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comparison tango/tango/net/cluster/tina/ProtocolReader.d @ 132:1700239cab2e trunk

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[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
date Fri, 11 Jan 2008 17:57:40 +0100
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131:5825d48b27d1 132:1700239cab2e
1 /*******************************************************************************
2
3 copyright: Copyright (c) 2004 Kris Bell. All rights reserved
4
5 license: BSD style: $(LICENSE)
6
7 version: July 2004: Initial release
8
9 author: Kris
10
11 *******************************************************************************/
12
13 module tango.net.cluster.tina.ProtocolReader;
14
15 private import tango.io.protocol.Reader,
16 tango.io.protocol.Allocator,
17 tango.io.protocol.PickleProtocol;
18
19 private import tango.net.cluster.model.IMessage;
20
21 private import tango.net.cluster.NetworkRegistry;
22
23 private import tango.net.cluster.tina.ClusterTypes;
24
25 /*******************************************************************************
26
27 Objects passed around a cluster are prefixed with a header, so the
28 receiver can pick them apart correctly. This header consists of:
29 ---
30 * the packet size, including the header (16 bits)
31 * a command code (8 bits)
32 * a version id (8 bits)
33 * a timestamp (64 bits)
34 * length of the channel name (32 bits)
35 * the channel name
36 * length of the key (32 bits)
37 * the key
38 * an optional payload (an IMessage instance)
39 ---
40
41 Everything is written in Network order (big endian).
42
43 *******************************************************************************/
44
45 class ProtocolReader : Reader
46 {
47 /***********************************************************************
48
49 Construct a ProtocolReader upon the given buffer. As
50 Objects are serialized their content is written to this
51 buffer. The buffer content is then typically flushed to
52 some external conduit, such as a file or socket.
53
54 Note that arrays (such as text) are *always* sliced from
55 the buffer -- there's no heap activity involved. Thus it
56 may be necessary to .dup content where appropriate
57
58 ***********************************************************************/
59
60 this (IBuffer buffer)
61 {
62 super (new BufferSlice (new PickleProtocol (buffer)));
63 }
64
65 /***********************************************************************
66
67 deserialize a payload into a provided host, or via
68 the registered instance of the incoming payload
69
70 ***********************************************************************/
71
72 IMessage thaw (IMessage host = null)
73 {
74 return thaw (NetworkRegistry.shared, host);
75 }
76
77 /***********************************************************************
78
79 deserialize a payload into a provided host, or via
80 the registered instance of the incoming payload
81
82 ***********************************************************************/
83
84 IMessage thaw (NetworkRegistry registry, IMessage host = null)
85 {
86 return registry.thaw (this, host);
87 }
88
89 /***********************************************************************
90
91 Read the protocol header and return true if there's a
92 payload available
93
94 ***********************************************************************/
95
96 bool getHeader (inout ubyte cmd, inout char[] channel, inout char[] element)
97 {
98 auto position = buffer.position;
99
100 long time;
101 ushort size;
102 ubyte versn;
103
104 get (size) (cmd) (versn) (time);
105
106 // avoid allocation for these two strings
107 get (channel) (element);
108
109 // is there a payload attached?
110 if (size > (buffer.position - position))
111 return true;
112
113 return false;
114 }
115
116 /***********************************************************************
117
118 Return an aliased slice of the buffer representing the
119 recieved payload. This is a bit of a hack, but eliminates
120 a reasonable amount of overhead. Note that the channel/key
121 text is retained right at the start of the returned content,
122 enabling the host to toss the whole thing back without any
123 further munging.
124
125 ***********************************************************************/
126
127 ClusterContent getPacket (inout ubyte cmd, inout char[] channel, inout char[] element, inout long time)
128 {
129 ushort size;
130 ubyte versn;
131
132 // load up the header
133 get (size) (cmd) (versn) (time);
134
135 //printf ("size: %d\n", cast(int) size);
136
137 // subtract header size
138 size -= buffer.position;
139
140 // may throw an exception if the payload is too large to fit
141 // completely inside the buffer!
142 buffer.slice (size, false);
143
144 // slice the remaining packet (with channel/key text)
145 auto content = cast(ClusterContent) buffer.slice;
146
147 // get a slice upon the channel name
148 get (channel);
149
150 // get a slice upon the element name
151 get (element);
152
153 // return the aliased payload (including channel/key text)
154 return content;
155 }
156 }
157