[libcamera-devel] [RFC PATCH 2/6] libcamera: base: Add mutex classes with thread safety annotations

[Hirokazu Honda]

Mutex2 and MutexLocker2 are annotated by clang thread safety
annotations. So we can add annotation to code where the classes
are used.
In the future, they will replace Mutex and MutexLocker.

Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
---
 include/libcamera/base/meson.build |  1 +
 include/libcamera/base/mutex.h     | 66 ++++++++++++++++++++++++++++++
 include/libcamera/base/thread.h    |  5 +--
 3 files changed, 68 insertions(+), 4 deletions(-)
 create mode 100644 include/libcamera/base/mutex.h

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..d130988e
--- /dev/null
+++ b/include/libcamera/base/mutex.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * thread.h - Thread support
+ */
+#ifndef __LIBCAMERA_BASE_MUTEX_H__
+#define __LIBCAMERA_BASE_MUTEX_H__
+
+#include <mutex>
+
+#include <libcamera/base/thread_annotations.h>
+
+namespace libcamera {
+
+using Mutex = std::mutex;
+using MutexLocker = std::unique_lock<std::mutex>;
+
+class CAPABILITY("mutex") Mutex2 final
+{
+public:
+	void lock() ACQUIRE()
+	{
+		mutex_.lock();
+	}
+
+	void unlock() RELEASE()
+	{
+		mutex_.unlock();
+	}
+
+	std::mutex &get() { return mutex_; }
+private:
+	std::mutex mutex_;
+};
+
+class SCOPED_CAPABILITY MutexLocker2 final
+{
+public:
+	MutexLocker2(Mutex2 &mutex) ACQUIRE(mutex)
+		: lock_(mutex.get())
+	{
+	}
+
+	~MutexLocker2() RELEASE()
+	{
+	}
+
+	void lock() ACQUIRE()
+	{
+		lock_.lock();
+	}
+
+	void unlock() RELEASE()
+	{
+		lock_.unlock();
+	}
+
+	std::unique_lock<std::mutex> &get() { return lock_; }
+private:
+	std::unique_lock<std::mutex> lock_;
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_BASE_MUTEX_H__ */
diff --git a/include/libcamera/base/thread.h b/include/libcamera/base/thread.h
index e0ca0aea..ae630563 100644
--- a/include/libcamera/base/thread.h
+++ b/include/libcamera/base/thread.h
@@ -8,13 +8,13 @@
 #define __LIBCAMERA_BASE_THREAD_H__
 
 #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>
 
@@ -26,9 +26,6 @@ class Object;
 class ThreadData;
 class ThreadMain;
 
-using Mutex = std::mutex;
-using MutexLocker = std::unique_lock<std::mutex>;
-
 class Thread
 {
 public:
-- 
2.33.1.1089.g2158813163f-goog