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Allow re-entrance in the same named mutex within the same PHP page.

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SVN:trunk[3115]
This commit is contained in:
Denis Flaven
2014-04-01 09:50:21 +00:00
parent 7a193d1c24
commit ce9806b01c
1 changed files with 34 additions and 8 deletions
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42
core/mutex.class.inc.php
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@@ -31,12 +31,18 @@ class iTopMutex
{
protected $sName;
protected $hDBLink;
static protected $aAcquiredLocks = array();
public function __construct($sName)
{
// Compute the name of a lock for mysql
// Note: the name is server-wide!!!
$this->sName = 'itop.'.$sName;
if (!array_key_exists($this->sName, self::$aAcquiredLocks))
{
self::$aAcquiredLocks[$this->sName] = 0;
}
// It is a MUST to create a dedicated session each time a lock is required, because
// using GET_LOCK anytime on the same session will RELEASE the current and unique session lock (known issue)
@@ -55,17 +61,21 @@ class iTopMutex
*/
public function Lock()
{
do
if (self::$aAcquiredLocks[$this->sName] == 0)
{
$res = $this->QueryToScalar("SELECT GET_LOCK('".$this->sName."', 3600)");
if (is_null($res))
do
{
throw new Exception("Failed to acquire the lock '".$this->sName."'");
$res = $this->QueryToScalar("SELECT GET_LOCK('".$this->sName."', 3600)");
if (is_null($res))
{
throw new Exception("Failed to acquire the lock '".$this->sName."'");
}
// $res === '1' means I hold the lock
// $res === '0' means it timed out
}
// $res === '1' means I hold the lock
// $res === '0' means it timed out
while ($res !== '1');
}
while ($res !== '1');
self::$aAcquiredLocks[$this->sName]++;
}
/**
@@ -74,6 +84,12 @@ class iTopMutex
*/
public function TryLock()
{
if (self::$aAcquiredLocks[$this->sName] > 0)
{
self::$aAcquiredLocks[$this->sName]++;
return true;
}
$res = $this->QueryToScalar("SELECT GET_LOCK('".$this->sName."', 0)");
if (is_null($res))
{
@@ -81,6 +97,10 @@ class iTopMutex
}
// $res === '1' means I hold the lock
// $res === '0' means it timed out
if ($res === '1')
{
self::$aAcquiredLocks[$this->sName]++;
}
return ($res === '1');
}
@@ -89,7 +109,13 @@ class iTopMutex
*/
public function Unlock()
{
$res = $this->QueryToScalar("SELECT RELEASE_LOCK('".$this->sName."')");
if (self::$aAcquiredLocks[$this->sName] == 0) return; // Safety net
if (self::$aAcquiredLocks[$this->sName] == 1)
{
$res = $this->QueryToScalar("SELECT RELEASE_LOCK('".$this->sName."')");
}
self::$aAcquiredLocks[$this->sName]--;
}