async_req: Move to top level dir

2 files changed, 500 insertions, 0 deletions

diff --git a/lib/async_req/async_req.c b/lib/async_req/async_req.c
new file mode 100644
index 0000000000..011948a158
--- /dev/null
+++ b/lib/async_req/async_req.c
@@ -0,0 +1,340 @@
+/*
+   Unix SMB/CIFS implementation.
+   Infrastructure for async requests
+   Copyright (C) Volker Lendecke 2008
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#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, "
+			       "priv=%s", req->state, nt_errstr(req->status),
+			       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 async_req *result;
+
+	result = TALLOC_ZERO_P(mem_ctx, struct async_req);
+	if (result == NULL) {
+		return NULL;
+	}
+	result->state = ASYNC_REQ_IN_PROGRESS;
+	result->print = async_req_print;
+	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;
+	req->state = ASYNC_REQ_DONE;
+	if (req->async.fn != NULL) {
+		req->async.fn(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;
+	req->state = ASYNC_REQ_ERROR;
+	if (req->async.fn != NULL) {
+		req->async.fn(req);
+	}
+}
+
+/**
+ * @brief Timed event callback
+ * @param[in] ev	Event context
+ * @param[in] te	The timed event
+ * @param[in] now	zero time
+ * @param[in] priv	The async request to be finished
+ */
+
+static void async_trigger(struct event_context *ev, struct timed_event *te,
+			  struct timeval now, void *priv)
+{
+	struct async_req *req = talloc_get_type_abort(priv, struct async_req);
+
+	TALLOC_FREE(te);
+	if (NT_STATUS_IS_OK(req->status)) {
+		async_req_done(req);
+	}
+	else {
+		async_req_error(req, req->status);
+	}
+}
+
+/**
+ * @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, struct event_context *ev,
+		       NTSTATUS status)
+{
+	req->status = status;
+
+	if (event_add_timed(ev, req, timeval_zero(),
+			    async_trigger, req) == NULL) {
+		return false;
+	}
+	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) {
+		return false;
+	}
+	async_req_error(req, NT_STATUS_NO_MEMORY);
+	return true;
+}
+
+bool async_req_is_error(struct async_req *req, NTSTATUS *status)
+{
+	if (req->state < ASYNC_REQ_DONE) {
+		*status = NT_STATUS_INTERNAL_ERROR;
+		return true;
+	}
+	if (req->state == ASYNC_REQ_ERROR) {
+		*status = req->status;
+		return true;
+	}
+	return false;
+}
+
+NTSTATUS async_req_simple_recv(struct async_req *req)
+{
+	NTSTATUS status;
+
+	if (async_req_is_error(req, &status)) {
+		return status;
+	}
+	return NT_STATUS_OK;
+}
+
+static void async_req_timedout(struct event_context *ev,
+			       struct timed_event *te,
+			       struct timeval now,
+			       void *priv)
+{
+	struct async_req *req = talloc_get_type_abort(
+		priv, struct async_req);
+	TALLOC_FREE(te);
+	async_req_error(req, NT_STATUS_IO_TIMEOUT);
+}
+
+bool async_req_set_timeout(struct async_req *req, struct event_context *ev,
+			   struct timeval to)
+{
+	return (event_add_timed(ev, req,
+				timeval_current_ofs(to.tv_sec, to.tv_usec),
+				async_req_timedout, req)
+		!= NULL);
+}
+
+struct async_req *async_wait_send(TALLOC_CTX *mem_ctx,
+				  struct event_context *ev,
+				  struct timeval to)
+{
+	struct async_req *result;
+
+	result = async_req_new(mem_ctx);
+	if (result == NULL) {
+		return result;
+	}
+	if (!async_req_set_timeout(result, ev, to)) {
+		TALLOC_FREE(result);
+		return NULL;
+	}
+	return result;
+}
+
+NTSTATUS async_wait_recv(struct async_req *req)
+{
+	return NT_STATUS_OK;
+}
+
+struct async_queue_entry {
+	struct async_queue_entry *prev, *next;
+	struct async_req_queue *queue;
+	struct async_req *req;
+	void (*trigger)(struct async_req *req);
+};
+
+struct async_req_queue {
+	struct async_queue_entry *queue;
+};
+
+struct async_req_queue *async_req_queue_init(TALLOC_CTX *mem_ctx)
+{
+	return TALLOC_ZERO_P(mem_ctx, struct async_req_queue);
+}
+
+static int async_queue_entry_destructor(struct async_queue_entry *e)
+{
+	struct async_req_queue *queue = e->queue;
+
+	DLIST_REMOVE(queue->queue, e);
+
+	if (queue->queue != NULL) {
+		queue->queue->trigger(queue->queue->req);
+	}
+
+	return 0;
+}
+
+static void async_req_immediate_trigger(struct event_context *ev,
+					struct timed_event *te,
+					struct timeval now,
+					void *priv)
+{
+	struct async_queue_entry *e = talloc_get_type_abort(
+		priv, struct async_queue_entry);
+
+	TALLOC_FREE(te);
+	e->trigger(e->req);
+}
+
+bool async_req_enqueue(struct async_req_queue *queue, struct event_context *ev,
+		       struct async_req *req,
+		       void (*trigger)(struct async_req *req))
+{
+	struct async_queue_entry *e;
+	bool busy;
+
+	busy = (queue->queue != NULL);
+
+	e = talloc(req, struct async_queue_entry);
+	if (e == NULL) {
+		return false;
+	}
+
+	e->req = req;
+	e->trigger = trigger;
+	e->queue = queue;
+
+	DLIST_ADD_END(queue->queue, e, struct async_queue_entry *);
+	talloc_set_destructor(e, async_queue_entry_destructor);
+
+	if (!busy) {
+		struct timed_event *te;
+
+		te = event_add_timed(ev, e, timeval_zero(),
+				     async_req_immediate_trigger,
+				     e);
+		if (te == NULL) {
+			TALLOC_FREE(e);
+			return false;
+		}
+	}
+
+	return true;
+}
+
+bool _async_req_setup(TALLOC_CTX *mem_ctx, struct async_req **preq,
+		      void *pstate, size_t state_size, const char *typename)
+{
+	struct async_req *req;
+	void **ppstate = (void **)pstate;
+	void *state;
+
+	req = async_req_new(mem_ctx);
+	if (req == NULL) {
+		return false;
+	}
+	state = talloc_size(req, state_size);
+	if (state == NULL) {
+		TALLOC_FREE(req);
+		return false;
+	}
+	talloc_set_name(state, typename);
+	req->private_data = state;
+
+	*preq = req;
+	*ppstate = state;
+
+	return true;
+}
diff --git a/lib/async_req/async_req.h b/lib/async_req/async_req.h
new file mode 100644
index 0000000000..3907a08f67
--- /dev/null
+++ b/lib/async_req/async_req.h
@@ -0,0 +1,160 @@
+/*
+   Unix SMB/CIFS implementation.
+   Infrastructure for async requests
+   Copyright (C) Volker Lendecke 2008
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __ASYNC_REQ_H__
+#define __ASYNC_REQ_H__
+
+#include "includes.h"
+
+/**
+ * An async request moves between the following 4 states:
+ */
+
+enum async_req_state {
+	/**
+	 * 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 {
+	/**
+	 * @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;
+
+	/**
+	 * @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;
+
+	/**
+	 * @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 *);
+
+	/**
+	 * @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;
+
+	/**
+	 * @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;
+};
+
+struct async_req *async_req_new(TALLOC_CTX *mem_ctx);
+
+char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req);
+
+void async_req_done(struct async_req *req);
+
+void async_req_error(struct async_req *req, NTSTATUS status);
+
+bool async_post_status(struct async_req *req, struct event_context *ev,
+		       NTSTATUS status);
+
+bool async_req_nomem(const void *p, struct async_req *req);
+
+bool async_req_is_error(struct async_req *req, NTSTATUS *status);
+
+NTSTATUS async_req_simple_recv(struct async_req *req);
+
+bool async_req_set_timeout(struct async_req *req, struct event_context *ev,
+			   struct timeval to);
+
+struct async_req *async_wait_send(TALLOC_CTX *mem_ctx,
+				  struct event_context *ev,
+				  struct timeval to);
+
+NTSTATUS async_wait_recv(struct async_req *req);
+
+struct async_req_queue;
+
+struct async_req_queue *async_req_queue_init(TALLOC_CTX *mem_ctx);
+
+bool async_req_enqueue(struct async_req_queue *queue,
+		       struct event_context *ev,
+		       struct async_req *req,
+		       void (*trigger)(struct async_req *req));
+
+bool _async_req_setup(TALLOC_CTX *mem_ctx, struct async_req **preq,
+		      void *pstate, size_t state_size, const char *typename);
+
+#define async_req_setup(_mem_ctx, _preq, _pstate, type) \
+	_async_req_setup((_mem_ctx), (_preq), (_pstate), sizeof(type), #type)
+
+
+#endif