2 * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
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
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.
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.
19 #ifndef _LIBLTTKCONSUMERD_H
20 #define _LIBLTTKCONSUMERD_H
22 #include <lttng-sessiond-comm.h>
23 #include "lttng-kconsumerd.h"
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.
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.
37 * The value of 2 seconds is an arbitrary choice.
39 #define KCONSUMERD_POLL_GRACE_PERIOD 2000
41 struct kconsumerd_fd_list
{
42 struct cds_list_head head
;
46 * Internal representation of the FDs,
47 * sessiond_fd is used to identify uniquely a fd
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 */
60 enum lttng_event_output output
; /* splice or mmap */
63 struct 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];
80 * initialise the necessary environnement :
81 * - create a new context
82 * - create the poll_pipe
83 * - create the should_quit pipe (for signal handler)
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.
91 struct kconsumerd_local_data
*kconsumerd_create(
92 int (*buffer_ready
)(struct kconsumerd_fd
*kconsumerd_fd
));
96 * Close all fds associated with the instance and free the context
98 void kconsumerd_destroy(struct kconsumerd_local_data
*ctx
);
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
105 int kconsumerd_on_read_subbuffer_mmap(struct kconsumerd_local_data
*ctx
,
106 struct kconsumerd_fd
*kconsumerd_fd
, unsigned long len
);
109 * kconsumerd_on_read_subbuffer
111 * Splice the data from the ring buffer to the tracefile.
112 * Returns the number of bytes spliced
114 int kconsumerd_on_read_subbuffer_splice(struct kconsumerd_local_data
*ctx
,
115 struct kconsumerd_fd
*kconsumerd_fd
, unsigned long len
);
118 * kconsumerd_send_error
119 * send return code to ltt-sessiond
120 * returns the return code of sendmsg : the number of bytes transmitted
123 int kconsumerd_send_error(struct kconsumerd_local_data
*ctx
,
124 enum lttcomm_return_code cmd
);
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
132 int kconsumerd_poll_socket(struct pollfd
*kconsumerd_sockpoll
);
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.
139 void *kconsumerd_thread_poll_fds(void *data
);
142 * kconsumerd_thread_receive_fds
143 * This thread listens on the consumerd socket and
144 * receives the file descriptors from ltt-sessiond
146 void *kconsumerd_thread_receive_fds(void *data
);
149 * kconsumerd_should_exit
150 * Called from signal handler to ensure a clean exit
152 void kconsumerd_should_exit(struct kconsumerd_local_data
*ctx
);
156 * Cleanup the daemon's socket on exit
158 void kconsumerd_cleanup(void);
161 * kconsumerd_set_error_socket
162 * Set the error socket for communication with a session daemon
164 void kconsumerd_set_error_socket(struct kconsumerd_local_data
*ctx
, int sock
);
167 * kconsumerd_set_command_socket_path
168 * Set the command socket path for communication with a session daemon
170 void kconsumerd_set_command_socket_path(struct kconsumerd_local_data
*ctx
, char *sock
);
172 #endif /* _LIBLTTKCONSUMERD_H */