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authorrowanbeentje <rowan@beent.je>2010-09-03 01:42:16 +0000
committerrowanbeentje <rowan@beent.je>2010-09-03 01:42:16 +0000
commit4aaa7dda2d01afbebb9f7c2a6ba8537a3206858a (patch)
tree593f08dac8ecbd3a9d06b8d768f863d4bcaa73d7 /Frameworks/MCPKit/MCPFoundationKit
parentb66f9afbcd48b62d8adc3cfc5f27da099b129646 (diff)
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Update background keepalive pings:
- Fully lock the connection for background pings; this may slow down queries after connection disuse (when the keepalive is still active/blocked), but strengens thread safety to hopefully fix vio_delete crashes - Fix pthread_cancel use; previously pthread_cancel after a keepalive may have resulted in cancelling unrelated threads where the thread ID was reused This should increase stability and improve program consistency.
Diffstat (limited to 'Frameworks/MCPKit/MCPFoundationKit')
-rw-r--r--Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m44
1 files changed, 33 insertions, 11 deletions
diff --git a/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m b/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m
index ab635e03..d8905d8d 100644
--- a/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m
+++ b/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m
@@ -44,6 +44,7 @@
BOOL lastPingSuccess;
BOOL pingActive;
NSInteger pingFailureCount;
+BOOL keepAliveActive;
const NSUInteger kMCPConnectionDefaultOption = CLIENT_COMPRESS | CLIENT_REMEMBER_OPTIONS | CLIENT_MULTI_RESULTS;
const char *kMCPConnectionDefaultSocket = MYSQL_UNIX_ADDR;
@@ -778,9 +779,7 @@ void pingConnectionTask(void *ptr)
}
// Attempt to lock the connection. If the connection currently is busy,
- // we don't need a ping. The connection is unlocked in threadedKeepAlive
- // before the ping actually returns, to prevent the ping from delaying
- // other queries
+ // we don't need a ping.
if (![self tryLockConnection]) return;
// Store the ping time
@@ -796,6 +795,10 @@ void pingConnectionTask(void *ptr)
*/
- (void)threadedKeepAlive
{
+ uint64_t currentTime_t;
+ Nanoseconds currentNanoseconds;
+ double pingStartTime;
+
if (!mConnected || keepAliveThread != NULL) {
// unlock the connection now. it has been locked in keepAlive:
[self unlockConnection];
@@ -816,18 +819,36 @@ void pingConnectionTask(void *ptr)
if (connectionTimeout > 0 && connectionTimeout < pingTimeout) pingTimeout = connectionTimeout;
// Create a pthread for the actual keepalive
+ keepAliveActive = YES;
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
pthread_create(&keepAliveThread, &attr, (void *)&performThreadedKeepAlive, (void *)mConnection);
- // unlock the connection now. it has been locked in keepAlive:
+ // Record the ping start time
+ currentTime_t = mach_absolute_time() - connectionStartTime;
+ currentNanoseconds = AbsoluteToNanoseconds(*(AbsoluteTime *)&(currentTime_t));
+ pingStartTime = UnsignedWideToUInt64(currentNanoseconds);
+
+ // Loop until the ping completes
+ do {
+ usleep(10000);
+
+ // If the ping timeout has been exceeded, force a timeout; double-check that keepAliveActive
+ // is still set to NO, as otherwise the thread id may have already been reused causing
+ // cancellation of the incorrect thread.
+ currentTime_t = mach_absolute_time() - connectionStartTime;
+ currentNanoseconds = AbsoluteToNanoseconds(*(AbsoluteTime *)&(currentTime_t));
+ if ((UnsignedWideToUInt64(currentNanoseconds) - pingStartTime) * 1e-9 > pingTimeout && keepAliveActive) {
+ pthread_cancel(keepAliveThread);
+ keepAliveActive = NO;
+ }
+ } while (keepAliveActive);
+
+ // Unlock the connection now, locked in keepAlive: at the start of the ping
[self unlockConnection];
- // Give the connection time to respond, but force a timeout after the ping timeout
- // if the thread hasn't already closed itself.
- sleep(pingTimeout);
- pthread_cancel(keepAliveThread);
+ // Clean up
keepAliveThread = NULL;
pthread_attr_destroy(&attr);
}
@@ -842,6 +863,7 @@ void performThreadedKeepAlive(void *ptr)
} else {
pingFailureCount = 0;
}
+ keepAliveActive = NO;
}
/**
@@ -1632,7 +1654,7 @@ void performThreadedKeepAlive(void *ptr)
return nil;
}
}
-
+
[self lockConnection];
// Run (or re-run) the query, timing the execution time of the query - note
@@ -1641,14 +1663,14 @@ void performThreadedKeepAlive(void *ptr)
queryResultCode = mysql_real_query(mConnection, theCQuery, theCQueryLength);
lastQueryExecutedAtTime = [self timeConnected];
queryExecutionTime = lastQueryExecutedAtTime - queryStartTime;
-
+
// On success, capture the results
if (0 == queryResultCode) {
queryAffectedRows = mysql_affected_rows(mConnection);
if (mysql_field_count(mConnection) != 0) {
-
+
// For normal result sets, fetch the results and unlock the connection
if (streamResultType == MCPStreamingNone) {
theResult = [[MCPResult alloc] initWithMySQLPtr:mConnection encoding:stringEncoding timeZone:mTimeZone];