libctdb/sync.c

   1 /*
   2    synchronous wrappers for libctdb
   3
   4    Copyright (C) Rusty Russell 2010
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, see <http://www.gnu.org/licenses/>.
  18 */
  19 #include <ctdb.h>
  20 #include <stdbool.h>
  21 #include <poll.h>
  22 #include <errno.h>
  23 #include <stdlib.h>
  24 #include "libctdb_private.h"
  25
  26 /* Remove type-safety macros. */
  27 #undef ctdb_set_message_handler
  28
  29 /* On failure, frees req and returns NULL. */
  30 static struct ctdb_request *synchronous(struct ctdb_connection *ctdb,
  31                                         struct ctdb_request *req,
  32                                         bool *done)
  33 {
  34         struct pollfd fds;
  35
  36         /* Pass through allocation failures. */
  37         if (!req)
  38                 return NULL;
  39
  40         fds.fd = ctdb_get_fd(ctdb);
  41         while (!*done) {
  42                 fds.events = ctdb_which_events(ctdb);
  43                 if (poll(&fds, 1, -1) < 0) {
  44                         /* Signalled is OK, other error is bad. */
  45                         if (errno == EINTR)
  46                                 continue;
  47                         ctdb_cancel(ctdb, req);
  48                         DEBUG(ctdb, LOG_ERR, "ctdb_synchronous: poll failed");
  49                         return NULL;
  50                 }
  51                 if (!ctdb_service(ctdb, fds.revents)) {
  52                         /* It can have failed after it completed request. */
  53                         if (!*done)
  54                                 ctdb_cancel(ctdb, req);
  55                         else
  56                                 ctdb_request_free(ctdb, req);
  57                         return NULL;
  58                 }
  59         }
  60         return req;
  61 }
  62
  63 static void set(struct ctdb_connection *ctdb,
  64                 struct ctdb_request *req, bool *done)
  65 {
  66         *done = true;
  67 }
  68
  69 bool ctdb_getrecmaster(struct ctdb_connection *ctdb,
  70                        uint32_t destnode, uint32_t *recmaster)
  71 {
  72         struct ctdb_request *req;
  73         bool done = false;
  74         bool ret = false;
  75
  76         req = synchronous(ctdb,
  77                           ctdb_getrecmaster_send(ctdb, destnode, set, &done),
  78                           &done);
  79         if (req != NULL) {
  80                 ret = ctdb_getrecmaster_recv(ctdb, req, recmaster);
  81                 ctdb_request_free(ctdb, req);
  82         }
  83         return ret;
  84 }
  85
  86 struct ctdb_db *ctdb_attachdb(struct ctdb_connection *ctdb,
  87                               const char *name, bool persistent,
  88                               uint32_t tdb_flags)
  89 {
  90         struct ctdb_request *req;
  91         bool done = false;
  92         struct ctdb_db *ret = NULL;
  93
  94         req = synchronous(ctdb,
  95                           ctdb_attachdb_send(ctdb, name, persistent, tdb_flags,
  96                                              set, &done),
  97                           &done);
  98         if (req != NULL) {
  99                 ret = ctdb_attachdb_recv(ctdb, req);
 100                 ctdb_request_free(ctdb, req);
 101         }
 102         return ret;
 103 }
 104
 105 bool ctdb_getpnn(struct ctdb_connection *ctdb,
 106                  uint32_t destnode, uint32_t *pnn)
 107 {
 108         struct ctdb_request *req;
 109         bool done = false;
 110         bool ret = false;
 111
 112         req = synchronous(ctdb,
 113                           ctdb_getpnn_send(ctdb, destnode, set, &done),
 114                           &done);
 115         if (req != NULL) {
 116                 ret = ctdb_getpnn_recv(ctdb, req, pnn);
 117                 ctdb_request_free(ctdb, req);
 118         }
 119         return ret;
 120 }
 121
 122 bool ctdb_set_message_handler(struct ctdb_connection *ctdb, uint64_t srvid,
 123                               ctdb_message_fn_t handler, void *cbdata)
 124 {
 125         struct ctdb_request *req;
 126         bool done = false;
 127         bool ret = false;
 128
 129         req = synchronous(ctdb,
 130                           ctdb_set_message_handler_send(ctdb, srvid, handler,
 131                                                         cbdata, set, &done),
 132                           &done);
 133         if (req != NULL) {
 134                 ret = ctdb_set_message_handler_recv(ctdb, req);
 135                 ctdb_request_free(ctdb, req);
 136         }
 137         return ret;
 138 }
 139
 140 struct rrl_info {
 141         bool done;
 142         struct ctdb_lock *lock;
 143         TDB_DATA *data;
 144 };
 145
 146 static void rrl_callback(struct ctdb_db *ctdb_db,
 147                          struct ctdb_lock *lock,
 148                          TDB_DATA data,
 149                          struct rrl_info *rrl)
 150 {
 151         rrl->done = true;
 152         rrl->lock = lock;
 153         *rrl->data = data;
 154 }
 155
 156 struct ctdb_lock *ctdb_readrecordlock(struct ctdb_connection *ctdb,
 157                                       struct ctdb_db *ctdb_db, TDB_DATA key,
 158                                       TDB_DATA *data)
 159 {
 160         struct pollfd fds;
 161         struct rrl_info rrl;
 162
 163         rrl.done = false;
 164         rrl.lock = NULL;
 165         rrl.data = data;
 166
 167         /* Immediate failure is easy. */
 168         if (!ctdb_readrecordlock_async(ctdb_db, key, rrl_callback, &rrl))
 169                 return NULL;
 170
 171         /* Immediate success is easy. */
 172         if (!rrl.done) {
 173                 /* Otherwise wait until callback called. */
 174                 fds.fd = ctdb_get_fd(ctdb);
 175                 while (!rrl.done) {
 176                         fds.events = ctdb_which_events(ctdb);
 177                         if (poll(&fds, 1, -1) < 0) {
 178                                 /* Signalled is OK, other error is bad. */
 179                                 if (errno == EINTR)
 180                                         continue;
 181                                 DEBUG(ctdb, LOG_ERR,
 182                                       "ctdb_readrecordlock: poll failed");
 183                                 return NULL;
 184                         }
 185                         if (!ctdb_service(ctdb, fds.revents)) {
 186                                 break;
 187                         }
 188                 }
 189         }
 190         return rrl.lock;
 191 }