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* Turn -[SPMySQLConnection checkConnectionIfNecessary] into a publi…
…c method, since it is actually the preferable way to `-[SPMySQLConnection checkConnection]` (which forces network IO in a new thread each time)

* Change `-[SPDatabaseStructure queryDbStructureWithUserInfo:]` doing a forced connection check inside a tight loop (#2306)
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dmoagx committed Mar 9, 2017
1 parent 6c3ab14 commit 7c56b11
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Showing 6 changed files with 37 additions and 35 deletions.
@@ -47,7 +47,6 @@
- (void)_disconnect;
- (void)_updateConnectionVariables;
- (void)_restoreConnectionVariables;
- (BOOL)_checkConnectionIfNecessary;
- (void)_validateThreadSetup;
+ (void)_removeThreadVariables:(NSNotification *)aNotification;

@@ -79,7 +79,7 @@ - (NSString *)escapeString:(NSString *)theString includingQuotes:(BOOL)includeQu
// Ensure per-thread variables are set up
[self _validateThreadSetup];

if (![self _checkConnectionIfNecessary]) return nil;
if (![self checkConnectionIfNecessary]) return nil;

// Perform a lossy conversion to bytes, using NSData to do the hard work. Preserves
// nul characters correctly.
@@ -259,7 +259,7 @@ - (id)queryString:(NSString *)theQueryString usingEncoding:(NSStringEncoding)the
[self _validateThreadSetup];

// Check the connection if necessary, returning nil if the state couldn't be validated
if (![self _checkConnectionIfNecessary]) return nil;
if (![self checkConnectionIfNecessary]) return nil;

// Determine whether a maximum query size needs to be restored from a previous query
if (queryActionShouldRestoreMaxQuerySize != NSNotFound) {
@@ -107,7 +107,7 @@ - (SPMySQLResult *)listProcesses
if (state != SPMySQLConnected) return nil;

// Check the connection if appropriate
if (![self _checkConnectionIfNecessary]) return nil;
if (![self checkConnectionIfNecessary]) return nil;

// Lock the connection before using it
[self _lockConnection];
@@ -153,7 +153,7 @@ - (BOOL)killQueryOnThreadID:(unsigned long)theThreadID

- (BOOL)serverShutdown
{
if([self _checkConnectionIfNecessary]) {
if([self checkConnectionIfNecessary]) {
[self _lockConnection];
// Ensure per-thread variables are set up
[self _validateThreadSetup];
@@ -188,6 +188,7 @@
- (BOOL)isConnected;
- (BOOL)isConnectedViaSSL;
- (BOOL)checkConnection;
- (BOOL)checkConnectionIfNecessary;
- (double)timeConnected;
- (BOOL)userTriggeredDisconnect;

@@ -336,6 +336,8 @@ - (BOOL)isConnectedViaSSL
*
* WARNING: This method may return NO if the current thread is cancelled!
* You MUST check the isCancelled flag before using the result!
*
* NOTE: In general -checkConnectionIfNecessary should be used instead!
*/
- (BOOL)checkConnection
{
@@ -374,6 +376,35 @@ - (BOOL)checkConnection
return connectionVerified;
}

/**
* If thirty seconds have passed since the last time the connection was
* used, check the connection.
* This minimises the impact of continuous additional connection checks -
* each of which requires a round trip to the server - but handles most
* network issues.
* Returns whether the connection is considered still valid.
*
* WARNING: This method may return NO if the current thread is cancelled!
* You MUST check the isCancelled flag before using the result!
*/
- (BOOL)checkConnectionIfNecessary
{

// If the connection has been dropped in the background, trigger a
// reconnect and return the success state here
if (state == SPMySQLConnectionLostInBackground) {
return [self _reconnectAllowingRetries:YES];
}

// If the connection was recently used, return success
if (_elapsedSecondsSinceAbsoluteTime(lastConnectionUsedTime) < 30) {
return YES;
}

// Otherwise check the connection
return [self checkConnection];
}

/**
* Retrieve the time elapsed since the connection was established, in seconds.
* This time is retrieved in a monotonically increasing fashion and is high
@@ -1042,35 +1073,6 @@ - (void)_restoreConnectionVariables
[self setEncodingUsesLatin1Transport:encodingUsesLatin1Transport];
}

/**
* If thirty seconds have passed since the last time the connection was
* used, check the connection.
* This minimises the impact of continuous additional connection checks -
* each of which requires a round trip to the server - but handles most
* network issues.
* Returns whether the connection is considered still valid.
*
* WARNING: This method may return NO if the current thread is cancelled!
* You MUST check the isCancelled flag before using the result!
*/
- (BOOL)_checkConnectionIfNecessary
{

// If the connection has been dropped in the background, trigger a
// reconnect and return the success state here
if (state == SPMySQLConnectionLostInBackground) {
return [self _reconnectAllowingRetries:YES];
}

// If the connection was recently used, return success
if (_elapsedSecondsSinceAbsoluteTime(lastConnectionUsedTime) < 30) {
return YES;
}

// Otherwise check the connection
return [self checkConnection];
}

/**
* Ensure that the thread this method is called on has been registered for
* use with MySQL. MySQL requires thread-specific variables for safe
@@ -551,7 +551,7 @@ - (BOOL)_ensureConnectionUnsafe
if (!mySQLConnection || !delegate) return NO;

// Check the connection state
if ([mySQLConnection isConnected] && [mySQLConnection checkConnection]) return YES;
if ([mySQLConnection isConnected] && [mySQLConnection checkConnectionIfNecessary]) return YES;

// the result of checkConnection may be meaningless if the thread was cancelled during execution. (issue #2353)
if([[NSThread currentThread] isCancelled]) return NO;

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