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[Database] Added onTransactionPreCommitOrIdle() function.

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* Also fixed case where onTransactionIdle() could start uncommitted
  transactions if there was no transanction and DBO_TRX was set.

Change-Id: I0bf6171fac692cf3d6e04011321bed075f58724b
This commit is contained in:
Aaron Schulz 2013-04-10 23:54:14 -07:00 committed by Gerrit Code Review
parent 1e8a9aba9c
commit 75b16dfb5f
1 changed files with 60 additions and 15 deletions
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75
includes/db/Database.php
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@ -230,11 +230,10 @@ abstract class DatabaseBase implements DatabaseType {
protected $mConn = null;
protected $mOpened = false;
/**
* @since 1.20
* @var array of Closure
*/
/** @var array of Closure */
protected $mTrxIdleCallbacks = array();
/** @var array of Closure */
protected $mTrxPreCommitCallbacks = array();
protected $mTablePrefix;
protected $mFlags;
@ -553,12 +552,14 @@ abstract class DatabaseBase implements DatabaseType {
/**
* Returns true if there is a transaction open with possible write
* queries or transaction idle callbacks waiting on it to finish.
* queries or transaction pre-commit/idle callbacks waiting on it to finish.
*
* @return bool
*/
public function writesOrCallbacksPending() {
return $this->mTrxLevel && ( $this->mTrxDoneWrites || $this->mTrxIdleCallbacks );
return $this->mTrxLevel && (
$this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
);
}
/**
@ -964,6 +965,7 @@ abstract class DatabaseBase implements DatabaseType {
# Transaction is gone, like it or not
$this->mTrxLevel = 0;
$this->mTrxIdleCallbacks = array(); // cancel
$this->mTrxPreCommitCallbacks = array(); // cancel
wfDebug( "Connection lost, reconnecting...\n" );
if ( $this->ping() ) {
@ -2967,21 +2969,39 @@ abstract class DatabaseBase implements DatabaseType {
* Callbacks must commit any transactions that they begin.
*
* This is useful for updates to different systems or separate transactions are needed.
*
* @since 1.20
* It can also be used for updates that easily cause deadlocks if locks are held too long.
*
* @param Closure $callback
* @since 1.20
*/
final public function onTransactionIdle( Closure $callback ) {
if ( $this->mTrxLevel ) {
$this->mTrxIdleCallbacks[] = $callback;
} else {
$callback();
$this->mTrxIdleCallbacks[] = $callback;
if ( !$this->mTrxLevel ) {
$this->runOnTransactionIdleCallbacks();
}
}
/**
* Actually run the "on transaction idle" callbacks.
* Run an anonymous function before the current transaction commits or now if there is none.
* If there is a transaction and it is rolled back, then the callback is cancelled.
* Callbacks must not start nor commit any transactions.
*
* This is useful for updates that easily cause deadlocks if locks are held too long
* but where atomicity is strongly desired for these and some related updates.
*
* @param Closure $callback
* @since 1.22
*/
final public function onTransactionPreCommitOrIdle( Closure $callback ) {
if ( $this->mTrxLevel ) {
$this->mTrxPreCommitCallbacks[] = $callback;
} else {
$this->onTransactionIdle( $callback ); // this will trigger immediately
}
}
/**
* Actually any "on transaction idle" callbacks.
*
* @since 1.20
*/
@ -3007,6 +3027,28 @@ abstract class DatabaseBase implements DatabaseType {
}
}
/**
* Actually any "on transaction pre-commit" callbacks.
*
* @since 1.22
*/
protected function runOnTransactionPreCommitCallbacks() {
$e = null; // last exception
do { // callbacks may add callbacks :)
$callbacks = $this->mTrxPreCommitCallbacks;
$this->mTrxPreCommitCallbacks = array(); // recursion guard
foreach ( $callbacks as $callback ) {
try {
$callback();
} catch ( Exception $e ) {}
}
} while ( count( $this->mTrxPreCommitCallbacks ) );
if ( $e instanceof Exception ) {
throw $e; // re-throw any last exception
}
}
/**
* Begin a transaction. If a transaction is already in progress, that transaction will be committed before the
* new transaction is started.
@ -3040,6 +3082,7 @@ abstract class DatabaseBase implements DatabaseType {
}
}
$this->runOnTransactionPreCommitCallbacks();
$this->doCommit( $fname );
$this->runOnTransactionIdleCallbacks();
}
@ -3088,6 +3131,7 @@ abstract class DatabaseBase implements DatabaseType {
}
}
$this->runOnTransactionPreCommitCallbacks();
$this->doCommit( $fname );
$this->runOnTransactionIdleCallbacks();
}
@ -3119,6 +3163,7 @@ abstract class DatabaseBase implements DatabaseType {
}
$this->doRollback( $fname );
$this->mTrxIdleCallbacks = array(); // cancel
$this->mTrxPreCommitCallbacks = array(); // cancel
}
/**
@ -3704,8 +3749,8 @@ abstract class DatabaseBase implements DatabaseType {
}
public function __destruct() {
if ( count( $this->mTrxIdleCallbacks ) ) { // sanity
trigger_error( "Transaction idle callbacks still pending." );
if ( count( $this->mTrxIdleCallbacks ) || count( $this->mTrxPreCommitCallbacks ) ) {
trigger_error( "Transaction idle or pre-commit callbacks still pending." ); // sanity
}
}
}