Commit | Line | Data |
---|---|---|
1e494cf4 JB |
1 | /* |
2 | * Copyright 2009, The Android Open Source Project | |
3 | * | |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
5 | * you may not use this file except in compliance with the License. | |
6 | * You may obtain a copy of the License at | |
7 | * | |
8 | * http://www.apache.org/licenses/LICENSE-2.0 | |
9 | * | |
10 | * Unless required by applicable law or agreed to in writing, software | |
11 | * distributed under the License is distributed on an "AS IS" BASIS, | |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 | * See the License for the specific language governing permissions and | |
14 | * limitations under the License. | |
15 | */ | |
16 | ||
17 | /* Helper to perform abortable blocking operations on a socket: | |
18 | * asocket_connect() | |
19 | * asocket_accept() | |
20 | * asocket_read() | |
21 | * asocket_write() | |
22 | * These calls are similar to the regular syscalls, but can be aborted with: | |
23 | * asocket_abort() | |
24 | * | |
25 | * Calling close() on a regular POSIX socket does not abort blocked syscalls on | |
26 | * that socket in other threads. | |
27 | * | |
28 | * After calling asocket_abort() the socket cannot be reused. | |
29 | * | |
30 | * Call asocket_destory() *after* all threads have finished with the socket to | |
31 | * finish closing the socket and free the asocket structure. | |
32 | * | |
33 | * The helper is implemented by setting the socket non-blocking to initiate | |
34 | * syscalls connect(), accept(), read(), write(), then using a blocking poll() | |
35 | * on both the primary socket and a local pipe. This makes the poll() abortable | |
36 | * by writing a byte to the local pipe in asocket_abort(). | |
37 | * | |
38 | * asocket_create() sets the fd to non-blocking mode. It must not be changed to | |
39 | * blocking mode. | |
40 | * | |
41 | * Using asocket will triple the number of file descriptors required per | |
42 | * socket, due to the local pipe. It may be possible to use a global pipe per | |
43 | * process rather than per socket, but we have not been able to come up with a | |
44 | * race-free implementation yet. | |
45 | * | |
46 | * All functions except asocket_init() and asocket_destroy() are thread safe. | |
47 | */ | |
48 | ||
49 | #include <stdlib.h> | |
50 | #include <sys/socket.h> | |
51 | ||
52 | #ifndef __CUTILS_ABORT_SOCKET_H__ | |
53 | #define __CUTILS_ABORT_SOCKET_H__ | |
54 | #ifdef __cplusplus | |
55 | extern "C" { | |
56 | #endif | |
57 | ||
58 | struct asocket { | |
59 | int fd; /* primary socket fd */ | |
60 | int abort_fd[2]; /* pipe used to abort */ | |
61 | }; | |
62 | ||
63 | /* Create an asocket from fd. | |
64 | * Sets the socket to non-blocking mode. | |
65 | * Returns NULL on error with errno set. | |
66 | */ | |
67 | struct asocket *asocket_init(int fd); | |
68 | ||
69 | /* Blocking socket I/O with timeout. | |
70 | * Calling asocket_abort() from another thread will cause each of these | |
71 | * functions to immediately return with value -1 and errno ECANCELED. | |
72 | * timeout is in ms, use -1 to indicate no timeout. On timeout -1 is returned | |
73 | * with errno ETIMEDOUT. | |
74 | * EINTR is handled in-call. | |
75 | * Other semantics are identical to the regular syscalls. | |
76 | */ | |
77 | int asocket_connect(struct asocket *s, const struct sockaddr *addr, | |
78 | socklen_t addrlen, int timeout); | |
79 | ||
80 | int asocket_accept(struct asocket *s, struct sockaddr *addr, | |
81 | socklen_t *addrlen, int timeout); | |
82 | ||
83 | int asocket_read(struct asocket *s, void *buf, size_t count, int timeout); | |
84 | ||
85 | int asocket_write(struct asocket *s, const void *buf, size_t count, | |
86 | int timeout); | |
87 | ||
88 | /* Abort above calls and shutdown socket. | |
89 | * Further I/O operations on this socket will immediately fail after this call. | |
90 | * asocket_destroy() should be used to release resources once all threads | |
91 | * have returned from blocking calls on the socket. | |
92 | */ | |
93 | void asocket_abort(struct asocket *s); | |
94 | ||
95 | /* Close socket and free asocket structure. | |
96 | * Must not be called until all calls on this structure have completed. | |
97 | */ | |
98 | void asocket_destroy(struct asocket *s); | |
99 | ||
100 | #ifdef __cplusplus | |
101 | } | |
102 | #endif | |
103 | #endif //__CUTILS_ABORT_SOCKET__H__ |