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Proper handling of the re-entrence of the Lock/Unlock within the same PHP page. Previously the code was sometimes performing 2 Unlock() for each Lock().

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SVN:trunk[3217]
This commit is contained in:
Denis Flaven
2014-06-18 15:24:31 +00:00
parent 7ddd74a95e
commit a72e15023f
1 changed files with 30 additions and 4 deletions
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34
core/mutex.class.inc.php
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@@ -31,14 +31,16 @@ class iTopMutex
{
protected $sName;
protected $hDBLink;
static protected $aAcquiredLocks = array();
protected $bLocked; // Whether or not this instance of the Mutex is locked
static protected $aAcquiredLocks = array(); // Number of instances of the Mutex, having the lock, in this page
public function __construct($sName)
{
// Compute the name of a lock for mysql
// Note: the name is server-wide!!!
$this->sName = 'itop.'.$sName;
$this->bLocked = false; // Not yet locked
if (!array_key_exists($this->sName, self::$aAcquiredLocks))
{
self::$aAcquiredLocks[$this->sName] = 0;
@@ -52,7 +54,10 @@ class iTopMutex
public function __destruct()
{
$this->Unlock();
if ($this->bLocked)
{
$this->Unlock();
}
mysqli_close($this->hDBLink);
}
@@ -61,6 +66,11 @@ class iTopMutex
*/
public function Lock()
{
if ($this->bLocked)
{
// Lock already acquired
return;
}
if (self::$aAcquiredLocks[$this->sName] == 0)
{
do
@@ -75,6 +85,7 @@ class iTopMutex
}
while ($res !== '1');
}
$this->bLocked = true;
self::$aAcquiredLocks[$this->sName]++;
}
@@ -84,9 +95,14 @@ class iTopMutex
*/
public function TryLock()
{
if ($this->bLocked)
{
return true; // Already acquired
}
if (self::$aAcquiredLocks[$this->sName] > 0)
{
self::$aAcquiredLocks[$this->sName]++;
$this->bLocked = true;
return true;
}
@@ -99,6 +115,7 @@ class iTopMutex
// $res === '0' means it timed out
if ($res === '1')
{
$this->bLocked = true;
self::$aAcquiredLocks[$this->sName]++;
}
return ($res === '1');
@@ -109,12 +126,21 @@ class iTopMutex
*/
public function Unlock()
{
if (self::$aAcquiredLocks[$this->sName] == 0) return; // Safety net
if (!$this->bLocked)
{
// ??? the lock is not acquired, exit
return;
}
if (self::$aAcquiredLocks[$this->sName] == 0)
{
return; // Safety net
}
if (self::$aAcquiredLocks[$this->sName] == 1)
{
$res = $this->QueryToScalar("SELECT RELEASE_LOCK('".$this->sName."')");
}
$this->bLocked = false;
self::$aAcquiredLocks[$this->sName]--;
}