Add IpcSharedSignal.

Author: asfernandes

src/common/ipc/IpcSharedSignal.h

@@ -0,0 +1,178 @@
+/*
+ *  The contents of this file are subject to the Initial
+ *  Developer's Public License Version 1.0 (the "License");
+ *  you may not use this file except in compliance with the
+ *  License. You may obtain a copy of the License at
+ *  http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_idpl.
+ *
+ *  Software distributed under the License is distributed AS IS,
+ *  WITHOUT WARRANTY OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing rights
+ *  and limitations under the License.
+ *
+ *  The Original Code was created by Adriano dos Santos Fernandes
+ *  for the Firebird Open Source RDBMS project.
+ *
+ *  Copyright (c) 2025 Adriano dos Santos Fernandes <[email protected]>
+ *  and all contributors signed below.
+ *
+ *  All Rights Reserved.
+ *  Contributor(s): ______________________________________.
+ */
+
+#ifndef COMMON_IPC_SHARED_SIGNAL_H
+#define COMMON_IPC_SHARED_SIGNAL_H
+
+#include "firebird.h"
+
+#ifdef WIN_NT
+#error This is not supported in Windows.
+#endif
+
+#ifndef PTHREAD_PROCESS_SHARED
+#error Your system must support PTHREAD_PROCESS_SHARED to use firebird.
+#endif
+
+#include "../StatusArg.h"
+#include "../common/os/mac_utils.h"
+#include "../utils_proto.h"
+#include <chrono>
+#include "fb_pthread.h"
+
+namespace Firebird {
+
+
+class IpcSharedSignal
+{
+public:
+	explicit IpcSharedSignal();
+	~IpcSharedSignal();
+
+	IpcSharedSignal(const IpcSharedSignal&) = delete;
+	IpcSharedSignal& operator=(const IpcSharedSignal&) = delete;
+
+public:
+	void reset();
+	void signal();
+	bool wait(std::chrono::microseconds timeout);
+
+private:
+	pthread_mutex_t mutex[1];
+	pthread_cond_t cond[1];
+	std::atomic_uint8_t flag = 0;
+};
+
+
+inline IpcSharedSignal::IpcSharedSignal()
+{
+	pthread_mutexattr_t mattr;
+	pthread_condattr_t cattr;
+
+	if (pthread_mutexattr_init(&mattr) != 0)
+		system_error::raise("pthread_mutexattr_init");
+
+	if (pthread_condattr_init(&cattr) != 0)
+		system_error::raise("pthread_condattr_init");
+
+	if (!isSandboxed())
+	{
+		if (pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED) != 0)
+			system_error::raise("pthread_mutexattr_setpshared");
+
+		if (pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED) != 0)
+			system_error::raise("pthread_condattr_setpshared");
+	}
+
+	if (pthread_mutex_init(mutex, &mattr) != 0)
+		system_error::raise("pthread_mutex_init");
+
+	if (pthread_cond_init(cond, &cattr) != 0)
+		system_error::raise("pthread_cond_init");
+
+	if (pthread_mutexattr_destroy(&mattr) != 0)
+		system_error::raise("pthread_mutexattr_destroy");
+
+	if (pthread_condattr_destroy(&cattr) != 0)
+		system_error::raise("pthread_condattr_destroy");
+}
+
+inline IpcSharedSignal::~IpcSharedSignal()
+{
+	pthread_mutex_destroy(mutex);
+	pthread_cond_destroy(cond);
+}
+
+inline void IpcSharedSignal::reset()
+{
+	flag.store(0, std::memory_order_relaxed);
+}
+
+inline void IpcSharedSignal::signal()
+{
+	// FIXME: check errors
+
+	if (pthread_mutex_lock(mutex) != 0)
+		system_error::raise("pthread_mutex_lock");
+
+	flag.store(1, std::memory_order_relaxed);
+	const int ret = pthread_cond_broadcast(cond);
+	pthread_mutex_unlock(mutex);
+
+	if (ret != 0)
+		system_error::raise("pthread_cond_broadcast");
+}
+
+inline bool IpcSharedSignal::wait(std::chrono::microseconds timeout)
+{
+	if (flag.load(std::memory_order_acquire) == 1)
+		return true;
+
+	timespec timer;
+
+#if defined(HAVE_CLOCK_GETTIME)
+	clock_gettime(CLOCK_REALTIME, &timer);
+#elif defined(HAVE_GETTIMEOFDAY)
+	struct timeval tp;
+	GETTIMEOFDAY(&tp);
+	timer.tv_sec = tp.tv_sec;
+	timer.tv_nsec = tp.tv_usec * 1'000;
+#else
+	struct timeb time_buffer;
+	ftime(&time_buffer);
+	timer.tv_sec = time_buffer.time;
+	timer.tv_nsec = time_buffer.millitm * 1'000'000;
+#endif
+
+	bool ret = true;
+	pthread_mutex_lock(mutex);
+
+	do
+	{
+		if (flag.load(std::memory_order_relaxed) == 1)
+		{
+			ret = true;
+			break;
+		}
+
+		// The Posix pthread_cond_wait & pthread_cond_timedwait calls
+		// atomically release the mutex and start a wait.
+		// The mutex is reacquired before the call returns.
+		const auto wait = pthread_cond_timedwait(cond, mutex, &timer);
+
+		if (wait == ETIMEDOUT)
+		{
+			// The timer expired - see if the event occurred and return
+			ret = flag.load(std::memory_order_relaxed) == 1;
+			break;
+		}
+	} while(true);
+
+	pthread_mutex_unlock(mutex);
+
+	return ret;
+}
+
+
+} // namespace Firebird
+
+#endif // COMMON_IPC_SHARED_SIGNAL_H