Mercurial > projects > ldc
view tango/tango/io/selector/Selector.d @ 132:1700239cab2e trunk
[svn r136] MAJOR UNSTABLE UPDATE!!!
Initial commit after moving to Tango instead of Phobos.
Lots of bugfixes...
This build is not suitable for most things.
author | lindquist |
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date | Fri, 11 Jan 2008 17:57:40 +0100 |
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/******************************************************************************* copyright: Copyright (c) 2006 Juan Jose Comellas. All rights reserved license: BSD style: $(LICENSE) author: Juan Jose Comellas <juanjo@comellas.com.ar> *******************************************************************************/ module tango.io.selector.Selector; /** * A multiplexor of conduit I/O events. * * A Selector can wait for I/O events (Read, Write, etc.) for multiple * conduits efficiently (i.e. without consuming CPU cycles). * * The Selector is an alias for your system's most efficient I/O multiplexor, * which will be determined during compilation. * * To create a Selector you need to use the open() method and when you decide * you no longer need it you should call its close() method to free any system * resources it may be consuming. All selectors that need to free resources * when close() is called also implement a destructor that automatically calls * this method. This means that if you declare your selector instance with the * 'auto' keyword you won't have to worry about doing it manually. * * Once you have open()'ed your selector you need to associate the conduits to * it by using the register() method. This method receives the conduit and the * events you want to track for it. For example, if you wanted to read from * the conduit you would do: * * --- * selector.register(conduit, Event.Read, myObject); * --- * * This method also accepts an optional third parameter to associate a * user-defined object to the conduit. These three parameters together define * a SelectionKey, which is what you'll receive when the conduit is "selected" * (i.e. receives an event). * * If you need to modify your conduit's registration you need to use the * reregister() method, which works like register(), but expects to be passed * a conduit that has already been associated to the selector: * * --- * selector.reregister(conduit, Event.Write, myObject); * --- * * If you need to remove a conduit from the selector you do it by calling * unregister(): * * --- * selector.unregister(conduit); * --- * * Once you are done setting up the conduits you will want to wait for I/O * events for them. To do that you need to use the select() method. This * method blocks until either one of the conduits is selected or the * specified timeout is reached. Even though it has two different versions: * a) select(); b) select(Interval); the first one is just the same as doing * select(Interval.max). In that case we don't have a timeout and * select() blocks until a conduit receives an event. * * When select() returns you will receive an integer; if this integer is * bigger than 0, it indicates the number of conduits that have been selected. * If this number is 0, the it means that the selector reached a timeout, and * if it's -1, then it means that there was an error. A normal block that deals * with the selection process would look like this: * * --- * try * { * int eventCount = selector.select(10.0); * if (eventCount > 0) * { * // Process the I/O events in the selected set * } * else if (eventCount == 0) * { * // Timeout * } * else if (eventCount == -1) * { * // Error * } * else * { * // Error: should never happen. * } * } * catch (SelectorException e) * { * Stdout.format("Exception caught: {0}", e.toString()).newline(); * } * --- * * Finally, to gather the events you need to iterate over the selector's * selection set, which can be accessed via the selectedSet() method. * * --- * foreach (SelectionKey key; selector.selectedSet()) * { * if (key.isReadable()) * { * // Read from conduit * // [...] * // Then register it for writing * selector.reregister(key.conduit, Event.Write, key.attachment); * } * * if (key.isWriteable()) * { * // Write to conduit * // [...] * // Then register it for reading * selector.reregister(key.conduit, Event.Read, key.attachment); * } * * if (key.isError()) * { * // Problem with conduit; remove it from selector * selector.remove(conduit); * } * } * --- */ version (linux) { public import tango.io.selector.EpollSelector; /** * Default Selector for Linux. */ alias EpollSelector Selector; } else version(Posix) { public import tango.io.selector.PollSelector; /** * Default Selector for POSIX-compatible platforms. */ alias PollSelector Selector; } else { public import tango.io.selector.SelectSelector; /** * Default Selector for Windows. */ alias SelectSelector Selector; }