1 /* Copyright (c) 2013 Nicira, Inc.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
18 /* This implementation of the async-append.h interface uses the POSIX
19 * asynchronous I/O interface. */
21 #include "async-append.h"
29 #include "ovs-thread.h"
32 /* Maximum number of bytes of buffered data. */
33 enum { BUFFER_SIZE = 65536 };
35 /* Maximum number of aiocbs to use.
37 * aiocbs are big (144 bytes with glibc 2.11 on i386) so we try to allow for a
38 * reasonable number by basing the number we allocate on the amount of buffer
40 enum { MAX_CBS = ROUND_DOWN_POW2(BUFFER_SIZE / sizeof(struct aiocb)) };
41 BUILD_ASSERT_DECL(IS_POW2(MAX_CBS));
47 unsigned int aiocb_head, aiocb_tail;
54 async_append_create(int fd)
56 struct async_append *ap;
58 ap = xmalloc(sizeof *ap);
60 ap->aiocbs = xmalloc(MAX_CBS * sizeof *ap->aiocbs);
61 ap->aiocb_head = ap->aiocb_tail = 0;
62 ap->buffer = xmalloc(BUFFER_SIZE);
63 byteq_init(&ap->byteq, ap->buffer, BUFFER_SIZE);
69 async_append_destroy(struct async_append *ap)
72 async_append_flush(ap);
80 async_append_is_full(const struct async_append *ap)
82 return (ap->aiocb_head - ap->aiocb_tail >= MAX_CBS
83 || byteq_is_full(&ap->byteq));
87 async_append_is_empty(const struct async_append *ap)
89 return byteq_is_empty(&ap->byteq);
93 async_append_wait(struct async_append *ap)
97 while (!async_append_is_empty(ap)) {
98 struct aiocb *aiocb = &ap->aiocbs[ap->aiocb_tail & (MAX_CBS - 1)];
99 int error = aio_error(aiocb);
101 if (error == EINPROGRESS) {
102 const struct aiocb *p = aiocb;
106 aio_suspend(&p, 1, NULL);
108 ignore(aio_return(aiocb));
110 byteq_advance_tail(&ap->byteq, aiocb->aio_nbytes);
117 async_append_write(struct async_append *ap, const void *data_, size_t size)
119 const uint8_t *data = data_;
126 while (async_append_is_full(ap)) {
127 async_append_wait(ap);
130 chunk = byteq_head(&ap->byteq);
131 chunk_size = byteq_headroom(&ap->byteq);
132 if (chunk_size > size) {
135 memcpy(chunk, data, chunk_size);
137 aiocb = &ap->aiocbs[ap->aiocb_head & (MAX_CBS - 1)];
138 memset(aiocb, 0, sizeof *aiocb);
139 aiocb->aio_fildes = ap->fd;
140 aiocb->aio_offset = 0;
141 aiocb->aio_buf = chunk;
142 aiocb->aio_nbytes = chunk_size;
143 aiocb->aio_sigevent.sigev_notify = SIGEV_NONE;
144 if (aio_write(aiocb) == -1) {
145 async_append_flush(ap);
146 ignore(write(ap->fd, data, size));
152 byteq_advance_head(&ap->byteq, chunk_size);
158 async_append_flush(struct async_append *ap)
160 while (!async_append_is_empty(ap)) {
161 async_append_wait(ap);