2 CTDB cluster mutex handling
4 Copyright (C) Andrew Tridgell 2007
5 Copyright (C) Ronnie Sahlberg 2007
6 Copyright (C) Martin Schwenke 2016
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, see <http://www.gnu.org/licenses/>.
23 #include "system/network.h"
27 #include "lib/util/debug.h"
28 #include "lib/util/time.h"
29 #include "lib/util/strv.h"
30 #include "lib/util/strv_util.h"
31 #include "lib/util/sys_rw.h"
32 #include "lib/util/blocking.h"
34 #include "ctdb_private.h"
35 #include "common/common.h"
36 #include "common/logging.h"
38 #include "ctdb_cluster_mutex.h"
40 struct ctdb_cluster_mutex_handle {
41 struct ctdb_context *ctdb;
42 cluster_mutex_handler_t handler;
44 cluster_mutex_lost_handler_t lost_handler;
47 struct tevent_timer *te;
48 struct tevent_fd *fde;
50 struct timeval start_time;
54 static void cluster_mutex_timeout(struct tevent_context *ev,
55 struct tevent_timer *te,
56 struct timeval t, void *private_data)
58 struct ctdb_cluster_mutex_handle *h =
59 talloc_get_type(private_data, struct ctdb_cluster_mutex_handle);
60 double latency = timeval_elapsed(&h->start_time);
62 if (h->handler != NULL) {
63 h->handler('2', latency, h->private_data);
68 /* When the handle is freed it causes any child holding the mutex to
69 * be killed, thus freeing the mutex */
70 static int cluster_mutex_destructor(struct ctdb_cluster_mutex_handle *h)
75 ctdb_kill(h->ctdb, h->child, SIGTERM);
79 /* this is called when the client process has completed ctdb_recovery_lock()
80 and has written data back to us through the pipe.
82 static void cluster_mutex_handler(struct tevent_context *ev,
83 struct tevent_fd *fde,
84 uint16_t flags, void *private_data)
86 struct ctdb_cluster_mutex_handle *h=
87 talloc_get_type(private_data, struct ctdb_cluster_mutex_handle);
88 double latency = timeval_elapsed(&h->start_time);
92 /* Got response from child process so abort timeout */
95 ret = sys_read(h->fd[0], &c, 1);
97 /* Don't call the handler more than once. It only exists to
98 * process the initial response from the helper. */
99 if (h->have_response) {
100 /* Only deal with EOF due to process exit. Silently
101 * ignore any other output. */
103 if (h->lost_handler != NULL) {
104 h->lost_handler(h->lost_data);
109 h->have_response = true;
111 /* If the child wrote status then just pass it to the handler.
112 * If no status was written then this is an unexpected error
113 * so pass generic error code to handler. */
114 if (h->handler != NULL) {
115 h->handler(ret == 1 ? c : '3', latency, h->private_data);
119 static char cluster_mutex_helper[PATH_MAX+1] = "";
121 static bool cluster_mutex_helper_args(TALLOC_CTX *mem_ctx,
122 const char *argstring, char ***argv)
124 int nargs, i, ret, n;
125 bool is_command = false;
130 if (argstring != NULL && argstring[0] == '!') {
131 /* This is actually a full command */
133 t = discard_const(&argstring[1]);
136 t = discard_const(argstring);
139 ret = strv_split(mem_ctx, &strv, t, " \t");
142 ("Unable to parse mutex helper string \"%s\" (%s)\n",
143 argstring, strerror(ret)));
146 n = strv_count(strv);
148 args = talloc_array(mem_ctx, char *, n + (is_command ? 1 : 2));
151 DEBUG(DEBUG_ERR,(__location__ " out of memory\n"));
158 if (!ctdb_set_helper("cluster mutex helper",
159 cluster_mutex_helper,
160 sizeof(cluster_mutex_helper),
161 "CTDB_CLUSTER_MUTEX_HELPER",
163 "ctdb_mutex_fcntl_helper")) {
164 DEBUG(DEBUG_ERR,("ctdb exiting with error: %s\n",
166 " Unable to set cluster mutex helper\n"));
170 args[nargs++] = cluster_mutex_helper;
174 for (i = 0; i < n; i++) {
175 /* Don't copy, just keep cmd_args around */
176 t = strv_next(strv, t);
180 /* Make sure last argument is NULL */
187 struct ctdb_cluster_mutex_handle *
188 ctdb_cluster_mutex(TALLOC_CTX *mem_ctx,
189 struct ctdb_context *ctdb,
190 const char *argstring,
192 cluster_mutex_handler_t handler,
194 cluster_mutex_lost_handler_t lost_handler,
197 struct ctdb_cluster_mutex_handle *h;
201 h = talloc(mem_ctx, struct ctdb_cluster_mutex_handle);
203 DEBUG(DEBUG_ERR, (__location__ " out of memory\n"));
207 h->start_time = timeval_current();
210 h->have_response = false;
215 DEBUG(DEBUG_ERR, (__location__ " Failed to open pipe\n"));
218 set_close_on_exec(h->fd[0]);
220 /* Create arguments for lock helper */
221 if (!cluster_mutex_helper_args(h, argstring, &args)) {
228 h->child = ctdb_fork(ctdb);
229 if (h->child == (pid_t)-1) {
237 /* Make stdout point to the pipe */
238 close(STDOUT_FILENO);
239 dup2(h->fd[1], STDOUT_FILENO);
242 execv(args[0], args);
244 /* Only happens on error */
245 DEBUG(DEBUG_ERR, (__location__ "execv() failed\n"));
251 DEBUG(DEBUG_DEBUG, (__location__ " Created PIPE FD:%d\n", h->fd[0]));
252 set_close_on_exec(h->fd[0]);
257 talloc_set_destructor(h, cluster_mutex_destructor);
260 h->te = tevent_add_timer(ctdb->ev, h,
261 timeval_current_ofs(timeout, 0),
262 cluster_mutex_timeout, h);
267 h->fde = tevent_add_fd(ctdb->ev, h, h->fd[0], TEVENT_FD_READ,
268 cluster_mutex_handler, (void *)h);
270 if (h->fde == NULL) {
274 tevent_fd_set_auto_close(h->fde);
277 h->handler = handler;
278 h->private_data = private_data;
279 h->lost_handler = lost_handler;
280 h->lost_data = lost_data;