src/replication.c

   1 #include "redis.h"
   2
   3 #include <sys/time.h>
   4 #include <unistd.h>
   5 #include <fcntl.h>
   6 #include <sys/stat.h>
   7
   8 void replicationFeedSlaves(list *slaves, int dictid, robj **argv, int argc) {
   9     listNode *ln;
  10     listIter li;
  11     int outc = 0, j;
  12     robj **outv;
  13     /* We need 1+(ARGS*3) objects since commands are using the new protocol
  14      * and we one 1 object for the first "*<count>\r\n" multibulk count, then
  15      * for every additional object we have "$<count>\r\n" + object + "\r\n". */
  16     robj *static_outv[REDIS_STATIC_ARGS*3+1];
  17     robj *lenobj;
  18
  19     if (argc <= REDIS_STATIC_ARGS) {
  20         outv = static_outv;
  21     } else {
  22         outv = zmalloc(sizeof(robj*)*(argc*3+1));
  23     }
  24
  25     lenobj = createObject(REDIS_STRING,
  26             sdscatprintf(sdsempty(), "*%d\r\n", argc));
  27     lenobj->refcount = 0;
  28     outv[outc++] = lenobj;
  29     for (j = 0; j < argc; j++) {
  30         lenobj = createObject(REDIS_STRING,
  31             sdscatprintf(sdsempty(),"$%lu\r\n",
  32                 (unsigned long) stringObjectLen(argv[j])));
  33         lenobj->refcount = 0;
  34         outv[outc++] = lenobj;
  35         outv[outc++] = argv[j];
  36         outv[outc++] = shared.crlf;
  37     }
  38
  39     /* Increment all the refcounts at start and decrement at end in order to
  40      * be sure to free objects if there is no slave in a replication state
  41      * able to be feed with commands */
  42     for (j = 0; j < outc; j++) incrRefCount(outv[j]);
  43     listRewind(slaves,&li);
  44     while((ln = listNext(&li))) {
  45         redisClient *slave = ln->value;
  46
  47         /* Don't feed slaves that are still waiting for BGSAVE to start */
  48         if (slave->replstate == REDIS_REPL_WAIT_BGSAVE_START) continue;
  49
  50         /* Feed all the other slaves, MONITORs and so on */
  51         if (slave->slaveseldb != dictid) {
  52             robj *selectcmd;
  53
  54             switch(dictid) {
  55             case 0: selectcmd = shared.select0; break;
  56             case 1: selectcmd = shared.select1; break;
  57             case 2: selectcmd = shared.select2; break;
  58             case 3: selectcmd = shared.select3; break;
  59             case 4: selectcmd = shared.select4; break;
  60             case 5: selectcmd = shared.select5; break;
  61             case 6: selectcmd = shared.select6; break;
  62             case 7: selectcmd = shared.select7; break;
  63             case 8: selectcmd = shared.select8; break;
  64             case 9: selectcmd = shared.select9; break;
  65             default:
  66                 selectcmd = createObject(REDIS_STRING,
  67                     sdscatprintf(sdsempty(),"select %d\r\n",dictid));
  68                 selectcmd->refcount = 0;
  69                 break;
  70             }
  71             addReply(slave,selectcmd);
  72             slave->slaveseldb = dictid;
  73         }
  74         for (j = 0; j < outc; j++) addReply(slave,outv[j]);
  75     }
  76     for (j = 0; j < outc; j++) decrRefCount(outv[j]);
  77     if (outv != static_outv) zfree(outv);
  78 }
  79
  80 void replicationFeedMonitors(list *monitors, int dictid, robj **argv, int argc) {
  81     listNode *ln;
  82     listIter li;
  83     int j;
  84     sds cmdrepr = sdsnew("+");
  85     robj *cmdobj;
  86     struct timeval tv;
  87
  88     gettimeofday(&tv,NULL);
  89     cmdrepr = sdscatprintf(cmdrepr,"%ld.%ld ",(long)tv.tv_sec,(long)tv.tv_usec);
  90     if (dictid != 0) cmdrepr = sdscatprintf(cmdrepr,"(db %d) ", dictid);
  91
  92     for (j = 0; j < argc; j++) {
  93         if (argv[j]->encoding == REDIS_ENCODING_INT) {
  94             cmdrepr = sdscatprintf(cmdrepr, "\"%ld\"", (long)argv[j]->ptr);
  95         } else {
  96             cmdrepr = sdscatrepr(cmdrepr,(char*)argv[j]->ptr,
  97                         sdslen(argv[j]->ptr));
  98         }
  99         if (j != argc-1)
 100             cmdrepr = sdscatlen(cmdrepr," ",1);
 101     }
 102     cmdrepr = sdscatlen(cmdrepr,"\r\n",2);
 103     cmdobj = createObject(REDIS_STRING,cmdrepr);
 104
 105     listRewind(monitors,&li);
 106     while((ln = listNext(&li))) {
 107         redisClient *monitor = ln->value;
 108         addReply(monitor,cmdobj);
 109     }
 110     decrRefCount(cmdobj);
 111 }
 112
 113 int syncWrite(int fd, char *ptr, ssize_t size, int timeout) {
 114     ssize_t nwritten, ret = size;
 115     time_t start = time(NULL);
 116
 117     timeout++;
 118     while(size) {
 119         if (aeWait(fd,AE_WRITABLE,1000) & AE_WRITABLE) {
 120             nwritten = write(fd,ptr,size);
 121             if (nwritten == -1) return -1;
 122             ptr += nwritten;
 123             size -= nwritten;
 124         }
 125         if ((time(NULL)-start) > timeout) {
 126             errno = ETIMEDOUT;
 127             return -1;
 128         }
 129     }
 130     return ret;
 131 }
 132
 133 int syncRead(int fd, char *ptr, ssize_t size, int timeout) {
 134     ssize_t nread, totread = 0;
 135     time_t start = time(NULL);
 136
 137     timeout++;
 138     while(size) {
 139         if (aeWait(fd,AE_READABLE,1000) & AE_READABLE) {
 140             nread = read(fd,ptr,size);
 141             if (nread <= 0) return -1;
 142             ptr += nread;
 143             size -= nread;
 144             totread += nread;
 145         }
 146         if ((time(NULL)-start) > timeout) {
 147             errno = ETIMEDOUT;
 148             return -1;
 149         }
 150     }
 151     return totread;
 152 }
 153
 154 int syncReadLine(int fd, char *ptr, ssize_t size, int timeout) {
 155     ssize_t nread = 0;
 156
 157     size--;
 158     while(size) {
 159         char c;
 160
 161         if (syncRead(fd,&c,1,timeout) == -1) return -1;
 162         if (c == '\n') {
 163             *ptr = '\0';
 164             if (nread && *(ptr-1) == '\r') *(ptr-1) = '\0';
 165             return nread;
 166         } else {
 167             *ptr++ = c;
 168             *ptr = '\0';
 169             nread++;
 170         }
 171     }
 172     return nread;
 173 }
 174
 175 void syncCommand(redisClient *c) {
 176     /* ignore SYNC if aleady slave or in monitor mode */
 177     if (c->flags & REDIS_SLAVE) return;
 178
 179     /* Refuse SYNC requests if we are a slave but the link with our master
 180      * is not ok... */
 181     if (server.masterhost && server.replstate != REDIS_REPL_CONNECTED) {
 182         addReplySds(c,sdsnew("-ERR Can't SYNC while not connected with my master\r\n"));
 183         return;
 184     }
 185
 186     /* SYNC can't be issued when the server has pending data to send to
 187      * the client about already issued commands. We need a fresh reply
 188      * buffer registering the differences between the BGSAVE and the current
 189      * dataset, so that we can copy to other slaves if needed. */
 190     if (listLength(c->reply) != 0) {
 191         addReplySds(c,sdsnew("-ERR SYNC is invalid with pending input\r\n"));
 192         return;
 193     }
 194
 195     redisLog(REDIS_NOTICE,"Slave ask for synchronization");
 196     /* Here we need to check if there is a background saving operation
 197      * in progress, or if it is required to start one */
 198     if (server.bgsavechildpid != -1) {
 199         /* Ok a background save is in progress. Let's check if it is a good
 200          * one for replication, i.e. if there is another slave that is
 201          * registering differences since the server forked to save */
 202         redisClient *slave;
 203         listNode *ln;
 204         listIter li;
 205
 206         listRewind(server.slaves,&li);
 207         while((ln = listNext(&li))) {
 208             slave = ln->value;
 209             if (slave->replstate == REDIS_REPL_WAIT_BGSAVE_END) break;
 210         }
 211         if (ln) {
 212             /* Perfect, the server is already registering differences for
 213              * another slave. Set the right state, and copy the buffer. */
 214             listRelease(c->reply);
 215             c->reply = listDup(slave->reply);
 216             c->replstate = REDIS_REPL_WAIT_BGSAVE_END;
 217             redisLog(REDIS_NOTICE,"Waiting for end of BGSAVE for SYNC");
 218         } else {
 219             /* No way, we need to wait for the next BGSAVE in order to
 220              * register differences */
 221             c->replstate = REDIS_REPL_WAIT_BGSAVE_START;
 222             redisLog(REDIS_NOTICE,"Waiting for next BGSAVE for SYNC");
 223         }
 224     } else {
 225         /* Ok we don't have a BGSAVE in progress, let's start one */
 226         redisLog(REDIS_NOTICE,"Starting BGSAVE for SYNC");
 227         if (rdbSaveBackground(server.dbfilename) != REDIS_OK) {
 228             redisLog(REDIS_NOTICE,"Replication failed, can't BGSAVE");
 229             addReplySds(c,sdsnew("-ERR Unalbe to perform background save\r\n"));
 230             return;
 231         }
 232         c->replstate = REDIS_REPL_WAIT_BGSAVE_END;
 233     }
 234     c->repldbfd = -1;
 235     c->flags |= REDIS_SLAVE;
 236     c->slaveseldb = 0;
 237     listAddNodeTail(server.slaves,c);
 238     return;
 239 }
 240
 241 void sendBulkToSlave(aeEventLoop *el, int fd, void *privdata, int mask) {
 242     redisClient *slave = privdata;
 243     REDIS_NOTUSED(el);
 244     REDIS_NOTUSED(mask);
 245     char buf[REDIS_IOBUF_LEN];
 246     ssize_t nwritten, buflen;
 247
 248     if (slave->repldboff == 0) {
 249         /* Write the bulk write count before to transfer the DB. In theory here
 250          * we don't know how much room there is in the output buffer of the
 251          * socket, but in pratice SO_SNDLOWAT (the minimum count for output
 252          * operations) will never be smaller than the few bytes we need. */
 253         sds bulkcount;
 254
 255         bulkcount = sdscatprintf(sdsempty(),"$%lld\r\n",(unsigned long long)
 256             slave->repldbsize);
 257         if (write(fd,bulkcount,sdslen(bulkcount)) != (signed)sdslen(bulkcount))
 258         {
 259             sdsfree(bulkcount);
 260             freeClient(slave);
 261             return;
 262         }
 263         sdsfree(bulkcount);
 264     }
 265     lseek(slave->repldbfd,slave->repldboff,SEEK_SET);
 266     buflen = read(slave->repldbfd,buf,REDIS_IOBUF_LEN);
 267     if (buflen <= 0) {
 268         redisLog(REDIS_WARNING,"Read error sending DB to slave: %s",
 269             (buflen == 0) ? "premature EOF" : strerror(errno));
 270         freeClient(slave);
 271         return;
 272     }
 273     if ((nwritten = write(fd,buf,buflen)) == -1) {
 274         redisLog(REDIS_VERBOSE,"Write error sending DB to slave: %s",
 275             strerror(errno));
 276         freeClient(slave);
 277         return;
 278     }
 279     slave->repldboff += nwritten;
 280     if (slave->repldboff == slave->repldbsize) {
 281         close(slave->repldbfd);
 282         slave->repldbfd = -1;
 283         aeDeleteFileEvent(server.el,slave->fd,AE_WRITABLE);
 284         slave->replstate = REDIS_REPL_ONLINE;
 285         if (aeCreateFileEvent(server.el, slave->fd, AE_WRITABLE,
 286             sendReplyToClient, slave) == AE_ERR) {
 287             freeClient(slave);
 288             return;
 289         }
 290         addReplySds(slave,sdsempty());
 291         redisLog(REDIS_NOTICE,"Synchronization with slave succeeded");
 292     }
 293 }
 294
 295 /* This function is called at the end of every backgrond saving.
 296  * The argument bgsaveerr is REDIS_OK if the background saving succeeded
 297  * otherwise REDIS_ERR is passed to the function.
 298  *
 299  * The goal of this function is to handle slaves waiting for a successful
 300  * background saving in order to perform non-blocking synchronization. */
 301 void updateSlavesWaitingBgsave(int bgsaveerr) {
 302     listNode *ln;
 303     int startbgsave = 0;
 304     listIter li;
 305
 306     listRewind(server.slaves,&li);
 307     while((ln = listNext(&li))) {
 308         redisClient *slave = ln->value;
 309
 310         if (slave->replstate == REDIS_REPL_WAIT_BGSAVE_START) {
 311             startbgsave = 1;
 312             slave->replstate = REDIS_REPL_WAIT_BGSAVE_END;
 313         } else if (slave->replstate == REDIS_REPL_WAIT_BGSAVE_END) {
 314             struct redis_stat buf;
 315
 316             if (bgsaveerr != REDIS_OK) {
 317                 freeClient(slave);
 318                 redisLog(REDIS_WARNING,"SYNC failed. BGSAVE child returned an error");
 319                 continue;
 320             }
 321             if ((slave->repldbfd = open(server.dbfilename,O_RDONLY)) == -1 ||
 322                 redis_fstat(slave->repldbfd,&buf) == -1) {
 323                 freeClient(slave);
 324                 redisLog(REDIS_WARNING,"SYNC failed. Can't open/stat DB after BGSAVE: %s", strerror(errno));
 325                 continue;
 326             }
 327             slave->repldboff = 0;
 328             slave->repldbsize = buf.st_size;
 329             slave->replstate = REDIS_REPL_SEND_BULK;
 330             aeDeleteFileEvent(server.el,slave->fd,AE_WRITABLE);
 331             if (aeCreateFileEvent(server.el, slave->fd, AE_WRITABLE, sendBulkToSlave, slave) == AE_ERR) {
 332                 freeClient(slave);
 333                 continue;
 334             }
 335         }
 336     }
 337     if (startbgsave) {
 338         if (rdbSaveBackground(server.dbfilename) != REDIS_OK) {
 339             listIter li;
 340
 341             listRewind(server.slaves,&li);
 342             redisLog(REDIS_WARNING,"SYNC failed. BGSAVE failed");
 343             while((ln = listNext(&li))) {
 344                 redisClient *slave = ln->value;
 345
 346                 if (slave->replstate == REDIS_REPL_WAIT_BGSAVE_START)
 347                     freeClient(slave);
 348             }
 349         }
 350     }
 351 }
 352
 353 int syncWithMaster(void) {
 354     char buf[1024], tmpfile[256], authcmd[1024];
 355     long dumpsize;
 356     int fd = anetTcpConnect(NULL,server.masterhost,server.masterport);
 357     int dfd, maxtries = 5;
 358
 359     if (fd == -1) {
 360         redisLog(REDIS_WARNING,"Unable to connect to MASTER: %s",
 361             strerror(errno));
 362         return REDIS_ERR;
 363     }
 364
 365     /* AUTH with the master if required. */
 366     if(server.masterauth) {
 367         snprintf(authcmd, 1024, "AUTH %s\r\n", server.masterauth);
 368         if (syncWrite(fd, authcmd, strlen(server.masterauth)+7, 5) == -1) {
 369             close(fd);
 370             redisLog(REDIS_WARNING,"Unable to AUTH to MASTER: %s",
 371                 strerror(errno));
 372             return REDIS_ERR;
 373         }
 374         /* Read the AUTH result.  */
 375         if (syncReadLine(fd,buf,1024,3600) == -1) {
 376             close(fd);
 377             redisLog(REDIS_WARNING,"I/O error reading auth result from MASTER: %s",
 378                 strerror(errno));
 379             return REDIS_ERR;
 380         }
 381         if (buf[0] != '+') {
 382             close(fd);
 383             redisLog(REDIS_WARNING,"Cannot AUTH to MASTER, is the masterauth password correct?");
 384             return REDIS_ERR;
 385         }
 386     }
 387
 388     /* Issue the SYNC command */
 389     if (syncWrite(fd,"SYNC \r\n",7,5) == -1) {
 390         close(fd);
 391         redisLog(REDIS_WARNING,"I/O error writing to MASTER: %s",
 392             strerror(errno));
 393         return REDIS_ERR;
 394     }
 395     /* Read the bulk write count */
 396     if (syncReadLine(fd,buf,1024,3600) == -1) {
 397         close(fd);
 398         redisLog(REDIS_WARNING,"I/O error reading bulk count from MASTER: %s",
 399             strerror(errno));
 400         return REDIS_ERR;
 401     }
 402     if (buf[0] == '-') {
 403         close(fd);
 404         redisLog(REDIS_WARNING,"MASTER aborted replication with an error: %s",
 405             buf+1);
 406         return REDIS_ERR;
 407     } else if (buf[0] != '$') {
 408         close(fd);
 409         redisLog(REDIS_WARNING,"Bad protocol from MASTER, the first byte is not '$', are you sure the host and port are right?");
 410         return REDIS_ERR;
 411     }
 412     dumpsize = strtol(buf+1,NULL,10);
 413     redisLog(REDIS_NOTICE,"Receiving %ld bytes data dump from MASTER",dumpsize);
 414     /* Read the bulk write data on a temp file */
 415     while(maxtries--) {
 416         snprintf(tmpfile,256,
 417             "temp-%d.%ld.rdb",(int)time(NULL),(long int)getpid());
 418         dfd = open(tmpfile,O_CREAT|O_WRONLY|O_EXCL,0644);
 419         if (dfd != -1) break;
 420         sleep(1);
 421     }
 422     if (dfd == -1) {
 423         close(fd);
 424         redisLog(REDIS_WARNING,"Opening the temp file needed for MASTER <-> SLAVE synchronization: %s",strerror(errno));
 425         return REDIS_ERR;
 426     }
 427     while(dumpsize) {
 428         int nread, nwritten;
 429
 430         nread = read(fd,buf,(dumpsize < 1024)?dumpsize:1024);
 431         if (nread <= 0) {
 432             redisLog(REDIS_WARNING,"I/O error trying to sync with MASTER: %s",
 433                 (nread == -1) ? strerror(errno) : "connection lost");
 434             close(fd);
 435             close(dfd);
 436             return REDIS_ERR;
 437         }
 438         nwritten = write(dfd,buf,nread);
 439         if (nwritten == -1) {
 440             redisLog(REDIS_WARNING,"Write error writing to the DB dump file needed for MASTER <-> SLAVE synchrnonization: %s", strerror(errno));
 441             close(fd);
 442             close(dfd);
 443             return REDIS_ERR;
 444         }
 445         dumpsize -= nread;
 446     }
 447     close(dfd);
 448     if (rename(tmpfile,server.dbfilename) == -1) {
 449         redisLog(REDIS_WARNING,"Failed trying to rename the temp DB into dump.rdb in MASTER <-> SLAVE synchronization: %s", strerror(errno));
 450         unlink(tmpfile);
 451         close(fd);
 452         return REDIS_ERR;
 453     }
 454     emptyDb();
 455     if (rdbLoad(server.dbfilename) != REDIS_OK) {
 456         redisLog(REDIS_WARNING,"Failed trying to load the MASTER synchronization DB from disk");
 457         close(fd);
 458         return REDIS_ERR;
 459     }
 460     server.master = createClient(fd);
 461     server.master->flags |= REDIS_MASTER;
 462     server.master->authenticated = 1;
 463     server.replstate = REDIS_REPL_CONNECTED;
 464     return REDIS_OK;
 465 }
 466
 467 void slaveofCommand(redisClient *c) {
 468     if (!strcasecmp(c->argv[1]->ptr,"no") &&
 469         !strcasecmp(c->argv[2]->ptr,"one")) {
 470         if (server.masterhost) {
 471             sdsfree(server.masterhost);
 472             server.masterhost = NULL;
 473             if (server.master) freeClient(server.master);
 474             server.replstate = REDIS_REPL_NONE;
 475             redisLog(REDIS_NOTICE,"MASTER MODE enabled (user request)");
 476         }
 477     } else {
 478         sdsfree(server.masterhost);
 479         server.masterhost = sdsdup(c->argv[1]->ptr);
 480         server.masterport = atoi(c->argv[2]->ptr);
 481         if (server.master) freeClient(server.master);
 482         server.replstate = REDIS_REPL_CONNECT;
 483         redisLog(REDIS_NOTICE,"SLAVE OF %s:%d enabled (user request)",
 484             server.masterhost, server.masterport);
 485     }
 486     addReply(c,shared.ok);
 487 }