Fixed a serious bug - a race condition where a data buffer in the writer's queue could be dealloced (not the NSData, but its bytes themselves) before the writer sent it, resulting in an EFAULT error.
5 // Created by Jens Alfke on 5/18/08.
6 // Copyright 2008 Jens Alfke. All rights reserved.
10 #import "BLIPWriter.h"
11 #import "BLIP_Internal.h"
17 #define kDefaultFrameSize 4096
20 @implementation BLIPWriter
31 [_outBox makeObjectsPerformSelector: @selector(_connectionClosed) withObject: nil];
36 @synthesize numQueriesSent=_numQueriesSent;
41 return _outBox.count>0 || [super isBusy];
45 - (void) _queueMessage: (BLIPMessage*)msg isNew: (BOOL)isNew
47 int n = _outBox.count, index;
48 if( msg.urgent && n > 1 ) {
49 // High-priority gets queued after the last existing high-priority message,
50 // leaving one regular-priority message in between if possible.
51 for( index=n-1; index>0; index-- ) {
52 BLIPMessage *otherMsg = [_outBox objectAtIndex: index];
53 if( [otherMsg urgent] ) {
54 index = MIN(index+2, n);
56 } else if( isNew && otherMsg._bytesWritten==0 ) {
57 // But have to keep message starts in order
65 // Regular priority goes at the end of the queue:
69 _outBox = [[NSMutableArray alloc] init];
70 [_outBox insertObject: msg atIndex: index];
73 LogTo(BLIP,@"%@ queuing outgoing %@ at index %i",self,msg,index);
80 - (BOOL) sendMessage: (BLIPMessage*)message
83 Warn(@"%@: Attempt to send a message after the connection has started closing",self);
86 Assert(!message.sent,@"message has already been sent");
87 [self _queueMessage: message isNew: YES];
92 - (BOOL) sendRequest: (BLIPRequest*)q response: (BLIPResponse*)response
95 [q _assignedNumber: ++_numQueriesSent];
97 [response _assignedNumber: _numQueriesSent];
98 [(BLIPReader*)self.reader _addPendingResponse: response];
101 return [self sendMessage: q];
105 - (void) queueIsEmpty
107 if( _outBox.count > 0 ) {
108 // Pop first message in queue:
109 BLIPMessage *msg = [[_outBox objectAtIndex: 0] retain];
110 [_outBox removeObjectAtIndex: 0];
112 // As an optimization, allow message to send a big frame unless there's a higher-priority
113 // message right behind it:
114 size_t frameSize = kDefaultFrameSize;
115 if( msg.urgent || _outBox.count==0 || ! [[_outBox objectAtIndex: 0] urgent] )
118 if( [msg _writeFrameTo: self maxSize: frameSize] ) {
119 // add it back so it can send its next frame later:
120 [self _queueMessage: msg isNew: NO];
124 LogTo(BLIPVerbose,@"%@: no more work for writer",self);
134 Copyright (c) 2008, Jens Alfke <jens@mooseyard.com>. All rights reserved.
136 Redistribution and use in source and binary forms, with or without modification, are permitted
137 provided that the following conditions are met:
139 * Redistributions of source code must retain the above copyright notice, this list of conditions
140 and the following disclaimer.
141 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions
142 and the following disclaimer in the documentation and/or other materials provided with the
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