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Diffstat (limited to 'misc/apr_queue.c')
| -rw-r--r-- | misc/apr_queue.c | 398 |
1 files changed, 398 insertions, 0 deletions
diff --git a/misc/apr_queue.c b/misc/apr_queue.c new file mode 100644 index 0000000..82859c8 --- /dev/null +++ b/misc/apr_queue.c @@ -0,0 +1,398 @@ +/* Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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. + */ + +#include "apr.h" + +#if APR_HAVE_STDIO_H +#include <stdio.h> +#endif +#if APR_HAVE_STDLIB_H +#include <stdlib.h> +#endif +#if APR_HAVE_UNISTD_H +#include <unistd.h> +#endif + +#include "apu.h" +#include "apr_portable.h" +#include "apr_thread_mutex.h" +#include "apr_thread_cond.h" +#include "apr_errno.h" +#include "apr_queue.h" + +#if APR_HAS_THREADS +/* + * define this to get debug messages + * +#define QUEUE_DEBUG + */ + +struct apr_queue_t { + void **data; + unsigned int nelts; /**< # elements */ + unsigned int in; /**< next empty location */ + unsigned int out; /**< next filled location */ + unsigned int bounds;/**< max size of queue */ + unsigned int full_waiters; + unsigned int empty_waiters; + apr_thread_mutex_t *one_big_mutex; + apr_thread_cond_t *not_empty; + apr_thread_cond_t *not_full; + int terminated; +}; + +#ifdef QUEUE_DEBUG +static void Q_DBG(char*msg, apr_queue_t *q) { + fprintf(stderr, "%ld\t#%d in %d out %d\t%s\n", + apr_os_thread_current(), + q->nelts, q->in, q->out, + msg + ); +} +#else +#define Q_DBG(x,y) +#endif + +/** + * Detects when the apr_queue_t is full. This utility function is expected + * to be called from within critical sections, and is not threadsafe. + */ +#define apr_queue_full(queue) ((queue)->nelts == (queue)->bounds) + +/** + * Detects when the apr_queue_t is empty. This utility function is expected + * to be called from within critical sections, and is not threadsafe. + */ +#define apr_queue_empty(queue) ((queue)->nelts == 0) + +/** + * Callback routine that is called to destroy this + * apr_queue_t when its pool is destroyed. + */ +static apr_status_t queue_destroy(void *data) +{ + apr_queue_t *queue = data; + + /* Ignore errors here, we can't do anything about them anyway. */ + + apr_thread_cond_destroy(queue->not_empty); + apr_thread_cond_destroy(queue->not_full); + apr_thread_mutex_destroy(queue->one_big_mutex); + + return APR_SUCCESS; +} + +/** + * Initialize the apr_queue_t. + */ +APU_DECLARE(apr_status_t) apr_queue_create(apr_queue_t **q, + unsigned int queue_capacity, + apr_pool_t *a) +{ + apr_status_t rv; + apr_queue_t *queue; + queue = apr_palloc(a, sizeof(apr_queue_t)); + *q = queue; + + /* nested doesn't work ;( */ + rv = apr_thread_mutex_create(&queue->one_big_mutex, + APR_THREAD_MUTEX_UNNESTED, + a); + if (rv != APR_SUCCESS) { + return rv; + } + + rv = apr_thread_cond_create(&queue->not_empty, a); + if (rv != APR_SUCCESS) { + return rv; + } + + rv = apr_thread_cond_create(&queue->not_full, a); + if (rv != APR_SUCCESS) { + return rv; + } + + /* Set all the data in the queue to NULL */ + queue->data = apr_pcalloc(a, queue_capacity * sizeof(void*)); + queue->bounds = queue_capacity; + queue->nelts = 0; + queue->in = 0; + queue->out = 0; + queue->terminated = 0; + queue->full_waiters = 0; + queue->empty_waiters = 0; + + apr_pool_cleanup_register(a, queue, queue_destroy, apr_pool_cleanup_null); + + return APR_SUCCESS; +} + +/** + * Push new data onto the queue. Blocks if the queue is full. Once + * the push operation has completed, it signals other threads waiting + * in apr_queue_pop() that they may continue consuming sockets. + */ +APU_DECLARE(apr_status_t) apr_queue_push(apr_queue_t *queue, void *data) +{ + apr_status_t rv; + + if (queue->terminated) { + return APR_EOF; /* no more elements ever again */ + } + + rv = apr_thread_mutex_lock(queue->one_big_mutex); + if (rv != APR_SUCCESS) { + return rv; + } + + if (apr_queue_full(queue)) { + if (!queue->terminated) { + queue->full_waiters++; + rv = apr_thread_cond_wait(queue->not_full, queue->one_big_mutex); + queue->full_waiters--; + if (rv != APR_SUCCESS) { + apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; + } + } + /* If we wake up and it's still empty, then we were interrupted */ + if (apr_queue_full(queue)) { + Q_DBG("queue full (intr)", queue); + rv = apr_thread_mutex_unlock(queue->one_big_mutex); + if (rv != APR_SUCCESS) { + return rv; + } + if (queue->terminated) { + return APR_EOF; /* no more elements ever again */ + } + else { + return APR_EINTR; + } + } + } + + queue->data[queue->in] = data; + queue->in++; + if (queue->in >= queue->bounds) + queue->in -= queue->bounds; + queue->nelts++; + + if (queue->empty_waiters) { + Q_DBG("sig !empty", queue); + rv = apr_thread_cond_signal(queue->not_empty); + if (rv != APR_SUCCESS) { + apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; + } + } + + rv = apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; +} + +/** + * Push new data onto the queue. If the queue is full, return APR_EAGAIN. If + * the push operation completes successfully, it signals other threads + * waiting in apr_queue_pop() that they may continue consuming sockets. + */ +APU_DECLARE(apr_status_t) apr_queue_trypush(apr_queue_t *queue, void *data) +{ + apr_status_t rv; + + if (queue->terminated) { + return APR_EOF; /* no more elements ever again */ + } + + rv = apr_thread_mutex_lock(queue->one_big_mutex); + if (rv != APR_SUCCESS) { + return rv; + } + + if (apr_queue_full(queue)) { + rv = apr_thread_mutex_unlock(queue->one_big_mutex); + return APR_EAGAIN; + } + + queue->data[queue->in] = data; + queue->in++; + if (queue->in >= queue->bounds) + queue->in -= queue->bounds; + queue->nelts++; + + if (queue->empty_waiters) { + Q_DBG("sig !empty", queue); + rv = apr_thread_cond_signal(queue->not_empty); + if (rv != APR_SUCCESS) { + apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; + } + } + + rv = apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; +} + +/** + * not thread safe + */ +APU_DECLARE(unsigned int) apr_queue_size(apr_queue_t *queue) { + return queue->nelts; +} + +/** + * Retrieves the next item from the queue. If there are no + * items available, it will block until one becomes available. + * Once retrieved, the item is placed into the address specified by + * 'data'. + */ +APU_DECLARE(apr_status_t) apr_queue_pop(apr_queue_t *queue, void **data) +{ + apr_status_t rv; + + if (queue->terminated) { + return APR_EOF; /* no more elements ever again */ + } + + rv = apr_thread_mutex_lock(queue->one_big_mutex); + if (rv != APR_SUCCESS) { + return rv; + } + + /* Keep waiting until we wake up and find that the queue is not empty. */ + if (apr_queue_empty(queue)) { + if (!queue->terminated) { + queue->empty_waiters++; + rv = apr_thread_cond_wait(queue->not_empty, queue->one_big_mutex); + queue->empty_waiters--; + if (rv != APR_SUCCESS) { + apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; + } + } + /* If we wake up and it's still empty, then we were interrupted */ + if (apr_queue_empty(queue)) { + Q_DBG("queue empty (intr)", queue); + rv = apr_thread_mutex_unlock(queue->one_big_mutex); + if (rv != APR_SUCCESS) { + return rv; + } + if (queue->terminated) { + return APR_EOF; /* no more elements ever again */ + } + else { + return APR_EINTR; + } + } + } + + *data = queue->data[queue->out]; + queue->nelts--; + + queue->out++; + if (queue->out >= queue->bounds) + queue->out -= queue->bounds; + if (queue->full_waiters) { + Q_DBG("signal !full", queue); + rv = apr_thread_cond_signal(queue->not_full); + if (rv != APR_SUCCESS) { + apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; + } + } + + rv = apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; +} + +/** + * Retrieves the next item from the queue. If there are no + * items available, return APR_EAGAIN. Once retrieved, + * the item is placed into the address specified by 'data'. + */ +APU_DECLARE(apr_status_t) apr_queue_trypop(apr_queue_t *queue, void **data) +{ + apr_status_t rv; + + if (queue->terminated) { + return APR_EOF; /* no more elements ever again */ + } + + rv = apr_thread_mutex_lock(queue->one_big_mutex); + if (rv != APR_SUCCESS) { + return rv; + } + + if (apr_queue_empty(queue)) { + rv = apr_thread_mutex_unlock(queue->one_big_mutex); + return APR_EAGAIN; + } + + *data = queue->data[queue->out]; + queue->nelts--; + + queue->out++; + if (queue->out >= queue->bounds) + queue->out -= queue->bounds; + if (queue->full_waiters) { + Q_DBG("signal !full", queue); + rv = apr_thread_cond_signal(queue->not_full); + if (rv != APR_SUCCESS) { + apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; + } + } + + rv = apr_thread_mutex_unlock(queue->one_big_mutex); + return rv; +} + +APU_DECLARE(apr_status_t) apr_queue_interrupt_all(apr_queue_t *queue) +{ + apr_status_t rv; + Q_DBG("intr all", queue); + if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) { + return rv; + } + apr_thread_cond_broadcast(queue->not_empty); + apr_thread_cond_broadcast(queue->not_full); + + if ((rv = apr_thread_mutex_unlock(queue->one_big_mutex)) != APR_SUCCESS) { + return rv; + } + + return APR_SUCCESS; +} + +APU_DECLARE(apr_status_t) apr_queue_term(apr_queue_t *queue) +{ + apr_status_t rv; + + if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) { + return rv; + } + + /* we must hold one_big_mutex when setting this... otherwise, + * we could end up setting it and waking everybody up just after a + * would-be popper checks it but right before they block + */ + queue->terminated = 1; + if ((rv = apr_thread_mutex_unlock(queue->one_big_mutex)) != APR_SUCCESS) { + return rv; + } + return apr_queue_interrupt_all(queue); +} + +#endif /* APR_HAS_THREADS */ |