Fixed 1 second delay for child processes.

lib/base/process.cpp

@@ -24,7 +24,7 @@ using namespace icinga;
 bool Process::m_ThreadCreated = false;
 boost::mutex Process::m_Mutex;
 deque<Process::Ptr> Process::m_Tasks;
-condition_variable Process::m_TasksCV;
+int Process::m_TaskFd;
 
 Process::Process(const String& command, const Dictionary::Ptr& environment)
 	: AsyncTask<Process, ProcessResult>(), m_Command(command),
@@ -33,7 +33,14 @@ Process::Process(const String& command, const Dictionary::Ptr& environment)
 	assert(Application::IsMainThread());
 
 	if (!m_ThreadCreated) {
-		thread t(&Process::WorkerThreadProc);
+		int fds[2];
+
+		if (pipe(fds) < 0)
+			BOOST_THROW_EXCEPTION(PosixException("pipe() failed.", errno));
+
+		m_TaskFd = fds[1];
+
+		thread t(&Process::WorkerThreadProc, fds[0]);
 		t.detach();
 
 		m_ThreadCreated = true;
@@ -42,21 +49,24 @@ Process::Process(const String& command, const Dictionary::Ptr& environment)
 
 void Process::Run(void)
 {
+	{
 		boost::mutex::scoped_lock lock(m_Mutex);
 		m_Tasks.push_back(GetSelf());
-	m_TasksCV.notify_all();
+	}
+
+	/**
+	 * This little gem which is commonly known as the "self-pipe trick"
+	 * takes care of waking up the select() call in the worker thread.
+	 */
+	if (write(m_TaskFd, "T", 1) < 0)
+		BOOST_THROW_EXCEPTION(PosixException("write() failed.", errno));
 }
 
-void Process::WorkerThreadProc(void)
+void Process::WorkerThreadProc(int taskFd)
 {
-	boost::mutex::scoped_lock lock(m_Mutex);
-
 	map<int, Process::Ptr> tasks;
 
 	for (;;) {
-		while (m_Tasks.empty() || tasks.size() >= MaxTasksPerThread) {
-			lock.unlock();
-
 		map<int, Process::Ptr>::iterator it, prev;
 
 #ifndef _MSC_VER
@@ -64,6 +74,10 @@ void Process::WorkerThreadProc(void)
 		int nfds = 0;
 
 		FD_ZERO(&readfds);
+		FD_SET(taskFd, &readfds);
+
+		if (taskFd > nfds)
+			nfds = taskFd;
 
 		int fd;
 		BOOST_FOREACH(tie(fd, tuples::ignore), tasks) {
@@ -81,6 +95,37 @@ void Process::WorkerThreadProc(void)
 		Utility::Sleep(1);
 #endif /* _MSC_VER */
 
+		if (FD_ISSET(taskFd, &readfds)) {
+			/* clear pipe */
+			char buffer[512];
+			int rc = read(taskFd, buffer, sizeof(buffer));
+			assert(rc >= 1);
+
+			while (tasks.size() < MaxTasksPerThread) {
+				Process::Ptr task;
+
+				{
+					boost::mutex::scoped_lock lock(m_Mutex);
+
+					if (m_Tasks.empty())
+						break;
+
+					task = m_Tasks.front();
+					m_Tasks.pop_front();
+				}
+
+				try {
+					task->InitTask();
+
+					int fd = task->GetFD();
+					if (fd >= 0)
+						tasks[fd] = task;
+				} catch (...) {
+					Event::Post(boost::bind(&Process::FinishException, task, boost::current_exception()));
+				}
+			}
+		}
+
 		for (it = tasks.begin(); it != tasks.end(); ) {
 			int fd = it->first;
 			Process::Ptr task = it->second;
@@ -102,28 +147,6 @@ void Process::WorkerThreadProc(void)
 				it++;
 			}
 		}
-
-			lock.lock();
-		}
-
-		while (!m_Tasks.empty() && tasks.size() < MaxTasksPerThread) {
-			Process::Ptr task = m_Tasks.front();
-			m_Tasks.pop_front();
-
-			lock.unlock();
-
-			try {
-				task->InitTask();
-
-				int fd = task->GetFD();
-				if (fd >= 0)
-					tasks[fd] = task;
-			} catch (...) {
-				Event::Post(boost::bind(&Process::FinishException, task, boost::current_exception()));
-			}
-
-			lock.lock();
-		}
 	}
 }
 

lib/base/process.h

@@ -71,9 +71,9 @@ private:
 
 	static boost::mutex m_Mutex;
 	static deque<Process::Ptr> m_Tasks;
-	static condition_variable m_TasksCV;
+	static int m_TaskFd;
 
-	static void WorkerThreadProc(void);
+	static void WorkerThreadProc(int taskFd);
 
 	void InitTask(void);
 	bool RunTask(void);