From 39ccb4b21ed0954900aeb38545b2a65f9ffdc562 Mon Sep 17 00:00:00 2001
From: Robert Sesek <rsesek@bluestatic.org>
Date: Tue, 16 Feb 2010 23:35:23 -0500
Subject: [PATCH] Use a lock to make |-sendQueuedWrites| a critical section

---
 Source/GDBpConnection.h |  5 +++++
 Source/GDBpConnection.m | 17 +++++++++++------
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/Source/GDBpConnection.h b/Source/GDBpConnection.h
index ab538a4..f5d8de9 100644
--- a/Source/GDBpConnection.h
+++ b/Source/GDBpConnection.h
@@ -57,6 +57,11 @@
 	// array. We use this as a stack (FIFO), with index 0 being first.
 	NSMutableArray* queuedWrites_;
 	
+	// We send queued writes in multiple places, sometimes of a run loop event.
+	// Because of this, we need to ensure that only one client is dequeing and
+	// sending at a time.
+	NSRecursiveLock* writeQueueLock_;
+	
 	// The write stream. Weak.
 	CFWriteStreamRef writeStream_;
 	
diff --git a/Source/GDBpConnection.m b/Source/GDBpConnection.m
index ee88581..bc52a99 100644
--- a/Source/GDBpConnection.m
+++ b/Source/GDBpConnection.m
@@ -281,6 +281,7 @@ void SocketAcceptCallback(CFSocketRef socket,
 	transactionID = 1;
 	stackFrames_ = [[NSMutableDictionary alloc] init];
 	self.queuedWrites = [NSMutableArray array];
+	writeQueueLock_ = [NSRecursiveLock new];
 }
 
 /**
@@ -463,6 +464,7 @@ void SocketAcceptCallback(CFSocketRef socket,
 	CFRelease(socket_);
 	[stackFrames_ release];
 	self.queuedWrites = nil;
+	[writeQueueLock_ release];
 }
 
 /**
@@ -613,6 +615,7 @@ void SocketAcceptCallback(CFSocketRef socket,
 	if (txnID != lastWrittenTransaction_)
 		NSLog(@"txn doesn't match last written %@", response);
 	
+	lastReadTransaction_ = [transaction intValue];
 	NSLog(@"read=%d, write=%d", lastReadTransaction_, lastWrittenTransaction_);
 	
 	// Dispatch the command response to an appropriate handler.
@@ -645,7 +648,7 @@ void SocketAcceptCallback(CFSocketRef socket,
 	// Load the debugger to make it look active.
 	[delegate debuggerConnected];
 	
-	[self send:[self createCommand:@"status"]];
+	// TODO: update the status.
 }
 
 /**
@@ -805,6 +808,7 @@ void SocketAcceptCallback(CFSocketRef socket,
  */
 - (void)sendQueuedWrites
 {
+	[writeQueueLock_ lock];
 	if (lastReadTransaction_ >= lastWrittenTransaction_ && [queuedWrites_ count] > 0)
 	{
 		NSString* command = [queuedWrites_ objectAtIndex:0];
@@ -813,12 +817,13 @@ void SocketAcceptCallback(CFSocketRef socket,
 		// We don't want to block because this is called from the main thread.
 		// |-performSend:| busy waits when the stream is not ready. Bail out
 		// before we do that becuase busy waiting is BAD.
-		if (!CFWriteStreamCanAcceptBytes(writeStream_))
-			return;
-		
-		[self performSend:command];
-		[queuedWrites_ removeObjectAtIndex:0];
+		if (CFWriteStreamCanAcceptBytes(writeStream_))
+		{
+			[self performSend:command];
+			[queuedWrites_ removeObjectAtIndex:0];
+		}
 	}
+	[writeQueueLock_ unlock];
 }
 
 /**
-- 
2.22.5