m_lock )
+t.m_curr.tstack = cast(void*) context.Esp;
+// eax,ebx,ecx,edx,edi,esi,ebp,esp
+t.m_reg[0] = context.Eax;
+t.m_reg[1] = context.Ebx;
+t.m_reg[2] = context.Ecx;
+t.m_reg[3] = context.Edx;
+t.m_reg[4] = context.Edi;
+t.m_reg[5] = context.Esi;
+t.m_reg[6] = context.Ebp;
+t.m_reg[7] = context.Esp;
+}
+else
+{
+static assert( "Architecture not supported." );
+}
+}
+else version( OSX )
+{
+if( t.m_addr != pthread_self() && thread_suspend( t.m_tmach ) != KERN_SUCCESS )
+{
+if( !t.isRunning )
+{
+Thread.remove( t );
+return;
+}
+throw new ThreadException( "Unable to suspend thread" );
+}
+version( X86 )
+{
+x86_thread_state32_t    state = void;
+mach_msg_type_number_t  count = x86_THREAD_STATE32_COUNT;
+if( thread_get_state( t.m_tmach, x86_THREAD_STATE32, &state, &count ) != KERN_SUCCESS )
+throw new ThreadException( "Unable to load thread state" );
+if( !t.m_lock )
+t.m_curr.tstack = cast(void*) state.esp;
+// eax,ebx,ecx,edx,edi,esi,ebp,esp
+t.m_reg[0] = state.eax;
+t.m_reg[1] = state.ebx;
+t.m_reg[2] = state.ecx;
+t.m_reg[3] = state.edx;
+t.m_reg[4] = state.edi;
+t.m_reg[5] = state.esi;
+t.m_reg[6] = state.ebp;
+t.m_reg[7] = state.esp;
+}
+else version( X86_64 )
+{
+x86_thread_state64_t    state = void;
+mach_msg_type_number_t  count = x86_THREAD_STATE64_COUNT;
+if( thread_get_state( t.m_tmach, x86_THREAD_STATE64, &state, &count ) != KERN_SUCCESS )
+throw new ThreadException( "Unable to load thread state" );
+if( !t.m_lock )
+t.m_curr.tstack = cast(void*) state.rsp;
+// rax,rbx,rcx,rdx,rdi,rsi,rbp,rsp
+t.m_reg[0] = state.rax;
+t.m_reg[1] = state.rbx;
+t.m_reg[2] = state.rcx;
+t.m_reg[3] = state.rdx;
+t.m_reg[4] = state.rdi;
+t.m_reg[5] = state.rsi;
+t.m_reg[6] = state.rbp;
+t.m_reg[7] = state.rsp;
+// r8,r9,r10,r11,r12,r13,r14,r15
+t.m_reg[8]  = state.r8;
+t.m_reg[9]  = state.r9;
+t.m_reg[10] = state.r10;
+t.m_reg[11] = state.r11;
+t.m_reg[12] = state.r12;
+t.m_reg[13] = state.r13;
+t.m_reg[14] = state.r14;
+t.m_reg[15] = state.r15;
+}
+else
+{
+static assert( "Architecture not supported." );
+}
+}
+else version( Posix )
+{
+if( t.m_addr != pthread_self() )
+{
+if( pthread_kill( t.m_addr, SIGUSR1 ) != 0 )
+{
+if( !t.isRunning )
+{
+Thread.remove( t );
+return;
+}
+throw new ThreadException( "Unable to suspend thread" );
+}
+// NOTE: It's really not ideal to wait for each thread to
+//       signal individually -- rather, it would be better to
+//       suspend them all and wait once at the end.  However,
+//       semaphores don't really work this way, and the obvious
+//       alternative (looping on an atomic suspend count)
+//       requires either the atomic module (which only works on
+//       x86) or other specialized functionality.  It would
+//       also be possible to simply loop on sem_wait at the
+//       end, but I'm not convinced that this would be much
+//       faster than the current approach.
+sem_wait( &suspendCount );
+}
+else if( !t.m_lock )
+{
+t.m_curr.tstack = getStackTop();
+}
+}
+}
+// NOTE: We've got an odd chicken & egg problem here, because while the GC
+//       is required to call thread_init before calling any other thread
+//       routines, thread_init may allocate memory which could in turn
+//       trigger a collection.  Thus, thread_suspendAll, thread_scanAll,
+//       and thread_resumeAll must be callable before thread_init
+//       completes, with the assumption that no other GC memory has yet
+//       been allocated by the system, and thus there is no risk of losing
+//       data if the global thread list is empty.  The check of
+//       Thread.sm_tbeg below is done to ensure thread_init has completed,
+//       and therefore that calling Thread.getThis will not result in an
+//       error.  For the short time when Thread.sm_tbeg is null, there is
+//       no reason not to simply call the multithreaded code below, with
+//       the expectation that the foreach loop will never be entered.
+if( !multiThreadedFlag && Thread.sm_tbeg )
+{
+if( ++suspendDepth == 1 )
+suspend( Thread.getThis() );
+return;
+}
+synchronized( Thread.slock )
+{
+if( ++suspendDepth > 1 )
+return;
+// NOTE: I'd really prefer not to check isRunning within this loop but
+//       not doing so could be problematic if threads are termianted
+//       abnormally and a new thread is created with the same thread
+//       address before the next GC run.  This situation might cause
+//       the same thread to be suspended twice, which would likely
+//       cause the second suspend to fail, the garbage collection to
+//       abort, and Bad Things to occur.
+for( Thread t = Thread.sm_tbeg; t; t = t.next )
+{
+if( t.isRunning )
+suspend( t );
+else
+Thread.remove( t );
+}
+version( Posix )
+{
+// wait on semaphore -- see note in suspend for
+// why this is currently not implemented
+}
+}
+}
+/**
+* Resume all threads but the calling thread for "stop the world" garbage
+* collection runs.  This function must be called once for each preceding
+* call to thread_suspendAll before the threads are actually resumed.
+*
+* In:
+*  This routine must be preceded by a call to thread_suspendAll.
+*
+* Throws:
+*  ThreadException if the resume operation fails for a running thread.
+*/
+extern (C) void thread_resumeAll()
+in
+{
+assert( suspendDepth > 0 );
+}
+body
+{
+/**
+* Resume the specified thread and unload stack and register information.
+* If the supplied thread is the calling thread, stack and register
+* information will be unloaded but the thread will not be resumed.  If
+* the resume operation fails and the thread is not running then it will
+* be removed from the global thread list, otherwise an exception will be
+* thrown.
+*
+* Params:
+*  t = The thread to resume.
+*
+* Throws:
+*  ThreadException if the resume fails for a running thread.
+*/
+void resume( Thread t )
+{
+version( Windows )
+{
+if( t.m_addr != GetCurrentThreadId() && ResumeThread( t.m_hndl ) == 0xFFFFFFFF )
+{
+if( !t.isRunning )
+{
+Thread.remove( t );
+return;
+}
+throw new ThreadException( "Unable to resume thread" );
+}
+if( !t.m_lock )
+t.m_curr.tstack = t.m_curr.bstack;
+t.m_reg[0 .. $] = 0;
+}
+else version( OSX )
+{
+if( t.m_addr != pthread_self() && thread_resume( t.m_tmach ) != KERN_SUCCESS )
+{
+if( !t.isRunning )
+{
+Thread.remove( t );
+return;
+}
+throw new ThreadException( "Unable to resume thread" );
+}
+if( !t.m_lock )
+t.m_curr.tstack = t.m_curr.bstack;
+t.m_reg[0 .. $] = 0;
+}
+else version( Posix )
+{
+if( t.m_addr != pthread_self() )
+{
+if( pthread_kill( t.m_addr, SIGUSR2 ) != 0 )
+{
+if( !t.isRunning )
+{
+Thread.remove( t );
+return;
+}
+throw new ThreadException( "Unable to resume thread" );
+}
+}
+else if( !t.m_lock )
+{
+t.m_curr.tstack = t.m_curr.bstack;
+}
+}
+}
+// NOTE: See thread_suspendAll for the logic behind this.
+if( !multiThreadedFlag && Thread.sm_tbeg )
+{
+if( --suspendDepth == 0 )
+resume( Thread.getThis() );
+return;
+}
+synchronized( Thread.slock )
+{
+if( --suspendDepth > 0 )
+return;
+for( Thread t = Thread.sm_tbeg; t; t = t.next )
+{
+resume( t );
+}
+}
+}
+private alias void delegate( void*, void* ) scanAllThreadsFn;
+/**
+* The main entry point for garbage collection.  The supplied delegate
+* will be passed ranges representing both stack and register values.
+*
+* Params:
+*  scan        = The scanner function.  It should scan from p1 through p2 - 1.
+*  curStackTop = An optional pointer to the top of the calling thread's stack.
+*
+* In:
+*  This routine must be preceded by a call to thread_suspendAll.
+*/
+extern (C) void thread_scanAll( scanAllThreadsFn scan, void* curStackTop = null )
+in
+{
+assert( suspendDepth > 0 );
+}
+body
+{
+Thread  thisThread  = null;
+void*   oldStackTop = null;
+if( curStackTop && Thread.sm_tbeg )
+{
+thisThread  = Thread.getThis();
+if( !thisThread.m_lock )
+{
+oldStackTop = thisThread.m_curr.tstack;
+thisThread.m_curr.tstack = curStackTop;
+}
+}
+scope( exit )
+{
+if( curStackTop && Thread.sm_tbeg )
+{
+if( !thisThread.m_lock )
+{
+thisThread.m_curr.tstack = oldStackTop;
+}
+}
+}
+// NOTE: Synchronizing on Thread.slock is not needed because this
+//       function may only be called after all other threads have
+//       been suspended from within the same lock.
+for( Thread.Context* c = Thread.sm_cbeg; c; c = c.next )
+{
+version( StackGrowsDown )
+{
+// NOTE: We can't index past the bottom of the stack
+//       so don't do the "+1" for StackGrowsDown.
+if( c.tstack && c.tstack < c.bstack )
+scan( c.tstack, c.bstack );
+}
+else
+{
+if( c.bstack && c.bstack < c.tstack )
+scan( c.bstack, c.tstack + 1 );
+}
+}
+for( Thread t = Thread.sm_tbeg; t; t = t.next )
+{
+scan( &t.m_tls[0], &t.m_tls[0] + t.m_tls.length );
+version( Windows )
+{
+scan( &t.m_reg[0], &t.m_reg[0] + t.m_reg.length );
+}
+}
+}
+///////////////////////////////////////////////////////////////////////////////
+// Thread Local
+///////////////////////////////////////////////////////////////////////////////
+/**
+* This class encapsulates the operations required to initialize, access, and
+* destroy thread local data.
+*/
+class ThreadLocal( T )
+{
+///////////////////////////////////////////////////////////////////////////
+// Initialization
+///////////////////////////////////////////////////////////////////////////
+/**
+* Initializes thread local storage for the indicated value which will be
+* initialized to def for all threads.
+*
+* Params:
+*  def = The default value to return if no value has been explicitly set.
+*/
+this( T def = T.init )
+{
+m_def = def;
+m_key = Thread.createLocal();
+}
+~this()
+{
+Thread.deleteLocal( m_key );
+}
+///////////////////////////////////////////////////////////////////////////
+// Accessors
+///////////////////////////////////////////////////////////////////////////
+/**
+* Gets the value last set by the calling thread, or def if no such value
+* has been set.
+*
+* Returns:
+*  The stored value or def if no value is stored.
+*/
+T val()
+{
+Wrap* wrap = cast(Wrap*) Thread.getLocal( m_key );
+return wrap ? wrap.val : m_def;
+}
+/**
+* Copies newval to a location specific to the calling thread, and returns
+* newval.
+*
+* Params:
+*  newval = The value to set.
+*
+* Returns:
+*  The value passed to this function.
+*/
+T val( T newval )
+{
+Wrap* wrap = cast(Wrap*) Thread.getLocal( m_key );
+if( wrap is null )
+{
+wrap = new Wrap;
+Thread.setLocal( m_key, wrap );
+}
+wrap.val = newval;
+return newval;
+}
+private:
+//
+// A wrapper for the stored data.  This is needed for determining whether
+// set has ever been called for this thread (and therefore whether the
+// default value should be returned) and also to flatten the differences
+// between data that is smaller and larger than (void*).sizeof.  The
+// obvious tradeoff here is an extra per-thread allocation for each
+// ThreadLocal value as compared to calling the Thread routines directly.
+//
+struct Wrap
+{
+T   val;
+}
+T       m_def;
+uint    m_key;
+}
+///////////////////////////////////////////////////////////////////////////////
+// Thread Group
+///////////////////////////////////////////////////////////////////////////////
+/**
+* This class is intended to simplify certain common programming techniques.
+*/
+class ThreadGroup
+{
+/**
+* Creates and starts a new Thread object that executes fn and adds it to
+* the list of tracked threads.
+*
+* Params:
+*  fn = The thread function.
+*
+* Returns:
+*  A reference to the newly created thread.
+*/
+final Thread create( void function() fn )
+{
+Thread t = new Thread( fn );
+t.start();
+synchronized( this )
+{
+m_all[t] = t;
+}
+return t;
+}
+/**
+* Creates and starts a new Thread object that executes dg and adds it to
+* the list of tracked threads.
+*
+* Params:
+*  dg = The thread function.
+*
+* Returns:
+*  A reference to the newly created thread.
+*/
+final Thread create( void delegate() dg )
+{
+Thread t = new Thread( dg );
+t.start();
+synchronized( this )
+{
+m_all[t] = t;
+}
+return t;
+}
+/**
+* Add t to the list of tracked threads if it is not already being tracked.
+*
+* Params:
+*  t = The thread to add.
+*
+* In:
+*  t must not be null.
+*/
+final void add( Thread t )
+in
+{
+assert( t );
+}
+body
+{
+synchronized( this )
+{
+m_all[t] = t;
+}
+}
+/**
+* Removes t from the list of tracked threads.  No operation will be
+* performed if t is not currently being tracked by this object.
+*
+* Params:
+*  t = The thread to remove.
+*
+* In:
+*  t must not be null.
+*/
+final void remove( Thread t )
+in
+{
+assert( t );
+}
+body
+{
+synchronized( this )
+{
+m_all.remove( t );
+}
+}
+/**
+* Operates on all threads currently tracked by this object.
+*/
+final int opApply( int delegate( inout Thread ) dg )
+{
+synchronized( this )
+{
+int ret = 0;
+// NOTE: This loop relies on the knowledge that m_all uses the
+//       Thread object for both the key and the mapped value.
+foreach( Thread t; m_all.keys )
+{
+ret = dg( t );
+if( ret )
+break;
+}
+return ret;
+}
+}
+/**
+* Iteratively joins all tracked threads.  This function will block add,
+* remove, and opApply until it completes.
+*
+* Params:
+*  rethrow = Rethrow any unhandled exception which may have caused the
+*            current thread to terminate.
+*
+* Throws:
+*  Any exception not handled by the joined threads.
+*/
+final void joinAll( bool rethrow = true )
+{
+synchronized( this )
+{
+// NOTE: This loop relies on the knowledge that m_all uses the
+//       Thread object for both the key and the mapped value.
+foreach( Thread t; m_all.keys )
+{
+t.join( rethrow );
+}
+}
+}
+private:
+Thread[Thread]  m_all;
+}
+///////////////////////////////////////////////////////////////////////////////
+// Fiber Platform Detection and Memory Allocation
+///////////////////////////////////////////////////////////////////////////////
+private
+{
+version( D_InlineAsm_X86 )
+{
+version( X86_64 )
+{
+}
+else
+{
+version( Windows )
+version = AsmX86_Win32;
+else version( Posix )
+version = AsmX86_Posix;
+}
+}
+else version( PPC )
+{
+version( Posix )
+version = AsmPPC_Posix;
+}
+version( Posix )
+{
+import core.sys.posix.unistd;   // for sysconf
+import core.sys.posix.sys.mman; // for mmap
+import core.sys.posix.stdlib;   // for malloc, valloc, free
+version( AsmX86_Win32 ) {} else
+version( AsmX86_Posix ) {} else
+version( AsmPPC_Posix ) {} else
+{
+// NOTE: The ucontext implementation requires architecture specific
+//       data definitions to operate so testing for it must be done
+//       by checking for the existence of ucontext_t rather than by
+//       a version identifier.  Please note that this is considered
+//       an obsolescent feature according to the POSIX spec, so a
+//       custom solution is still preferred.
+import core.sys.posix.ucontext;
+}
+}
+const size_t PAGESIZE;
+}
+static this()
+{
+static if( is( typeof( GetSystemInfo ) ) )
+{
+SYSTEM_INFO info;
+GetSystemInfo( &info );
+PAGESIZE = info.dwPageSize;
+assert( PAGESIZE < int.max );
+}
+else static if( is( typeof( sysconf ) ) &&
+is( typeof( _SC_PAGESIZE ) ) )
+{
+PAGESIZE = cast(size_t) sysconf( _SC_PAGESIZE );
+assert( PAGESIZE < int.max );
+}
+else
+{
+version( PPC )
+PAGESIZE = 8192;
+else
+PAGESIZE = 4096;
+}
+}
+///////////////////////////////////////////////////////////////////////////////
+// Fiber Entry Point and Context Switch
+///////////////////////////////////////////////////////////////////////////////
+private
+{
+extern (C) void fiber_entryPoint()
+{
+Fiber   obj = Fiber.getThis();
+assert( obj );
+assert( Thread.getThis().m_curr is obj.m_ctxt );
+volatile Thread.getThis().m_lock = false;
+obj.m_ctxt.tstack = obj.m_ctxt.bstack;
+obj.m_state = Fiber.State.EXEC;
+try
+{
+obj.run();
+}
+catch( Object o )
+{
+obj.m_unhandled = o;
+}
+static if( is( ucontext_t ) )
+obj.m_ucur = &obj.m_utxt;
+obj.m_state = Fiber.State.TERM;
+obj.switchOut();
+}
+// NOTE: If AsmPPC_Posix is defined then the context switch routine will
+//       be defined externally until GDC supports inline PPC ASM.
+version( AsmPPC_Posix )
+extern (C) void fiber_switchContext( void** oldp, void* newp );
+else
+extern (C) void fiber_switchContext( void** oldp, void* newp )
+{
+// NOTE: The data pushed and popped in this routine must match the
+//       default stack created by Fiber.initStack or the initial
+//       switch into a new context will fail.
+version( AsmX86_Win32 )
+{
+asm
+{
+naked;
+// save current stack state
+push EBP;
+mov  EBP, ESP;
+push EAX;
+push dword ptr FS:[0];
+push dword ptr FS:[4];
+push dword ptr FS:[8];
+push EBX;
+push ESI;
+push EDI;
+// store oldp again with more accurate address
+mov EAX, dword ptr 8[EBP];
+mov [EAX], ESP;
+// load newp to begin context switch
+mov ESP, dword ptr 12[EBP];
+// load saved state from new stack
+pop EDI;
+pop ESI;
+pop EBX;
+pop dword ptr FS:[8];
+pop dword ptr FS:[4];
+pop dword ptr FS:[0];
+pop EAX;
+pop EBP;
+// 'return' to complete switch
+ret;
+}
+}
+else version( AsmX86_Posix )
+{
+asm
+{
+naked;
+// save current stack state
+push EBP;
+mov  EBP, ESP;
+push EAX;
+push EBX;
+push ESI;
+push EDI;
+// store oldp again with more accurate address
+mov EAX, dword ptr 8[EBP];
+mov [EAX], ESP;
+// load newp to begin context switch
+mov ESP, dword ptr 12[EBP];
+// load saved state from new stack
+pop EDI;
+pop ESI;
+pop EBX;
+pop EAX;
+pop EBP;
+// 'return' to complete switch
+ret;
+}
+}
+else static if( is( ucontext_t ) )
+{
+Fiber   cfib = Fiber.getThis();
+void*   ucur = cfib.m_ucur;
+*oldp = &ucur;
+swapcontext( **(cast(ucontext_t***) oldp),
+*(cast(ucontext_t**)  newp) );
+}
+}
+}
+///////////////////////////////////////////////////////////////////////////////
+// Fiber
+///////////////////////////////////////////////////////////////////////////////
+/**
+* This class provides a cooperative concurrency mechanism integrated with the
+* threading and garbage collection functionality.  Calling a fiber may be
+* considered a blocking operation that returns when the fiber yields (via
+* Fiber.yield()).  Execution occurs within the context of the calling thread
+* so synchronization is not necessary to guarantee memory visibility so long
+* as the same thread calls the fiber each time.  Please note that there is no
+* requirement that a fiber be bound to one specific thread.  Rather, fibers
+* may be freely passed between threads so long as they are not currently
+* executing.  Like threads, a new fiber thread may be created using either
+* derivation or composition, as in the following example.
+*
+* Example:
+* ----------------------------------------------------------------------
+*
+* class DerivedFiber : Fiber
+* {
+*     this()
+*     {
+*         super( &run );
+*     }
+*
+* private :
+*     void run()
+*     {
+*         printf( "Derived fiber running.\n" );
+*     }
+* }
+*
+* void fiberFunc()
+* {
+*     printf( "Composed fiber running.\n" );
+*     Fiber.yield();
+*     printf( "Composed fiber running.\n" );
+* }
+*
+* // create instances of each type
+* Fiber derived = new DerivedFiber();
+* Fiber composed = new Fiber( &fiberFunc );
+*
+* // call both fibers once
+* derived.call();
+* composed.call();
+* printf( "Execution returned to calling context.\n" );
+* composed.call();
+*
+* // since each fiber has run to completion, each should have state TERM
+* assert( derived.state == Fiber.State.TERM );
+* assert( composed.state == Fiber.State.TERM );
+*
+* ----------------------------------------------------------------------
+*
+* Authors: Based on a design by Mikola Lysenko.
+*/
+class Fiber
+{
+///////////////////////////////////////////////////////////////////////////
+// Initialization
+///////////////////////////////////////////////////////////////////////////
+/**
+* Initializes a fiber object which is associated with a static
+* D function.
+*
+* Params:
+*  fn = The thread function.
+*  sz = The stack size for this fiber.
+*
+* In:
+*  fn must not be null.
+*/
+this( void function() fn, size_t sz = PAGESIZE )
+in
+{
+assert( fn );
+}
+body
+{
+m_fn    = fn;
+m_call  = Call.FN;
+m_state = State.HOLD;
+allocStack( sz );
+initStack();
+}
+/**
+* Initializes a fiber object which is associated with a dynamic
+* D function.
+*
+* Params:
+*  dg = The thread function.
+*  sz = The stack size for this fiber.
+*
+* In:
+*  dg must not be null.
+*/
+this( void delegate() dg, size_t sz = PAGESIZE )
+in
+{
+assert( dg );
+}
+body
+{
+m_dg    = dg;
+m_call  = Call.DG;
+m_state = State.HOLD;
+allocStack( sz );
+initStack();
+}
+/**
+* Cleans up any remaining resources used by this object.
+*/
+~this()
+{
+// NOTE: A live reference to this object will exist on its associated
+//       stack from the first time its call() method has been called
+//       until its execution completes with State.TERM.  Thus, the only
+//       times this dtor should be called are either if the fiber has
+//       terminated (and therefore has no active stack) or if the user
+//       explicitly deletes this object.  The latter case is an error
+//       but is not easily tested for, since State.HOLD may imply that
+//       the fiber was just created but has never been run.  There is
+//       not a compelling case to create a State.INIT just to offer a
+//       means of ensuring the user isn't violating this object's
+//       contract, so for now this requirement will be enforced by
+//       documentation only.
+freeStack();
+}
+///////////////////////////////////////////////////////////////////////////
+// General Actions
+///////////////////////////////////////////////////////////////////////////
+/**
+* Transfers execution to this fiber object.  The calling context will be
+* suspended until the fiber calls Fiber.yield() or until it terminates
+* via an unhandled exception.
+*
+* Params:
+*  rethrow = Rethrow any unhandled exception which may have caused this
+*            fiber to terminate.
+*
+* In:
+*  This fiber must be in state HOLD.
+*
+* Throws:
+*  Any exception not handled by the joined thread.
+*
+* Returns:
+*  Any exception not handled by this fiber if rethrow = false, null
+*  otherwise.
+*/
+final Object call( bool rethrow = true )
+in
+{
+assert( m_state == State.HOLD );
+}
+body
+{
+Fiber   cur = getThis();
+static if( is( ucontext_t ) )
+m_ucur = cur ? &cur.m_utxt : &Fiber.sm_utxt;
+setThis( this );
+this.switchIn();
+setThis( cur );
+static if( is( ucontext_t ) )
+m_ucur = null;
+// NOTE: If the fiber has terminated then the stack pointers must be
+//       reset.  This ensures that the stack for this fiber is not
+//       scanned if the fiber has terminated.  This is necessary to
+//       prevent any references lingering on the stack from delaying
+//       the collection of otherwise dead objects.  The most notable
+//       being the current object, which is referenced at the top of
+//       fiber_entryPoint.
+if( m_state == State.TERM )
+{
+m_ctxt.tstack = m_ctxt.bstack;
+}
+if( m_unhandled )
+{
+Object obj  = m_unhandled;
+m_unhandled = null;
+if( rethrow )
+throw obj;
+return obj;
+}
+return null;
+}
+/**
+* Resets this fiber so that it may be re-used.  This routine may only be
+* called for fibers that have terminated, as doing otherwise could result
+* in scope-dependent functionality that is not executed.  Stack-based
+* classes, for example, may not be cleaned up properly if a fiber is reset
+* before it has terminated.
+*
+* In:
+*  This fiber must be in state TERM.
+*/
+final void reset()
+in
+{
+assert( m_state == State.TERM );
+assert( m_ctxt.tstack == m_ctxt.bstack );
+}
+body
+{
+m_state = State.HOLD;
+initStack();
+m_unhandled = null;
+}
+///////////////////////////////////////////////////////////////////////////
+// General Properties
+///////////////////////////////////////////////////////////////////////////
+/**
+* A fiber may occupy one of three states: HOLD, EXEC, and TERM.  The HOLD
+* state applies to any fiber that is suspended and ready to be called.
+* The EXEC state will be set for any fiber that is currently executing.
+* And the TERM state is set when a fiber terminates.  Once a fiber
+* terminates, it must be reset before it may be called again.
+*/
+enum State
+{
+HOLD,   ///
+EXEC,   ///
+TERM    ///
+}
+/**
+* Gets the current state of this fiber.
+*
+* Returns:
+*  The state of this fiber as an enumerated value.
+*/
+final State state()
+{
+return m_state;
+}
+///////////////////////////////////////////////////////////////////////////
+// Actions on Calling Fiber
+///////////////////////////////////////////////////////////////////////////
+/**
+* Forces a context switch to occur away from the calling fiber.
+*/
+static void yield()
+{
+Fiber   cur = getThis();
+assert( cur, "Fiber.yield() called with no active fiber" );
+assert( cur.m_state == State.EXEC );
+static if( is( ucontext_t ) )
+cur.m_ucur = &cur.m_utxt;
+cur.m_state = State.HOLD;
+cur.switchOut();
+cur.m_state = State.EXEC;
+}
+/**
+* Forces a context switch to occur away from the calling fiber and then
+* throws obj in the calling fiber.
+*
+* Params:
+*  obj = The object to throw.
+*
+* In:
+*  obj must not be null.
+*/
+static void yieldAndThrow( Object obj )
+in
+{
+assert( obj );
+}
+body
+{
+Fiber   cur = getThis();
+assert( cur, "Fiber.yield() called with no active fiber" );
+assert( cur.m_state == State.EXEC );
+static if( is( ucontext_t ) )
+cur.m_ucur = &cur.m_utxt;
+cur.m_unhandled = obj;
+cur.m_state = State.HOLD;
+cur.switchOut();
+cur.m_state = State.EXEC;
+}
+///////////////////////////////////////////////////////////////////////////
+// Fiber Accessors
+///////////////////////////////////////////////////////////////////////////
+/**
+* Provides a reference to the calling fiber or null if no fiber is
+* currently active.
+*
+* Returns:
+*  The fiber object representing the calling fiber or null if no fiber
+*  is currently active.  The result of deleting this object is undefined.
+*/
+static Fiber getThis()
+{
+version( Windows )
+{
+return cast(Fiber) TlsGetValue( sm_this );
+}
+else version( Posix )
+{
+return cast(Fiber) pthread_getspecific( sm_this );
+}
+}
+///////////////////////////////////////////////////////////////////////////
+// Static Initialization
+///////////////////////////////////////////////////////////////////////////
+static this()
+{
+version( Windows )
+{
+sm_this = TlsAlloc();
+assert( sm_this != TLS_OUT_OF_INDEXES );
+}
+else version( Posix )
+{
+int status;
+status = pthread_key_create( &sm_this, null );
+assert( status == 0 );
+static if( is( ucontext_t ) )
+{
+status = getcontext( &sm_utxt );
+assert( status == 0 );
+}
+}
+}
+private:
+//
+// Initializes a fiber object which has no associated executable function.
+//
+this()
+{
+m_call = Call.NO;
+}
+//
+// Fiber entry point.  Invokes the function or delegate passed on
+// construction (if any).
+//
+final void run()
+{
+switch( m_call )
+{
+case Call.FN:
+m_fn();
+break;
+case Call.DG:
+m_dg();
+break;
+default:
+break;
+}
+}
+private:
+//
+// The type of routine passed on fiber construction.
+//
+enum Call
+{
+NO,
+FN,
+DG
+}
+//
+// Standard fiber data
+//
+Call                m_call;
+union
+{
+void function() m_fn;
+void delegate() m_dg;
+}
+bool                m_isRunning;
+Object              m_unhandled;
+State               m_state;
+private:
+///////////////////////////////////////////////////////////////////////////
+// Stack Management
+///////////////////////////////////////////////////////////////////////////
+//
+// Allocate a new stack for this fiber.
+//
+final void allocStack( size_t sz )
+in
+{
+assert( !m_pmem && !m_ctxt );
+}
+body
+{
+// adjust alloc size to a multiple of PAGESIZE
+sz += PAGESIZE - 1;
+sz -= sz % PAGESIZE;
+// NOTE: This instance of Thread.Context is dynamic so Fiber objects
+//       can be collected by the GC so long as no user level references
+//       to the object exist.  If m_ctxt were not dynamic then its
+//       presence in the global context list would be enough to keep
+//       this object alive indefinitely.  An alternative to allocating
+//       room for this struct explicitly would be to mash it into the
+//       base of the stack being allocated below.  However, doing so
+//       requires too much special logic to be worthwhile.
+m_ctxt = new Thread.Context;
+static if( is( typeof( VirtualAlloc ) ) )
+{
+// reserve memory for stack
+m_pmem = VirtualAlloc( null,
+sz + PAGESIZE,
+MEM_RESERVE,
+PAGE_NOACCESS );
+if( !m_pmem )
+{
+throw new FiberException( "Unable to reserve memory for stack" );
+}
+version( StackGrowsDown )
+{
+void* stack = m_pmem + PAGESIZE;
+void* guard = m_pmem;
+void* pbase = stack + sz;
+}
+else
+{
+void* stack = m_pmem;
+void* guard = m_pmem + sz;
+void* pbase = stack;
+}
+// allocate reserved stack segment
+stack = VirtualAlloc( stack,
+sz,
+MEM_COMMIT,
+PAGE_READWRITE );
+if( !stack )
+{
+throw new FiberException( "Unable to allocate memory for stack" );
+}
+// allocate reserved guard page
+guard = VirtualAlloc( guard,
+PAGESIZE,
+MEM_COMMIT,
+PAGE_READWRITE | PAGE_GUARD );
+if( !guard )
+{
+throw new FiberException( "Unable to create guard page for stack" );
+}
+m_ctxt.bstack = pbase;
+m_ctxt.tstack = pbase;
+m_size = sz;
+}
+else
+{   static if( is( typeof( mmap ) ) )
+{
+m_pmem = mmap( null,
+sz,
+PROT_READ | PROT_WRITE,
+MAP_PRIVATE | MAP_ANON,
+-1,
+0 );
+if( m_pmem == MAP_FAILED )
+m_pmem = null;
+}
+else static if( is( typeof( valloc ) ) )
+{
+m_pmem = valloc( sz );
+}
+else static if( is( typeof( malloc ) ) )
+{
+m_pmem = malloc( sz );
+}
+else
+{
+m_pmem = null;
+}
+if( !m_pmem )
+{
+throw new FiberException( "Unable to allocate memory for stack" );
+}
+version( StackGrowsDown )
+{
+m_ctxt.bstack = m_pmem + sz;
+m_ctxt.tstack = m_pmem + sz;
+}
+else
+{
+m_ctxt.bstack = m_pmem;
+m_ctxt.tstack = m_pmem;
+}
+m_size = sz;
+}
+Thread.add( m_ctxt );
+}
+//
+// Free this fiber's stack.
+//
+final void freeStack()
+in
+{
+assert( m_pmem && m_ctxt );
+}
+body
+{
+// NOTE: Since this routine is only ever expected to be called from
+//       the dtor, pointers to freed data are not set to null.
+// NOTE: m_ctxt is guaranteed to be alive because it is held in the
+//       global context list.
+Thread.remove( m_ctxt );
+static if( is( typeof( VirtualAlloc ) ) )
+{
+VirtualFree( m_pmem, 0, MEM_RELEASE );
+}
+else static if( is( typeof( mmap ) ) )
+{
+munmap( m_pmem, m_size );
+}
+else static if( is( typeof( valloc ) ) )
+{
+free( m_pmem );
+}
+else static if( is( typeof( malloc ) ) )
+{
+free( m_pmem );
+}
+delete m_ctxt;
+}
+//
+// Initialize the allocated stack.
+//
+final void initStack()
+in
+{
+assert( m_ctxt.tstack && m_ctxt.tstack == m_ctxt.bstack );
+assert( cast(size_t) m_ctxt.bstack % (void*).sizeof == 0 );
+}
+body
+{
+void* pstack = m_ctxt.tstack;
+scope( exit )  m_ctxt.tstack = pstack;
+void push( size_t val )
+{
+version( StackGrowsDown )
+{
+pstack -= size_t.sizeof;
+*(cast(size_t*) pstack) = val;
+}
+else
+{
+pstack += size_t.sizeof;
+*(cast(size_t*) pstack) = val;
+}
+}
+// NOTE: On OS X the stack must be 16-byte aligned according to the
+// IA-32 call spec.
+version( OSX )
+{
+version( StackGrowsDown )
+{
+pstack = cast(void*)(cast(uint)(pstack) - (cast(uint)(pstack) & 0x0F));
+}
+else
+{
+pstack = cast(void*)(cast(uint)(pstack) + (cast(uint)(pstack) & 0x0F));
+}
+}
+version( AsmX86_Win32 )
+{
+push( cast(size_t) &fiber_entryPoint );                 // EIP
+push( 0xFFFFFFFF );                                     // EBP
+push( 0x00000000 );                                     // EAX
+push( 0xFFFFFFFF );                                     // FS:[0]
+version( StackGrowsDown )
+{
+push( cast(size_t) m_ctxt.bstack );                 // FS:[4]
+push( cast(size_t) m_ctxt.bstack - m_size );        // FS:[8]
+}
+else
+{
+push( cast(size_t) m_ctxt.bstack );                 // FS:[4]
+push( cast(size_t) m_ctxt.bstack + m_size );        // FS:[8]
+}
+push( 0x00000000 );                                     // EBX
+push( 0x00000000 );                                     // ESI
+push( 0x00000000 );                                     // EDI
+}
+else version( AsmX86_Posix )
+{
+push( 0x00000000 );                                     // Pad stack for OSX
+push( cast(size_t) &fiber_entryPoint );                 // EIP
+push( 0x00000000 );                                     // EBP
+push( 0x00000000 );                                     // EAX
+push( 0x00000000 );                                     // EBX
+push( 0x00000000 );                                     // ESI
+push( 0x00000000 );                                     // EDI
+}
+else version( AsmPPC_Posix )
+{
+version( StackGrowsDown )
+{
+pstack -= int.sizeof * 5;
+}
+else
+{
+pstack += int.sizeof * 5;
+}
+push( cast(size_t) &fiber_entryPoint );     // link register
+push( 0x00000000 );                         // control register
+push( 0x00000000 );                         // old stack pointer
+// GPR values
+version( StackGrowsDown )
+{
+pstack -= int.sizeof * 20;
+}
+else
+{
+pstack += int.sizeof * 20;
+}
+assert( cast(uint) pstack & 0x0f == 0 );
+}
+else static if( is( ucontext_t ) )
+{
+getcontext( &m_utxt );
+m_utxt.uc_stack.ss_sp   = m_ctxt.bstack;
+m_utxt.uc_stack.ss_size = m_size;
+makecontext( &m_utxt, &fiber_entryPoint, 0 );
+// NOTE: If ucontext is being used then the top of the stack will
+//       be a pointer to the ucontext_t struct for that fiber.
+push( cast(size_t) &m_utxt );
+}
+}
+Thread.Context* m_ctxt;
+size_t          m_size;
+void*           m_pmem;
+static if( is( ucontext_t ) )
+{
+// NOTE: The static ucontext instance is used to represent the context
+//       of the main application thread.
+static ucontext_t   sm_utxt = void;
+ucontext_t          m_utxt  = void;
+ucontext_t*         m_ucur  = null;
+}
+private:
+///////////////////////////////////////////////////////////////////////////
+// Storage of Active Fiber
+///////////////////////////////////////////////////////////////////////////
+//
+// Sets a thread-local reference to the current fiber object.
+//
+static void setThis( Fiber f )
+{
+version( Windows )
+{
+TlsSetValue( sm_this, cast(void*) f );
+}
+else version( Posix )
+{
+pthread_setspecific( sm_this, cast(void*) f );
+}
+}
+__gshared Thread.TLSKey    sm_this;
+private:
+///////////////////////////////////////////////////////////////////////////
+// Context Switching
+///////////////////////////////////////////////////////////////////////////
+//
+// Switches into the stack held by this fiber.
+//
+final void switchIn()
+{
+Thread  tobj = Thread.getThis();
+void**  oldp = &tobj.m_curr.tstack;
+void*   newp = m_ctxt.tstack;
+// NOTE: The order of operations here is very important.  The current
+//       stack top must be stored before m_lock is set, and pushContext
+//       must not be called until after m_lock is set.  This process
+//       is intended to prevent a race condition with the suspend
+//       mechanism used for garbage collection.  If it is not followed,
+//       a badly timed collection could cause the GC to scan from the
+//       bottom of one stack to the top of another, or to miss scanning
+//       a stack that still contains valid data.  The old stack pointer
+//       oldp will be set again before the context switch to guarantee
+//       that it points to exactly the correct stack location so the
+//       successive pop operations will succeed.
+*oldp = getStackTop();
+volatile tobj.m_lock = true;
+tobj.pushContext( m_ctxt );
+fiber_switchContext( oldp, newp );
+// NOTE: As above, these operations must be performed in a strict order
+//       to prevent Bad Things from happening.
+tobj.popContext();
+volatile tobj.m_lock = false;
+tobj.m_curr.tstack = tobj.m_curr.bstack;
+}
+//
+// Switches out of the current stack and into the enclosing stack.
+//
+final void switchOut()
+{
+Thread  tobj = Thread.getThis();
+void**  oldp = &m_ctxt.tstack;
+void*   newp = tobj.m_curr.within.tstack;
+// NOTE: The order of operations here is very important.  The current
+//       stack top must be stored before m_lock is set, and pushContext
+//       must not be called until after m_lock is set.  This process
+//       is intended to prevent a race condition with the suspend
+//       mechanism used for garbage collection.  If it is not followed,
+//       a badly timed collection could cause the GC to scan from the
+//       bottom of one stack to the top of another, or to miss scanning
+//       a stack that still contains valid data.  The old stack pointer
+//       oldp will be set again before the context switch to guarantee
+//       that it points to exactly the correct stack location so the
+//       successive pop operations will succeed.
+*oldp = getStackTop();
+volatile tobj.m_lock = true;
+fiber_switchContext( oldp, newp );
+// NOTE: As above, these operations must be performed in a strict order
+//       to prevent Bad Things from happening.
+volatile tobj.m_lock = false;
+tobj.m_curr.tstack = tobj.m_curr.bstack;
+}
+}
+version (OSX)
+{
+/* The Mach-O object file format does not allow for thread local storage
+* declarations. So, instead we roll our own by putting tls into
+* the sections __tlsdata and __tlscoal_nt.
+*/
+extern (D)
+void* ___tls_get_addr(void* p)
+{
+	return p;
+}
+}

Mercurial > projects > ldc

comparison druntime/src/common/core/thread.d @ 1458:e0b2d67cfe7c