Cleanup mmap consuming
[lttng-tools.git] / liblttkconsumerd / lttkconsumerd.h
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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
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6 * as published by the Free Software Foundation; only version 2
7 * of the License.
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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
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19#ifndef _LIBLTTKCONSUMERD_H
20#define _LIBLTTKCONSUMERD_H
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e88129fc 22#include <lttng-sessiond-comm.h>
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23#include "lttng-kconsumerd.h"
24
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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
41struct kconsumerd_fd_list {
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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 */
1ce86c9a 49struct kconsumerd_fd {
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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 */
5dc18550 56 enum kconsumerd_fd_state state;
d4a1283e 57 unsigned long max_sb_size; /* the subbuffer size for this channel */
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58 void *mmap_base;
59 size_t mmap_len;
60 enum lttng_event_output output; /* splice or mmap */
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61};
62
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63struct kconsumerd_local_data {
64 /* function to call when data is available on a buffer */
65 int (*on_buffer_ready)(struct kconsumerd_fd *kconsumerd_fd);
66 /* socket to communicate errors with sessiond */
67 int kconsumerd_error_socket;
68 /* socket to exchange commands with sessiond */
69 char *kconsumerd_command_sock_path;
70 /* communication with splice */
71 int kconsumerd_thread_pipe[2];
72 /* pipe to wake the poll thread when necessary */
73 int kconsumerd_poll_pipe[2];
74 /* to let the signal handler wake up the fd receiver thread */
75 int kconsumerd_should_quit[2];
76};
77
c72c2927 78/*
cb040cc1 79 * kconsumerd_create
c72c2927 80 * initialise the necessary environnement :
cb040cc1 81 * - create a new context
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82 * - create the poll_pipe
83 * - create the should_quit pipe (for signal handler)
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84 * - create the thread pipe (for splice)
85 * Takes a function pointer as argument, this function is called when data is
86 * available on a buffer. This function is responsible to do the
87 * kernctl_get_next_subbuf, read the data with mmap or splice depending on the
88 * buffer configuration and then kernctl_put_next_subbuf at the end.
89 * Returns a pointer to the new context or NULL on error.
90 */
91struct kconsumerd_local_data *kconsumerd_create(
92 int (*buffer_ready)(struct kconsumerd_fd *kconsumerd_fd));
93
94/*
95 * kconsumerd_destroy
96 * Close all fds associated with the instance and free the context
97 */
98void kconsumerd_destroy(struct kconsumerd_local_data *ctx);
99
100/*
101 * kconsumerd_on_read_subbuffer_mmap
102 * mmap the ring buffer, read it and write the data to the tracefile.
103 * Returns the number of bytes written
104 */
105int kconsumerd_on_read_subbuffer_mmap(struct kconsumerd_local_data *ctx,
106 struct kconsumerd_fd *kconsumerd_fd, unsigned long len);
107
108/*
109 * kconsumerd_on_read_subbuffer
110 *
111 * Splice the data from the ring buffer to the tracefile.
112 * Returns the number of bytes spliced
c72c2927 113 */
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114int kconsumerd_on_read_subbuffer_splice(struct kconsumerd_local_data *ctx,
115 struct kconsumerd_fd *kconsumerd_fd, unsigned long len);
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116
117/*
118 * kconsumerd_send_error
119 * send return code to ltt-sessiond
120 * returns the return code of sendmsg : the number of bytes transmitted
121 * or -1 on error.
122 */
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123int kconsumerd_send_error(struct kconsumerd_local_data *ctx,
124 enum lttcomm_return_code cmd);
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125
126/*
127 * kconsumerd_poll_socket
128 * Poll on the should_quit pipe and the command socket
129 * return -1 on error and should exit, 0 if data is
130 * available on the command socket
131 */
4de84ad9 132int kconsumerd_poll_socket(struct pollfd *kconsumerd_sockpoll);
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133
134/*
135 * kconsumerd_thread_poll_fds
136 * This thread polls the fds in the ltt_fd_list to consume the data
137 * and write it to tracefile if necessary.
138 */
1ce86c9a 139void *kconsumerd_thread_poll_fds(void *data);
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140
141/*
142 * kconsumerd_thread_receive_fds
143 * This thread listens on the consumerd socket and
144 * receives the file descriptors from ltt-sessiond
145 */
1ce86c9a 146void *kconsumerd_thread_receive_fds(void *data);
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147
148/*
149 * kconsumerd_should_exit
150 * Called from signal handler to ensure a clean exit
151 */
cb040cc1 152void kconsumerd_should_exit(struct kconsumerd_local_data *ctx);
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153
154/*
155 * kconsumerd_cleanup
156 * Cleanup the daemon's socket on exit
157 */
3dcd2721 158void kconsumerd_cleanup(void);
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159
160/*
161 * kconsumerd_set_error_socket
162 * Set the error socket for communication with a session daemon
163 */
cb040cc1 164void kconsumerd_set_error_socket(struct kconsumerd_local_data *ctx, int sock);
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165
166/*
167 * kconsumerd_set_command_socket_path
168 * Set the command socket path for communication with a session daemon
169 */
cb040cc1 170void kconsumerd_set_command_socket_path(struct kconsumerd_local_data *ctx, char *sock);
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171
172#endif /* _LIBLTTKCONSUMERD_H */
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