Fix #540, add OSAL event framework

Define an interface to allow an app/PSP to be notified when state changes
or other events occur at the OS level.  Initially defined events are resource
creation/deletion and task startup.

The interface is easily extendable with more events as needed.

This can be used to add platform-specific/nonstandard functions by putting
the code inside the event handler at the PSP level.

Author: jphickey

src/os/inc/osapi-os-core.h

@@ -173,6 +173,75 @@ typedef enum
     OS_STREAM_STATE_WRITABLE   = 0x08, /**< @brief whether the stream is writable  */
 } OS_StreamState_t;
 
+/**
+ * @brief A set of events that can be used with event callback routines
+ */
+typedef enum
+{
+    OS_EVENT_RESERVED = 0,          /**< no-op/reserved event id value */
+
+    /**
+     * resource/id has been newly allocated but not yet created.
+     *
+     * This event is invoked from WITHIN the locked region, in
+     * the context of the task which is allocating the resource.
+     *
+     * If the handler returns non-success, the error will be returned
+     * to the caller and the creation process is aborted.
+     */
+    OS_EVENT_RESOURCE_ALLOCATED,
+
+    /**
+     * resource/id has been fully created/finalized.
+     *
+     * Invoked outside locked region, in the context
+     * of the task which created the resource.
+     *
+     * Data object is not used, passed as NULL.
+     *
+     * Return value is ignored - this is for information purposes only.
+     */
+    OS_EVENT_RESOURCE_CREATED,
+
+    /**
+     * resource/id has been deleted.
+     *
+     * Invoked outside locked region, in the context
+     * of the task which deleted the resource.
+     *
+     * Data object is not used, passed as NULL.
+     *
+     * Return value is ignored - this is for information purposes only.
+     */
+    OS_EVENT_RESOURCE_DELETED,
+
+    /**
+     * New task is starting.
+     *
+     * Invoked outside locked region, in the context
+     * of the task which is currently starting, before
+     * the entry point is called.
+     *
+     * Data object is not used, passed as NULL.
+     *
+     * If the handler returns non-success, task startup is aborted
+     * and the entry point is not called.
+     */
+    OS_EVENT_TASK_STARTUP,
+
+    OS_EVENT_MAX                    /**< placeholder for end of enum, not used */
+} OS_Event_t;
+
+/**
+ * @brief A callback routine for event handling.
+ *
+ * @param[in]    event      The event that occurred
+ * @param[in]    object_id  The associated object_id, or 0 if not associated with an object
+ * @param[inout] data       An abstract data/context object associated with the event, or NULL.
+ * @return status Execution status, see @ref OSReturnCodes.
+ */
+typedef int32 (*OS_EventHandler_t)(OS_Event_t event, uint32 object_id, void *data);
+
 /**
  * @brief For the @ref OS_GetErrorName() function, to ensure
  * everyone is making an array of the same length.
@@ -360,7 +429,6 @@ int32 OS_ConvertToArrayIndex   (uint32 object_id, uint32 *ArrayIndex);
  * @param[in]  callback_arg Opaque Argument to pass to callback function
  */
 void OS_ForEachObject           (uint32 creator_id, OS_ArgCallback_t callback_ptr, void *callback_arg);
-/**@}*/
 
 /*-------------------------------------------------------------------------------------*/
 /**
@@ -377,6 +445,26 @@ void OS_ForEachObject           (uint32 creator_id, OS_ArgCallback_t callback_pt
   */
 void OS_ForEachObjectOfType     (uint32 objtype, uint32 creator_id, OS_ArgCallback_t callback_ptr, void *callback_arg);
 
+/*-------------------------------------------------------------------------------------*/
+/**
+ * @brief Callback routine registration
+ *
+ * This hook enables the application code to perform extra platform-specific
+ * operations on various system events such as resource creation/deletion.
+ *
+ * @note Some events are invoked while the resource is "locked" and therefore
+ * application-defined handlers for these events should not block or attempt
+ * to access other OSAL resources.
+ *
+ * @param[in] handler The application-provided event handler
+ * @return Execution status, see @ref OSReturnCodes.
+ * @retval #OS_SUCCESS @copybrief OS_SUCCESS
+ * @retval #OS_ERROR   @copybrief OS_ERROR
+ */
+int32 OS_RegisterEventHandler (OS_EventHandler_t handler);
+
+/**@}*/
+
 
 /** @defgroup OSAPITask OSAL Task APIs
  * @{

src/os/shared/inc/os-shared-common.h

@@ -57,6 +57,12 @@ struct OS_shared_global_vars
    int32             MicroSecPerTick;
    int32             TicksPerSecond;
 
+   /*
+    * The event handler is an application-defined callback
+    * that gets invoked as resources are created/configured/deleted.
+    */
+   OS_EventHandler_t EventHandler;
+
 #ifdef OSAL_CONFIG_DEBUG_PRINTF
    uint8             DebugLevel;
 #endif
@@ -69,6 +75,16 @@ struct OS_shared_global_vars
  */
 extern OS_SharedGlobalVars_t OS_SharedGlobalVars;
 
+/*---------------------------------------------------------------------------------------
+   Name: OS_NotifyEvent
+
+   Purpose: Notify the user application of a change in the state of an OSAL resource
+
+   returns: OS_SUCCESS on success, or relevant error code
+---------------------------------------------------------------------------------------*/
+int32 OS_NotifyEvent(OS_Event_t event, uint32 object_id, void *data);
+
+
 /*---------------------------------------------------------------------------------------
    Name: OS_API_Impl_Init
 

src/os/shared/src/osapi-common.c

@@ -65,11 +65,36 @@ OS_SharedGlobalVars_t OS_SharedGlobalVars =
             .ShutdownFlag = 0,
             .MicroSecPerTick = 0, /* invalid, _must_ be set by implementation init */
             .TicksPerSecond = 0,  /* invalid, _must_ be set by implementation init */
+            .EventHandler = NULL,
 #if defined(OSAL_CONFIG_DEBUG_PRINTF)
             .DebugLevel = 1,
 #endif
       };
 
+
+/*----------------------------------------------------------------
+ *
+ * Function: OS_NotifyEvent
+ *
+ *  Purpose: Helper function to invoke the user-defined event handler
+ *
+ *-----------------------------------------------------------------*/
+int32 OS_NotifyEvent(OS_Event_t event, uint32 object_id, void *data)
+{
+    int32 status;
+
+    if (OS_SharedGlobalVars.EventHandler != NULL)
+    {
+        status = OS_SharedGlobalVars.EventHandler(event, object_id, data);
+    }
+    else
+    {
+        status = OS_SUCCESS;
+    }
+
+    return status;
+}
+
 /*
  *********************************************************************************
  *          PUBLIC API (application-callable functions)
@@ -199,6 +224,24 @@ int32 OS_API_Init(void)
    return(return_code);
 } /* end OS_API_Init */
 
+/*----------------------------------------------------------------
+ *
+ * Function: OS_RegisterEventHandler
+ *
+ *  Purpose: Implemented per public OSAL API
+ *           See description in API and header file for detail
+ *
+ *-----------------------------------------------------------------*/
+int32 OS_RegisterEventHandler (OS_EventHandler_t handler)
+{
+    if (handler == NULL)
+    {
+        return OS_INVALID_POINTER;
+    }
+
+    OS_SharedGlobalVars.EventHandler = handler;
+    return OS_SUCCESS;
+}
 
 /*----------------------------------------------------------------
  *

src/os/shared/src/osapi-idmap.c

@@ -766,6 +766,12 @@ int32 OS_ObjectIdFinalizeNew(int32 operation_status, OS_common_record_t *record,
     /* Either way we must unlock the object type */
     OS_Unlock_Global(idtype);
 
+    /* Give event callback to the application */
+    if (operation_status == OS_SUCCESS)
+    {
+        OS_NotifyEvent(OS_EVENT_RESOURCE_CREATED, record->active_id, NULL);
+    }
+
     return operation_status;
 } /* end OS_ObjectIdFinalizeNew */
 
@@ -794,6 +800,12 @@ int32 OS_ObjectIdFinalizeDelete(int32 operation_status, OS_common_record_t *reco
     /* Either way we must unlock the object type */
     OS_Unlock_Global(idtype);
 
+    /* Give event callback to the application */
+    if (saved_id != 0)
+    {
+        OS_NotifyEvent(OS_EVENT_RESOURCE_DELETED, saved_id, NULL);
+    }
+
     return operation_status;
 }
 
@@ -1078,6 +1090,11 @@ int32 OS_ObjectIdAllocateNew(uint32 idtype, const char *name, uint32 *array_inde
       return_code = OS_ObjectIdFindNext(idtype, array_index, record);
    }
 
+   if (return_code == OS_SUCCESS)
+   {
+       return_code = OS_NotifyEvent(OS_EVENT_RESOURCE_ALLOCATED, (*record)->active_id, NULL);
+   }
+
    /* If allocation failed for any reason, unlock the global.
     * otherwise the global should stay locked so remaining initialization can be done */
    if (return_code != OS_SUCCESS)

src/os/shared/src/osapi-task.c

@@ -120,6 +120,12 @@ static int32 OS_TaskPrepare(uint32 task_id, osal_task_entry *entrypt)
        return_code = OS_TaskRegister_Impl(task_id);
    }
 
+   if (return_code == OS_SUCCESS)
+   {
+      /* Give event callback to the application */
+      return_code = OS_NotifyEvent(OS_EVENT_TASK_STARTUP, task_id, NULL);
+   }
+
    if (return_code != OS_SUCCESS)
    {
       *entrypt = NULL;

src/ut-stubs/osapi-utstub-common.c

@@ -49,6 +49,34 @@ int32 OS_API_Init(void)
     return status;
 }
 
+/*****************************************************************************
+ *
+ * Stub function for OS_NotifyEvent()
+ *
+ *****************************************************************************/
+int32 OS_NotifyEvent(OS_Event_t event, uint32 object_id, void *data)
+{
+    int32 status;
+
+    status = UT_DEFAULT_IMPL(OS_NotifyEvent);
+
+    return status;
+}
+
+/*****************************************************************************
+ *
+ * Stub function for OS_RegisterEventHandler()
+ *
+ *****************************************************************************/
+int32 OS_RegisterEventHandler (OS_EventHandler_t handler)
+{
+    int32 status;
+
+    status = UT_DEFAULT_IMPL(OS_RegisterEventHandler);
+
+    return status;
+}
+
 
 /*****************************************************************************
  *