From 50a283b6d1f3ce48e3a06eceeed3a466c6259fe7 Mon Sep 17 00:00:00 2001 From: rowanbeentje Date: Sun, 15 Nov 2009 23:58:21 +0000 Subject: Implement query cancellation support within MCPKit, and add it to the task functionality: - MCPKit now supports cancelling the active query; for MySQL servers >= 5.0.0 a query kill is attempted from a new connection, and if that fails or for MySQL < 5 a reconnect is triggered. - TableDocument now supports enabling a cancel task button on the task interface, including an optional callback - Implement query cancellation for custom queries. This addresses Issue #86. - Implement query cancellation for table content loads, filters, and sorts. --- Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m | 138 +++++++++++++++++++-- 1 file changed, 127 insertions(+), 11 deletions(-) (limited to 'Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m') diff --git a/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m b/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m index e55568d5..7db3ec2d 100644 --- a/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m +++ b/Frameworks/MCPKit/MCPFoundationKit/MCPConnection.m @@ -101,6 +101,8 @@ static BOOL sTruncateLongFieldInLogs = YES; connectionProxy = nil; connectionStartTime = -1; lastQueryExecutedAtTime = CGFLOAT_MAX; + queryCancelled = NO; + queryCancelUsedReconnect = NO; // Initialize ivar defaults connectionTimeout = 10; @@ -1261,6 +1263,9 @@ void performThreadedKeepAlive(void *ptr) NSInteger currentMaxAllowedPacket = -1; BOOL isQueryRetry = NO; NSString *queryErrorMessage = nil; + + // Reset the query cancelled boolean + queryCancelled = NO; // If no connection is present, return nil. if (!mConnected) { @@ -1290,7 +1295,6 @@ void performThreadedKeepAlive(void *ptr) // minimising the impact of performing lots of additional checks. if ([self timeConnected] - lastQueryExecutedAtTime > 30 && ![self checkConnection]) { - NSLog(@"returning nil!"); return nil; } @@ -1366,7 +1370,7 @@ void performThreadedKeepAlive(void *ptr) // For normal result sets, fetch the results and unlock the connection if (streamResultType == MCP_NO_STREAMING) { theResult = [[MCPResult alloc] initWithMySQLPtr:mConnection encoding:mEncoding timeZone:mTimeZone]; - [queryLock unlock]; + if (!queryCancelled || !queryCancelUsedReconnect) [queryLock unlock]; // For streaming result sets, fetch the result pointer and leave the connection locked } else if (streamResultType == MCP_FAST_STREAMING) { @@ -1394,16 +1398,23 @@ void performThreadedKeepAlive(void *ptr) // On failure, set the error messages and IDs } else { - if (streamResultType == MCP_NO_STREAMING) [queryLock unlock]; - else [self unlockConnection]; + if (!queryCancelled || !queryCancelUsedReconnect) { + if (streamResultType == MCP_NO_STREAMING) [queryLock unlock]; + else [self unlockConnection]; + } - queryErrorMessage = [[NSString alloc] initWithString:[self stringWithCString:mysql_error(mConnection)]]; - queryErrorId = mysql_errno(mConnection); - - // If the error was a connection error, retry once - if (!isQueryRetry && retryAllowed && [MCPConnection isErrorNumberConnectionError:queryErrorId]) { - isQueryRetry = YES; - continue; + if (queryCancelled) { + queryErrorMessage = [[NSString alloc] initWithString:NSLocalizedString(@"Query cancelled.", @"Query cancelled error")]; + queryErrorId = 1152; + } else { + queryErrorMessage = [[NSString alloc] initWithString:[self stringWithCString:mysql_error(mConnection)]]; + queryErrorId = mysql_errno(mConnection); + + // If the error was a connection error, retry once + if (!isQueryRetry && retryAllowed && [MCPConnection isErrorNumberConnectionError:queryErrorId]) { + isQueryRetry = YES; + continue; + } } } @@ -1464,6 +1475,104 @@ void performThreadedKeepAlive(void *ptr) return 0; } +/** + * Cancel the currently running query. This tries to kill the current query, and if that + * isn't possible, resets the connection. + */ +- (void) cancelCurrentQuery +{ + + // If not connected, return. + if (![self isConnected]) return; + + // Check whether a query is actually being performed - if not, also return. + if ([queryLock tryLock]) { + [queryLock unlock]; + return; + } + + // Set queryCancelled to prevent query retries + queryCancelled = YES; + + // For MySQL server versions >=5, try to kill the connection. This requires + // setting up a new connection, and running a KILL QUERY via it. + if ([self serverMajorVersion] >= 5) { + + MYSQL *killerConnection = mysql_init(NULL); + if (killerConnection) { + const char *theLogin = [self cStringFromString:connectionLogin]; + const char *theHost; + const char *thePass; + const char *theSocket; + void *connectionSetupStatus; + + mysql_options(killerConnection, MYSQL_OPT_CONNECT_TIMEOUT, (const void *)&connectionTimeout); + + // Set up the host, socket and password as per the connect method + if (!connectionHost || ![connectionHost length]) { + theHost = NULL; + } else { + theHost = [self cStringFromString:connectionHost]; + } + if (connectionSocket == nil || ![connectionSocket length]) { + theSocket = kMCPConnectionDefaultSocket; + } else { + theSocket = [self cStringFromString:connectionSocket]; + } + if (!connectionPassword) { + if (delegate && [delegate respondsToSelector:@selector(keychainPasswordForConnection:)]) { + thePass = [self cStringFromString:[delegate keychainPasswordForConnection:self]]; + } + } else { + thePass = [self cStringFromString:connectionPassword]; + } + + // Connect + connectionSetupStatus = mysql_real_connect(killerConnection, theHost, theLogin, thePass, NULL, connectionPort, theSocket, mConnectionFlags); + thePass = NULL; + if (connectionSetupStatus) { + NSStringEncoding killerConnectionEncoding = [MCPConnection encodingForMySQLEncoding:mysql_character_set_name(killerConnection)]; + NSString *killerQueryString = [NSString stringWithFormat:@"KILL QUERY %lu", mConnection->thread_id]; + NSData *encodedKillerQueryData = NSStringDataUsingLossyEncoding(killerQueryString, killerConnectionEncoding, 1); + const char *killerQueryCString = [encodedKillerQueryData bytes]; + unsigned long killerQueryCStringLength = [encodedKillerQueryData length]; + if (mysql_real_query(killerConnection, killerQueryCString, killerQueryCStringLength) == 0) { + mysql_close(killerConnection); + queryCancelUsedReconnect = NO; + return; + } + mysql_close(killerConnection); + } + } + } + + // Reset the connection + [self unlockConnection]; + [self reconnect]; + + // Set queryCancelled again to handle requery cleanups, and return. + queryCancelled = YES; + queryCancelUsedReconnect = YES; +} + +/** + * Return whether the last query was cancelled + */ +- (BOOL)queryCancelled +{ + return queryCancelled; +} + +/** + * If the last query was cancelled, returns whether that cancellation + * required a connection reset. If the last query was not cancelled + * the behaviour is undefined. + */ +- (BOOL)queryCancellationUsedReconnect +{ + return queryCancelUsedReconnect; +} + #pragma mark - #pragma mark Connection locking @@ -1483,6 +1592,13 @@ void performThreadedKeepAlive(void *ptr) */ - (void)unlockConnection { + + // Make sure the unlock is performed safely - eg for reconnected queries + if ([queryLock tryLock]) { + [queryLock unlock]; + return; + } + if ([NSThread isMainThread]) [queryLock unlock]; else [queryLock performSelectorOnMainThread:@selector(unlock) withObject:nil waitUntilDone:YES]; } -- cgit v1.2.3