diff options
| -rw-r--r-- | source3/include/async_req.h | 123 | ||||
| -rw-r--r-- | source3/lib/async_req.c | 84 |
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) { |