Merge remote-tracking branch 'origin/topic/johanna/threads'

Tweaked the new threading code a bit more.

* origin/topic/johanna/threads:
  Move threading to c++11 primitives (mostly).

src/threading/Queue.h

@@ -1,7 +1,8 @@
 #ifndef THREADING_QUEUE_H
 #define THREADING_QUEUE_H
 
-#include <pthread.h>
+#include <mutex>
+#include <condition_variable>
 #include <queue>
 #include <deque>
 #include <stdint.h>
@@ -22,7 +23,7 @@ namespace threading {
  *
  * All Queue instances must be instantiated by Bro's main thread.
  *
- * TODO: Unclear how critical performance is for this qeueue. We could like;y
+ * TODO: Unclear how critical performance is for this qeueue. We could likely
  * optimize it further if helpful.
  */
 template<typename T>
@@ -71,9 +72,10 @@ public:
 	 */
 	bool MaybeReady() { return (num_reads != num_writes); }
 
-	/** Wake up the reader if it's currently blocked for input. This is
-	 primarily to give it a chance to check termination quickly.
-	**/
+	/**
+	 * Wake up the reader if it's currently blocked for input. This is
+	 * primarily to give it a chance to check termination quickly.
+	 */
 	void WakeUp();
 
 	/**
@@ -94,14 +96,17 @@ public:
 	 * Returns statistics about the queue's usage.
 	 *
 	 * @param stats A pointer to a structure that will be filled with
-	 * current numbers. */
+	 * current numbers.
+	 */
 	void GetStats(Stats* stats);
 
 private:
 	static const int NUM_QUEUES = 8;
 
-	pthread_mutex_t mutex[NUM_QUEUES];	// Mutex protected shared accesses.
-	pthread_cond_t has_data[NUM_QUEUES];	// Signals when data becomes available
+	std::vector<std::unique_lock<std::mutex>> LocksForAllQueues();
+
+	std::mutex mutex[NUM_QUEUES];	// Mutex protected shared accesses.
+	std::condition_variable has_data[NUM_QUEUES];	// Signals when data becomes available
 	std::queue<T> messages[NUM_QUEUES];	// Actually holds the queued messages
 
 	int read_ptr;	// Where the next operation will read from
@@ -115,17 +120,18 @@ private:
 	uint64_t num_writes;
 };
 
-inline static void safe_lock(pthread_mutex_t* mutex)
+inline static std::unique_lock<std::mutex> acquire_lock(std::mutex& m)
 	{
-	int res = pthread_mutex_lock(mutex);
-	if ( res != 0 )
-		reporter->FatalErrorWithCore("cannot lock mutex: %d(%s)", res, strerror(res));
-	}
-
-inline static void safe_unlock(pthread_mutex_t* mutex)
-	{
-	if ( pthread_mutex_unlock(mutex) != 0 )
-		reporter->FatalErrorWithCore("cannot unlock mutex");
+	try
+		{
+		return std::move(std::unique_lock<std::mutex>(m));
+		}
+	catch ( const std::system_error& e )
+		{
+		reporter->FatalErrorWithCore("cannot lock mutex: %s", e.what());
+		// Never gets here.
+		throw std::exception();
+		}
 	}
 
 template<typename T>
@@ -136,50 +142,28 @@ inline Queue<T>::Queue(BasicThread* arg_reader, BasicThread* arg_writer)
 	num_reads = num_writes = 0;
 	reader = arg_reader;
 	writer = arg_writer;
-
-	for( int i = 0; i < NUM_QUEUES; ++i )
-		{
-		if ( pthread_cond_init(&has_data[i], 0) != 0 )
-			reporter->FatalError("cannot init queue condition variable");
-
-		if ( pthread_mutex_init(&mutex[i], 0) != 0 )
-			reporter->FatalError("cannot init queue mutex");
-		}
 	}
 
 template<typename T>
 inline Queue<T>::~Queue()
 	{
-	for( int i = 0; i < NUM_QUEUES; ++i )
-		{
-		pthread_cond_destroy(&has_data[i]);
-		pthread_mutex_destroy(&mutex[i]);
-		}
 	}
 
 template<typename T>
 inline T Queue<T>::Get()
 	{
-	safe_lock(&mutex[read_ptr]);
+	auto lock = acquire_lock(mutex[read_ptr]);
 
 	int old_read_ptr = read_ptr;
 
 	if ( messages[read_ptr].empty() && ! ((reader && reader->Killed()) || (writer && writer->Killed())) )
 		{
-		struct timespec ts;
-		ts.tv_sec = time(0) + 5;
-		ts.tv_nsec = 0;
-
-		pthread_cond_timedwait(&has_data[read_ptr], &mutex[read_ptr], &ts);
-		safe_unlock(&mutex[read_ptr]);
-		return 0;
+		if ( has_data[read_ptr].wait_for(lock, std::chrono::seconds(5)) == std::cv_status::timeout )
+			return nullptr;
 		}
 
-	else if ( messages[read_ptr].empty() )
-		{
-		safe_unlock(&mutex[read_ptr]);
-		return 0;
-		}
+	if ( messages[read_ptr].empty() )
+		return nullptr;
 
 	T data = messages[read_ptr].front();
 	messages[read_ptr].pop();
@@ -187,15 +171,13 @@ inline T Queue<T>::Get()
 	read_ptr = (read_ptr + 1) % NUM_QUEUES;
 	++num_reads;
 
-	safe_unlock(&mutex[old_read_ptr]);
-
 	return data;
 	}
 
 template<typename T>
 inline void Queue<T>::Put(T data)
 	{
-	safe_lock(&mutex[write_ptr]);
+	auto lock = acquire_lock(mutex[write_ptr]);
 
 	int old_write_ptr = write_ptr;
 
@@ -203,43 +185,59 @@ inline void Queue<T>::Put(T data)
 
 	messages[write_ptr].push(data);
 
-	if ( need_signal )
-		pthread_cond_signal(&has_data[write_ptr]);
-
 	write_ptr = (write_ptr + 1) % NUM_QUEUES;
 	++num_writes;
 
-	safe_unlock(&mutex[old_write_ptr]);
+	if ( need_signal )
+		{
+		lock.unlock();
+		has_data[old_write_ptr].notify_one();
+		}
 	}
 
 
 template<typename T>
 inline bool Queue<T>::Ready()
 	{
-	safe_lock(&mutex[read_ptr]);
+	auto lock = acquire_lock(mutex[read_ptr]);
 
 	bool ret = (messages[read_ptr].size());
 
-	safe_unlock(&mutex[read_ptr]);
-
 	return ret;
 	}
 
+template<typename T>
+inline std::vector<std::unique_lock<std::mutex>> Queue<T>::LocksForAllQueues()
+	{
+	std::vector<std::unique_lock<std::mutex>> locks;
+
+	try
+		{
+		for ( int i = 0; i < NUM_QUEUES; i++ )
+			locks.emplace_back(std::unique_lock<std::mutex>(mutex[i]));
+		}
+
+	catch ( const std::system_error& e )
+		{
+		reporter->FatalErrorWithCore("cannot lock all mutexes: %s", e.what());
+		// Never gets here.
+		throw std::exception();
+		}
+
+	return std::move(locks);
+	}
+
 template<typename T>
 inline uint64_t Queue<T>::Size()
 	{
 	// Need to lock all queues.
-	for ( int i = 0; i < NUM_QUEUES; i++ )
-		safe_lock(&mutex[i]);
+	auto locks = LocksForAllQueues();
 
 	uint64_t size = 0;
 
 	for ( int i = 0; i < NUM_QUEUES; i++ )
 		size += messages[i].size();
 
-	for ( int i = 0; i < NUM_QUEUES; i++ )
-		safe_unlock(&mutex[i]);
-
 	return size;
 	}
 
@@ -248,29 +246,19 @@ inline void Queue<T>::GetStats(Stats* stats)
 	{
 	// To be safe, we look all queues. That's probably unneccessary, but
 	// doesn't really hurt.
-	for ( int i = 0; i < NUM_QUEUES; i++ )
-		safe_lock(&mutex[i]);
+	auto locks = LocksForAllQueues();
 
 	stats->num_reads = num_reads;
 	stats->num_writes = num_writes;
-
-	for ( int i = 0; i < NUM_QUEUES; i++ )
-		safe_unlock(&mutex[i]);
 	}
 
 template<typename T>
 inline void Queue<T>::WakeUp()
 	{
 	for ( int i = 0; i < NUM_QUEUES; i++ )
-		{
-		safe_lock(&mutex[i]);
-		pthread_cond_signal(&has_data[i]);
-		safe_unlock(&mutex[i]);
-		}
+		has_data[i].notify_all();
 	}
 
 }
 
-
 #endif
-