cbdedd213ba0c614e3336d91378c780ac26af618
[lttng-tools.git] / liblttkconsumerd / lttkconsumerd.h
1 /*
2 * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; only version 2
7 * of the License.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 */
18
19 #ifndef _LIBLTTKCONSUMERD_H
20 #define _LIBLTTKCONSUMERD_H
21
22 #include <lttng-sessiond-comm.h>
23 #include "lttng-kconsumerd.h"
24
25 /*
26 * When the receiving thread dies, we need to have a way to make
27 * the polling thread exit eventually.
28 * If all FDs hang up (normal case when the ltt-sessiond stops),
29 * we can exit cleanly, but if there is a problem and for whatever
30 * reason some FDs remain open, the consumer should still exit eventually.
31 *
32 * If the timeout is reached, it means that during this period
33 * no events occurred on the FDs so we need to force an exit.
34 * This case should not happen but it is a safety to ensure we won't block
35 * the consumer indefinitely.
36 *
37 * The value of 2 seconds is an arbitrary choice.
38 */
39 #define KCONSUMERD_POLL_GRACE_PERIOD 2000
40
41 struct kconsumerd_fd_list {
42 struct cds_list_head head;
43 };
44
45 /*
46 * Internal representation of the FDs,
47 * sessiond_fd is used to identify uniquely a fd
48 */
49 struct kconsumerd_fd {
50 struct cds_list_head list;
51 int sessiond_fd; /* used to identify uniquely a fd with sessiond */
52 int consumerd_fd; /* fd to consume */
53 int out_fd; /* output file to write the data */
54 off_t out_fd_offset; /* write position in the output file descriptor */
55 char path_name[PATH_MAX]; /* tracefile name */
56 enum kconsumerd_fd_state state;
57 unsigned long max_sb_size; /* the subbuffer size for this channel */
58 };
59
60 /*
61 * kconsumerd_init(void)
62 * initialise the necessary environnement :
63 * - inform the polling thread to update the polling array
64 * - create the poll_pipe
65 * - create the should_quit pipe (for signal handler)
66 * returns the return code of pipe, 0 on success, -1 on error
67 */
68 int kconsumerd_init(void);
69
70 /*
71 * kconsumerd_send_error
72 * send return code to ltt-sessiond
73 * returns the return code of sendmsg : the number of bytes transmitted
74 * or -1 on error.
75 */
76 int kconsumerd_send_error(enum lttcomm_return_code cmd);
77
78 /*
79 * kconsumerd_poll_socket
80 * Poll on the should_quit pipe and the command socket
81 * return -1 on error and should exit, 0 if data is
82 * available on the command socket
83 */
84 int kconsumerd_poll_socket(struct pollfd *kconsumerd_sockpoll);
85
86 /*
87 * kconsumerd_thread_poll_fds
88 * This thread polls the fds in the ltt_fd_list to consume the data
89 * and write it to tracefile if necessary.
90 */
91 void *kconsumerd_thread_poll_fds(void *data);
92
93 /*
94 * kconsumerd_thread_receive_fds
95 * This thread listens on the consumerd socket and
96 * receives the file descriptors from ltt-sessiond
97 */
98 void *kconsumerd_thread_receive_fds(void *data);
99
100 /*
101 * kconsumerd_should_exit
102 * Called from signal handler to ensure a clean exit
103 */
104 void kconsumerd_should_exit(void);
105
106 /*
107 * kconsumerd_cleanup
108 * Cleanup the daemon's socket on exit
109 */
110 void kconsumerd_cleanup(void);
111
112 /*
113 * kconsumerd_set_error_socket
114 * Set the error socket for communication with a session daemon
115 */
116 void kconsumerd_set_error_socket(int sock);
117
118 /*
119 * kconsumerd_set_command_socket_path
120 * Set the command socket path for communication with a session daemon
121 */
122 void kconsumerd_set_command_socket_path(char *sock);
123
124 #endif /* _LIBLTTKCONSUMERD_H */
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