Final feature work on the SPMySQL branch before merging:

 - Add a ping keepalive managing object to prevent retain cycles from the NSTimer
 - Add -[SPMySQLConnection copy] support
 - Refactor Hans-Jörg Bibiko's database structure retrieval, moving it out of the MySQL framework and building it around a copy of the connection.  This reduces the amount of connections-over-time used by Sequel Pro to two constant connections (addressing Issue #1097) and improves robustness.
 - Use the database structure retrieval connection for faster query cancellation without an extra connection required, if possible

11 files changed, 311 insertions, 37 deletions

diff --git a/Frameworks/SPMySQLFramework/SPMySQLFramework.xcodeproj/project.pbxproj b/Frameworks/SPMySQLFramework/SPMySQLFramework.xcodeproj/project.pbxproj
index 933a68b7..2f8d300c 100644
--- a/Frameworks/SPMySQLFramework/SPMySQLFramework.xcodeproj/project.pbxproj
+++ b/Frameworks/SPMySQLFramework/SPMySQLFramework.xcodeproj/project.pbxproj
@@ -28,6 +28,10 @@
 		584294FB14CB8002000F8438 /* Encoding.m in Sources */ = {isa = PBXBuildFile; fileRef = 584294F914CB8002000F8438 /* Encoding.m */; };
 		584294FE14CB8002000F8438 /* Server Info.h in Headers */ = {isa = PBXBuildFile; fileRef = 584294FC14CB8002000F8438 /* Server Info.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		584294FF14CB8002000F8438 /* Server Info.m in Sources */ = {isa = PBXBuildFile; fileRef = 584294FD14CB8002000F8438 /* Server Info.m */; };
+		584D812E15057ECD00F24774 /* SPMySQLKeepAliveTimer.h in Headers */ = {isa = PBXBuildFile; fileRef = 584D812C15057ECD00F24774 /* SPMySQLKeepAliveTimer.h */; };
+		584D812F15057ECD00F24774 /* SPMySQLKeepAliveTimer.m in Sources */ = {isa = PBXBuildFile; fileRef = 584D812D15057ECD00F24774 /* SPMySQLKeepAliveTimer.m */; };
+		584D82551509775000F24774 /* Copying.h in Headers */ = {isa = PBXBuildFile; fileRef = 584D82531509775000F24774 /* Copying.h */; };
+		584D82561509775000F24774 /* Copying.m in Sources */ = {isa = PBXBuildFile; fileRef = 584D82541509775000F24774 /* Copying.m */; };
 		586A99FB14F02E21007F82BF /* SPMySQLStreamingResult.h in Headers */ = {isa = PBXBuildFile; fileRef = 586A99F914F02E21007F82BF /* SPMySQLStreamingResult.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		586A99FC14F02E21007F82BF /* SPMySQLStreamingResult.m in Sources */ = {isa = PBXBuildFile; fileRef = 586A99FA14F02E21007F82BF /* SPMySQLStreamingResult.m */; };
 		586AA16714F30C5F007F82BF /* Convenience Methods.h in Headers */ = {isa = PBXBuildFile; fileRef = 586AA16514F30C5F007F82BF /* Convenience Methods.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -92,6 +96,10 @@
 		584294F914CB8002000F8438 /* Encoding.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = Encoding.m; path = "Source/SPMySQLConnection Categories/Encoding.m"; sourceTree = "<group>"; };
 		584294FC14CB8002000F8438 /* Server Info.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = "Server Info.h"; path = "Source/SPMySQLConnection Categories/Server Info.h"; sourceTree = "<group>"; };
 		584294FD14CB8002000F8438 /* Server Info.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = "Server Info.m"; path = "Source/SPMySQLConnection Categories/Server Info.m"; sourceTree = "<group>"; };
+		584D812C15057ECD00F24774 /* SPMySQLKeepAliveTimer.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = SPMySQLKeepAliveTimer.h; path = Source/SPMySQLKeepAliveTimer.h; sourceTree = "<group>"; };
+		584D812D15057ECD00F24774 /* SPMySQLKeepAliveTimer.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = SPMySQLKeepAliveTimer.m; path = Source/SPMySQLKeepAliveTimer.m; sourceTree = "<group>"; };
+		584D82531509775000F24774 /* Copying.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = Copying.h; path = "Source/SPMySQLConnection Categories/Copying.h"; sourceTree = "<group>"; };
+		584D82541509775000F24774 /* Copying.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = Copying.m; path = "Source/SPMySQLConnection Categories/Copying.m"; sourceTree = "<group>"; };
 		586A99F914F02E21007F82BF /* SPMySQLStreamingResult.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = SPMySQLStreamingResult.h; path = Source/SPMySQLStreamingResult.h; sourceTree = "<group>"; };
 		586A99FA14F02E21007F82BF /* SPMySQLStreamingResult.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = SPMySQLStreamingResult.m; path = Source/SPMySQLStreamingResult.m; sourceTree = "<group>"; };
 		586AA0E714F1CEC8007F82BF /* Readme.txt */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = Readme.txt; sourceTree = "<group>"; };
@@ -202,6 +210,8 @@
 				58C7C1E314DB6E4C00436315 /* SPMySQLFastStreamingResult.m */,
 				58C7C1E114DB6E3000436315 /* Result Categories */,
 				580A331B14D75CCF000D6933 /* Result types */,
+				584D812C15057ECD00F24774 /* SPMySQLKeepAliveTimer.h */,
+				584D812D15057ECD00F24774 /* SPMySQLKeepAliveTimer.m */,
 			);
 			name = Classes;
 			sourceTree = "<group>";
@@ -288,6 +298,8 @@
 		584294EB14CB8002000F8438 /* Connection Categories */ = {
 			isa = PBXGroup;
 			children = (
+				584D82531509775000F24774 /* Copying.h */,
+				584D82541509775000F24774 /* Copying.m */,
 				58C00AB314E4892E00AC489A /* Delegate & Proxy.h */,
 				58C00AB414E4892E00AC489A /* Delegate & Proxy.m */,
 				58C00BCF14E7459600AC489A /* Databases & Tables.h */,
@@ -387,6 +399,8 @@
 				586A99FB14F02E21007F82BF /* SPMySQLStreamingResult.h in Headers */,
 				586AA16714F30C5F007F82BF /* Convenience Methods.h in Headers */,
 				586AA81414F6C648007F82BF /* SPMySQLArrayAdditions.h in Headers */,
+				584D812E15057ECD00F24774 /* SPMySQLKeepAliveTimer.h in Headers */,
+				584D82551509775000F24774 /* Copying.h in Headers */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -470,6 +484,8 @@
 				58C00BD214E7459600AC489A /* Databases & Tables.m in Sources */,
 				586A99FC14F02E21007F82BF /* SPMySQLStreamingResult.m in Sources */,
 				586AA16814F30C5F007F82BF /* Convenience Methods.m in Sources */,
+				584D812F15057ECD00F24774 /* SPMySQLKeepAliveTimer.m in Sources */,
+				584D82561509775000F24774 /* Copying.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Copying.h b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Copying.h
new file mode 100644
index 00000000..83d055d5
--- /dev/null
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Copying.h
@@ -0,0 +1,36 @@
+//
+//  $Id$
+//
+//  Copying.h
+//  SPMySQLFramework
+//
+//  Created by Rowan Beentje (rowan.beent.je) on March 8, 2012
+//  Copyright (c) 2012 Rowan Beentje. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person
+//  obtaining a copy of this software and associated documentation
+//  files (the "Software"), to deal in the Software without
+//  restriction, including without limitation the rights to use,
+//  copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the
+//  Software is furnished to do so, subject to the following
+//  conditions:
+//
+//  The above copyright notice and this permission notice shall be
+//  included in all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+//  OTHER DEALINGS IN THE SOFTWARE.
+//
+//  More info at <http://code.google.com/p/sequel-pro/>
+
+
+@interface SPMySQLConnection (Copying) <NSCopying>
+
+@end
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Copying.m b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Copying.m
new file mode 100644
index 00000000..c2df2a4b
--- /dev/null
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Copying.m
@@ -0,0 +1,71 @@
+//
+//  $Id$
+//
+//  Copying.m
+//  SPMySQLFramework
+//
+//  Created by Rowan Beentje (rowan.beent.je) on March 8, 2012
+//  Copyright (c) 2012 Rowan Beentje. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person
+//  obtaining a copy of this software and associated documentation
+//  files (the "Software"), to deal in the Software without
+//  restriction, including without limitation the rights to use,
+//  copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the
+//  Software is furnished to do so, subject to the following
+//  conditions:
+//
+//  The above copyright notice and this permission notice shall be
+//  included in all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+//  OTHER DEALINGS IN THE SOFTWARE.
+//
+//  More info at <http://code.google.com/p/sequel-pro/>
+
+#import "Copying.h"
+
+@implementation SPMySQLConnection (Copying)
+
+/**
+ * Provide a copy of the SPMySQLConnection instance.
+ * The copy should inherit the full setup, but will not inherit
+ * the connection state - it will not be connected, and any connection
+ * details such as the selected database/encoding will not be inherited.
+ * Note that any proxy will not be referenced in the new connection, and
+ * should also be set if desired.
+ */
+- (id)copyWithZone:(NSZone *)zone
+{
+	SPMySQLConnection *copy = [[[self class] allocWithZone:zone] init];
+
+	// Synthesized details
+	[copy setDelegate:delegate];
+	[copy setHost:host];
+	[copy setUsername:username];
+	[copy setPassword:password];
+	[copy setPort:port];
+	[copy setUseSocket:useSocket];
+	[copy setSocketPath:socketPath];
+	[copy setUseSSL:useSSL];
+	[copy setSslKeyFilePath:sslKeyFilePath];
+	[copy setSslCertificatePath:sslCertificatePath];
+	[copy setSslCACertificatePath:sslCACertificatePath];
+	[copy setTimeout:timeout];
+	[copy setUseKeepAlive:useKeepAlive];
+	[copy setRetryQueriesOnConnectionFailure:retryQueriesOnConnectionFailure];
+	[copy setDelegateQueryLogging:delegateQueryLogging];
+
+	// Active connection state details, like selected database and encoding, are *not* copied.
+
+	return copy;
+}
+
+@end
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Ping & KeepAlive.h b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Ping & KeepAlive.h
index 3788c653..e84c4ca6 100644
--- a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Ping & KeepAlive.h
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Ping & KeepAlive.h
@@ -40,11 +40,8 @@ typedef struct {
 
 @interface SPMySQLConnection (Ping_and_KeepAlive)
 
-// Setup functions
-- (void)_initKeepAlivePingTimer;
-
 // Keepalive ping initialisation
-- (void)_keepAlive:(NSTimer *)theTimer;
+- (void)_keepAlive;
 - (void)_threadedKeepAlive;
 
 // Master ping method
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Ping & KeepAlive.m b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Ping & KeepAlive.m
index 9e25edcb..3ce0c0cd 100644
--- a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Ping & KeepAlive.m
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Ping & KeepAlive.m
@@ -38,19 +38,6 @@
 @implementation SPMySQLConnection (Ping_and_KeepAlive)
 
 #pragma mark -
-#pragma mark Setup functions
-
-/**
- * Set up the keepalive timer; this should be called on the main
- * thread, to ensure the timer isn't descheduled when child threads
- * terminate.
- */
-- (void)_initKeepAlivePingTimer
-{
-	keepAliveTimer = [[NSTimer scheduledTimerWithTimeInterval:10 target:self selector:@selector(_keepAlive:) userInfo:nil repeats:YES] retain];
-}
-
-#pragma mark -
 #pragma mark Keepalive ping initialisation
 
 /**
@@ -58,7 +45,7 @@
  * This method is called every ten seconds and spawns a thread which determines
  * whether or not it should perform a ping.
  */
-- (void)_keepAlive:(NSTimer *)theTimer
+- (void)_keepAlive
 {
 
 	// Do nothing if not connected or if keepalive is disabled
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Querying & Preparation.h b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Querying & Preparation.h
index 9ab8bc6a..0f086a89 100644
--- a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Querying & Preparation.h
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Querying & Preparation.h
@@ -61,7 +61,6 @@
 
 // Query cancellation
 - (void)cancelCurrentQuery;
-- (BOOL)lastQueryWasCancelled;
 - (BOOL)lastQueryWasCancelledUsingReconnect;
 
 @end
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Querying & Preparation.m b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Querying & Preparation.m
index cb5ce70d..9b54029c 100644
--- a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Querying & Preparation.m
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection Categories/Querying & Preparation.m
@@ -282,7 +282,7 @@
 		} else {
 
 			// Prevent retries if the query was cancelled or not a connection error
-			if (lastQueryWasCancelled && ![SPMySQLConnection isErrorIDConnectionError:mysql_errno(mySQLConnection)]) {
+			if (lastQueryWasCancelled || ![SPMySQLConnection isErrorIDConnectionError:mysql_errno(mySQLConnection)]) {
 				break;
 			}
 		}
@@ -549,14 +549,6 @@
 }
 
 /**
- * Returns whether the last query was cancelled using cancelCurrentQuery.
- */
-- (BOOL)lastQueryWasCancelled
-{
-	return lastQueryWasCancelled;
-}
-
-/**
  * If the last query was cancelled, returns whether that query cancellation
  * required the connection to be reset or whether the query was successfully
  * cancelled leaving the connection intact.
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection.h b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection.h
index 5d1a5d11..8f3b7f9f 100644
--- a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection.h
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection.h
@@ -30,6 +30,8 @@
 //
 //  More info at <http://code.google.com/p/sequel-pro/>
 
+@class SPMySQLKeepAliveTimer;
+
 @interface SPMySQLConnection : NSObject {
 
 	// Delegate
@@ -80,7 +82,7 @@
 	// Timeout and keep-alive
 	NSUInteger timeout;
 	BOOL useKeepAlive;
-	NSTimer *keepAliveTimer;
+	SPMySQLKeepAliveTimer *keepAliveTimer;
 	CGFloat keepAliveInterval;
 	uint64_t lastKeepAliveTime;
 	NSUInteger keepAlivePingFailures;
@@ -153,6 +155,8 @@
 
 @property (readwrite, assign) BOOL delegateQueryLogging;
 
+@property (readwrite, assign) BOOL lastQueryWasCancelled;
+
 #pragma mark -
 #pragma mark Connection and disconnection
 
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection.m b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection.m
index 4968266d..4f1e8a74 100644
--- a/Frameworks/SPMySQLFramework/Source/SPMySQLConnection.m
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLConnection.m
@@ -31,6 +31,7 @@
 //  More info at <http://code.google.com/p/sequel-pro/>
 
 #import "SPMySQL Private APIs.h"
+#import "SPMySQLKeepAliveTimer.h"
 #include <mach/mach_time.h>
 #include <pthread.h>
 #include <SystemConfiguration/SCNetworkReachability.h>
@@ -71,6 +72,7 @@ const char *SPMySQLSSLPermissibleCiphers = "DHE-RSA-AES256-SHA:AES256-SHA:DHE-RS
 @synthesize mysqlConnectionThreadId;
 @synthesize retryQueriesOnConnectionFailure;
 @synthesize delegateQueryLogging;
+@synthesize lastQueryWasCancelled;
 
 #pragma mark -
 #pragma mark Initialisation and teardown
@@ -161,11 +163,7 @@ const char *SPMySQLSSLPermissibleCiphers = "DHE-RSA-AES256-SHA:AES256-SHA:DHE-RS
 		retryQueriesOnConnectionFailure = YES;
 
 		// Start the ping keepalive timer
-		if ([NSThread isMainThread]) {
-			[self _initKeepAlivePingTimer];
-		} else {
-			[self performSelectorOnMainThread:@selector(_initKeepAlivePingTimer) withObject:nil waitUntilDone:YES];
-		}
+		keepAliveTimer = [[SPMySQLKeepAliveTimer alloc] initWithInterval:10 target:self selector:@selector(_keepAlive)];
 	}
 
 	return self;
@@ -181,6 +179,10 @@ const char *SPMySQLSSLPermissibleCiphers = "DHE-RSA-AES256-SHA:AES256-SHA:DHE-RS
 	// Unset the delegate
 	[self setDelegate:nil];
 
+	// Clear the keepalive timer
+	[keepAliveTimer invalidate];
+	[keepAliveTimer release];
+
 	// Disconnect if appropriate (which should also disconnect any proxy)
 	[self disconnect];
 
@@ -196,14 +198,12 @@ const char *SPMySQLSSLPermissibleCiphers = "DHE-RSA-AES256-SHA:AES256-SHA:DHE-RS
 	}
 	[connectionLock release], connectionLock = nil;
 
-	[encoding dealloc];
+	[encoding release];
 	if (previousEncoding) [previousEncoding release], previousEncoding = nil;
 
 	if (database) [database release], database = nil;
 	if (serverVersionString) [serverVersionString release], serverVersionString = nil;
 	if (queryErrorMessage) [queryErrorMessage release], queryErrorMessage = nil;
-	[keepAliveTimer invalidate];
-	[keepAliveTimer release];
 	[delegateDecisionLock release];
 
 	[NSObject cancelPreviousPerformRequestsWithTarget:self];
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLKeepAliveTimer.h b/Frameworks/SPMySQLFramework/Source/SPMySQLKeepAliveTimer.h
new file mode 100644
index 00000000..ebe46bed
--- /dev/null
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLKeepAliveTimer.h
@@ -0,0 +1,45 @@
+//
+//  $Id$
+//
+//  SPMySQLKeepAliveTimer.h
+//  SPMySQLFramework
+//
+//  Created by Rowan Beentje (rowan.beent.je) on March 5, 2012
+//  Copyright (c) 2012 Rowan Beentje. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person
+//  obtaining a copy of this software and associated documentation
+//  files (the "Software"), to deal in the Software without
+//  restriction, including without limitation the rights to use,
+//  copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the
+//  Software is furnished to do so, subject to the following
+//  conditions:
+//
+//  The above copyright notice and this permission notice shall be
+//  included in all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+//  OTHER DEALINGS IN THE SOFTWARE.
+//
+//  More info at <http://code.google.com/p/sequel-pro/>
+
+
+@interface SPMySQLKeepAliveTimer : NSObject {
+	id timerTarget;
+	SEL timerSelector;
+	NSTimeInterval timerRepeatInterval;
+
+	NSTimer *wrappedTimer;
+}
+
+- (id)initWithInterval:(NSTimeInterval)anInterval target:(id)aTarget selector:(SEL)aSelector;
+- (void)invalidate;
+
+@end
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLKeepAliveTimer.m b/Frameworks/SPMySQLFramework/Source/SPMySQLKeepAliveTimer.m
new file mode 100644
index 00000000..f9164aff
--- /dev/null
+++ b/Frameworks/SPMySQLFramework/Source/SPMySQLKeepAliveTimer.m
@@ -0,0 +1,127 @@
+//
+//  $Id$
+//
+//  SPMySQLKeepAliveTimer.m
+//  SPMySQLFramework
+//
+//  Created by Rowan Beentje (rowan.beent.je) on March 5, 2012
+//  Copyright (c) 2012 Rowan Beentje. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person
+//  obtaining a copy of this software and associated documentation
+//  files (the "Software"), to deal in the Software without
+//  restriction, including without limitation the rights to use,
+//  copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the
+//  Software is furnished to do so, subject to the following
+//  conditions:
+//
+//  The above copyright notice and this permission notice shall be
+//  included in all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+//  OTHER DEALINGS IN THE SOFTWARE.
+//
+//  More info at <http://code.google.com/p/sequel-pro/>
+
+
+#import "SPMySQLKeepAliveTimer.h"
+#import "SPMySQL Private APIs.h"
+
+@interface SPMySQLKeepAliveTimer (Private_API)
+
+- (void)_initKeepAliveTimer;
+- (void)_forwardPing;
+
+@end
+
+#pragma mark -
+
+@implementation SPMySQLKeepAliveTimer
+
+/**
+ * Prevent SPMySQLKeepAliveTimer from being init'd normally.
+ */
+- (id)init
+{
+	[NSException raise:NSInternalInconsistencyException format:@"SPMySQLKeepAliveTimers should not be init'd directly; use initWithInterval:target:selector: instead."];
+	return nil;
+}
+
+/**
+ * Initialise the SPMySQLKeepAliveTimer.  This also sets up the contained timer,
+ * which has to be wrapped in this class to prevent retain cycles preventing the
+ * parent connection from being released.
+ *
+ * After initialisation, the delegate should be set to ensure that the timer events
+ * are received.
+ */
+- (id)initWithInterval:(NSTimeInterval)anInterval target:(id)aTarget selector:(SEL)aSelector
+{
+	if ((self = [super init])) {
+		wrappedTimer = nil;
+
+		// Keep a weak reference to the target
+		timerTarget = aTarget;
+		timerSelector = aSelector;
+		timerRepeatInterval = anInterval;
+
+		// Ensure the timer is set up on the main thread
+		if ([NSThread isMainThread]) {
+			[self _initKeepAliveTimer];
+		} else {
+			[self performSelectorOnMainThread:@selector(_initKeepAliveTimer) withObject:nil waitUntilDone:YES];
+		}
+	}
+
+	return self;
+}
+
+/**
+ * Invalidate the wrapped timer, which also releases the reference to the timer
+ * target (this object), breaking retain loops.
+ */
+- (void)invalidate
+{
+	if ([NSThread isMainThread]) {
+		[wrappedTimer invalidate];
+	} else {
+		[wrappedTimer performSelectorOnMainThread:@selector(invalidate) withObject:nil waitUntilDone:YES];
+	}
+}
+
+- (void)dealloc
+{
+	[wrappedTimer dealloc];
+	[super dealloc];
+}
+
+@end
+
+@implementation SPMySQLKeepAliveTimer (Private_API)
+
+/**
+ * Set up the timer to tickle the target.  This must be set up on the main thread
+ * to ensure the timer events keep firing.
+ */
+- (void)_initKeepAliveTimer
+{
+	wrappedTimer = [[NSTimer scheduledTimerWithTimeInterval:timerRepeatInterval target:self	selector:@selector(_forwardPing) userInfo:nil repeats:YES] retain];
+}
+
+/**
+ * Forward the NSTimer-fired ping to the target object.  Performing this forwarding
+ * breaks the retain cycle.
+ */
+- (void)_forwardPing
+{
+	[timerTarget performSelector:timerSelector];
+}
+
+@end