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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 $sName;
protected $hDBLink; protected $hDBLink;
static protected $aAcquiredLocks = array();
public function __construct($sName) public function __construct($sName)
{ {
// Compute the name of a lock for mysql // Compute the name of a lock for mysql
// Note: the name is server-wide!!! // Note: the name is server-wide!!!
$this->sName = 'itop.'.$sName; $this->sName = 'itop.'.$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 // 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) // 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() public function Lock()
{ {
do if (self::$aAcquiredLocks[$this->sName] == 0)
{ {
$res = $this->QueryToScalar("SELECT GET_LOCK('".$this->sName."', 3600)"); do
if (is_null($res))
{ {
throw new Exception("Failed to acquire the lock '".$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
} }
// $res === '1' means I hold the lock while ($res !== '1');
// $res === '0' means it timed out
} }
while ($res !== '1'); self::$aAcquiredLocks[$this->sName]++;
} }
/** /**
@@ -74,6 +84,12 @@ class iTopMutex
*/ */
public function TryLock() public function TryLock()
{ {
if (self::$aAcquiredLocks[$this->sName] > 0)
{
self::$aAcquiredLocks[$this->sName]++;
return true;
}
$res = $this->QueryToScalar("SELECT GET_LOCK('".$this->sName."', 0)"); $res = $this->QueryToScalar("SELECT GET_LOCK('".$this->sName."', 0)");
if (is_null($res)) if (is_null($res))
{ {
@@ -81,6 +97,10 @@ class iTopMutex
} }
// $res === '1' means I hold the lock // $res === '1' means I hold the lock
// $res === '0' means it timed out // $res === '0' means it timed out
if ($res === '1')
{
self::$aAcquiredLocks[$this->sName]++;
}
return ($res === '1'); return ($res === '1');
} }
@@ -89,7 +109,13 @@ class iTopMutex
*/ */
public function Unlock() 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]--;
} }