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authorrowanbeentje <rowan@beent.je>2010-03-08 10:11:29 +0000
committerrowanbeentje <rowan@beent.je>2010-03-08 10:11:29 +0000
commitc10728213ede7dbdd37493aca9657ab4010edbdc (patch)
tree0a474d090b87c5d833e77b75654871de040293ad /Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m
parentd638ce370f202cb9d8338eeb3f981d9f70f548ff (diff)
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Rework MCPConnection for greater thread safety:
- The delegate is now triggered for connectionLost: on the main thread, as this action will probably trigger a GUI update; this addresses http://log.sequelpro.com/view/10 . - Connection proxy disconnects are now triggered on the main thread - Connection checks are now made via a pthread'd ping in a loop, removing the reliance on SIGALRM which may hop thread execution back to the main thread when called on another thread. The new approach is cleaner but does rely on a loop with a sleep. This will hopefully improve the disconnect/retry/reconnect crashes.
Diffstat (limited to 'Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m')
-rw-r--r--Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m141
1 files changed, 81 insertions, 60 deletions
diff --git a/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m b/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m
index 8cb80048..a1feb05b 100644
--- a/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m
+++ b/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m
@@ -34,11 +34,10 @@
#import "MCPConnectionProxy.h"
#include <unistd.h>
-#include <setjmp.h>
#include <mach/mach_time.h>
-static jmp_buf pingTimeoutJumpLocation;
-static void forcePingTimeout(int signalNumber);
+BOOL lastPingSuccess;
+BOOL pingActive;
const NSUInteger kMCPConnectionDefaultOption = CLIENT_COMPRESS | CLIENT_REMEMBER_OPTIONS ;
const char *kMCPConnectionDefaultSocket = MYSQL_UNIX_ADDR;
@@ -98,9 +97,11 @@ static BOOL sTruncateLongFieldInLogs = YES;
connectionPassword = nil;
keepAliveTimer = nil;
keepAliveThread = NULL;
+ pingThread = NULL;
connectionProxy = nil;
connectionStartTime = -1;
lastQueryExecutedAtTime = CGFLOAT_MAX;
+ lastDelegateDecisionForLostConnection = NSNotFound;
queryCancelled = NO;
queryCancelUsedReconnect = NO;
serverVersionString = nil;
@@ -120,6 +121,9 @@ static BOOL sTruncateLongFieldInLogs = YES;
lastQueryErrorId = 0;
lastQueryErrorMessage = nil;
lastQueryAffectedRows = 0;
+ lastPingSuccess = NO;
+ delegateSupportsConnectionLostDecisions = NO;
+ delegateResponseToWillQueryString = NO;
// Enable delegate query logging by default
delegateQueryLogging = YES;
@@ -202,6 +206,36 @@ static BOOL sTruncateLongFieldInLogs = YES;
// Check that the delegate implements willQueryString:connection: and cache the result as its used very frequently.
delegateResponseToWillQueryString = [delegate respondsToSelector:@selector(willQueryString:connection:)];
+
+ // Check whether the delegate supports returning a connection lost action decision
+ delegateSupportsConnectionLostDecisions = [delegate respondsToSelector:@selector(connectionLost:)];
+}
+
+/**
+ * Ask the delegate for the connection lost decision, on the main thread.
+ */
+- (MCPConnectionCheck)delegateDecisionForLostConnection
+{
+
+ // Return the "Disconnect" decision if the delegate doesn't support connectionLost: checks
+ if (!delegateSupportsConnectionLostDecisions) return MCPConnectionCheckDisconnect;
+
+ lastDelegateDecisionForLostConnection = NSNotFound;
+
+ // If on the main thread, ask the delegate directly. Perform this in an NSLock to confirm thread safety,
+ // as this method may be called within itself.
+ if ([NSThread isMainThread]) {
+ NSLock *delegateDecisionLock = [[NSLock alloc] init];
+ [delegateDecisionLock lock];
+ lastDelegateDecisionForLostConnection = [delegate connectionLost:self];
+ [delegateDecisionLock unlock];
+
+ // Otherwise call ourself on the main thread, waiting until the reply is received.
+ } else {
+ [self performSelectorOnMainThread:@selector(delegateDecisionForLostConnection) withObject:nil waitUntilDone:YES];
+ }
+
+ return lastDelegateDecisionForLostConnection;
}
#pragma mark -
@@ -376,7 +410,7 @@ static BOOL sTruncateLongFieldInLogs = YES;
mConnected = NO;
if (connectionProxy) {
- [connectionProxy disconnect];
+ [connectionProxy performSelectorOnMainThread:@selector(disconnect) withObject:nil waitUntilDone:YES];
}
if (serverVersionString) [serverVersionString release], serverVersionString = nil;
@@ -384,6 +418,7 @@ static BOOL sTruncateLongFieldInLogs = YES;
if (uniqueDbIdentifier) [uniqueDbIdentifier release], uniqueDbIdentifier = nil;
[self stopKeepAliveTimer];
+ if (pingThread != NULL) pthread_cancel(pingThread), pingThread = NULL;
}
/**
@@ -483,8 +518,8 @@ static BOOL sTruncateLongFieldInLogs = YES;
MCPConnectionCheck failureDecision = MCPConnectionCheckReconnect;
// Ask delegate what to do
- if (delegate && [delegate respondsToSelector:@selector(connectionLost:)]) {
- failureDecision = [delegate connectionLost:self];
+ if (delegateSupportsConnectionLostDecisions) {
+ failureDecision = [self delegateDecisionForLostConnection];
}
switch (failureDecision) {
@@ -523,8 +558,11 @@ static BOOL sTruncateLongFieldInLogs = YES;
// If the connection doesn't appear to be responding, show a dialog asking how to proceed
if (!connectionVerified) {
- // Ask delegate what to do
- MCPConnectionCheck failureDecision = (delegate && [delegate respondsToSelector:@selector(connectionLost:)]) ? [delegate connectionLost:self] : MCPConnectionCheckDisconnect;
+ // Ask delegate what to do, defaulting to "disconnect".
+ MCPConnectionCheck failureDecision = MCPConnectionCheckDisconnect;
+ if (delegateSupportsConnectionLostDecisions) {
+ failureDecision = [self delegateDecisionForLostConnection];
+ }
switch (failureDecision) {
// 'Reconnect' has been selected. Request a reconnect, and retry.
@@ -554,71 +592,54 @@ static BOOL sTruncateLongFieldInLogs = YES;
}
/**
- * This function provides a method of pinging the remote server while running a SIGALRM
- * to enforce the specified connection time. This is low-level but effective, and required
- * because low-level net reads can block indefintely if the remote server disappears or on
- * network issues - setting the MYSQL_OPT_READ_TIMEOUT (and the WRITE equivalent) would "fix"
- * ping, but cause long queries to be terminated.
+ * This function provides a method of pinging the remote server while also enforcing
+ * the specified connection time. This is required because low-level net reads can
+ * block indefinitely if the remote server disappears or on network issues - setting
+ * the MYSQL_OPT_READ_TIMEOUT (and the WRITE equivalent) would "fix" ping, but cause
+ * long queries to be terminated.
* Unlike mysql_ping, this function returns FALSE on failure and TRUE on success.
*/
- (BOOL)pingConnection
{
- struct sigaction timeoutAction;
- NSDate *startDate = [[NSDate alloc] initWithTimeIntervalSinceNow:0];
- BOOL pingSuccess = FALSE;
-
- // Construct the SIGALRM to fire after the connection timeout if it isn't cleared, calling the forcePingTimeout function.
- timeoutAction.sa_handler = forcePingTimeout;
- sigemptyset(&timeoutAction.sa_mask);
- timeoutAction.sa_flags = 0;
- sigaction(SIGALRM, &timeoutAction, NULL);
- alarm(connectionTimeout+1);
-
+ // Set up a query lock
[queryLock lock];
-
- // Set up a "restore point", returning 0; if longjmp is used later with this reference, execution
- // jumps back to this point and returns a nonzero value, so this function evaluates to false when initially
- // set and true if it's called again.
- if (setjmp(pingTimeoutJumpLocation)) {
-
- // The connection timed out - we want to return false.
- pingSuccess = FALSE;
-
- // On direct execution:
- } else {
-
- // Run mysql_ping, which returns 0 on success, and otherwise an error.
- pingSuccess = (BOOL)(! mysql_ping(mConnection));
-
- // If the ping failed within a second, try another one; this is because a terminated-but-then
- // restored connection is at times restored or functional after a ping, but the ping still returns
- // an error. This additional check ensures the returned status is correct with minimal other effect.
- if (!pingSuccess && ([startDate timeIntervalSinceNow] > -1)) {
- pingSuccess = (BOOL)(! mysql_ping(mConnection));
- }
+
+ uint64_t currentTime_t;
+ Nanoseconds elapsedTime;
+ uint64_t pingStartTime_t = mach_absolute_time();
+ lastPingSuccess = FALSE;
+ pingActive = YES;
+
+ // Create a pthread for the ping, so we can force it to end after the connection timeout
+ pthread_create(&pingThread, NULL, (void *)&pingConnectionTask, (void *)mConnection);
+
+ // Loop tightly until the ping responds, or the elapsed time exceeds the connection timeout
+ while (pingActive) {
+ currentTime_t = mach_absolute_time() - pingStartTime_t;
+ elapsedTime = AbsoluteToNanoseconds(*(AbsoluteTime *)&(currentTime_t));
+ if (((double)UnsignedWideToUInt64(elapsedTime)) * 1e-9 > connectionTimeout) break;
+ usleep(400);
}
-
+
+ // If the connection timed out, kill the thread and set status to failed
+ if (pingActive) {
+ pthread_cancel(pingThread);
+ lastPingSuccess = FALSE;
+ }
+
[queryLock unlock];
- // Reset and clear the SIGALRM used to check connection timeouts.
- alarm(0);
- timeoutAction.sa_handler = SIG_IGN;
- sigemptyset(&timeoutAction.sa_mask);
- timeoutAction.sa_flags = 0;
- sigaction(SIGALRM, &timeoutAction, NULL);
-
- [startDate release];
-
- return pingSuccess;
+ return lastPingSuccess;
}
/**
- * This function is paired with pingConnection, and provides a method of enforcing the connection
- * timeout when mysql_ping does not respect the specified limits.
+ * This function is paired with pingConnection, and performs the keepalive ping in a pthread,
+ * allowing the thread to be cancelled if it does not respond.
*/
-static void forcePingTimeout(int signalNumber)
+void pingConnectionTask(void *ptr)
{
- longjmp(pingTimeoutJumpLocation, 1);
+ lastPingSuccess = (BOOL)(!mysql_ping((MYSQL *)ptr));
+ pingActive = NO;
}
/**