/* This is how rewriting of the append only file in background works:
*
* 1) The user calls BGREWRITEAOF
* 2) Redis calls this function, that forks():
* 2a) the child rewrite the append only file in a temp file.
* 2b) the parent accumulates differences in server.bgrewritebuf.
* 3) When the child finished '2a' exists.
* 4) The parent will trap the exit code, if it's OK, will append the
* data accumulated into server.bgrewritebuf into the temp file, and
* finally will rename(2) the temp file in the actual file name.
* The the new file is reopened as the new append only file. Profit!
*/
static int rewriteAppendOnlyFileBackground(void) {
pid_t childpid;
if (server.bgrewritechildpid != -1) return REDIS_ERR;
if (server.vm_enabled) waitEmptyIOJobsQueue();
if ((childpid = fork()) == 0) {
/* Child */
char tmpfile[256];
if (server.vm_enabled) vmReopenSwapFile();
close(server.fd);
snprintf(tmpfile,256,"temp-rewriteaof-bg-%d.aof", (int) getpid());
if (rewriteAppendOnlyFile(tmpfile) == REDIS_OK) {
_exit(0);
}
} else {
server.bgrewritechildpid = childpid;
/* We set appendseldb to -1 in order to force the next call to the
* feedAppendOnlyFile() to issue a SELECT command, so the differences
* accumulated by the parent into server.bgrewritebuf will start
* with a SELECT statement and it will be safe to merge. */
server.appendseldb = -1;
return REDIS_OK;
}
return REDIS_OK; /* unreached */
}
/* This is how rewriting of the append only file in background works:
*
* 1) The user calls BGREWRITEAOF
* 2) Redis calls this function, that forks():
* 2a) the child rewrite the append only file in a temp file.
* 2b) the parent accumulates differences in server.bgrewritebuf.
* 3) When the child finished '2a' exists.
* 4) The parent will trap the exit code, if it's OK, will append the
* data accumulated into server.bgrewritebuf into the temp file, and
* finally will rename(2) the temp file in the actual file name.
* The the new file is reopened as the new append only file. Profit!
*/
int rewriteAppendOnlyFileBackground(void) {
pid_t childpid;
long long start;
if (server.bgrewritechildpid != -1) return REDIS_ERR;
if (server.vm_enabled) waitEmptyIOJobsQueue();
start = ustime();
if ((childpid = fork()) == 0) {
char tmpfile[256];
/* Child */
if (server.vm_enabled) vmReopenSwapFile();
if (server.ipfd > 0) close(server.ipfd);
if (server.sofd > 0) close(server.sofd);
snprintf(tmpfile,256,"temp-rewriteaof-bg-%d.aof", (int) getpid());
if (rewriteAppendOnlyFile(tmpfile) == REDIS_OK) {
_exit(0);
} else {
_exit(1);
}
} else {
/* Parent */
server.stat_fork_time = ustime()-start;
if (childpid == -1) {
redisLog(REDIS_WARNING,
"Can't rewrite append only file in background: fork: %s",
strerror(errno));
return REDIS_ERR;
}
redisLog(REDIS_NOTICE,
"Background append only file rewriting started by pid %d",childpid);
server.aofrewrite_scheduled = 0;
server.bgrewritechildpid = childpid;
updateDictResizePolicy();
/* We set appendseldb to -1 in order to force the next call to the
* feedAppendOnlyFile() to issue a SELECT command, so the differences
* accumulated by the parent into server.bgrewritebuf will start
* with a SELECT statement and it will be safe to merge. */
server.appendseldb = -1;
return REDIS_OK;
}
return REDIS_OK; /* unreached */
}
void lookupWaitBusyKey(redisDb *db, robj *key) {
/* FIXME: wait just for this key, not everything */
waitEmptyIOJobsQueue();
processAllPendingIOJobs();
redisAssert((cacheScheduleIOGetFlags(db,key) & REDIS_IO_SAVEINPROG) == 0);
}
