7 files changed, 192 insertions, 23 deletions

diff --git a/include/libcamera/base/meson.build b/include/libcamera/base/meson.build
index 1a71ce5a..37c4435a 100644
--- a/include/libcamera/base/meson.build
+++ b/include/libcamera/base/meson.build
@@ -13,6 +13,7 @@ libcamera_base_headers = files([
     'flags.h',
     'log.h',
     'message.h',
+    'mutex.h',
     'object.h',
     'private.h',
     'semaphore.h',
diff --git a/include/libcamera/base/mutex.h b/include/libcamera/base/mutex.h
new file mode 100644
index 00000000..2d23e49e
--- /dev/null
+++ b/include/libcamera/base/mutex.h
@@ -0,0 +1,132 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * mutex.h - Mutex classes with clang thread safety annotation
+ */
+
+#pragma once
+
+#include <condition_variable>
+#include <mutex>
+
+#include <libcamera/base/thread_annotations.h>
+
+namespace libcamera {
+
+/* \todo using Mutex = std::mutex if libc++ is used. */
+
+#ifndef __DOXYGEN__
+
+class LIBCAMERA_TSA_CAPABILITY("mutex") Mutex final
+{
+public:
+	constexpr Mutex()
+	{
+	}
+
+	void lock() LIBCAMERA_TSA_ACQUIRE()
+	{
+		mutex_.lock();
+	}
+
+	void unlock() LIBCAMERA_TSA_RELEASE()
+	{
+		mutex_.unlock();
+	}
+
+private:
+	friend class MutexLocker;
+
+	std::mutex mutex_;
+};
+
+class LIBCAMERA_TSA_SCOPED_CAPABILITY MutexLocker final
+{
+public:
+	explicit MutexLocker(Mutex &mutex) LIBCAMERA_TSA_ACQUIRE(mutex)
+		: lock_(mutex.mutex_)
+	{
+	}
+
+	MutexLocker(Mutex &mutex, std::defer_lock_t t) noexcept LIBCAMERA_TSA_EXCLUDES(mutex)
+		: lock_(mutex.mutex_, t)
+	{
+	}
+
+	~MutexLocker() LIBCAMERA_TSA_RELEASE()
+	{
+	}
+
+	void lock() LIBCAMERA_TSA_ACQUIRE()
+	{
+		lock_.lock();
+	}
+
+	bool try_lock() LIBCAMERA_TSA_TRY_ACQUIRE(true)
+	{
+		return lock_.try_lock();
+	}
+
+	void unlock() LIBCAMERA_TSA_RELEASE()
+	{
+		lock_.unlock();
+	}
+
+private:
+	friend class ConditionVariable;
+
+	std::unique_lock<std::mutex> lock_;
+};
+
+class ConditionVariable final
+{
+public:
+	ConditionVariable()
+	{
+	}
+
+	void notify_one() noexcept
+	{
+		cv_.notify_one();
+	}
+
+	void notify_all() noexcept
+	{
+		cv_.notify_all();
+	}
+
+	template<class Predicate>
+	void wait(MutexLocker &locker, Predicate stopWaiting)
+	{
+		cv_.wait(locker.lock_, stopWaiting);
+	}
+
+	template<class Rep, class Period, class Predicate>
+	bool wait_for(MutexLocker &locker,
+		      const std::chrono::duration<Rep, Period> &relTime,
+		      Predicate stopWaiting)
+	{
+		return cv_.wait_for(locker.lock_, relTime, stopWaiting);
+	}
+
+private:
+	std::condition_variable cv_;
+};
+
+#else /* __DOXYGEN__ */
+
+class Mutex final
+{
+};
+
+class MutexLocker final
+{
+};
+
+class ConditionVariable final
+{
+};
+
+#endif /* __DOXYGEN__ */
+} /* namespace libcamera */
diff --git a/include/libcamera/base/thread.h b/include/libcamera/base/thread.h
index 1ebf8363..44678c34 100644
--- a/include/libcamera/base/thread.h
+++ b/include/libcamera/base/thread.h
@@ -7,15 +7,14 @@
 
 #pragma once
 
-#include <condition_variable>
 #include <memory>
-#include <mutex>
 #include <sys/types.h>
 #include <thread>
 
 #include <libcamera/base/private.h>
 
 #include <libcamera/base/message.h>
+#include <libcamera/base/mutex.h>
 #include <libcamera/base/signal.h>
 #include <libcamera/base/utils.h>
 
@@ -27,10 +26,6 @@ class Object;
 class ThreadData;
 class ThreadMain;
 
-using ConditionVariable = std::condition_variable;
-using Mutex = std::mutex;
-using MutexLocker = std::unique_lock<std::mutex>;
-
 class Thread
 {
 public:
diff --git a/src/libcamera/base/meson.build b/src/libcamera/base/meson.build
index 05fed7ac..b93b8505 100644
--- a/src/libcamera/base/meson.build
+++ b/src/libcamera/base/meson.build
@@ -11,6 +11,7 @@ libcamera_base_sources = files([
     'flags.cpp',
     'log.cpp',
     'message.cpp',
+    'mutex.cpp',
     'object.cpp',
     'semaphore.cpp',
     'signal.cpp',
diff --git a/src/libcamera/base/mutex.cpp b/src/libcamera/base/mutex.cpp
new file mode 100644
index 00000000..e34e8618
--- /dev/null
+++ b/src/libcamera/base/mutex.cpp
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * mutex.cpp - Mutex classes with clang thread safety annotation
+ */
+
+#include <libcamera/base/mutex.h>
+
+/**
+ * \file base/mutex.h
+ * \brief Mutex classes with clang thread safety annotation
+ */
+
+namespace libcamera {
+
+/**
+ * \class Mutex
+ * \brief std::mutex wrapper with clang thread safety annotation
+ *
+ * The Mutex class wraps a std::mutex instance to add clang thread safety
+ * annotation support. The class exposes the same interface as std::mutex and
+ * can be used as a transparent replacement. It integrates with the
+ * MutexLocker and ConditionVariable classes.
+ *
+ * See https://en.cppreference.com/w/cpp/thread/mutex for the complete API
+ * documentation.
+ */
+
+/**
+ * \class MutexLocker
+ * \brief std::unique_lock wrapper with clang thread safety annotation
+ *
+ * The MutexLocker class wraps a std::unique_lock instance to add clang thread
+ * safety annotation support. The class exposes the same interface as
+ * std::unique_lock and can be used as a transparent replacement. It integrates
+ * with the Mutex and ConditionVariable classes.
+ *
+ * See https://en.cppreference.com/w/cpp/thread/unique_lock for the complete API
+ * documentation.
+ */
+
+/**
+ * \class ConditionVariable
+ * \brief std::condition_variable wrapper integrating with MutexLocker
+ *
+ * The ConditionVariable class wraps a std::condition_variable instance to
+ * integrate with the MutexLocker class. The class exposes the same interface as
+ * std::condition_variable and can be used as a transparent replacement.
+ *
+ * See https://en.cppreference.com/w/cpp/thread/condition_variable for the
+ * complete API documentation.
+ */
+
+} /* namespace libcamera */
diff --git a/src/libcamera/base/thread.cpp b/src/libcamera/base/thread.cpp
index b893135f..b2043b7e 100644
--- a/src/libcamera/base/thread.cpp
+++ b/src/libcamera/base/thread.cpp
@@ -205,21 +205,6 @@ ThreadData *ThreadData::current()
 }
 
 /**
- * \typedef ConditionVariable
- * \brief An alias for std::condition_variable
- */
-
-/**
- * \typedef Mutex
- * \brief An alias for std::mutex
- */
-
-/**
- * \typedef MutexLocker
- * \brief An alias for std::unique_lock<std::mutex>
- */
-
-/**
  * \class Thread
  * \brief A thread of execution
  *
diff --git a/src/v4l2/v4l2_camera_proxy.h b/src/v4l2/v4l2_camera_proxy.h
index 040954dd..fa0a49e0 100644
--- a/src/v4l2/v4l2_camera_proxy.h
+++ b/src/v4l2/v4l2_camera_proxy.h
@@ -14,7 +14,7 @@
 #include <sys/types.h>
 #include <vector>
 
-#include <libcamera/base/thread.h>
+#include <libcamera/base/mutex.h>
 
 #include <libcamera/camera.h>
 
@@ -59,7 +59,7 @@ private:
 	int vidioc_querybuf(V4L2CameraFile *file, struct v4l2_buffer *arg);
 	int vidioc_qbuf(V4L2CameraFile *file, struct v4l2_buffer *arg);
 	int vidioc_dqbuf(V4L2CameraFile *file, struct v4l2_buffer *arg,
-			 libcamera::Mutex *lock);
+			 libcamera::Mutex *lock) LIBCAMERA_TSA_REQUIRES(*lock);
 	int vidioc_streamon(V4L2CameraFile *file, int *arg);
 	int vidioc_streamoff(V4L2CameraFile *file, int *arg);