Merge pull request #410 from vibe-d/log_yield_lock_improvement

Fix issues with the yield locking in the logging code

source/vibe/core/core.d

@@ -1660,6 +1660,15 @@ unittest {
 	assert(!tf.isInYieldLock());
 }
 
+
+/** Less strict version of `yieldLock` that only locks if called within a task.
+*/
+auto taskYieldLock(string file = __FILE__, int line = __LINE__)
+@safe nothrow {
+	if (!Fiber.getThis()) return typeof(yieldLock()).init;
+	return yieldLock(file, line);
+}
+
 debug (VibeRunningTasks) {
 	/** Dumps a list of all active tasks of the calling thread.
 	*/

source/vibe/core/log.d

@@ -1075,7 +1075,7 @@ unittest { // ensure arguments are evaluated lazily
 }
 
 private struct LogOutputRange {
-	import vibe.core.core : yieldLock;
+	import vibe.core.core : taskYieldLock;
 
 	LogLine info;
 	ScopedLock!Logger* logger;
@@ -1084,7 +1084,7 @@ private struct LogOutputRange {
 
 	this(ref ScopedLock!Logger logger, string file, int line, LogLevel level)
 	{
-		auto l = yieldLock();
+		auto l = taskYieldLock();
 
 		() @trusted { this.logger = &logger; } ();
 		try {
@@ -1111,7 +1111,7 @@ private struct LogOutputRange {
 
 	void finalize()
 	{
-		auto l = yieldLock();
+		auto l = taskYieldLock();
 
 		logger.endLine();
 	}
@@ -1121,7 +1121,7 @@ private struct LogOutputRange {
 		if (text.empty)
 			return;
 
-		auto l = yieldLock();
+		auto l = taskYieldLock();
 
 		if (logger.multilineLogger) {
 			logger.put(text);

source/vibe/core/task.d

@@ -707,18 +707,20 @@ final package class TaskFiber : Fiber {
 	@safe nothrow @nogc {
 		// only record the outermost lock
 		if (m_yieldLockCount > 0) return;
+		assert (m_yieldLockCount == 0, "Yield lock counter negative!?");
 		m_yieldLockFile = file;
 		m_yieldLockLine = line;
 	}
 
 	package void acquireYieldLock()
 	@safe nothrow @nogc {
+		assert (m_yieldLockCount >= 0, "Acquiring yield lock with negative yield lock counter!?");
 		m_yieldLockCount++;
 	}
 
 	package void releaseYieldLock()
 	@safe nothrow @nogc {
-		assert(m_yieldLockCount > 0);
+		assert (m_yieldLockCount > 0, "Releasing yield lock with non-positive yield lock counter!?");
 		if (!--m_yieldLockCount) {
 			m_yieldLockFile = null;
 			m_yieldLockLine = -1;
@@ -729,7 +731,7 @@ final package class TaskFiber : Fiber {
 	@safe nothrow {
 		if (m_yieldLockCount > 0 && m_yieldLockFile.length)
 			logError("Yield lock violation for lock at %s:%s", m_yieldLockFile, m_yieldLockLine);
-		assert(m_yieldLockCount == 0, "May not yield while in an active yieldLock()!");
+		assert (m_yieldLockCount == 0, "May not yield while in an active yieldLock()!");
 	}
 
 	package bool isInYieldLock()