[libcamera-devel] [PATCH v3 05/12] libcamera: base: Add mutex classes with thread safety annotations
Hirokazu Honda
hiroh at chromium.org
Tue Nov 30 16:55:53 CET 2021
This replaces Mutex and MutexLocker with our own defined classes.
The classes are annotated by clang thread safety annotations.
So we can add annotation to code where the classes are used.
v4l2 code needs to be annotated, which violates Mutex capability.
Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
---
include/libcamera/base/meson.build | 1 +
include/libcamera/base/mutex.h | 131 +++++++++++++++++++++++++++++
include/libcamera/base/thread.h | 7 +-
src/libcamera/base/meson.build | 1 +
src/libcamera/base/mutex.cpp | 121 ++++++++++++++++++++++++++
src/libcamera/base/thread.cpp | 15 ----
src/v4l2/v4l2_camera_proxy.h | 5 +-
7 files changed, 258 insertions(+), 23 deletions(-)
create mode 100644 include/libcamera/base/mutex.h
create mode 100644 src/libcamera/base/mutex.cpp
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..2792551c
--- /dev/null
+++ b/include/libcamera/base/mutex.h
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * thread.h - Thread support
+ */
+
+#pragma once
+
+#include <condition_variable>
+#include <mutex>
+
+#include <libcamera/base/thread_annotations.h>
+
+namespace libcamera {
+
+class ConditionVariable;
+
+#ifndef __DOXYGEN__
+class LIBCAMERA_TSA_SCOPED_CAPABILITY MutexLocker;
+#else
+class MutexLocker;
+#endif /* __DOXYGEN__ */
+
+/* \todo using Mutex = std::mutex if lib++ is used. */
+
+#ifndef __DOXYGEN__
+class LIBCAMERA_TSA_CAPABILITY("mutex") Mutex final
+#else
+class Mutex final
+#endif /* __DOXYGEN__ */
+{
+public:
+ constexpr Mutex()
+ {
+ }
+
+ void lock() LIBCAMERA_TSA_ACQUIRE()
+ {
+ mutex_.lock();
+ }
+
+ void unlock() LIBCAMERA_TSA_RELEASE()
+ {
+ mutex_.unlock();
+ }
+
+private:
+ friend MutexLocker;
+
+ std::mutex mutex_;
+};
+
+#ifndef __DOXYGEN__
+class LIBCAMERA_TSA_SCOPED_CAPABILITY MutexLocker final
+#else
+class MutexLocker final
+#endif /* __DOXYGEN__ */
+{
+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 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_;
+};
+
+} /* 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..327b90c0
--- /dev/null
+++ b/src/libcamera/base/mutex.cpp
@@ -0,0 +1,121 @@
+/* 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
+ */
+
+/**
+ * \fn Mutex::Mutex()
+ * \brief Construct a Mutex instance
+ */
+
+/**
+ * \fn Mutex::lock()
+ * \brief Locks std::mutex
+ */
+
+/**
+ * \fn Mutex::unlock()
+ * \brief Unlocks std::mutex
+ */
+
+/**
+ * \class MutexLocker
+ * \brief std::unique_lock wrapper with clang thread safety annotation
+ */
+
+/**
+ * \fn MutexLocker::MutexLocker(Mutex &mutex)
+ * \brief Constructs MutexLocker with \a mutex as as the associated mutex and
+ * locks \a mutex
+ * \param[in] mutex Mutex to be locked/unlocked by MutexLocker
+ *
+ * This blocks until \a mutex is acquired.
+ */
+
+/**
+ * \fn MutexLocker::MutexLocker(Mutex &mutex, std::defer_lock_t t)
+ * \brief Constructs MutexLocker with \a mutex as as the associated mutex but
+ * does not lock \a mutex
+ * \param[in] mutex Mutex to be locked/unlocked by MutexLocker
+ * \param[in] t mark to specify this constructor is called1
+ *
+ */
+
+/**
+ * \fn MutexLocker::~MutexLocker()
+ * \brief Destroys MutexLocker and unlock the associated mutex if it is locked
+ */
+
+/**
+ * \fn MutexLocker::lock()
+ * \brief Locks the associated mutex
+ */
+
+/**
+ * \fn MutexLocker::try_lock()
+ * \brief Tries to lock the associated mutex
+ * \return True if the ownership of the mutex has been acquired successfully,
+ false otherwise.
+ */
+
+/**
+ * \fn MutexLocker::unlock()
+ * \brief Unlocks the associated mutex
+ */
+
+/**
+ * \class ConditionVariable
+ * \brief std::condition_variable wrapper with clang thread safety annotation
+ */
+
+/**
+ * \fn ConditionVariable::ConditionVariable()
+ * \brief Constructs ConditionVariable
+ */
+
+/**
+ * \fn ConditionVariable::notify_one()
+ * \brief Delegates std::condition_variable::notify_one()
+ */
+
+/**
+ * \fn ConditionVariable::notify_all()
+ * \brief Delegates std::condition_variable::notify_all()
+ */
+
+/**
+ * \fn ConditionVariable::wait(MutexLocker& locker, Predicate stopWaiting)
+ * \brief Call std::condition_variable::wait() with \a locker and \a stopWaiting
+ * \param[in] locker MutexLocker that is locked/unlocked during wait()
+ * \param[in] stopWaiting The predicate to be satisfied
+ */
+
+/**
+ * \fn ConditionVariable::wait_for(MutexLocker& locker,
+ const std::chrono::duration<Rep, Period> &relTime,
+ Predicate stopWaiting)
+ * \brief Call std::condition_variable::wait_for() with \a locker, \a relTime,
+ \a stopWaiting
+ * \param[in] locker MutexLocker that is locked/unlocked during wait()
+ * \param[in] relTime std::chrono::duration representing the maximum time to
+ spend waiting
+ * \param[in] stopWaiting The predicate to be satisfied
+ */
+
+} /* 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
@@ -204,21 +204,6 @@ ThreadData *ThreadData::current()
return data;
}
-/**
- * \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..23be995d 100644
--- a/src/v4l2/v4l2_camera_proxy.h
+++ b/src/v4l2/v4l2_camera_proxy.h
@@ -14,7 +14,8 @@
#include <sys/types.h>
#include <vector>
-#include <libcamera/base/thread.h>
+#include <libcamera/base/mutex.h>
+#include <libcamera/base/thread_annotations.h>
#include <libcamera/camera.h>
@@ -59,7 +60,7 @@ 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);
--
2.34.0.rc2.393.gf8c9666880-goog
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