Max limit to 10k clients removed, this implements feature request on issue #194

[redis.git] / src / aof.c

diff --git a/src/aof.c b/src/aof.c
index ac6b97915e26b5f61ef85b10afee377ab9f4c31d..bfa8163d3fd57e32d4aa2bf6b90e1ed5f840f3cc 100644 (file)
--- a/src/aof.c
+++ b/src/aof.c
@@ -1,4 +1,6 @@
 #include "redis.h"
 #include "redis.h"

+#include "bio.h"
+#include "rio.h"

 
 #include <signal.h>
 #include <fcntl.h>
 
 #include <signal.h>
 #include <fcntl.h>


@@ -10,10 +12,14 @@
 
 void aofUpdateCurrentSize(void);
 
 
 void aofUpdateCurrentSize(void);
 

+void aof_background_fsync(int fd) {
+    bioCreateBackgroundJob(REDIS_BIO_AOF_FSYNC,(void*)(long)fd,NULL,NULL);
+}
+

 /* Called when the user switches from "appendonly yes" to "appendonly no"
  * at runtime using the CONFIG command. */
 void stopAppendOnly(void) {
 /* Called when the user switches from "appendonly yes" to "appendonly no"
  * at runtime using the CONFIG command. */
 void stopAppendOnly(void) {

-    flushAppendOnlyFile();
+    flushAppendOnlyFile(1);

     aof_fsync(server.appendfd);
     close(server.appendfd);
 
     aof_fsync(server.appendfd);
     close(server.appendfd);
 


@@ -46,7 +52,7 @@ int startAppendOnly(void) {
     if (rewriteAppendOnlyFileBackground() == REDIS_ERR) {
         server.appendonly = 0;
         close(server.appendfd);
     if (rewriteAppendOnlyFileBackground() == REDIS_ERR) {
         server.appendonly = 0;
         close(server.appendfd);

-        redisLog(REDIS_WARNING,"Used tried to switch on AOF via CONFIG, I can't trigger a background AOF rewrite operation. Check the above logs for more info about the error.",strerror(errno));
+        redisLog(REDIS_WARNING,"User tried turning on AOF with CONFIG SET but I can't trigger a background AOF rewrite operation. Check the above logs for more info about the error.");

         return REDIS_ERR;
     }
     return REDIS_OK;
         return REDIS_ERR;
     }
     return REDIS_OK;


@@ -58,80 +64,155 @@ int startAppendOnly(void) {
  * and the only way the client socket can get a write is entering when the
  * the event loop, we accumulate all the AOF writes in a memory
  * buffer and write it on disk using this function just before entering
  * and the only way the client socket can get a write is entering when the
  * the event loop, we accumulate all the AOF writes in a memory
  * buffer and write it on disk using this function just before entering

- * the event loop again. */
-void flushAppendOnlyFile(void) {
-    time_t now;
+ * the event loop again.
+ *
+ * About the 'force' argument:
+ *
+ * When the fsync policy is set to 'everysec' we may delay the flush if there
+ * is still an fsync() going on in the background thread, since for instance
+ * on Linux write(2) will be blocked by the background fsync anyway.
+ * When this happens we remember that there is some aof buffer to be
+ * flushed ASAP, and will try to do that in the serverCron() function.
+ *
+ * However if force is set to 1 we'll write regardless of the background
+ * fsync. */
+void flushAppendOnlyFile(int force) {

     ssize_t nwritten;
     ssize_t nwritten;

+    int sync_in_progress = 0;

 
     if (sdslen(server.aofbuf) == 0) return;
 
 
     if (sdslen(server.aofbuf) == 0) return;
 

+    if (server.appendfsync == APPENDFSYNC_EVERYSEC)
+        sync_in_progress = bioPendingJobsOfType(REDIS_BIO_AOF_FSYNC) != 0;
+
+    if (server.appendfsync == APPENDFSYNC_EVERYSEC && !force) {
+        /* With this append fsync policy we do background fsyncing.
+         * If the fsync is still in progress we can try to delay
+         * the write for a couple of seconds. */
+        if (sync_in_progress) {
+            if (server.aof_flush_postponed_start == 0) {
+                /* No previous write postponinig, remember that we are
+                 * postponing the flush and return. */
+                server.aof_flush_postponed_start = server.unixtime;
+                return;
+            } else if (server.unixtime - server.aof_flush_postponed_start < 2) {
+                /* We were already waiting for fsync to finish, but for less
+                 * than two seconds this is still ok. Postpone again. */
+                return;
+            }
+            /* Otherwise fall trough, and go write since we can't wait
+             * over two seconds. */
+            redisLog(REDIS_NOTICE,"Asynchronous AOF fsync is taking too long (disk is busy?). Writing the AOF buffer without waiting for fsync to complete, this may slow down Redis.");
+        }
+    }
+    /* If you are following this code path, then we are going to write so
+     * set reset the postponed flush sentinel to zero. */
+    server.aof_flush_postponed_start = 0;
+

     /* We want to perform a single write. This should be guaranteed atomic
      * at least if the filesystem we are writing is a real physical one.
      * While this will save us against the server being killed I don't think
      * there is much to do about the whole server stopping for power problems
      * or alike */
     /* We want to perform a single write. This should be guaranteed atomic
      * at least if the filesystem we are writing is a real physical one.
      * While this will save us against the server being killed I don't think
      * there is much to do about the whole server stopping for power problems
      * or alike */

-     nwritten = write(server.appendfd,server.aofbuf,sdslen(server.aofbuf));
-     if (nwritten != (signed)sdslen(server.aofbuf)) {
+    nwritten = write(server.appendfd,server.aofbuf,sdslen(server.aofbuf));
+    if (nwritten != (signed)sdslen(server.aofbuf)) {

         /* Ooops, we are in troubles. The best thing to do for now is
          * aborting instead of giving the illusion that everything is
          * working as expected. */
         /* Ooops, we are in troubles. The best thing to do for now is
          * aborting instead of giving the illusion that everything is
          * working as expected. */

-         if (nwritten == -1) {
+        if (nwritten == -1) {

             redisLog(REDIS_WARNING,"Exiting on error writing to the append-only file: %s",strerror(errno));
             redisLog(REDIS_WARNING,"Exiting on error writing to the append-only file: %s",strerror(errno));

-         } else {
+        } else {

             redisLog(REDIS_WARNING,"Exiting on short write while writing to the append-only file: %s",strerror(errno));
             redisLog(REDIS_WARNING,"Exiting on short write while writing to the append-only file: %s",strerror(errno));

-         }
-         exit(1);
+        }
+        exit(1);

     }
     }

-    sdsfree(server.aofbuf);
-    server.aofbuf = sdsempty();

     server.appendonly_current_size += nwritten;
 
     server.appendonly_current_size += nwritten;
 

-    /* Don't Fsync if no-appendfsync-on-rewrite is set to yes and we have
-     * childs performing heavy I/O on disk. */
+    /* Re-use AOF buffer when it is small enough. The maximum comes from the
+     * arena size of 4k minus some overhead (but is otherwise arbitrary). */
+    if ((sdslen(server.aofbuf)+sdsavail(server.aofbuf)) < 4000) {
+        sdsclear(server.aofbuf);
+    } else {
+        sdsfree(server.aofbuf);
+        server.aofbuf = sdsempty();
+    }
+
+    /* Don't fsync if no-appendfsync-on-rewrite is set to yes and there are
+     * children doing I/O in the background. */

     if (server.no_appendfsync_on_rewrite &&
         (server.bgrewritechildpid != -1 || server.bgsavechildpid != -1))
             return;
     if (server.no_appendfsync_on_rewrite &&
         (server.bgrewritechildpid != -1 || server.bgsavechildpid != -1))
             return;

-    /* Fsync if needed */
-    now = time(NULL);
-    if (server.appendfsync == APPENDFSYNC_ALWAYS ||
-        (server.appendfsync == APPENDFSYNC_EVERYSEC &&
-         now-server.lastfsync > 1))
-    {
+
+    /* Perform the fsync if needed. */
+    if (server.appendfsync == APPENDFSYNC_ALWAYS) {

         /* aof_fsync is defined as fdatasync() for Linux in order to avoid
          * flushing metadata. */
         aof_fsync(server.appendfd); /* Let's try to get this data on the disk */
         /* aof_fsync is defined as fdatasync() for Linux in order to avoid
          * flushing metadata. */
         aof_fsync(server.appendfd); /* Let's try to get this data on the disk */

-        server.lastfsync = now;
+        server.lastfsync = server.unixtime;
+    } else if ((server.appendfsync == APPENDFSYNC_EVERYSEC &&
+                server.unixtime > server.lastfsync)) {
+        if (!sync_in_progress) aof_background_fsync(server.appendfd);
+        server.lastfsync = server.unixtime;

     }
 }
 
     }
 }
 

-sds catAppendOnlyGenericCommand(sds buf, int argc, robj **argv) {
-    int j;
-    buf = sdscatprintf(buf,"*%d\r\n",argc);
+sds catAppendOnlyGenericCommand(sds dst, int argc, robj **argv) {
+    char buf[32];
+    int len, j;
+    robj *o;
+
+    buf[0] = '*';
+    len = 1+ll2string(buf+1,sizeof(buf)-1,argc);
+    buf[len++] = '\r';
+    buf[len++] = '\n';
+    dst = sdscatlen(dst,buf,len);
+

     for (j = 0; j < argc; j++) {
     for (j = 0; j < argc; j++) {

-        robj *o = getDecodedObject(argv[j]);
-        buf = sdscatprintf(buf,"$%lu\r\n",(unsigned long)sdslen(o->ptr));
-        buf = sdscatlen(buf,o->ptr,sdslen(o->ptr));
-        buf = sdscatlen(buf,"\r\n",2);
+        o = getDecodedObject(argv[j]);
+        buf[0] = '$';
+        len = 1+ll2string(buf+1,sizeof(buf)-1,sdslen(o->ptr));
+        buf[len++] = '\r';
+        buf[len++] = '\n';
+        dst = sdscatlen(dst,buf,len);
+        dst = sdscatlen(dst,o->ptr,sdslen(o->ptr));
+        dst = sdscatlen(dst,"\r\n",2);

         decrRefCount(o);
     }
         decrRefCount(o);
     }

-    return buf;
+    return dst;

 }
 
 }
 

-sds catAppendOnlyExpireAtCommand(sds buf, robj *key, robj *seconds) {
-    int argc = 3;
-    long when;
+/* Create the sds representation of an PEXPIREAT command, using
+ * 'seconds' as time to live and 'cmd' to understand what command
+ * we are translating into a PEXPIREAT.
+ *
+ * This command is used in order to translate EXPIRE and PEXPIRE commands
+ * into PEXPIREAT command so that we retain precision in the append only
+ * file, and the time is always absolute and not relative. */
+sds catAppendOnlyExpireAtCommand(sds buf, struct redisCommand *cmd, robj *key, robj *seconds) {
+    long long when;

     robj *argv[3];
 
     /* Make sure we can use strtol */
     seconds = getDecodedObject(seconds);
     robj *argv[3];
 
     /* Make sure we can use strtol */
     seconds = getDecodedObject(seconds);

-    when = time(NULL)+strtol(seconds->ptr,NULL,10);
+    when = strtoll(seconds->ptr,NULL,10);
+    /* Convert argument into milliseconds for EXPIRE, SETEX, EXPIREAT */
+    if (cmd->proc == expireCommand || cmd->proc == setexCommand ||
+        cmd->proc == expireatCommand)
+    {
+        when *= 1000;
+    }
+    /* Convert into absolute time for EXPIRE, PEXPIRE, SETEX, PSETEX */
+    if (cmd->proc == expireCommand || cmd->proc == pexpireCommand ||
+        cmd->proc == setexCommand || cmd->proc == psetexCommand)
+    {
+        when += mstime();
+    }

     decrRefCount(seconds);
 
     decrRefCount(seconds);
 

-    argv[0] = createStringObject("EXPIREAT",8);
+    argv[0] = createStringObject("PEXPIREAT",9);

     argv[1] = key;
     argv[1] = key;

-    argv[2] = createObject(REDIS_STRING,
-        sdscatprintf(sdsempty(),"%ld",when));
-    buf = catAppendOnlyGenericCommand(buf, argc, argv);
+    argv[2] = createStringObjectFromLongLong(when);
+    buf = catAppendOnlyGenericCommand(buf, 3, argv);

     decrRefCount(argv[0]);
     decrRefCount(argv[2]);
     return buf;
     decrRefCount(argv[0]);
     decrRefCount(argv[2]);
     return buf;


@@ -152,18 +233,22 @@ void feedAppendOnlyFile(struct redisCommand *cmd, int dictid, robj **argv, int a
         server.appendseldb = dictid;
     }
 
         server.appendseldb = dictid;
     }
 

-    if (cmd->proc == expireCommand) {
-        /* Translate EXPIRE into EXPIREAT */
-        buf = catAppendOnlyExpireAtCommand(buf,argv[1],argv[2]);
-    } else if (cmd->proc == setexCommand) {
-        /* Translate SETEX to SET and EXPIREAT */
+    if (cmd->proc == expireCommand || cmd->proc == pexpireCommand ||
+        cmd->proc == expireatCommand) {
+        /* Translate EXPIRE/PEXPIRE/EXPIREAT into PEXPIREAT */
+        buf = catAppendOnlyExpireAtCommand(buf,cmd,argv[1],argv[2]);
+    } else if (cmd->proc == setexCommand || cmd->proc == psetexCommand) {
+        /* Translate SETEX/PSETEX to SET and PEXPIREAT */

         tmpargv[0] = createStringObject("SET",3);
         tmpargv[1] = argv[1];
         tmpargv[2] = argv[3];
         buf = catAppendOnlyGenericCommand(buf,3,tmpargv);
         decrRefCount(tmpargv[0]);
         tmpargv[0] = createStringObject("SET",3);
         tmpargv[1] = argv[1];
         tmpargv[2] = argv[3];
         buf = catAppendOnlyGenericCommand(buf,3,tmpargv);
         decrRefCount(tmpargv[0]);

-        buf = catAppendOnlyExpireAtCommand(buf,argv[1],argv[2]);
+        buf = catAppendOnlyExpireAtCommand(buf,cmd,argv[1],argv[2]);

     } else {
     } else {

+        /* All the other commands don't need translation or need the
+         * same translation already operated in the command vector
+         * for the replication itself. */

         buf = catAppendOnlyGenericCommand(buf,argc,argv);
     }
 
         buf = catAppendOnlyGenericCommand(buf,argc,argv);
     }
 


@@ -263,6 +348,8 @@ int loadAppendOnlyFile(char *filename) {
         }
         if (buf[0] != '*') goto fmterr;
         argc = atoi(buf+1);
         }
         if (buf[0] != '*') goto fmterr;
         argc = atoi(buf+1);

+        if (argc < 1) goto fmterr;
+

         argv = zmalloc(sizeof(robj*)*argc);
         for (j = 0; j < argc; j++) {
             if (fgets(buf,sizeof(buf),fp) == NULL) goto readerr;
         argv = zmalloc(sizeof(robj*)*argc);
         for (j = 0; j < argc; j++) {
             if (fgets(buf,sizeof(buf),fp) == NULL) goto readerr;


@@ -287,6 +374,8 @@ int loadAppendOnlyFile(char *filename) {
 
         /* The fake client should not have a reply */
         redisAssert(fakeClient->bufpos == 0 && listLength(fakeClient->reply) == 0);
 
         /* The fake client should not have a reply */
         redisAssert(fakeClient->bufpos == 0 && listLength(fakeClient->reply) == 0);

+        /* The fake client should never get blocked */
+        redisAssert((fakeClient->flags & REDIS_BLOCKED) == 0);

 
         /* Clean up. Command code may have changed argv/argc so we use the
          * argv/argc of the client instead of the local variables. */
 
         /* Clean up. Command code may have changed argv/argc so we use the
          * argv/argc of the client instead of the local variables. */


@@ -319,15 +408,258 @@ fmterr:
     exit(1);
 }
 
     exit(1);
 }
 

+/* Delegate writing an object to writing a bulk string or bulk long long.
+ * This is not placed in rio.c since that adds the redis.h dependency. */
+int rioWriteBulkObject(rio *r, robj *obj) {
+    /* Avoid using getDecodedObject to help copy-on-write (we are often
+     * in a child process when this function is called). */
+    if (obj->encoding == REDIS_ENCODING_INT) {
+        return rioWriteBulkLongLong(r,(long)obj->ptr);
+    } else if (obj->encoding == REDIS_ENCODING_RAW) {
+        return rioWriteBulkString(r,obj->ptr,sdslen(obj->ptr));
+    } else {
+        redisPanic("Unknown string encoding");
+    }
+}
+
+/* Emit the commands needed to rebuild a list object.
+ * The function returns 0 on error, 1 on success. */
+int rewriteListObject(rio *r, robj *key, robj *o) {
+    long long count = 0, items = listTypeLength(o);
+
+    if (o->encoding == REDIS_ENCODING_ZIPLIST) {
+        unsigned char *zl = o->ptr;
+        unsigned char *p = ziplistIndex(zl,0);
+        unsigned char *vstr;
+        unsigned int vlen;
+        long long vlong;
+
+        while(ziplistGet(p,&vstr,&vlen,&vlong)) {
+            if (count == 0) {
+                int cmd_items = (items > REDIS_AOFREWRITE_ITEMS_PER_CMD) ?
+                    REDIS_AOFREWRITE_ITEMS_PER_CMD : items;
+
+                if (rioWriteBulkCount(r,'*',2+cmd_items) == 0) return 0;
+                if (rioWriteBulkString(r,"RPUSH",5) == 0) return 0;
+                if (rioWriteBulkObject(r,key) == 0) return 0;
+            }
+            if (vstr) {
+                if (rioWriteBulkString(r,(char*)vstr,vlen) == 0) return 0;
+            } else {
+                if (rioWriteBulkLongLong(r,vlong) == 0) return 0;
+            }
+            p = ziplistNext(zl,p);
+            if (++count == REDIS_AOFREWRITE_ITEMS_PER_CMD) count = 0;
+            items--;
+        }
+    } else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
+        list *list = o->ptr;
+        listNode *ln;
+        listIter li;
+
+        listRewind(list,&li);
+        while((ln = listNext(&li))) {
+            robj *eleobj = listNodeValue(ln);
+
+            if (count == 0) {
+                int cmd_items = (items > REDIS_AOFREWRITE_ITEMS_PER_CMD) ?
+                    REDIS_AOFREWRITE_ITEMS_PER_CMD : items;
+
+                if (rioWriteBulkCount(r,'*',2+cmd_items) == 0) return 0;
+                if (rioWriteBulkString(r,"RPUSH",5) == 0) return 0;
+                if (rioWriteBulkObject(r,key) == 0) return 0;
+            }
+            if (rioWriteBulkObject(r,eleobj) == 0) return 0;
+            if (++count == REDIS_AOFREWRITE_ITEMS_PER_CMD) count = 0;
+            items--;
+        }
+    } else {
+        redisPanic("Unknown list encoding");
+    }
+    return 1;
+}
+
+/* Emit the commands needed to rebuild a set object.
+ * The function returns 0 on error, 1 on success. */
+int rewriteSetObject(rio *r, robj *key, robj *o) {
+    long long count = 0, items = setTypeSize(o);
+
+    if (o->encoding == REDIS_ENCODING_INTSET) {
+        int ii = 0;
+        int64_t llval;
+
+        while(intsetGet(o->ptr,ii++,&llval)) {
+            if (count == 0) {
+                int cmd_items = (items > REDIS_AOFREWRITE_ITEMS_PER_CMD) ?
+                    REDIS_AOFREWRITE_ITEMS_PER_CMD : items;
+
+                if (rioWriteBulkCount(r,'*',2+cmd_items) == 0) return 0;
+                if (rioWriteBulkString(r,"SADD",4) == 0) return 0;
+                if (rioWriteBulkObject(r,key) == 0) return 0;
+            }
+            if (rioWriteBulkLongLong(r,llval) == 0) return 0;
+            if (++count == REDIS_AOFREWRITE_ITEMS_PER_CMD) count = 0;
+            items--;
+        }
+    } else if (o->encoding == REDIS_ENCODING_HT) {
+        dictIterator *di = dictGetIterator(o->ptr);
+        dictEntry *de;
+
+        while((de = dictNext(di)) != NULL) {
+            robj *eleobj = dictGetKey(de);
+            if (count == 0) {
+                int cmd_items = (items > REDIS_AOFREWRITE_ITEMS_PER_CMD) ?
+                    REDIS_AOFREWRITE_ITEMS_PER_CMD : items;
+
+                if (rioWriteBulkCount(r,'*',2+cmd_items) == 0) return 0;
+                if (rioWriteBulkString(r,"SADD",4) == 0) return 0;
+                if (rioWriteBulkObject(r,key) == 0) return 0;
+            }
+            if (rioWriteBulkObject(r,eleobj) == 0) return 0;
+            if (++count == REDIS_AOFREWRITE_ITEMS_PER_CMD) count = 0;
+            items--;
+        }
+        dictReleaseIterator(di);
+    } else {
+        redisPanic("Unknown set encoding");
+    }
+    return 1;
+}
+
+/* Emit the commands needed to rebuild a sorted set object.
+ * The function returns 0 on error, 1 on success. */
+int rewriteSortedSetObject(rio *r, robj *key, robj *o) {
+    long long count = 0, items = zsetLength(o);
+
+    if (o->encoding == REDIS_ENCODING_ZIPLIST) {
+        unsigned char *zl = o->ptr;
+        unsigned char *eptr, *sptr;
+        unsigned char *vstr;
+        unsigned int vlen;
+        long long vll;
+        double score;
+
+        eptr = ziplistIndex(zl,0);
+        redisAssert(eptr != NULL);
+        sptr = ziplistNext(zl,eptr);
+        redisAssert(sptr != NULL);
+
+        while (eptr != NULL) {
+            redisAssert(ziplistGet(eptr,&vstr,&vlen,&vll));
+            score = zzlGetScore(sptr);
+
+            if (count == 0) {
+                int cmd_items = (items > REDIS_AOFREWRITE_ITEMS_PER_CMD) ?
+                    REDIS_AOFREWRITE_ITEMS_PER_CMD : items;
+
+                if (rioWriteBulkCount(r,'*',2+cmd_items*2) == 0) return 0;
+                if (rioWriteBulkString(r,"ZADD",4) == 0) return 0;
+                if (rioWriteBulkObject(r,key) == 0) return 0;
+            }
+            if (rioWriteBulkDouble(r,score) == 0) return 0;
+            if (vstr != NULL) {
+                if (rioWriteBulkString(r,(char*)vstr,vlen) == 0) return 0;
+            } else {
+                if (rioWriteBulkLongLong(r,vll) == 0) return 0;
+            }
+            zzlNext(zl,&eptr,&sptr);
+            if (++count == REDIS_AOFREWRITE_ITEMS_PER_CMD) count = 0;
+            items--;
+        }
+    } else if (o->encoding == REDIS_ENCODING_SKIPLIST) {
+        zset *zs = o->ptr;
+        dictIterator *di = dictGetIterator(zs->dict);
+        dictEntry *de;
+
+        while((de = dictNext(di)) != NULL) {
+            robj *eleobj = dictGetKey(de);
+            double *score = dictGetVal(de);
+
+            if (count == 0) {
+                int cmd_items = (items > REDIS_AOFREWRITE_ITEMS_PER_CMD) ?
+                    REDIS_AOFREWRITE_ITEMS_PER_CMD : items;
+
+                if (rioWriteBulkCount(r,'*',2+cmd_items*2) == 0) return 0;
+                if (rioWriteBulkString(r,"ZADD",4) == 0) return 0;
+                if (rioWriteBulkObject(r,key) == 0) return 0;
+            }
+            if (rioWriteBulkDouble(r,*score) == 0) return 0;
+            if (rioWriteBulkObject(r,eleobj) == 0) return 0;
+            if (++count == REDIS_AOFREWRITE_ITEMS_PER_CMD) count = 0;
+            items--;
+        }
+        dictReleaseIterator(di);
+    } else {
+        redisPanic("Unknown sorted zset encoding");
+    }
+    return 1;
+}
+
+/* Emit the commands needed to rebuild a hash object.
+ * The function returns 0 on error, 1 on success. */
+int rewriteHashObject(rio *r, robj *key, robj *o) {
+    long long count = 0, items = hashTypeLength(o);
+
+    if (o->encoding == REDIS_ENCODING_ZIPMAP) {
+        unsigned char *p = zipmapRewind(o->ptr);
+        unsigned char *field, *val;
+        unsigned int flen, vlen;
+
+        while((p = zipmapNext(p,&field,&flen,&val,&vlen)) != NULL) {
+            if (count == 0) {
+                int cmd_items = (items > REDIS_AOFREWRITE_ITEMS_PER_CMD) ?
+                    REDIS_AOFREWRITE_ITEMS_PER_CMD : items;
+
+                if (rioWriteBulkCount(r,'*',2+cmd_items*2) == 0) return 0;
+                if (rioWriteBulkString(r,"HMSET",5) == 0) return 0;
+                if (rioWriteBulkObject(r,key) == 0) return 0;
+            }
+            if (rioWriteBulkString(r,(char*)field,flen) == 0) return 0;
+            if (rioWriteBulkString(r,(char*)val,vlen) == 0) return 0;
+            if (++count == REDIS_AOFREWRITE_ITEMS_PER_CMD) count = 0;
+            items--;
+        }
+    } else {
+        dictIterator *di = dictGetIterator(o->ptr);
+        dictEntry *de;
+
+        while((de = dictNext(di)) != NULL) {
+            robj *field = dictGetKey(de);
+            robj *val = dictGetVal(de);
+
+            if (count == 0) {
+                int cmd_items = (items > REDIS_AOFREWRITE_ITEMS_PER_CMD) ?
+                    REDIS_AOFREWRITE_ITEMS_PER_CMD : items;
+
+                if (rioWriteBulkCount(r,'*',2+cmd_items*2) == 0) return 0;
+                if (rioWriteBulkString(r,"HMSET",5) == 0) return 0;
+                if (rioWriteBulkObject(r,key) == 0) return 0;
+            }
+            if (rioWriteBulkObject(r,field) == 0) return 0;
+            if (rioWriteBulkObject(r,val) == 0) return 0;
+            if (++count == REDIS_AOFREWRITE_ITEMS_PER_CMD) count = 0;
+            items--;
+        }
+        dictReleaseIterator(di);
+    }
+    return 1;
+}
+

 /* Write a sequence of commands able to fully rebuild the dataset into
 /* Write a sequence of commands able to fully rebuild the dataset into

- * "filename". Used both by REWRITEAOF and BGREWRITEAOF. */
+ * "filename". Used both by REWRITEAOF and BGREWRITEAOF.
+ *
+ * In order to minimize the number of commands needed in the rewritten
+ * log Redis uses variadic commands when possible, such as RPUSH, SADD
+ * and ZADD. However at max REDIS_AOFREWRITE_ITEMS_PER_CMD items per time
+ * are inserted using a single command. */

 int rewriteAppendOnlyFile(char *filename) {
     dictIterator *di = NULL;
     dictEntry *de;
 int rewriteAppendOnlyFile(char *filename) {
     dictIterator *di = NULL;
     dictEntry *de;

+    rio aof;

     FILE *fp;
     char tmpfile[256];
     int j;
     FILE *fp;
     char tmpfile[256];
     int j;

-    time_t now = time(NULL);
+    long long now = mstime();

 
     /* Note that we have to use a different temp name here compared to the
      * one used by rewriteAppendOnlyFileBackground() function. */
 
     /* Note that we have to use a different temp name here compared to the
      * one used by rewriteAppendOnlyFileBackground() function. */


@@ -337,6 +669,8 @@ int rewriteAppendOnlyFile(char *filename) {
         redisLog(REDIS_WARNING, "Failed rewriting the append only file: %s", strerror(errno));
         return REDIS_ERR;
     }
         redisLog(REDIS_WARNING, "Failed rewriting the append only file: %s", strerror(errno));
         return REDIS_ERR;
     }

+
+    rioInitWithFile(&aof,fp);

     for (j = 0; j < server.dbnum; j++) {
         char selectcmd[] = "*2\r\n$6\r\nSELECT\r\n";
         redisDb *db = server.db+j;
     for (j = 0; j < server.dbnum; j++) {
         char selectcmd[] = "*2\r\n$6\r\nSELECT\r\n";
         redisDb *db = server.db+j;


@@ -349,17 +683,17 @@ int rewriteAppendOnlyFile(char *filename) {
         }
 
         /* SELECT the new DB */
         }
 
         /* SELECT the new DB */

-        if (fwrite(selectcmd,sizeof(selectcmd)-1,1,fp) == 0) goto werr;
-        if (fwriteBulkLongLong(fp,j) == 0) goto werr;
+        if (rioWrite(&aof,selectcmd,sizeof(selectcmd)-1) == 0) goto werr;
+        if (rioWriteBulkLongLong(&aof,j) == 0) goto werr;

 
         /* Iterate this DB writing every entry */
         while((de = dictNext(di)) != NULL) {
             sds keystr;
             robj key, *o;
 
         /* Iterate this DB writing every entry */
         while((de = dictNext(di)) != NULL) {
             sds keystr;
             robj key, *o;

-            time_t expiretime;
+            long long expiretime;

 
 

-            keystr = dictGetEntryKey(de);
-            o = dictGetEntryVal(de);
+            keystr = dictGetKey(de);
+            o = dictGetVal(de);

             initStaticStringObject(key,keystr);
 
             expiretime = getExpire(db,&key);
             initStaticStringObject(key,keystr);
 
             expiretime = getExpire(db,&key);


@@ -368,167 +702,29 @@ int rewriteAppendOnlyFile(char *filename) {
             if (o->type == REDIS_STRING) {
                 /* Emit a SET command */
                 char cmd[]="*3\r\n$3\r\nSET\r\n";
             if (o->type == REDIS_STRING) {
                 /* Emit a SET command */
                 char cmd[]="*3\r\n$3\r\nSET\r\n";

-                if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
+                if (rioWrite(&aof,cmd,sizeof(cmd)-1) == 0) goto werr;

                 /* Key and value */
                 /* Key and value */

-                if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                if (fwriteBulkObject(fp,o) == 0) goto werr;
+                if (rioWriteBulkObject(&aof,&key) == 0) goto werr;
+                if (rioWriteBulkObject(&aof,o) == 0) goto werr;

             } else if (o->type == REDIS_LIST) {
             } else if (o->type == REDIS_LIST) {

-                /* Emit the RPUSHes needed to rebuild the list */
-                char cmd[]="*3\r\n$5\r\nRPUSH\r\n";
-                if (o->encoding == REDIS_ENCODING_ZIPLIST) {
-                    unsigned char *zl = o->ptr;
-                    unsigned char *p = ziplistIndex(zl,0);
-                    unsigned char *vstr;
-                    unsigned int vlen;
-                    long long vlong;
-
-                    while(ziplistGet(p,&vstr,&vlen,&vlong)) {
-                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
-                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                        if (vstr) {
-                            if (fwriteBulkString(fp,(char*)vstr,vlen) == 0)
-                                goto werr;
-                        } else {
-                            if (fwriteBulkLongLong(fp,vlong) == 0)
-                                goto werr;
-                        }
-                        p = ziplistNext(zl,p);
-                    }
-                } else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
-                    list *list = o->ptr;
-                    listNode *ln;
-                    listIter li;
-
-                    listRewind(list,&li);
-                    while((ln = listNext(&li))) {
-                        robj *eleobj = listNodeValue(ln);
-
-                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
-                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                        if (fwriteBulkObject(fp,eleobj) == 0) goto werr;
-                    }
-                } else {
-                    redisPanic("Unknown list encoding");
-                }
+                if (rewriteListObject(&aof,&key,o) == 0) goto werr;

             } else if (o->type == REDIS_SET) {
             } else if (o->type == REDIS_SET) {

-                char cmd[]="*3\r\n$4\r\nSADD\r\n";
-
-                /* Emit the SADDs needed to rebuild the set */
-                if (o->encoding == REDIS_ENCODING_INTSET) {
-                    int ii = 0;
-                    int64_t llval;
-                    while(intsetGet(o->ptr,ii++,&llval)) {
-                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
-                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                        if (fwriteBulkLongLong(fp,llval) == 0) goto werr;
-                    }
-                } else if (o->encoding == REDIS_ENCODING_HT) {
-                    dictIterator *di = dictGetIterator(o->ptr);
-                    dictEntry *de;
-                    while((de = dictNext(di)) != NULL) {
-                        robj *eleobj = dictGetEntryKey(de);
-                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
-                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                        if (fwriteBulkObject(fp,eleobj) == 0) goto werr;
-                    }
-                    dictReleaseIterator(di);
-                } else {
-                    redisPanic("Unknown set encoding");
-                }
+                if (rewriteSetObject(&aof,&key,o) == 0) goto werr;

             } else if (o->type == REDIS_ZSET) {
             } else if (o->type == REDIS_ZSET) {

-                /* Emit the ZADDs needed to rebuild the sorted set */
-                char cmd[]="*4\r\n$4\r\nZADD\r\n";
-
-                if (o->encoding == REDIS_ENCODING_ZIPLIST) {
-                    unsigned char *zl = o->ptr;
-                    unsigned char *eptr, *sptr;
-                    unsigned char *vstr;
-                    unsigned int vlen;
-                    long long vll;
-                    double score;
-
-                    eptr = ziplistIndex(zl,0);
-                    redisAssert(eptr != NULL);
-                    sptr = ziplistNext(zl,eptr);
-                    redisAssert(sptr != NULL);
-
-                    while (eptr != NULL) {
-                        redisAssert(ziplistGet(eptr,&vstr,&vlen,&vll));
-                        score = zzlGetScore(sptr);
-
-                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
-                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                        if (fwriteBulkDouble(fp,score) == 0) goto werr;
-                        if (vstr != NULL) {
-                            if (fwriteBulkString(fp,(char*)vstr,vlen) == 0)
-                                goto werr;
-                        } else {
-                            if (fwriteBulkLongLong(fp,vll) == 0)
-                                goto werr;
-                        }
-                        zzlNext(zl,&eptr,&sptr);
-                    }
-                } else if (o->encoding == REDIS_ENCODING_SKIPLIST) {
-                    zset *zs = o->ptr;
-                    dictIterator *di = dictGetIterator(zs->dict);
-                    dictEntry *de;
-
-                    while((de = dictNext(di)) != NULL) {
-                        robj *eleobj = dictGetEntryKey(de);
-                        double *score = dictGetEntryVal(de);
-
-                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
-                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                        if (fwriteBulkDouble(fp,*score) == 0) goto werr;
-                        if (fwriteBulkObject(fp,eleobj) == 0) goto werr;
-                    }
-                    dictReleaseIterator(di);
-                } else {
-                    redisPanic("Unknown sorted set encoding");
-                }
+                if (rewriteSortedSetObject(&aof,&key,o) == 0) goto werr;

             } else if (o->type == REDIS_HASH) {
             } else if (o->type == REDIS_HASH) {

-                char cmd[]="*4\r\n$4\r\nHSET\r\n";
-
-                /* Emit the HSETs needed to rebuild the hash */
-                if (o->encoding == REDIS_ENCODING_ZIPMAP) {
-                    unsigned char *p = zipmapRewind(o->ptr);
-                    unsigned char *field, *val;
-                    unsigned int flen, vlen;
-
-                    while((p = zipmapNext(p,&field,&flen,&val,&vlen)) != NULL) {
-                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
-                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                        if (fwriteBulkString(fp,(char*)field,flen) == 0)
-                            goto werr;
-                        if (fwriteBulkString(fp,(char*)val,vlen) == 0)
-                            goto werr;
-                    }
-                } else {
-                    dictIterator *di = dictGetIterator(o->ptr);
-                    dictEntry *de;
-
-                    while((de = dictNext(di)) != NULL) {
-                        robj *field = dictGetEntryKey(de);
-                        robj *val = dictGetEntryVal(de);
-
-                        if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
-                        if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                        if (fwriteBulkObject(fp,field) == 0) goto werr;
-                        if (fwriteBulkObject(fp,val) == 0) goto werr;
-                    }
-                    dictReleaseIterator(di);
-                }
+                if (rewriteHashObject(&aof,&key,o) == 0) goto werr;

             } else {
                 redisPanic("Unknown object type");
             }
             /* Save the expire time */
             if (expiretime != -1) {
             } else {
                 redisPanic("Unknown object type");
             }
             /* Save the expire time */
             if (expiretime != -1) {

-                char cmd[]="*3\r\n$8\r\nEXPIREAT\r\n";
+                char cmd[]="*3\r\n$9\r\nPEXPIREAT\r\n";

                 /* If this key is already expired skip it */
                 if (expiretime < now) continue;
                 /* If this key is already expired skip it */
                 if (expiretime < now) continue;

-                if (fwrite(cmd,sizeof(cmd)-1,1,fp) == 0) goto werr;
-                if (fwriteBulkObject(fp,&key) == 0) goto werr;
-                if (fwriteBulkLongLong(fp,expiretime) == 0) goto werr;
+                if (rioWrite(&aof,cmd,sizeof(cmd)-1) == 0) goto werr;
+                if (rioWriteBulkObject(&aof,&key) == 0) goto werr;
+                if (rioWriteBulkLongLong(&aof,expiretime) == 0) goto werr;

             }
         }
         dictReleaseIterator(di);
             }
         }
         dictReleaseIterator(di);


@@ -598,6 +794,7 @@ int rewriteAppendOnlyFileBackground(void) {
         }
         redisLog(REDIS_NOTICE,
             "Background append only file rewriting started by pid %d",childpid);
         }
         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
         server.bgrewritechildpid = childpid;
         updateDictResizePolicy();
         /* We set appendseldb to -1 in order to force the next call to the


@@ -649,56 +846,127 @@ void aofUpdateCurrentSize(void) {
  * Handle this. */
 void backgroundRewriteDoneHandler(int exitcode, int bysignal) {
     if (!bysignal && exitcode == 0) {
  * Handle this. */
 void backgroundRewriteDoneHandler(int exitcode, int bysignal) {
     if (!bysignal && exitcode == 0) {

-        int fd;
+        int newfd, oldfd;
+        int nwritten;

         char tmpfile[256];
         char tmpfile[256];

+        long long now = ustime();

 
         redisLog(REDIS_NOTICE,
 
         redisLog(REDIS_NOTICE,

-            "Background append only file rewriting terminated with success");
-        /* Now it's time to flush the differences accumulated by the parent */
-        snprintf(tmpfile,256,"temp-rewriteaof-bg-%d.aof", (int) server.bgrewritechildpid);
-        fd = open(tmpfile,O_WRONLY|O_APPEND);
-        if (fd == -1) {
-            redisLog(REDIS_WARNING, "Not able to open the temp append only file produced by the child: %s", strerror(errno));
+            "Background AOF rewrite terminated with success");
+
+        /* Flush the differences accumulated by the parent to the
+         * rewritten AOF. */
+        snprintf(tmpfile,256,"temp-rewriteaof-bg-%d.aof",
+            (int)server.bgrewritechildpid);
+        newfd = open(tmpfile,O_WRONLY|O_APPEND);
+        if (newfd == -1) {
+            redisLog(REDIS_WARNING,
+                "Unable to open the temporary AOF produced by the child: %s", strerror(errno));

             goto cleanup;
         }
             goto cleanup;
         }

-        /* Flush our data... */
-        if (write(fd,server.bgrewritebuf,sdslen(server.bgrewritebuf)) !=
-                (signed) sdslen(server.bgrewritebuf)) {
-            redisLog(REDIS_WARNING, "Error or short write trying to flush the parent diff of the append log file in the child temp file: %s", strerror(errno));
-            close(fd);
+
+        nwritten = write(newfd,server.bgrewritebuf,sdslen(server.bgrewritebuf));
+        if (nwritten != (signed)sdslen(server.bgrewritebuf)) {
+            if (nwritten == -1) {
+                redisLog(REDIS_WARNING,
+                    "Error trying to flush the parent diff to the rewritten AOF: %s", strerror(errno));
+            } else {
+                redisLog(REDIS_WARNING,
+                    "Short write trying to flush the parent diff to the rewritten AOF: %s", strerror(errno));
+            }
+            close(newfd);

             goto cleanup;
         }
             goto cleanup;
         }

-        redisLog(REDIS_NOTICE,"Parent diff flushed into the new append log file with success (%lu bytes)",sdslen(server.bgrewritebuf));
-        /* Now our work is to rename the temp file into the stable file. And
-         * switch the file descriptor used by the server for append only. */
+
+        redisLog(REDIS_NOTICE,
+            "Parent diff successfully flushed to the rewritten AOF (%lu bytes)", nwritten);
+
+        /* The only remaining thing to do is to rename the temporary file to
+         * the configured file and switch the file descriptor used to do AOF
+         * writes. We don't want close(2) or rename(2) calls to block the
+         * server on old file deletion.
+         *
+         * There are two possible scenarios:
+         *
+         * 1) AOF is DISABLED and this was a one time rewrite. The temporary
+         * file will be renamed to the configured file. When this file already
+         * exists, it will be unlinked, which may block the server.
+         *
+         * 2) AOF is ENABLED and the rewritten AOF will immediately start
+         * receiving writes. After the temporary file is renamed to the
+         * configured file, the original AOF file descriptor will be closed.
+         * Since this will be the last reference to that file, closing it
+         * causes the underlying file to be unlinked, which may block the
+         * server.
+         *
+         * To mitigate the blocking effect of the unlink operation (either
+         * caused by rename(2) in scenario 1, or by close(2) in scenario 2), we
+         * use a background thread to take care of this. First, we
+         * make scenario 1 identical to scenario 2 by opening the target file
+         * when it exists. The unlink operation after the rename(2) will then
+         * be executed upon calling close(2) for its descriptor. Everything to
+         * guarantee atomicity for this switch has already happened by then, so
+         * we don't care what the outcome or duration of that close operation
+         * is, as long as the file descriptor is released again. */
+        if (server.appendfd == -1) {
+            /* AOF disabled */
+
+             /* Don't care if this fails: oldfd will be -1 and we handle that.
+              * One notable case of -1 return is if the old file does
+              * not exist. */
+             oldfd = open(server.appendfilename,O_RDONLY|O_NONBLOCK);
+        } else {
+            /* AOF enabled */
+            oldfd = -1; /* We'll set this to the current AOF filedes later. */
+        }
+
+        /* Rename the temporary file. This will not unlink the target file if
+         * it exists, because we reference it with "oldfd". */

         if (rename(tmpfile,server.appendfilename) == -1) {
         if (rename(tmpfile,server.appendfilename) == -1) {

-            redisLog(REDIS_WARNING,"Can't rename the temp append only file into the stable one: %s", strerror(errno));
-            close(fd);
+            redisLog(REDIS_WARNING,
+                "Error trying to rename the temporary AOF: %s", strerror(errno));
+            close(newfd);
+            if (oldfd != -1) close(oldfd);

             goto cleanup;
         }
             goto cleanup;
         }

-        /* Mission completed... almost */
-        redisLog(REDIS_NOTICE,"Append only file successfully rewritten.");
-        if (server.appendfd != -1) {
-            /* If append only is actually enabled... */
-            close(server.appendfd);
-            server.appendfd = fd;
-            if (server.appendfsync != APPENDFSYNC_NO) aof_fsync(fd);
-            server.appendseldb = -1; /* Make sure it will issue SELECT */
-            redisLog(REDIS_NOTICE,"The new append only file was selected for future appends.");
+
+        if (server.appendfd == -1) {
+            /* AOF disabled, we don't need to set the AOF file descriptor
+             * to this new file, so we can close it. */
+            close(newfd);
+        } else {
+            /* AOF enabled, replace the old fd with the new one. */
+            oldfd = server.appendfd;
+            server.appendfd = newfd;
+            if (server.appendfsync == APPENDFSYNC_ALWAYS)
+                aof_fsync(newfd);
+            else if (server.appendfsync == APPENDFSYNC_EVERYSEC)
+                aof_background_fsync(newfd);
+            server.appendseldb = -1; /* Make sure SELECT is re-issued */

             aofUpdateCurrentSize();
             server.auto_aofrewrite_base_size = server.appendonly_current_size;
             aofUpdateCurrentSize();
             server.auto_aofrewrite_base_size = server.appendonly_current_size;

-        } else {
-            /* If append only is disabled we just generate a dump in this
-             * format. Why not? */
-            close(fd);
+
+            /* Clear regular AOF buffer since its contents was just written to
+             * the new AOF from the background rewrite buffer. */
+            sdsfree(server.aofbuf);
+            server.aofbuf = sdsempty();

         }
         }

+
+        redisLog(REDIS_NOTICE, "Background AOF rewrite successful");
+
+        /* Asynchronously close the overwritten AOF. */
+        if (oldfd != -1) bioCreateBackgroundJob(REDIS_BIO_CLOSE_FILE,(void*)(long)oldfd,NULL,NULL);
+
+        redisLog(REDIS_VERBOSE,
+            "Background AOF rewrite signal handler took %lldus", ustime()-now);

     } else if (!bysignal && exitcode != 0) {
     } else if (!bysignal && exitcode != 0) {

-        redisLog(REDIS_WARNING, "Background append only file rewriting error");
+        redisLog(REDIS_WARNING,
+            "Background AOF rewrite terminated with error");

     } else {
         redisLog(REDIS_WARNING,
     } else {
         redisLog(REDIS_WARNING,

-            "Background append only file rewriting terminated by signal %d",
-            bysignal);
+            "Background AOF rewrite terminated by signal %d", bysignal);

     }
     }

+

 cleanup:
     sdsfree(server.bgrewritebuf);
     server.bgrewritebuf = sdsempty();
 cleanup:
     sdsfree(server.bgrewritebuf);
     server.bgrewritebuf = sdsempty();