Create doxygen comments for async_req.[ch]

(This used to be commit 1dab45b16a23b1126fbf29890747a2b256f08968)

2 files changed, 162 insertions, 45 deletions

diff --git a/source3/include/async_req.h b/source3/include/async_req.h
index fb463d5b9a..2d01b53814 100644
--- a/source3/include/async_req.h
+++ b/source3/include/async_req.h
@@ -22,75 +22,116 @@
 
 #include "includes.h"
 
-/*
- * An async request moves between the following 4 states.
+/**
+ * An async request moves between the following 4 states:
  */
+
 enum async_req_state {
-	ASYNC_REQ_INIT,		/* we are creating the request */
-	ASYNC_REQ_IN_PROGRESS,	/* we are waiting the request to complete */
-	ASYNC_REQ_DONE,		/* the request is finished */
-	ASYNC_REQ_ERROR };	/* an error has occured */
+	/**
+	 * we are creating the request
+	 */
+	ASYNC_REQ_INIT,
+	/**
+	 * we are waiting the request to complete
+	 */
+	ASYNC_REQ_IN_PROGRESS,
+	/**
+	 * the request is finished
+	 */
+	ASYNC_REQ_DONE,
+	/**
+	 * an error has occured
+	 */
+	ASYNC_REQ_ERROR
+};
+
+/**
+ * @brief An async request
+ *
+ * This represents an async request being processed by callbacks via an event
+ * context. A user can issue for example a write request to a socket, giving
+ * an implementation function the fd, the buffer and the number of bytes to
+ * transfer. The function issuing the request will immediately return without
+ * blocking most likely without having sent anything. The API user then fills
+ * in req->async.fn and req->async.priv, functions that are called when the
+ * request is finished.
+ *
+ * It is up to the user of the async request to talloc_free it after it has
+ * finished. This can happen while the completion function is called.
+ */
 
 struct async_req {
-	/* the external state - will be queried by the caller */
+	/**
+	 * @brief The external state - will be queried by the caller
+	 *
+	 * While the async request is being processed, state will remain in
+	 * ASYNC_REQ_IN_PROGRESS. A request is finished if
+	 * req->state>=ASYNC_REQ_DONE.
+	 */
 	enum async_req_state state;
 
-	/* a private pointer for use by the async function implementation */
+	/**
+	 * @brief Private pointer for the actual implementation
+	 *
+	 * The implementation doing the work for the async request needs a
+	 * current state like for example a fd event. The user of an async
+	 * request should not touch this.
+	 */
 	void *private_data;
 
-	/* print yourself, for debugging purposes */
+	/**
+	 * @brief Print yourself, for debugging purposes
+	 *
+	 * Async requests are opaque data structures. The implementation of an
+	 * async request can define a custom function to print more debug
+	 * info.
+	 */
 	char *(*print)(TALLOC_CTX *mem_ctx, struct async_req *);
 
-	/* status code when finished */
+	/**
+	 * @brief status code when finished
+	 *
+	 * This status can be queried in the async completion function. It
+	 * will be set to NT_STATUS_OK when everything went fine.
+	 **/
 	NTSTATUS status;
 
-	/* the event context we are using */
+	/**
+	 * @brief The event context we are using
+	 *
+	 * The event context that this async request works on.
+	 */
 	struct event_context *event_ctx;
 
-	/* information on what to do on completion */
+	/**
+	 * @brief What to do on completion
+	 *
+	 * This is used for the user of an async request, fn is called when
+	 * the request completes, either successfully or with an error.
+	 */
 	struct {
+		/**
+		 * @brief Completion function
+		 * Completion function, to be filled by the API user
+		 */
 		void (*fn)(struct async_req *);
+		/**
+		 * @brief Private data for the completion function
+		 */
 		void *priv;
 	} async;
 };
 
-/*
- * Print an async_req structure for debugging purposes
- */
-char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req);
-
-/*
- * Create an async request
- */
 struct async_req *async_req_new(TALLOC_CTX *mem_ctx, struct event_context *ev);
 
-/*
- * An async request has successfully finished, invoke the callback
- */
+char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req);
+
 void async_req_done(struct async_req *req);
 
-/*
- * An async request has seen an error, invoke the callback
- */
 void async_req_error(struct async_req *req, NTSTATUS status);
 
-/*
- * If a request is finished or ends in error even before it has the chance to
- * trigger the event loop, post a status. This creates an immediate timed
- * event to call the async function if there is any.
- */
 bool async_post_status(struct async_req *req, NTSTATUS status);
 
-/*
- * Convenience helper to easily check alloc failure within a callback.
- *
- * Call pattern would be
- * p = talloc(mem_ctx, bla);
- * if (async_req_nomem(p, req)) {
- *	return;
- * }
- *
- */
 bool async_req_nomem(const void *p, struct async_req *req);
 
 #endif
diff --git a/source3/lib/async_req.c b/source3/lib/async_req.c
index 2e85d9a38d..501a6b5524 100644
--- a/source3/lib/async_req.c
+++ b/source3/lib/async_req.c
@@ -19,6 +19,20 @@
 
 #include "includes.h"
 
+/**
+ * @brief Print an async_req structure
+ * @param[in] mem_ctx	The memory context for the result
+ * @param[in] req	The request to be printed
+ * @retval		Text representation of req
+ *
+ * This is a default print function for async requests. Implementations should
+ * override this with more specific information.
+ *
+ * This function should not be used by async API users, this is non-static
+ * only to allow implementations to easily provide default information in
+ * their specific functions.
+ */
+
 char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req)
 {
 	return talloc_asprintf(mem_ctx, "async_req: state=%d, status=%s, "
@@ -26,6 +40,15 @@ char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req)
 			       talloc_get_name(req->private_data));
 }
 
+/**
+ * @brief Create an async request
+ * @param[in] mem_ctx	The memory context for the result
+ * @param[in] ev	The event context this async request will be driven by
+ * @retval		A new async request
+ *
+ * The new async request will be initialized in state ASYNC_REQ_IN_PROGRESS
+ */
+
 struct async_req *async_req_new(TALLOC_CTX *mem_ctx, struct event_context *ev)
 {
 	struct async_req *result;
@@ -40,6 +63,15 @@ struct async_req *async_req_new(TALLOC_CTX *mem_ctx, struct event_context *ev)
 	return result;
 }
 
+/**
+ * @brief An async request has successfully finished
+ * @param[in] req	The finished request
+ *
+ * async_req_done is to be used by implementors of async requests. When a
+ * request is successfully finished, this function calls the user's completion
+ * function.
+ */
+
 void async_req_done(struct async_req *req)
 {
 	req->status = NT_STATUS_OK;
@@ -49,6 +81,16 @@ void async_req_done(struct async_req *req)
 	}
 }
 
+/**
+ * @brief An async request has seen an error
+ * @param[in] req	The request with an error
+ * @param[in] status	The error code
+ *
+ * async_req_done is to be used by implementors of async requests. When a
+ * request can not successfully completed, the implementation should call this
+ * function with the appropriate status code.
+ */
+
 void async_req_error(struct async_req *req, NTSTATUS status)
 {
 	req->status = status;
@@ -58,6 +100,14 @@ void async_req_error(struct async_req *req, NTSTATUS status)
 	}
 }
 
+/**
+ * @brief Timed event callback
+ * @param[in] ev	Event context
+ * @param[in] te	The timed event
+ * @param[in] now	current time
+ * @param[in] priv	The async request to be finished
+ */
+
 static void async_trigger(struct event_context *ev, struct timed_event *te,
 			  const struct timeval *now, void *priv)
 {
@@ -72,12 +122,21 @@ static void async_trigger(struct event_context *ev, struct timed_event *te,
 	}
 }
 
+/**
+ * @brief Finish a request before it started processing
+ * @param[in] req	The finished request
+ * @param[in] status	The success code
+ *
+ * An implementation of an async request might find that it can either finish
+ * the request without waiting for an external event, or it can't even start
+ * the engine. To present the illusion of a callback to the user of the API,
+ * the implementation can call this helper function which triggers an
+ * immediate timed event. This way the caller can use the same calling
+ * conventions, independent of whether the request was actually deferred.
+ */
+
 bool async_post_status(struct async_req *req, NTSTATUS status)
 {
-	/*
-	 * Used if a request is finished before it even started
-	 */
-
 	req->status = status;
 
 	if (event_add_timed(req->event_ctx, req, timeval_zero(),
@@ -88,6 +147,23 @@ bool async_post_status(struct async_req *req, NTSTATUS status)
 	return true;
 }
 
+/**
+ * @brief Helper function for nomem check
+ * @param[in] p		The pointer to be checked
+ * @param[in] req	The request being processed
+ *
+ * Convenience helper to easily check alloc failure within a callback
+ * implementing the next step of an async request.
+ *
+ * Call pattern would be
+ * \code
+ * p = talloc(mem_ctx, bla);
+ * if (async_req_nomem(p, req)) {
+ *	return;
+ * }
+ * \endcode
+ */
+
 bool async_req_nomem(const void *p, struct async_req *req)
 {
 	if (p != NULL) {