| /****************************************************************************** |
| * |
| * Copyright (C) 2014 Google, Inc. |
| * |
| * 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. |
| * |
| ******************************************************************************/ |
| |
| #pragma once |
| |
| #include <stdbool.h> |
| #include <stdlib.h> |
| |
| struct fixed_queue_t; |
| typedef struct fixed_queue_t fixed_queue_t; |
| typedef struct reactor_t reactor_t; |
| |
| typedef void (*fixed_queue_free_cb)(void *data); |
| typedef void (*fixed_queue_cb)(fixed_queue_t *queue, void *context); |
| |
| // Creates a new fixed queue with the given |capacity|. If more elements than |
| // |capacity| are added to the queue, the caller is blocked until space is |
| // made available in the queue. Returns NULL on failure. The caller must free |
| // the returned queue with |fixed_queue_free|. |
| fixed_queue_t *fixed_queue_new(size_t capacity); |
| |
| // Freeing a queue that is currently in use (i.e. has waiters |
| // blocked on it) results in undefined behaviour. |
| void fixed_queue_free(fixed_queue_t *queue, fixed_queue_free_cb free_cb); |
| |
| // Returns a value indicating whether the given |queue| is empty. |queue| may |
| // not be NULL. |
| bool fixed_queue_is_empty(fixed_queue_t *queue); |
| |
| // Returns the maximum number of elements this queue may hold. |queue| may |
| // not be NULL. |
| size_t fixed_queue_capacity(fixed_queue_t *queue); |
| |
| // Enqueues the given |data| into the |queue|. The caller will be blocked |
| // if nore more space is available in the queue. Neither |queue| nor |data| |
| // may be NULL. |
| void fixed_queue_enqueue(fixed_queue_t *queue, void *data); |
| |
| // Dequeues the next element from |queue|. If the queue is currently empty, |
| // this function will block the caller until an item is enqueued. This |
| // function will never return NULL. |queue| may not be NULL. |
| void *fixed_queue_dequeue(fixed_queue_t *queue); |
| |
| // Tries to enqueue |data| into the |queue|. This function will never block |
| // the caller. If the queue capacity would be exceeded by adding one more |
| // element, this function returns false immediately. Otherwise, this function |
| // returns true. Neither |queue| nor |data| may be NULL. |
| bool fixed_queue_try_enqueue(fixed_queue_t *queue, void *data); |
| |
| // Tries to dequeue an element from |queue|. This function will never block |
| // the caller. If the queue is empty, this function returns NULL immediately. |
| // Otherwise, the next element in the queue is returned. |queue| may not be |
| // NULL. |
| void *fixed_queue_try_dequeue(fixed_queue_t *queue); |
| |
| // Returns the first element from |queue|, if present, without dequeuing it. |
| // This function will never block the caller. Returns NULL if there are no elements |
| // in the queue. |queue| may not be NULL. |
| void *fixed_queue_try_peek(fixed_queue_t *queue); |
| |
| // This function returns a valid file descriptor. Callers may perform one |
| // operation on the fd: select(2). If |select| indicates that the file |
| // descriptor is readable, the caller may call |fixed_queue_enqueue| without |
| // blocking. The caller must not close the returned file descriptor. |queue| |
| // may not be NULL. |
| int fixed_queue_get_enqueue_fd(const fixed_queue_t *queue); |
| |
| // This function returns a valid file descriptor. Callers may perform one |
| // operation on the fd: select(2). If |select| indicates that the file |
| // descriptor is readable, the caller may call |fixed_queue_dequeue| without |
| // blocking. The caller must not close the returned file descriptor. |queue| |
| // may not be NULL. |
| int fixed_queue_get_dequeue_fd(const fixed_queue_t *queue); |
| |
| // Registers |queue| with |reactor| for dequeue operations. When there is an element |
| // in the queue, ready_cb will be called. The |context| parameter is passed, untouched, |
| // to the callback routine. Neither |queue|, nor |reactor|, nor |read_cb| may be NULL. |
| // |context| may be NULL. |
| void fixed_queue_register_dequeue(fixed_queue_t *queue, reactor_t *reactor, fixed_queue_cb ready_cb, void *context); |
| |
| // Unregisters the dequeue ready callback for |queue| from whichever reactor |
| // it is registered with, if any. This function is idempotent. |
| void fixed_queue_unregister_dequeue(fixed_queue_t *queue); |