Merge pull request #5852 from maciejbocianski/scoped_lock

ScopedLock implementation

Author: cmonr

mbed.h

@@ -95,6 +95,7 @@
 // mbed Non-hardware components
 #include "platform/Callback.h"
 #include "platform/FunctionPointer.h"
+#include "platform/ScopedLock.h"
 
 using namespace mbed;
 using namespace std;

platform/ScopedLock.h

@@ -0,0 +1,87 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2018 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef MBED_SCOPEDLOCK_H
+#define MBED_SCOPEDLOCK_H
+
+#include "platform/NonCopyable.h"
+
+namespace mbed {
+
+/** \addtogroup platform */
+/** @{*/
+/**
+ * \defgroup platform_ScopedLock ScopedLock functions
+ * @{
+ */
+
+/** RAII-style mechanism for owning a lock of Lockable object for the duration of a scoped block
+ *
+ * @tparam Lockable The type implementing BasicLockable concept
+ *
+ * @note For type Lockable to be BasicLockable, the following conditions have to be satisfied:
+ *        - has public member function @a lock which blocks until a lock can be obtained for the current execution context
+ *        - has public member function @a unlock which releases the lock
+ *
+ * Usage:
+ *
+ * Example with rtos::Mutex
+ *
+ * @code
+ * void foo(Mutex &m) {
+ *     ScopedLock<Mutex> lock(m);
+ *     // Mutex lock protects code in this block
+ * }
+ * @endcode
+ *
+ *
+ * More generic example
+ *
+ * @code
+ * template<typename Lockable>
+ * void foo(Lockable& lockable) {
+ *     ScopedLock<Lockable> lock(lockable);
+ *     // Code in this block runs under lock
+ * }
+ * @endcode
+ */
+template <typename Lockable>
+class ScopedLock : private NonCopyable<ScopedLock<Lockable> > {
+public:
+    /** Locks given locable object
+     *
+     * @param lockable reference to the instance of Lockable object
+     * @note lockable object should outlive the ScopedLock object
+     */
+    ScopedLock(Lockable& lockable): _lockable(lockable)
+    {
+        _lockable.lock();
+    }
+
+    ~ScopedLock()
+    {
+        _lockable.unlock();
+    }
+private:
+    Lockable& _lockable;
+};
+
+/**@}*/
+
+/**@}*/
+
+} // embed
+
+#endif // MBED_SCOPEDLOCK_H

rtos/Mutex.h

@@ -28,10 +28,25 @@
 #include "mbed_rtos_storage.h"
 
 #include "platform/NonCopyable.h"
+#include "platform/ScopedLock.h"
 
 namespace rtos {
 /** \addtogroup rtos */
 /** @{*/
+
+class Mutex;
+/** Typedef for the mutex lock
+ *
+ * Usage:
+ * @code
+ * void foo(Mutex &m) {
+ *     ScopedMutexLock lock(m);
+ *     // Mutex lock protects code in this block
+ * }
+ * @endcode
+ */
+typedef mbed::ScopedLock<Mutex> ScopedMutexLock;
+
 /**
  * \defgroup rtos_Mutex Mutex class
  * @{
@@ -44,7 +59,7 @@ namespace rtos {
  ISR handler, consider using @a Semaphore.
 
  @note
- Memory considerations: The mutex control structures will be created on current thread's stack, both for the mbed OS
+ Memory considerations: The mutex control structures will be created on current thread's stack, both for the Mbed OS
  and underlying RTOS objects (static or dynamic RTOS memory pools are not being used).
 */
 class Mutex : private mbed::NonCopyable<Mutex> {