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/* Copyright (c) 2013 Nicira, 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.
*/
#include <config.h>
/* This implementation of the async-append.h interface uses the POSIX
* asynchronous I/O interface. */
#include "async-append.h"
#include <aio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include "byteq.h"
#include "ovs-thread.h"
#include "util.h"
/* Maximum number of bytes of buffered data. */
enum { BUFFER_SIZE = 65536 };
/* Maximum number of aiocbs to use.
*
* aiocbs are big (144 bytes with glibc 2.11 on i386) so we try to allow for a
* reasonable number by basing the number we allocate on the amount of buffer
* space. */
enum { MAX_CBS = ROUND_DOWN_POW2(BUFFER_SIZE / sizeof(struct aiocb)) };
BUILD_ASSERT_DECL(IS_POW2(MAX_CBS));
struct async_append {
int fd;
struct aiocb *aiocbs;
unsigned int aiocb_head, aiocb_tail;
uint8_t *buffer;
struct byteq byteq;
};
struct async_append *
async_append_create(int fd)
{
struct async_append *ap;
ap = xmalloc(sizeof *ap);
ap->fd = fd;
ap->aiocbs = xmalloc(MAX_CBS * sizeof *ap->aiocbs);
ap->aiocb_head = ap->aiocb_tail = 0;
ap->buffer = xmalloc(BUFFER_SIZE);
byteq_init(&ap->byteq, ap->buffer, BUFFER_SIZE);
return ap;
}
void
async_append_destroy(struct async_append *ap)
{
if (ap) {
async_append_flush(ap);
free(ap->aiocbs);
free(ap->buffer);
free(ap);
}
}
static bool
async_append_is_full(const struct async_append *ap)
{
return (ap->aiocb_head - ap->aiocb_tail >= MAX_CBS
|| byteq_is_full(&ap->byteq));
}
static bool
async_append_is_empty(const struct async_append *ap)
{
return byteq_is_empty(&ap->byteq);
}
static void
async_append_wait(struct async_append *ap)
{
int n = 0;
while (!async_append_is_empty(ap)) {
struct aiocb *aiocb = &ap->aiocbs[ap->aiocb_tail & (MAX_CBS - 1)];
int error = aio_error(aiocb);
if (error == EINPROGRESS) {
const struct aiocb *p = aiocb;
if (n > 0) {
return;
}
aio_suspend(&p, 1, NULL);
} else {
ignore(aio_return(aiocb));
ap->aiocb_tail++;
byteq_advance_tail(&ap->byteq, aiocb->aio_nbytes);
n++;
}
}
}
void
async_append_write(struct async_append *ap, const void *data_, size_t size)
{
const uint8_t *data = data_;
while (size > 0) {
struct aiocb *aiocb;
size_t chunk_size;
void *chunk;
while (async_append_is_full(ap)) {
async_append_wait(ap);
}
chunk = byteq_head(&ap->byteq);
chunk_size = byteq_headroom(&ap->byteq);
if (chunk_size > size) {
chunk_size = size;
}
memcpy(chunk, data, chunk_size);
aiocb = &ap->aiocbs[ap->aiocb_head & (MAX_CBS - 1)];
memset(aiocb, 0, sizeof *aiocb);
aiocb->aio_fildes = ap->fd;
aiocb->aio_offset = 0;
aiocb->aio_buf = chunk;
aiocb->aio_nbytes = chunk_size;
aiocb->aio_sigevent.sigev_notify = SIGEV_NONE;
if (aio_write(aiocb) == -1) {
async_append_flush(ap);
ignore(write(ap->fd, data, size));
return;
}
data += chunk_size;
size -= chunk_size;
byteq_advance_head(&ap->byteq, chunk_size);
ap->aiocb_head++;
}
}
void
async_append_flush(struct async_append *ap)
{
while (!async_append_is_empty(ap)) {
async_append_wait(ap);
}
}
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