1 files changed, 43 insertions, 6 deletions
diff --git a/indra/llcommon/llmutex.h b/indra/llcommon/llmutex.h
index db5b9357d9..3659a319a2 100644
--- a/indra/llcommon/llmutex.h
+++ b/indra/llcommon/llmutex.h
@@ -48,18 +48,19 @@ public:
 	LLMutex(apr_pool_t *apr_poolp = NULL); // NULL pool constructs a new pool for the mutex
 	virtual ~LLMutex();
 	
-	void lock();		       // blocks
-	void unlock();
-	bool isLocked(); 	       // non-blocking, but does do a lock/unlock so not free
-	bool isSelfLocked();       //return true if locked in a same thread
+	void lock();		// blocks
+	bool trylock();		// non-blocking, returns true if lock held.
+	void unlock();		// undefined behavior when called on mutex not being held
+	bool isLocked(); 	// non-blocking, but does do a lock/unlock so not free
+	bool isSelfLocked(); //return true if locked in a same thread
 	U32 lockingThread() const; //get ID of locking thread
 	
 protected:
-	apr_thread_mutex_t*	mAPRMutexp;
+	apr_thread_mutex_t *mAPRMutexp;
 	mutable U32			mCount;
 	mutable U32			mLockingThread;
 	
-	apr_pool_t*			mAPRPoolp;
+	apr_pool_t			*mAPRPoolp;
 	BOOL				mIsLocalPool;
 	
 #if MUTEX_DEBUG
@@ -101,4 +102,40 @@ private:
 	LLMutex* mMutex;
 };
 
+//============================================================================
+
+// Scoped locking class similar in function to LLMutexLock but uses
+// the trylock() method to conditionally acquire lock without
+// blocking.  Caller resolves the resulting condition by calling
+// the isLocked() method and either punts or continues as indicated.
+//
+// Mostly of interest to callers needing to avoid stalls who can
+// guarantee another attempt at a later time.
+
+class LLMutexTrylock
+{
+public:
+	LLMutexTrylock(LLMutex* mutex)
+		: mMutex(mutex),
+		  mLocked(false)
+	{
+		if (mMutex)
+			mLocked = mMutex->trylock();
+	}
+
+	~LLMutexTrylock()
+	{
+		if (mMutex && mLocked)
+			mMutex->unlock();
+	}
+
+	bool isLocked() const
+	{
+		return mLocked;
+	}
+	
+private:
+	LLMutex*	mMutex;
+	bool		mLocked;
+};
 #endif // LL_LLTHREAD_H