Create singleton class and update code to use it

Create the wrapper class SingletonPtr.  This provides a safe way to
declare and use singletons.  This class allows both the lazy
initialization of a singleton, and allows the singleton to be
garbage collected by the linker if it is never referenced.

This patch also updates the HAL to use SingletonPtr when declaring
singleton mutexes.

hal/api/AnalogIn.h

@@ -21,6 +21,7 @@
 #if DEVICE_ANALOGIN
 
 #include "analogin_api.h"
+#include "SingletonPtr.h"
 
 namespace mbed {
 
@@ -110,15 +111,15 @@ public:
 protected:
 
     virtual void lock() {
-        _mutex.lock();
+        _mutex->lock();
     }
 
     virtual void unlock() {
-        _mutex.unlock();
+        _mutex->unlock();
     }
 
     analogin_t _adc;
-    static PlatformMutex _mutex;
+    static SingletonPtr<PlatformMutex> _mutex;
 };
 
 } // namespace mbed

hal/api/FileBase.h

@@ -41,6 +41,7 @@ typedef long off_t;
 #endif
 
 #include "platform.h"
+#include "SingletonPtr.h"
 
 namespace mbed {
 
@@ -65,7 +66,7 @@ public:
     /* disallow copy constructor and assignment operators */
 private:
     static FileBase *_head;
-    static PlatformMutex _mutex;
+    static SingletonPtr<PlatformMutex> _mutex;
 
     FileBase   *_next;
     const char * const _name;

hal/api/I2C.h

@@ -21,6 +21,7 @@
 #if DEVICE_I2C
 
 #include "i2c_api.h"
+#include "SingletonPtr.h"
 
 #if DEVICE_I2C_ASYNCH
 #include "CThunk.h"
@@ -181,7 +182,7 @@ protected:
     i2c_t _i2c;
     static I2C  *_owner;
     int         _hz;
-    static PlatformMutex _mutex;
+    static SingletonPtr<PlatformMutex> _mutex;
 };
 
 } // namespace mbed

hal/api/SingletonPtr.h

@@ -0,0 +1,103 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 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 SINGLETONPTR_H
+#define SINGLETONPTR_H
+
+#include <stdint.h>
+#include <new>
+#include "mbed_assert.h"
+#ifdef MBED_CONF_RTOS_PRESENT
+#include "cmsis_os.h"
+#endif
+
+#ifdef MBED_CONF_RTOS_PRESENT
+extern osMutexId singleton_mutex_id;
+#endif
+
+/** Lock the singleton mutex
+ *
+ * This function is typically used to provide
+ * exclusive access when initializing a
+ * global object.
+ */
+inline static void singleton_lock(void)
+{
+#ifdef MBED_CONF_RTOS_PRESENT
+    osMutexWait(singleton_mutex_id, osWaitForever);
+#endif
+}
+
+/** Unlock the singleton mutex
+ *
+ * This function is typically used to provide
+ * exclusive access when initializing a
+ * global object.
+ */
+inline static void singleton_unlock(void)
+{
+#ifdef MBED_CONF_RTOS_PRESENT
+    osMutexRelease (singleton_mutex_id);
+#endif
+}
+
+/** Utility class for creating an using a singleton
+ *
+ * @Note Synchronization level: Thread safe
+ *
+ * @Note: This class must only be used in a static context -
+ * this class must never be allocated or created on the
+ * stack.
+ *
+ * @Note: This class is lazily initialized on first use.
+ * This class is a POD type so if it is not used it will
+ * be garbage collected.
+ */
+template <class T>
+struct SingletonPtr {
+
+    /** Get a pointer to the underlying singleton
+     *
+     * @returns
+     *   A pointer to the singleton
+     */
+    T* get() {
+        if (NULL == _ptr) {
+            singleton_lock();
+            _ptr = new (_data) T;
+            singleton_unlock();
+        }
+        // _ptr was not zero initialized or was
+        // corrupted if this assert is hit
+        MBED_ASSERT(_ptr == (T *)&_data);
+        return _ptr;
+    }
+
+    /** Get a pointer to the underlying singleton
+     *
+     * @returns
+     *   A pointer to the singleton
+     */
+    T* operator->() {
+        return get();
+    }
+
+    // This is zero initialized when in global scope
+    T *_ptr;
+    // Force data to be 4 byte aligned
+    uint32_t _data[(sizeof(T) + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
+};
+
+#endif

hal/common/AnalogIn.cpp

@@ -22,7 +22,7 @@
 
 namespace mbed {
 
-PlatformMutex AnalogIn::_mutex;
+SingletonPtr<PlatformMutex> AnalogIn::_mutex;
 
 };
 

hal/common/FileBase.cpp

@@ -18,12 +18,12 @@
 namespace mbed {
 
 FileBase *FileBase::_head = NULL;
-PlatformMutex FileBase::_mutex;
+SingletonPtr<PlatformMutex> FileBase::_mutex;
 
 FileBase::FileBase(const char *name, PathType t) : _next(NULL),
                                                    _name(name),
                                                    _path_type(t) {
-    _mutex.lock();
+    _mutex->lock();
     if (name != NULL) {
         // put this object at head of the list
         _next = _head;
@@ -31,11 +31,11 @@ FileBase::FileBase(const char *name, PathType t) : _next(NULL),
     } else {
         _next = NULL;
     }
-    _mutex.unlock();
+    _mutex->unlock();
 }
 
 FileBase::~FileBase() {
-    _mutex.lock();
+    _mutex->lock();
     if (_name != NULL) {
         // remove this object from the list
         if (_head == this) { // first in the list, so just drop me
@@ -48,38 +48,38 @@ FileBase::~FileBase() {
             p->_next = _next;
         }
     }
-    _mutex.unlock();
+    _mutex->unlock();
 }
 
 FileBase *FileBase::lookup(const char *name, unsigned int len) {
-    _mutex.lock();
+    _mutex->lock();
     FileBase *p = _head;
     while (p != NULL) {
         /* Check that p->_name matches name and is the correct length */
         if (p->_name != NULL && std::strncmp(p->_name, name, len) == 0 && std::strlen(p->_name) == len) {
-            _mutex.unlock();
+            _mutex->unlock();
             return p;
         }
         p = p->_next;
     }
-    _mutex.unlock();
+    _mutex->unlock();
     return NULL;
 }
 
 FileBase *FileBase::get(int n) {
-    _mutex.lock();
+    _mutex->lock();
     FileBase *p = _head;
     int m = 0;
     while (p != NULL) {
         if (m == n) {
-            _mutex.unlock();
+            _mutex->unlock();
             return p;
         }
 
         m++;
         p = p->_next;
     }
-    _mutex.unlock();
+    _mutex->unlock();
     return NULL;
 }
 

hal/common/I2C.cpp

@@ -20,7 +20,7 @@
 namespace mbed {
 
 I2C *I2C::_owner = NULL;
-PlatformMutex I2C::_mutex;
+SingletonPtr<PlatformMutex> I2C::_mutex;
 
 I2C::I2C(PinName sda, PinName scl) :
 #if DEVICE_I2C_ASYNCH
@@ -113,11 +113,11 @@ void I2C::stop(void) {
 }
 
 void I2C::lock() {
-    _mutex.lock();
+    _mutex->lock();
 }
 
 void I2C::unlock() {
-    _mutex.unlock();
+    _mutex->unlock();
 }
 
 #if DEVICE_I2C_ASYNCH

hal/common/retarget.cpp

@@ -21,6 +21,7 @@
 #include "toolchain.h"
 #include "semihost_api.h"
 #include "mbed_interface.h"
+#include "SingletonPtr.h"
 #if DEVICE_STDIO_MESSAGES
 #include <stdio.h>
 #endif
@@ -72,17 +73,17 @@ extern const char __stderr_name[] = "/stderr";
  * (or rather index+3, as filehandles 0-2 are stdin/out/err).
  */
 static FileHandle *filehandles[OPEN_MAX];
-static PlatformMutex filehandle_mutex;
+static SingletonPtr<PlatformMutex> filehandle_mutex;
 
 FileHandle::~FileHandle() {
-    filehandle_mutex.lock();
+    filehandle_mutex->lock();
     /* Remove all open filehandles for this */
     for (unsigned int fh_i = 0; fh_i < sizeof(filehandles)/sizeof(*filehandles); fh_i++) {
         if (filehandles[fh_i] == this) {
             filehandles[fh_i] = NULL;
         }
     }
-    filehandle_mutex.unlock();
+    filehandle_mutex->unlock();
 }
 
 #if DEVICE_SERIAL
@@ -162,17 +163,17 @@ extern "C" FILEHANDLE PREFIX(_open)(const char* name, int openmode) {
     #endif
 
     // find the first empty slot in filehandles
-    filehandle_mutex.lock();
+    filehandle_mutex->lock();
     unsigned int fh_i;
     for (fh_i = 0; fh_i < sizeof(filehandles)/sizeof(*filehandles); fh_i++) {
         if (filehandles[fh_i] == NULL) break;
     }
     if (fh_i >= sizeof(filehandles)/sizeof(*filehandles)) {
-        filehandle_mutex.unlock();
+        filehandle_mutex->unlock();
         return -1;
     }
     filehandles[fh_i] = (FileHandle*)FILE_HANDLE_RESERVED;
-    filehandle_mutex.unlock();
+    filehandle_mutex->unlock();
 
     FileHandle *res;
 

rtos/rtx/TARGET_CORTEX_A/RTX_CM_lib.h

@@ -225,6 +225,10 @@ uint32_t       os_tmr = 0;
 uint32_t const *m_tmr = NULL;
 uint16_t const mp_tmr_size = 0;
 
+/* singleton mutex */
+osMutexId singleton_mutex_id;
+osMutexDef(singleton_mutex);
+
 #if defined (__CC_ARM) && !defined (__MICROLIB)
  /* A memory space for arm standard library. */
  static uint32_t std_libspace[OS_TASK_CNT][96/4];
@@ -434,6 +438,7 @@ void $Sub$$__cpp_initialize__aeabi_(void)
 
 void pre_main()  
 {  
+  singleton_mutex_id = osMutexCreate(osMutex(singleton_mutex));
   $Super$$__cpp_initialize__aeabi_();  
   main();  
 }
@@ -447,6 +452,7 @@ int main(void);
 
 void pre_main (void)
 {
+    singleton_mutex_id = osMutexCreate(osMutex(singleton_mutex));
     __rt_lib_init((unsigned)armcc_heap_base, (unsigned)armcc_heap_top);
     main();
 }
@@ -484,6 +490,7 @@ extern void __libc_init_array (void);
 extern int main(int argc, char **argv);
 
 void pre_main(void) {
+    singleton_mutex_id = osMutexCreate(osMutex(singleton_mutex));
     atexit(__libc_fini_array);
     __libc_init_array();
     main(0, NULL);
@@ -516,6 +523,7 @@ extern int main(void);
 static uint8_t low_level_init_needed;
 
 void pre_main(void) {
+    singleton_mutex_id = osMutexCreate(osMutex(singleton_mutex));
     if (low_level_init_needed) {
         __iar_dynamic_initialization();
     }

rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h

@@ -187,6 +187,10 @@ uint32_t       os_tmr = 0U;
 uint32_t const *m_tmr = NULL;
 uint16_t const mp_tmr_size = 0U;
 
+/* singleton mutex */
+osMutexId singleton_mutex_id;
+osMutexDef(singleton_mutex);
+
 #if defined (__CC_ARM) && !defined (__MICROLIB)
  /* A memory space for arm standard library. */
  static uint32_t std_libspace[OS_TASK_CNT][96/4];
@@ -585,6 +589,7 @@ void $Sub$$__cpp_initialize__aeabi_(void)
 
 void pre_main()
 {
+  singleton_mutex_id = osMutexCreate(osMutex(singleton_mutex));
   $Super$$__cpp_initialize__aeabi_();
   main();
 }
@@ -598,6 +603,7 @@ int main(void);
 
 void pre_main (void)
 {
+    singleton_mutex_id = osMutexCreate(osMutex(singleton_mutex));
     __rt_lib_init((unsigned)armcc_heap_base, (unsigned)armcc_heap_top);
     main();
 }
@@ -664,6 +670,7 @@ extern void __libc_init_array (void);
 extern int main(int argc, char **argv);
 
 void pre_main(void) {
+    singleton_mutex_id = osMutexCreate(osMutex(singleton_mutex));
     malloc_mutex_id = osMutexCreate(osMutex(malloc_mutex));
     env_mutex_id = osMutexCreate(osMutex(env_mutex));
     atexit(__libc_fini_array);
@@ -725,6 +732,7 @@ extern void exit(int arg);
 static uint8_t low_level_init_needed;
 
 void pre_main(void) {
+    singleton_mutex_id = osMutexCreate(osMutex(singleton_mutex));
     if (low_level_init_needed) {
         __iar_dynamic_initialization();
     }