Source/DebuggerConnection.m

   1 /*
   2  * MacGDBp
   3  * Copyright (c) 2007 - 2010, Blue Static <http://www.bluestatic.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it under the terms of the GNU
   6  * General Public License as published by the Free Software Foundation; either version 2 of the
   7  * License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
  10  * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with this program; if not,
  14  * write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
  15  */
  16
  17 #import "DebuggerConnection.h"
  18
  19 #import <sys/socket.h>
  20 #import <netinet/in.h>
  21
  22 #import "AppDelegate.h"
  23 #import "LoggingController.h"
  24
  25 // DebuggerConnection (Private) ////////////////////////////////////////////////
  26
  27 @interface DebuggerConnection ()
  28
  29 @property (assign) CFSocketRef socket;
  30 @property (assign) CFReadStreamRef readStream;
  31 @property NSUInteger lastReadTransaction;
  32 @property (retain) NSMutableString* currentPacket;
  33 @property (assign) CFWriteStreamRef writeStream;
  34 @property NSUInteger lastWrittenTransaction;
  35 @property (retain) NSMutableArray* queuedWrites;
  36
  37 - (void)connectionThreadStart;
  38
  39 - (void)socketDidAccept;
  40 - (void)socketDisconnected;
  41 - (void)readStreamHasData;
  42
  43 - (void)performSend:(NSString*)command;
  44 - (void)sendQueuedWrites;
  45
  46 - (void)performQuitSignal;
  47
  48 - (void)handleResponse:(NSXMLDocument*)response;
  49 - (void)handlePacket:(NSString*)packet;
  50
  51 // Threadsafe wrappers for the delegate's methods.
  52 - (void)errorEncountered:(NSString*)error;
  53 - (LogEntry*)recordSend:(NSString*)command;
  54 - (LogEntry*)recordReceive:(NSString*)command;
  55
  56 @end
  57
  58 // CFNetwork Callbacks /////////////////////////////////////////////////////////
  59
  60 void ReadStreamCallback(CFReadStreamRef stream, CFStreamEventType eventType, void* connectionRaw)
  61 {
  62   DebuggerConnection* connection = (DebuggerConnection*)connectionRaw;
  63   switch (eventType)
  64   {
  65     case kCFStreamEventHasBytesAvailable:
  66       [connection readStreamHasData];
  67       break;
  68
  69     case kCFStreamEventErrorOccurred:
  70     {
  71       CFErrorRef error = CFReadStreamCopyError(stream);
  72       CFReadStreamUnscheduleFromRunLoop(stream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
  73       CFReadStreamClose(stream);
  74       CFRelease(stream);
  75       [connection errorEncountered:[[(NSError*)error autorelease] description]];
  76       break;
  77     }
  78
  79     case kCFStreamEventEndEncountered:
  80       CFReadStreamUnscheduleFromRunLoop(stream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
  81       CFReadStreamClose(stream);
  82       CFRelease(stream);
  83       [connection socketDisconnected];
  84       break;
  85   };
  86 }
  87
  88 void WriteStreamCallback(CFWriteStreamRef stream, CFStreamEventType eventType, void* connectionRaw)
  89 {
  90   DebuggerConnection* connection = (DebuggerConnection*)connectionRaw;
  91   switch (eventType)
  92   {
  93     case kCFStreamEventCanAcceptBytes:
  94       [connection sendQueuedWrites];
  95       break;
  96
  97     case kCFStreamEventErrorOccurred:
  98     {
  99       CFErrorRef error = CFWriteStreamCopyError(stream);
 100       CFWriteStreamUnscheduleFromRunLoop(stream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
 101       CFWriteStreamClose(stream);
 102       CFRelease(stream);
 103       [connection errorEncountered:[[(NSError*)error autorelease] description]];
 104       break;
 105     }
 106
 107     case kCFStreamEventEndEncountered:
 108       CFWriteStreamUnscheduleFromRunLoop(stream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
 109       CFWriteStreamClose(stream);
 110       CFRelease(stream);
 111       [connection socketDisconnected];
 112       break;
 113   }
 114 }
 115
 116 void SocketAcceptCallback(CFSocketRef socket,
 117                           CFSocketCallBackType callbackType,
 118                           CFDataRef address,
 119                           const void* data,
 120                           void* connectionRaw)
 121 {
 122   assert(callbackType == kCFSocketAcceptCallBack);
 123   NSLog(@"SocketAcceptCallback()");
 124
 125   DebuggerConnection* connection = (DebuggerConnection*)connectionRaw;
 126
 127   CFReadStreamRef readStream;
 128   CFWriteStreamRef writeStream;
 129
 130   // Create the streams on the socket.
 131   CFStreamCreatePairWithSocket(kCFAllocatorDefault,
 132                                *(CFSocketNativeHandle*)data,  // Socket handle.
 133                                &readStream,  // Read stream in-pointer.
 134                                &writeStream);  // Write stream in-pointer.
 135
 136   // Create struct to register callbacks for the stream.
 137   CFStreamClientContext context;
 138   context.version = 0;
 139   context.info = connection;
 140   context.retain = NULL;
 141   context.release = NULL;
 142   context.copyDescription = NULL;
 143
 144   // Set the client of the read stream.
 145   CFOptionFlags readFlags =
 146       kCFStreamEventOpenCompleted |
 147       kCFStreamEventHasBytesAvailable |
 148       kCFStreamEventErrorOccurred |
 149       kCFStreamEventEndEncountered;
 150   if (CFReadStreamSetClient(readStream, readFlags, ReadStreamCallback, &context))
 151     // Schedule in run loop to do asynchronous communication with the engine.
 152     CFReadStreamScheduleWithRunLoop(readStream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
 153   else
 154     return;
 155
 156   // Open the stream now that it's scheduled on the run loop.
 157   if (!CFReadStreamOpen(readStream))
 158   {
 159     CFStreamError error = CFReadStreamGetError(readStream);
 160     NSLog(@"error! %@", error);
 161     return;
 162   }
 163
 164   // Set the client of the write stream.
 165   CFOptionFlags writeFlags =
 166       kCFStreamEventOpenCompleted |
 167       kCFStreamEventCanAcceptBytes |
 168       kCFStreamEventErrorOccurred |
 169       kCFStreamEventEndEncountered;
 170   if (CFWriteStreamSetClient(writeStream, writeFlags, WriteStreamCallback, &context))
 171     // Schedule it in the run loop to receive error information.
 172     CFWriteStreamScheduleWithRunLoop(writeStream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
 173   else
 174     return;
 175
 176   // Open the write stream.
 177   if (!CFWriteStreamOpen(writeStream))
 178   {
 179     CFStreamError error = CFWriteStreamGetError(writeStream);
 180     NSLog(@"error! %@", error);
 181     return;
 182   }
 183
 184   connection.readStream = readStream;
 185   connection.writeStream = writeStream;
 186   [connection socketDidAccept];
 187 }
 188
 189 // Other Run Loop Callbacks ////////////////////////////////////////////////////
 190
 191 void PerformQuitSignal(void* info)
 192 {
 193   DebuggerConnection* obj = (DebuggerConnection*)info;
 194   [obj performQuitSignal];
 195 }
 196
 197 ////////////////////////////////////////////////////////////////////////////////
 198
 199 @implementation DebuggerConnection
 200
 201 @synthesize port = port_;
 202 @synthesize connected = connected_;
 203 @synthesize delegate = delegate_;
 204
 205 @synthesize socket = socket_;
 206 @synthesize readStream = readStream_;
 207 @synthesize lastReadTransaction = lastReadTransaction_;
 208 @synthesize currentPacket = currentPacket_;
 209 @synthesize writeStream = writeStream_;
 210 @synthesize lastWrittenTransaction = lastWrittenTransaction_;
 211 @synthesize queuedWrites = queuedWrites_;
 212
 213 - (id)initWithPort:(NSUInteger)aPort
 214 {
 215   if (self = [super init])
 216   {
 217     port_ = aPort;
 218   }
 219   return self;
 220 }
 221
 222 - (void)dealloc
 223 {
 224   self.currentPacket = nil;
 225   [super dealloc];
 226 }
 227
 228 /**
 229  * Kicks off the socket on another thread.
 230  */
 231 - (void)connect
 232 {
 233   [NSThread detachNewThreadSelector:@selector(connectionThreadStart) toTarget:self withObject:nil];
 234 }
 235
 236 /**
 237  * Creates, connects to, and schedules a CFSocket.
 238  */
 239 - (void)connectionThreadStart
 240 {
 241   NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];
 242
 243   thread_ = [NSThread currentThread];
 244   runLoop_ = [NSRunLoop currentRunLoop];
 245
 246   // Pass ourselves to the callback so we don't have to use ugly globals.
 247   CFSocketContext context;
 248   context.version = 0;
 249   context.info = self;
 250   context.retain = NULL;
 251   context.release = NULL;
 252   context.copyDescription = NULL;
 253
 254   // Create the address structure.
 255   struct sockaddr_in address;
 256   memset(&address, 0, sizeof(address));
 257   address.sin_len = sizeof(address);
 258   address.sin_family = AF_INET;
 259   address.sin_port = htons(port_);
 260   address.sin_addr.s_addr = htonl(INADDR_ANY);
 261
 262   // Create the socket signature.
 263   CFSocketSignature signature;
 264   signature.protocolFamily = PF_INET;
 265   signature.socketType = SOCK_STREAM;
 266   signature.protocol = IPPROTO_TCP;
 267   signature.address = (CFDataRef)[NSData dataWithBytes:&address length:sizeof(address)];
 268
 269   socket_ = CFSocketCreateWithSocketSignature(kCFAllocatorDefault,
 270                                               &signature,  // Socket signature.
 271                                               kCFSocketAcceptCallBack,  // Callback types.
 272                                               SocketAcceptCallback,  // Callout function pointer.
 273                                               &context);  // Context to pass to callout.
 274   if (!socket_)
 275   {
 276     [self errorEncountered:@"Could not open socket."];
 277     return;
 278   }
 279
 280   // Allow old, yet-to-be recycled sockets to be reused.
 281   BOOL yes = YES;
 282   setsockopt(CFSocketGetNative(socket_), SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(BOOL));
 283
 284   // Schedule the socket on the run loop.
 285   CFRunLoopSourceRef source = CFSocketCreateRunLoopSource(kCFAllocatorDefault, socket_, 0);
 286   CFRunLoopAddSource([runLoop_ getCFRunLoop], source, kCFRunLoopCommonModes);
 287   CFRelease(source);
 288
 289   // Create a source that is used to quit.
 290   CFRunLoopSourceContext quitContext = { 0 };
 291   quitContext.version = 0;
 292   quitContext.info = self;
 293   quitContext.perform = PerformQuitSignal;
 294   quitSource_ = CFRunLoopSourceCreate(kCFAllocatorDefault, 0, &quitContext);
 295   CFRunLoopAddSource([runLoop_ getCFRunLoop], quitSource_, kCFRunLoopCommonModes);
 296
 297   [runLoop_ run];
 298
 299   thread_ = nil;
 300   runLoop_ = nil;
 301
 302   CFRunLoopSourceInvalidate(quitSource_);
 303   CFRelease(quitSource_);
 304   quitSource_ = NULL;
 305
 306   [pool release];
 307 }
 308
 309 /**
 310  * Called by SocketWrapper after the connection is successful. This immediately calls
 311  * -[SocketWrapper receive] to clear the way for communication, though the information
 312  * could be useful server information that we don't use right now.
 313  */
 314 - (void)socketDidAccept
 315 {
 316   connected_ = YES;
 317   transactionID = 1;
 318   self.queuedWrites = [NSMutableArray array];
 319   writeQueueLock_ = [NSRecursiveLock new];
 320 }
 321
 322 /**
 323  * Closes a socket and releases the ref.
 324  */
 325 - (void)close
 326 {
 327   if (runLoop_ && quitSource_) {
 328     CFRunLoopSourceSignal(quitSource_);
 329     CFRunLoopWakeUp([runLoop_ getCFRunLoop]);
 330   }
 331 }
 332
 333 /**
 334  * Quits the run loop and stops the thread.
 335  */
 336 - (void)performQuitSignal
 337 {
 338   if (runLoop_) {
 339     CFRunLoopStop([runLoop_ getCFRunLoop]);
 340   }
 341
 342   // The socket goes down, so do the streams, which clean themselves up.
 343   if (socket_) {
 344     CFSocketInvalidate(socket_);
 345     CFRelease(socket_);
 346     socket_ = NULL;
 347   }
 348
 349   self.queuedWrites = nil;
 350   connected_ = NO;
 351   [writeQueueLock_ release];
 352 }
 353
 354 /**
 355  * Notification that the socket disconnected.
 356  */
 357 - (void)socketDisconnected
 358 {
 359   if (connected_) {
 360     // The state still is connected, which means that we did not get here
 361     // through normal disconnected procedure (a call to |-close|, followed by
 362     // the downing of the socket and the stream, which also produces this
 363     // messsage). Instead, the stream callbacks encountered EOF unexpectedly.
 364     [self close];
 365   }
 366   if ([delegate_ respondsToSelector:@selector(connectionDidClose:)])
 367     [delegate_ connectionDidClose:self];
 368 }
 369
 370 /**
 371  * Writes a command into the write stream. If the stream is ready for writing,
 372  * we do so immediately. If not, the command is queued and will be written
 373  * when the stream is ready.
 374  */
 375 - (void)send:(NSString*)command
 376 {
 377   if (lastReadTransaction_ >= lastWrittenTransaction_ && CFWriteStreamCanAcceptBytes(writeStream_)) {
 378     [self performSend:command];
 379   } else {
 380     [writeQueueLock_ lock];
 381     [queuedWrites_ addObject:command];
 382     [writeQueueLock_ unlock];
 383   }
 384   [self sendQueuedWrites];
 385 }
 386
 387 /**
 388  * This will send a command to the debugger engine. It will append the
 389  * transaction ID automatically. It accepts a NSString command along with a
 390  * a variable number of arguments to substitute into the command, a la
 391  * +[NSString stringWithFormat:]. Returns the transaction ID as a NSNumber.
 392  */
 393 - (NSNumber*)sendCommandWithFormat:(NSString*)format, ...
 394 {
 395   // Collect varargs and format command.
 396   va_list args;
 397   va_start(args, format);
 398   NSString* command = [[NSString alloc] initWithFormat:format arguments:args];
 399   va_end(args);
 400
 401   NSNumber* callbackKey = [NSNumber numberWithInt:transactionID++];
 402   NSString* taggedCommand = [NSString stringWithFormat:@"%@ -i %@", [command autorelease], callbackKey];
 403   [self performSelector:@selector(send:)
 404                onThread:thread_
 405              withObject:taggedCommand
 406           waitUntilDone:YES];
 407
 408   return callbackKey;
 409 }
 410
 411 /**
 412  * Given a file path, this returns a file:// URI and escapes any spaces for the
 413  * debugger engine.
 414  */
 415 - (NSString*)escapedURIPath:(NSString*)path
 416 {
 417   // Custon GDBp paths are fine.
 418   if ([[path substringToIndex:4] isEqualToString:@"gdbp"])
 419     return path;
 420
 421   // Create a temporary URL that will escape all the nasty characters.
 422   NSURL* url = [NSURL fileURLWithPath:path];
 423   NSString* urlString = [url absoluteString];
 424
 425   // Remove the host because this is a file:// URL;
 426   urlString = [urlString stringByReplacingOccurrencesOfString:[url host] withString:@""];
 427
 428   // Escape % for use in printf-style NSString formatters.
 429   urlString = [urlString stringByReplacingOccurrencesOfString:@"%" withString:@"%%"];
 430   return urlString;
 431 }
 432
 433 /**
 434  * Returns the transaction_id from an NSXMLDocument.
 435  */
 436 - (NSInteger)transactionIDFromResponse:(NSXMLDocument*)response
 437 {
 438   return [[[[response rootElement] attributeForName:@"transaction_id"] stringValue] intValue];
 439 }
 440
 441 /**
 442  * Scans a command string for the transaction ID component. If it is not found,
 443  * returns NSNotFound.
 444  */
 445 - (NSInteger)transactionIDFromCommand:(NSString*)command
 446 {
 447   NSRange occurrence = [command rangeOfString:@"-i "];
 448   if (occurrence.location == NSNotFound)
 449     return NSNotFound;
 450   NSString* transaction = [command substringFromIndex:occurrence.location + occurrence.length];
 451   return [transaction intValue];
 452 }
 453
 454 // Private /////////////////////////////////////////////////////////////////////
 455 #pragma mark Private
 456
 457 // Delegate Thread-Safe Wrappers ///////////////////////////////////////////////
 458
 459 /**
 460  * Receives errors from the SocketWrapper and updates the display
 461  */
 462 - (void)errorEncountered:(NSString*)error
 463 {
 464   if (![delegate_ respondsToSelector:@selector(errorEncountered:)])
 465     return;
 466   [delegate_ performSelectorOnMainThread:@selector(errorEncountered:)
 467                               withObject:error
 468                            waitUntilDone:NO];
 469 }
 470
 471 - (LogEntry*)recordSend:(NSString*)command
 472 {
 473   LoggingController* logger = [[AppDelegate instance] loggingController];
 474   LogEntry* entry = [LogEntry newSendEntry:command];
 475   entry.lastReadTransactionID = lastReadTransaction_;
 476   entry.lastWrittenTransactionID = lastWrittenTransaction_;
 477   [logger performSelectorOnMainThread:@selector(recordEntry:)
 478                            withObject:entry
 479                         waitUntilDone:NO];
 480   return [entry autorelease];
 481 }
 482
 483 - (LogEntry*)recordReceive:(NSString*)command
 484 {
 485   LoggingController* logger = [[AppDelegate instance] loggingController];
 486   LogEntry* entry = [LogEntry newReceiveEntry:command];
 487   entry.lastReadTransactionID = lastReadTransaction_;
 488   entry.lastWrittenTransactionID = lastWrittenTransaction_;
 489   [logger performSelectorOnMainThread:@selector(recordEntry:)
 490                            withObject:entry
 491                         waitUntilDone:NO];
 492   return [entry autorelease];
 493 }
 494
 495 // Stream Managers /////////////////////////////////////////////////////////////
 496
 497 /**
 498  * Callback from the CFReadStream that there is data waiting to be read.
 499  */
 500 - (void)readStreamHasData
 501 {
 502   const NSUInteger kBufferSize = 1024;
 503   UInt8 buffer[kBufferSize];
 504   CFIndex bufferOffset = 0;  // Starting point in |buffer| to work with.
 505   CFIndex bytesRead = CFReadStreamRead(readStream_, buffer, kBufferSize);
 506   const char* charBuffer = (const char*)buffer;
 507
 508   // The read loop works by going through the buffer until all the bytes have
 509   // been processed.
 510   while (bufferOffset < bytesRead)
 511   {
 512     // Find the NULL separator, or the end of the string.
 513     NSUInteger partLength = 0;
 514     for (NSUInteger i = bufferOffset; i < bytesRead && charBuffer[i] != '\0'; ++i, ++partLength) ;
 515
 516     // If there is not a current packet, set some state.
 517     if (!self.currentPacket)
 518     {
 519       // Read the message header: the size.  This will be |partLength| bytes.
 520       packetSize_ = atoi(charBuffer + bufferOffset);
 521       currentPacketIndex_ = 0;
 522       self.currentPacket = [NSMutableString stringWithCapacity:packetSize_];
 523       bufferOffset += partLength + 1;  // Pass over the NULL byte.
 524       continue;  // Spin the loop to begin reading actual data.
 525     }
 526
 527     // Substring the byte stream and append it to the packet string.
 528     CFStringRef bufferString = CFStringCreateWithBytes(kCFAllocatorDefault,
 529                                                        buffer + bufferOffset,  // Byte pointer, offset by start index.
 530                                                        partLength,  // Length.
 531                                                        kCFStringEncodingUTF8,
 532                                                        true);
 533     [self.currentPacket appendString:(NSString*)bufferString];
 534     CFRelease(bufferString);
 535
 536     // Advance counters.
 537     currentPacketIndex_ += partLength;
 538     bufferOffset += partLength + 1;
 539
 540     // If this read finished the packet, handle it and reset.
 541     if (currentPacketIndex_ >= packetSize_)
 542     {
 543       [self handlePacket:[[currentPacket_ retain] autorelease]];
 544       self.currentPacket = nil;
 545       packetSize_ = 0;
 546       currentPacketIndex_ = 0;
 547     }
 548   }
 549 }
 550
 551 /**
 552  * Performs the packet handling of a raw string XML packet. From this point on,
 553  * the packets are associated with a transaction and are then dispatched.
 554  */
 555 - (void)handlePacket:(NSString*)packet
 556 {
 557   // Test if we can convert it into an NSXMLDocument.
 558   NSError* error = nil;
 559   NSXMLDocument* xmlTest = [[NSXMLDocument alloc] initWithXMLString:currentPacket_ options:NSXMLDocumentTidyXML error:&error];
 560
 561   // Try to recover if we encountered an error.
 562   if (!xmlTest)
 563   {
 564     // We do not want to starve the write queue, so manually parse out the
 565     // transaction ID.
 566     NSRange location = [currentPacket_ rangeOfString:@"transaction_id"];
 567     if (location.location != NSNotFound)
 568     {
 569       NSUInteger start = location.location + location.length;
 570       NSUInteger end = start;
 571
 572       NSCharacterSet* numericSet = [NSCharacterSet decimalDigitCharacterSet];
 573
 574       // Loop over the characters after the attribute name to extract the ID.
 575       while (end < [currentPacket_ length])
 576       {
 577         unichar c = [currentPacket_ characterAtIndex:end];
 578         if ([numericSet characterIsMember:c])
 579         {
 580           // If this character is numeric, extend the range to substring.
 581           ++end;
 582         }
 583         else
 584         {
 585           if (start == end)
 586           {
 587             // If this character is nonnumeric and we have nothing in the
 588             // range, skip this character.
 589             ++start;
 590             ++end;
 591           }
 592           else
 593           {
 594             // We've moved past the numeric ID so we should stop searching.
 595             break;
 596           }
 597         }
 598       }
 599
 600       // If we were able to extract the transaction ID, update the last read.
 601       NSRange substringRange = NSMakeRange(start, end - start);
 602       NSString* transactionStr = [currentPacket_ substringWithRange:substringRange];
 603       if ([transactionStr length])
 604         lastReadTransaction_ = [transactionStr intValue];
 605     }
 606
 607     // Otherwise, assume +1 and hope it works.
 608     ++lastReadTransaction_;
 609   }
 610   else
 611   {
 612     // See if the transaction can be parsed out.
 613     NSInteger transaction = [self transactionIDFromResponse:xmlTest];
 614     if (transaction < lastReadTransaction_)
 615     {
 616       NSLog(@"tx = %d vs %d", transaction, lastReadTransaction_);
 617       NSLog(@"out of date transaction %@", packet);
 618       return;
 619     }
 620
 621     if (transaction != lastWrittenTransaction_)
 622       NSLog(@"txn %d <> %d last written, %d last read", transaction, lastWrittenTransaction_, lastReadTransaction_);
 623
 624     lastReadTransaction_ = transaction;
 625   }
 626
 627   // Log this receive event.
 628   LogEntry* log = [self recordReceive:currentPacket_];
 629   log.error = error;
 630
 631   // Finally, dispatch the handler for this response.
 632   [self handleResponse:[xmlTest autorelease]];
 633 }
 634
 635 - (void)handleResponse:(NSXMLDocument*)response
 636 {
 637   // Check and see if there's an error.
 638   NSArray* error = [[response rootElement] elementsForName:@"error"];
 639   if ([error count] > 0)
 640   {
 641     NSLog(@"Xdebug error: %@", error);
 642     NSString* errorMessage = [[[[error objectAtIndex:0] children] objectAtIndex:0] stringValue];
 643     [self errorEncountered:errorMessage];
 644   }
 645
 646   if ([[[response rootElement] name] isEqualToString:@"init"])
 647   {
 648     [delegate_ performSelectorOnMainThread:@selector(handleInitialResponse:)
 649                                 withObject:response
 650                              waitUntilDone:NO];
 651     return;
 652   }
 653
 654   if ([delegate_ respondsToSelector:@selector(handleResponse:)])
 655     [delegate_ performSelectorOnMainThread:@selector(handleResponse:)
 656                                 withObject:response
 657                              waitUntilDone:NO];
 658
 659   [self sendQueuedWrites];
 660 }
 661
 662 /**
 663  * This performs a blocking send. This should ONLY be called when we know we
 664  * have write access to the stream. We will busy wait in case we don't do a full
 665  * send.
 666  */
 667 - (void)performSend:(NSString*)command
 668 {
 669   // If this is an out-of-date transaction, do not bother sending it.
 670   NSInteger transaction = [self transactionIDFromCommand:command];
 671   if (transaction != NSNotFound && transaction < lastWrittenTransaction_)
 672     return;
 673
 674   BOOL done = NO;
 675
 676   char* string = (char*)[command UTF8String];
 677   int stringLength = strlen(string);
 678
 679   // Busy wait while writing. BAADD. Should background this operation.
 680   while (!done)
 681   {
 682     if (CFWriteStreamCanAcceptBytes(writeStream_))
 683     {
 684       // Include the NULL byte in the string when we write.
 685       int bytesWritten = CFWriteStreamWrite(writeStream_, (UInt8*)string, stringLength + 1);
 686       if (bytesWritten < 0)
 687       {
 688         NSLog(@"write error");
 689       }
 690       // Incomplete write.
 691       else if (bytesWritten < strlen(string))
 692       {
 693         // Adjust the buffer and wait for another chance to write.
 694         stringLength -= bytesWritten;
 695         memmove(string, string + bytesWritten, stringLength);
 696       }
 697       else
 698       {
 699         done = YES;
 700
 701         // We need to scan the string to find the transactionID.
 702         if (transaction == NSNotFound)
 703         {
 704           NSLog(@"sent %@ without a transaction ID", command);
 705           continue;
 706         }
 707         lastWrittenTransaction_ = transaction;
 708       }
 709     }
 710   }
 711
 712   // Log this trancation.
 713   [self recordSend:command];
 714 }
 715
 716 /**
 717  * Checks if there are unsent commands in the |queuedWrites_| queue and sends
 718  * them if it's OK to do so. This will not block.
 719  */
 720 - (void)sendQueuedWrites
 721 {
 722   if (!connected_)
 723     return;
 724
 725   [writeQueueLock_ lock];
 726   if (lastReadTransaction_ >= lastWrittenTransaction_ && [queuedWrites_ count] > 0)
 727   {
 728     NSString* command = [queuedWrites_ objectAtIndex:0];
 729
 730     // We don't want to block because this is called from the main thread.
 731     // |-performSend:| busy waits when the stream is not ready. Bail out
 732     // before we do that becuase busy waiting is BAD.
 733     if (CFWriteStreamCanAcceptBytes(writeStream_))
 734     {
 735       [self performSend:command];
 736       [queuedWrites_ removeObjectAtIndex:0];
 737     }
 738   }
 739   [writeQueueLock_ unlock];
 740 }
 741
 742 @end