]> git.saurik.com Git - redis.git/blobdiff - redis.c
update-scala-client script added
[redis.git] / redis.c
diff --git a/redis.c b/redis.c
index a8b5e2f2cffaffb78ca05ed9d54801ba3cf74295..607c827a4cb63d48ff1b342ef7949d6db60d4486 100644 (file)
--- a/redis.c
+++ b/redis.c
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#define REDIS_VERSION "0.101"
+#define REDIS_VERSION "0.900"
 
 #include "fmacros.h"
+#include "config.h"
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
+#define __USE_POSIX199309
 #include <signal.h>
+
+#ifdef HAVE_BACKTRACE
+#include <execinfo.h>
+#include <ucontext.h>
+#endif /* HAVE_BACKTRACE */
+
 #include <sys/wait.h>
 #include <errno.h>
 #include <assert.h>
@@ -49,8 +57,8 @@
 #include <sys/time.h>
 #include <sys/resource.h>
 #include <limits.h>
-#include <execinfo.h>
 
+#include "redis.h"
 #include "ae.h"     /* Event driven programming library */
 #include "sds.h"    /* Dynamic safe strings */
 #include "anet.h"   /* Networking the easy way */
 #define REDIS_OBJFREELIST_MAX   1000000 /* Max number of objects to cache */
 #define REDIS_MAX_SYNC_TIME     60      /* Slave can't take more to sync */
 #define REDIS_EXPIRELOOKUPS_PER_CRON    100 /* try to expire 100 keys/second */
+#define REDIS_MAX_WRITE_PER_EVENT (1024*64)
+#define REDIS_REQUEST_MAX_SIZE  (1024*1024*256) /* max bytes in inline command */
 
 /* Hash table parameters */
 #define REDIS_HT_MINFILL        10      /* Minimal hash table fill 10% */
-#define REDIS_HT_MINSLOTS       16384   /* Never resize the HT under this */
 
 /* Command flags */
 #define REDIS_CMD_BULK          1       /* Bulk write command */
 /* Anti-warning macro... */
 #define REDIS_NOTUSED(V) ((void) V)
 
+
 /*================================= Data types ============================== */
 
 /* A redis object, that is a type able to hold a string / list / set */
@@ -238,6 +248,7 @@ struct redisServer {
     int daemonize;
     char *pidfile;
     int bgsaveinprogress;
+    pid_t bgsavechildpid;
     struct saveparam *saveparams;
     int saveparamslen;
     char *logfile;
@@ -268,6 +279,11 @@ struct redisCommand {
     int flags;
 };
 
+struct redisFunctionSym {
+    char *name;
+    unsigned long pointer;
+};
+
 typedef struct _redisSortObject {
     robj *obj;
     union {
@@ -313,8 +329,11 @@ static int deleteIfVolatile(redisDb *db, robj *key);
 static int deleteKey(redisDb *db, robj *key);
 static time_t getExpire(redisDb *db, robj *key);
 static int setExpire(redisDb *db, robj *key, time_t when);
-static void updateSalvesWaitingBgsave(int bgsaveerr);
+static void updateSlavesWaitingBgsave(int bgsaveerr);
 static void freeMemoryIfNeeded(void);
+static int processCommand(redisClient *c);
+static void setupSigSegvAction(void);
+static void rdbRemoveTempFile(pid_t childpid);
 
 static void authCommand(redisClient *c);
 static void pingCommand(redisClient *c);
@@ -354,6 +373,7 @@ static void sremCommand(redisClient *c);
 static void smoveCommand(redisClient *c);
 static void sismemberCommand(redisClient *c);
 static void scardCommand(redisClient *c);
+static void spopCommand(redisClient *c);
 static void sinterCommand(redisClient *c);
 static void sinterstoreCommand(redisClient *c);
 static void sunionCommand(redisClient *c);
@@ -373,7 +393,6 @@ static void getSetCommand(redisClient *c);
 static void ttlCommand(redisClient *c);
 static void slaveofCommand(redisClient *c);
 static void debugCommand(redisClient *c);
-
 /*================================= Globals ================================= */
 
 /* Global vars */
@@ -402,6 +421,7 @@ static struct redisCommand cmdTable[] = {
     {"smove",smoveCommand,4,REDIS_CMD_BULK},
     {"sismember",sismemberCommand,3,REDIS_CMD_BULK},
     {"scard",scardCommand,2,REDIS_CMD_INLINE},
+    {"spop",spopCommand,2,REDIS_CMD_INLINE},
     {"sinter",sinterCommand,-2,REDIS_CMD_INLINE|REDIS_CMD_DENYOOM},
     {"sinterstore",sinterstoreCommand,-3,REDIS_CMD_INLINE|REDIS_CMD_DENYOOM},
     {"sunion",sunionCommand,-2,REDIS_CMD_INLINE|REDIS_CMD_DENYOOM},
@@ -439,7 +459,6 @@ static struct redisCommand cmdTable[] = {
     {"debug",debugCommand,-2,REDIS_CMD_INLINE},
     {NULL,NULL,0,0}
 };
-
 /*============================ Utility functions ============================ */
 
 /* Glob-style pattern matching. */
@@ -565,8 +584,7 @@ int stringmatchlen(const char *pattern, int patternLen,
     return 0;
 }
 
-void redisLog(int level, const char *fmt, ...)
-{
+static void redisLog(int level, const char *fmt, ...) {
     va_list ap;
     FILE *fp;
 
@@ -661,7 +679,7 @@ static void oom(const char *msg) {
 }
 
 /* ====================== Redis server networking stuff ===================== */
-void closeTimedoutClients(void) {
+static void closeTimedoutClients(void) {
     redisClient *c;
     listNode *ln;
     time_t now = time(NULL);
@@ -678,26 +696,32 @@ void closeTimedoutClients(void) {
     }
 }
 
+static int htNeedsResize(dict *dict) {
+    long long size, used;
+
+    size = dictSlots(dict);
+    used = dictSize(dict);
+    return (size && used && size > DICT_HT_INITIAL_SIZE &&
+            (used*100/size < REDIS_HT_MINFILL));
+}
+
 /* If the percentage of used slots in the HT reaches REDIS_HT_MINFILL
  * we resize the hash table to save memory */
-void tryResizeHashTables(void) {
+static void tryResizeHashTables(void) {
     int j;
 
     for (j = 0; j < server.dbnum; j++) {
-        long long size, used;
-
-        size = dictSlots(server.db[j].dict);
-        used = dictSize(server.db[j].dict);
-        if (size && used && size > REDIS_HT_MINSLOTS &&
-            (used*100/size < REDIS_HT_MINFILL)) {
-            redisLog(REDIS_NOTICE,"The hash table %d is too sparse, resize it...",j);
+        if (htNeedsResize(server.db[j].dict)) {
+            redisLog(REDIS_DEBUG,"The hash table %d is too sparse, resize it...",j);
             dictResize(server.db[j].dict);
-            redisLog(REDIS_NOTICE,"Hash table %d resized.",j);
+            redisLog(REDIS_DEBUG,"Hash table %d resized.",j);
         }
+        if (htNeedsResize(server.db[j].expires))
+            dictResize(server.db[j].expires);
     }
 }
 
-int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
+static int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
     int j, loops = server.cronloops++;
     REDIS_NOTUSED(eventLoop);
     REDIS_NOTUSED(id);
@@ -713,8 +737,8 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
         size = dictSlots(server.db[j].dict);
         used = dictSize(server.db[j].dict);
         vkeys = dictSize(server.db[j].expires);
-        if (!(loops % 5) && used > 0) {
-            redisLog(REDIS_DEBUG,"DB %d: %d keys (%d volatile) in %d slots HT.",j,used,vkeys,size);
+        if (!(loops % 5) && (used || vkeys)) {
+            redisLog(REDIS_DEBUG,"DB %d: %lld keys (%lld volatile) in %lld slots HT.",j,used,vkeys,size);
             /* dictPrintStats(server.dict); */
         }
     }
@@ -729,7 +753,7 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
 
     /* Show information about connected clients */
     if (!(loops % 5)) {
-        redisLog(REDIS_DEBUG,"%d clients connected (%d slaves), %zu bytes in use",
+        redisLog(REDIS_DEBUG,"%d clients connected (%d slaves), %zu bytes in use, %d shared objects",
             listLength(server.clients)-listLength(server.slaves),
             listLength(server.slaves),
             server.usedmemory,
@@ -743,20 +767,25 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
     /* Check if a background saving in progress terminated */
     if (server.bgsaveinprogress) {
         int statloc;
-        /* XXX: TODO handle the case of the saving child killed */
         if (wait4(-1,&statloc,WNOHANG,NULL)) {
             int exitcode = WEXITSTATUS(statloc);
-            if (exitcode == 0) {
+            int bysignal = WIFSIGNALED(statloc);
+
+            if (!bysignal && exitcode == 0) {
                 redisLog(REDIS_NOTICE,
                     "Background saving terminated with success");
                 server.dirty = 0;
                 server.lastsave = time(NULL);
+            } else if (!bysignal && exitcode != 0) {
+                redisLog(REDIS_WARNING, "Background saving error");
             } else {
                 redisLog(REDIS_WARNING,
-                    "Background saving error");
+                    "Background saving terminated by signal");
+                rdbRemoveTempFile(server.bgsavechildpid);
             }
             server.bgsaveinprogress = 0;
-            updateSalvesWaitingBgsave(exitcode == 0 ? REDIS_OK : REDIS_ERR);
+            server.bgsavechildpid = -1;
+            updateSlavesWaitingBgsave(exitcode == 0 ? REDIS_OK : REDIS_ERR);
         }
     } else {
         /* If there is not a background saving in progress check if
@@ -873,6 +902,7 @@ static void initServerConfig() {
     server.dbfilename = "dump.rdb";
     server.requirepass = NULL;
     server.shareobjects = 0;
+    server.sharingpoolsize = 1024;
     server.maxclients = 0;
     server.maxmemory = 0;
     ResetServerSaveParams();
@@ -893,6 +923,7 @@ static void initServer() {
 
     signal(SIGHUP, SIG_IGN);
     signal(SIGPIPE, SIG_IGN);
+    setupSigSegvAction();
 
     server.clients = listCreate();
     server.slaves = listCreate();
@@ -902,7 +933,6 @@ static void initServer() {
     server.el = aeCreateEventLoop();
     server.db = zmalloc(sizeof(redisDb)*server.dbnum);
     server.sharingpool = dictCreate(&setDictType,NULL);
-    server.sharingpoolsize = 1024;
     if (!server.db || !server.clients || !server.slaves || !server.monitors || !server.el || !server.objfreelist)
         oom("server initialization"); /* Fatal OOM */
     server.fd = anetTcpServer(server.neterr, server.port, server.bindaddr);
@@ -917,6 +947,7 @@ static void initServer() {
     }
     server.cronloops = 0;
     server.bgsaveinprogress = 0;
+    server.bgsavechildpid = -1;
     server.lastsave = time(NULL);
     server.dirty = 0;
     server.usedmemory = 0;
@@ -948,15 +979,20 @@ static int yesnotoi(char *s) {
 /* I agree, this is a very rudimental way to load a configuration...
    will improve later if the config gets more complex */
 static void loadServerConfig(char *filename) {
-    FILE *fp = fopen(filename,"r");
+    FILE *fp;
     char buf[REDIS_CONFIGLINE_MAX+1], *err = NULL;
     int linenum = 0;
     sds line = NULL;
-    
-    if (!fp) {
-        redisLog(REDIS_WARNING,"Fatal error, can't open config file");
-        exit(1);
+
+    if (filename[0] == '-' && filename[1] == '\0')
+        fp = stdin;
+    else {
+        if ((fp = fopen(filename,"r")) == NULL) {
+            redisLog(REDIS_WARNING,"Fatal error, can't open config file");
+            exit(1);
+        }
     }
+
     while(fgets(buf,REDIS_CONFIGLINE_MAX+1,fp) != NULL) {
         sds *argv;
         int argc, j;
@@ -1010,7 +1046,7 @@ static void loadServerConfig(char *filename) {
                 goto loaderr;
             }
         } else if (!strcasecmp(argv[0],"logfile") && argc == 2) {
-            FILE *fp;
+            FILE *logfp;
 
             server.logfile = zstrdup(argv[1]);
             if (!strcasecmp(server.logfile,"stdout")) {
@@ -1020,13 +1056,13 @@ static void loadServerConfig(char *filename) {
             if (server.logfile) {
                 /* Test if we are able to open the file. The server will not
                  * be able to abort just for this problem later... */
-                fp = fopen(server.logfile,"a");
-                if (fp == NULL) {
+                logfp = fopen(server.logfile,"a");
+                if (logfp == NULL) {
                     err = sdscatprintf(sdsempty(),
                         "Can't open the log file: %s", strerror(errno));
                     goto loaderr;
                 }
-                fclose(fp);
+                fclose(logfp);
             }
         } else if (!strcasecmp(argv[0],"databases") && argc == 2) {
             server.dbnum = atoi(argv[1]);
@@ -1072,7 +1108,7 @@ static void loadServerConfig(char *filename) {
         zfree(argv);
         sdsfree(line);
     }
-    fclose(fp);
+    if (fp != stdin) fclose(fp);
     return;
 
 loaderr:
@@ -1168,6 +1204,7 @@ static void sendReplyToClient(aeEventLoop *el, int fd, void *privdata, int mask)
         }
 
         if (c->flags & REDIS_MASTER) {
+            /* Don't reply to a master */
             nwritten = objlen - c->sentlen;
         } else {
             nwritten = write(fd, ((char*)o->ptr)+c->sentlen, objlen - c->sentlen);
@@ -1180,6 +1217,12 @@ static void sendReplyToClient(aeEventLoop *el, int fd, void *privdata, int mask)
             listDelNode(c->reply,listFirst(c->reply));
             c->sentlen = 0;
         }
+        /* Note that we avoid to send more thank REDIS_MAX_WRITE_PER_EVENT
+         * bytes, in a single threaded server it's a good idea to server
+         * other clients as well, even if a very large request comes from
+         * super fast link that is always able to accept data (in real world
+         * terms think to 'KEYS *' against the loopback interfae) */
+        if (totwritten > REDIS_MAX_WRITE_PER_EVENT) break;
     }
     if (nwritten == -1) {
         if (errno == EAGAIN) {
@@ -1403,6 +1446,7 @@ again:
         /* Read the first line of the query */
         char *p = strchr(c->querybuf,'\n');
         size_t querylen;
+
         if (p) {
             sds query, *argv;
             int argc, j;
@@ -1444,9 +1488,9 @@ again:
             /* Execute the command. If the client is still valid
              * after processCommand() return and there is something
              * on the query buffer try to process the next command. */
-            if (processCommand(c) && sdslen(c->querybuf)) goto again;
+            if (c->argc && processCommand(c) && sdslen(c->querybuf)) goto again;
             return;
-        } else if (sdslen(c->querybuf) >= 1024*32) {
+        } else if (sdslen(c->querybuf) >= REDIS_REQUEST_MAX_SIZE) {
             redisLog(REDIS_DEBUG, "Client protocol error");
             freeClient(c);
             return;
@@ -1756,7 +1800,7 @@ static int rdbSaveLen(FILE *fp, uint32_t len) {
 /* String objects in the form "2391" "-100" without any space and with a
  * range of values that can fit in an 8, 16 or 32 bit signed value can be
  * encoded as integers to save space */
-int rdbTryIntegerEncoding(sds s, unsigned char *enc) {
+static int rdbTryIntegerEncoding(sds s, unsigned char *enc) {
     long long value;
     char *endptr, buf[32];
 
@@ -1860,7 +1904,7 @@ static int rdbSave(char *filename) {
     int j;
     time_t now = time(NULL);
 
-    snprintf(tmpfile,256,"temp-%d.%ld.rdb",(int)time(NULL),(long int)random());
+    snprintf(tmpfile,256,"temp-%d.rdb", (int) getpid());
     fp = fopen(tmpfile,"w");
     if (!fp) {
         redisLog(REDIS_WARNING, "Failed saving the DB: %s", strerror(errno));
@@ -1981,11 +2025,19 @@ static int rdbSaveBackground(char *filename) {
         }
         redisLog(REDIS_NOTICE,"Background saving started by pid %d",childpid);
         server.bgsaveinprogress = 1;
+        server.bgsavechildpid = childpid;
         return REDIS_OK;
     }
     return REDIS_OK; /* unreached */
 }
 
+static void rdbRemoveTempFile(pid_t childpid) {
+    char tmpfile[256];
+
+    snprintf(tmpfile,256,"temp-%d.rdb", (int) childpid);
+    unlink(tmpfile);
+}
+
 static int rdbLoadType(FILE *fp) {
     unsigned char type;
     if (fread(&type,1,1,fp) == 0) return -1;
@@ -2503,15 +2555,26 @@ static void bgsaveCommand(redisClient *c) {
 
 static void shutdownCommand(redisClient *c) {
     redisLog(REDIS_WARNING,"User requested shutdown, saving DB...");
-    /* XXX: TODO kill the child if there is a bgsave in progress */
+    /* Kill the saving child if there is a background saving in progress.
+       We want to avoid race conditions, for instance our saving child may
+       overwrite the synchronous saving did by SHUTDOWN. */
+    if (server.bgsaveinprogress) {
+        redisLog(REDIS_WARNING,"There is a live saving child. Killing it!");
+        kill(server.bgsavechildpid,SIGKILL);
+        rdbRemoveTempFile(server.bgsavechildpid);
+    }
+    /* SYNC SAVE */
     if (rdbSave(server.dbfilename) == REDIS_OK) {
-        if (server.daemonize) {
+        if (server.daemonize)
             unlink(server.pidfile);
-        }
         redisLog(REDIS_WARNING,"%zu bytes used at exit",zmalloc_used_memory());
         redisLog(REDIS_WARNING,"Server exit now, bye bye...");
         exit(1);
     } else {
+        /* Ooops.. error saving! The best we can do is to continue operating.
+         * Note that if there was a background saving process, in the next
+         * cron() Redis will be notified that the background saving aborted,
+         * handling special stuff like slaves pending for synchronization... */
         redisLog(REDIS_WARNING,"Error trying to save the DB, can't exit"); 
         addReplySds(c,sdsnew("-ERR can't quit, problems saving the DB\r\n"));
     }
@@ -2847,8 +2910,8 @@ static void ltrimCommand(redisClient *c) {
                 ln = listLast(list);
                 listDelNode(list,ln);
             }
-            addReply(c,shared.ok);
             server.dirty++;
+            addReply(c,shared.ok);
         }
     }
 }
@@ -2858,7 +2921,7 @@ static void lremCommand(redisClient *c) {
     
     o = lookupKeyWrite(c->db,c->argv[1]);
     if (o == NULL) {
-        addReply(c,shared.nokeyerr);
+        addReply(c,shared.czero);
     } else {
         if (o->type != REDIS_LIST) {
             addReply(c,shared.wrongtypeerr);
@@ -2929,6 +2992,7 @@ static void sremCommand(redisClient *c) {
         }
         if (dictDelete(set->ptr,c->argv[2]) == DICT_OK) {
             server.dirty++;
+            if (htNeedsResize(set->ptr)) dictResize(set->ptr);
             addReply(c,shared.cone);
         } else {
             addReply(c,shared.czero);
@@ -3008,6 +3072,34 @@ static void scardCommand(redisClient *c) {
     }
 }
 
+static void spopCommand(redisClient *c) {
+    robj *set;
+    dictEntry *de;
+
+    set = lookupKeyWrite(c->db,c->argv[1]);
+    if (set == NULL) {
+        addReply(c,shared.nullbulk);
+    } else {
+        if (set->type != REDIS_SET) {
+            addReply(c,shared.wrongtypeerr);
+            return;
+        }
+        de = dictGetRandomKey(set->ptr);
+        if (de == NULL) {
+            addReply(c,shared.nullbulk);
+        } else {
+            robj *ele = dictGetEntryKey(de);
+
+            addReplySds(c,sdscatprintf(sdsempty(),"$%d\r\n",sdslen(ele->ptr)));
+            addReply(c,ele);
+            addReply(c,shared.crlf);
+            dictDelete(set->ptr,ele);
+            if (htNeedsResize(set->ptr)) dictResize(set->ptr);
+            server.dirty++;
+        }
+    }
+}
+
 static int qsortCompareSetsByCardinality(const void *s1, const void *s2) {
     dict **d1 = (void*) s1, **d2 = (void*) s2;
 
@@ -3243,7 +3335,7 @@ static void flushallCommand(redisClient *c) {
     server.dirty++;
 }
 
-redisSortOperation *createSortOperation(int type, robj *pattern) {
+static redisSortOperation *createSortOperation(int type, robj *pattern) {
     redisSortOperation *so = zmalloc(sizeof(*so));
     if (!so) oom("createSortOperation");
     so->type = type;
@@ -3253,7 +3345,7 @@ redisSortOperation *createSortOperation(int type, robj *pattern) {
 
 /* Return the value associated to the key with a name obtained
  * substituting the first occurence of '*' in 'pattern' with 'subst' */
-robj *lookupKeyByPattern(redisDb *db, robj *pattern, robj *subst) {
+static robj *lookupKeyByPattern(redisDb *db, robj *pattern, robj *subst) {
     char *p;
     sds spat, ssub;
     robj keyobj;
@@ -3528,6 +3620,7 @@ static void sortCommand(redisClient *c) {
 static void infoCommand(redisClient *c) {
     sds info;
     time_t uptime = time(NULL)-server.stat_starttime;
+    int j;
     
     info = sdscatprintf(sdsempty(),
         "redis_version:%s\r\n"
@@ -3568,6 +3661,16 @@ static void infoCommand(redisClient *c) {
             (int)(time(NULL)-server.master->lastinteraction)
         );
     }
+    for (j = 0; j < server.dbnum; j++) {
+        long long keys, vkeys;
+
+        keys = dictSize(server.db[j].dict);
+        vkeys = dictSize(server.db[j].expires);
+        if (keys || vkeys) {
+            info = sdscatprintf(info, "db%d: keys=%lld,expires=%lld\r\n",
+                j, keys, vkeys);
+        }
+    }
     addReplySds(c,sdscatprintf(sdsempty(),"$%d\r\n",sdslen(info)));
     addReplySds(c,info);
     addReply(c,shared.crlf);
@@ -3657,10 +3760,12 @@ static void expireCommand(redisClient *c) {
         return;
     } else {
         time_t when = time(NULL)+seconds;
-        if (setExpire(c->db,c->argv[1],when))
+        if (setExpire(c->db,c->argv[1],when)) {
             addReply(c,shared.cone);
-        else
+            server.dirty++;
+        } else {
             addReply(c,shared.czero);
+        }
         return;
     }
 }
@@ -3854,7 +3959,13 @@ static void sendBulkToSlave(aeEventLoop *el, int fd, void *privdata, int mask) {
     }
 }
 
-static void updateSalvesWaitingBgsave(int bgsaveerr) {
+/* This function is called at the end of every backgrond saving.
+ * The argument bgsaveerr is REDIS_OK if the background saving succeeded
+ * otherwise REDIS_ERR is passed to the function.
+ *
+ * The goal of this function is to handle slaves waiting for a successful
+ * background saving in order to perform non-blocking synchronization. */
+static void updateSlavesWaitingBgsave(int bgsaveerr) {
     listNode *ln;
     int startbgsave = 0;
 
@@ -3866,7 +3977,7 @@ static void updateSalvesWaitingBgsave(int bgsaveerr) {
             startbgsave = 1;
             slave->replstate = REDIS_REPL_WAIT_BGSAVE_END;
         } else if (slave->replstate == REDIS_REPL_WAIT_BGSAVE_END) {
-            struct stat buf;
+            struct redis_stat buf;
            
             if (bgsaveerr != REDIS_OK) {
                 freeClient(slave);
@@ -3874,7 +3985,7 @@ static void updateSalvesWaitingBgsave(int bgsaveerr) {
                 continue;
             }
             if ((slave->repldbfd = open(server.dbfilename,O_RDONLY)) == -1 ||
-                fstat(slave->repldbfd,&buf) == -1) {
+                redis_fstat(slave->repldbfd,&buf) == -1) {
                 freeClient(slave);
                 redisLog(REDIS_WARNING,"SYNC failed. Can't open/stat DB after BGSAVE: %s", strerror(errno));
                 continue;
@@ -4056,11 +4167,238 @@ static void freeMemoryIfNeeded(void) {
 static void debugCommand(redisClient *c) {
     if (!strcasecmp(c->argv[1]->ptr,"segfault")) {
         *((char*)-1) = 'x';
+    } else if (!strcasecmp(c->argv[1]->ptr,"object") && c->argc == 3) {
+        dictEntry *de = dictFind(c->db->dict,c->argv[2]);
+        robj *key, *val;
+
+        if (!de) {
+            addReply(c,shared.nokeyerr);
+            return;
+        }
+        key = dictGetEntryKey(de);
+        val = dictGetEntryVal(de);
+        addReplySds(c,sdscatprintf(sdsempty(),
+            "+Key at:%p refcount:%d, value at:%p refcount:%d\r\n",
+                key, key->refcount, val, val->refcount));
     } else {
-        addReplySds(c,sdsnew("-ERR Syntax error, try DEBUG SEGFAULT\r\n"));
+        addReplySds(c,sdsnew(
+            "-ERR Syntax error, try DEBUG [SEGFAULT|OBJECT <key>]\r\n"));
+    }
+}
+
+#ifdef HAVE_BACKTRACE
+static struct redisFunctionSym symsTable[] = {
+{"freeStringObject", (unsigned long)freeStringObject},
+{"freeListObject", (unsigned long)freeListObject},
+{"freeSetObject", (unsigned long)freeSetObject},
+{"decrRefCount", (unsigned long)decrRefCount},
+{"createObject", (unsigned long)createObject},
+{"freeClient", (unsigned long)freeClient},
+{"rdbLoad", (unsigned long)rdbLoad},
+{"addReply", (unsigned long)addReply},
+{"addReplySds", (unsigned long)addReplySds},
+{"incrRefCount", (unsigned long)incrRefCount},
+{"rdbSaveBackground", (unsigned long)rdbSaveBackground},
+{"createStringObject", (unsigned long)createStringObject},
+{"replicationFeedSlaves", (unsigned long)replicationFeedSlaves},
+{"syncWithMaster", (unsigned long)syncWithMaster},
+{"tryObjectSharing", (unsigned long)tryObjectSharing},
+{"removeExpire", (unsigned long)removeExpire},
+{"expireIfNeeded", (unsigned long)expireIfNeeded},
+{"deleteIfVolatile", (unsigned long)deleteIfVolatile},
+{"deleteKey", (unsigned long)deleteKey},
+{"getExpire", (unsigned long)getExpire},
+{"setExpire", (unsigned long)setExpire},
+{"updateSlavesWaitingBgsave", (unsigned long)updateSlavesWaitingBgsave},
+{"freeMemoryIfNeeded", (unsigned long)freeMemoryIfNeeded},
+{"authCommand", (unsigned long)authCommand},
+{"pingCommand", (unsigned long)pingCommand},
+{"echoCommand", (unsigned long)echoCommand},
+{"setCommand", (unsigned long)setCommand},
+{"setnxCommand", (unsigned long)setnxCommand},
+{"getCommand", (unsigned long)getCommand},
+{"delCommand", (unsigned long)delCommand},
+{"existsCommand", (unsigned long)existsCommand},
+{"incrCommand", (unsigned long)incrCommand},
+{"decrCommand", (unsigned long)decrCommand},
+{"incrbyCommand", (unsigned long)incrbyCommand},
+{"decrbyCommand", (unsigned long)decrbyCommand},
+{"selectCommand", (unsigned long)selectCommand},
+{"randomkeyCommand", (unsigned long)randomkeyCommand},
+{"keysCommand", (unsigned long)keysCommand},
+{"dbsizeCommand", (unsigned long)dbsizeCommand},
+{"lastsaveCommand", (unsigned long)lastsaveCommand},
+{"saveCommand", (unsigned long)saveCommand},
+{"bgsaveCommand", (unsigned long)bgsaveCommand},
+{"shutdownCommand", (unsigned long)shutdownCommand},
+{"moveCommand", (unsigned long)moveCommand},
+{"renameCommand", (unsigned long)renameCommand},
+{"renamenxCommand", (unsigned long)renamenxCommand},
+{"lpushCommand", (unsigned long)lpushCommand},
+{"rpushCommand", (unsigned long)rpushCommand},
+{"lpopCommand", (unsigned long)lpopCommand},
+{"rpopCommand", (unsigned long)rpopCommand},
+{"llenCommand", (unsigned long)llenCommand},
+{"lindexCommand", (unsigned long)lindexCommand},
+{"lrangeCommand", (unsigned long)lrangeCommand},
+{"ltrimCommand", (unsigned long)ltrimCommand},
+{"typeCommand", (unsigned long)typeCommand},
+{"lsetCommand", (unsigned long)lsetCommand},
+{"saddCommand", (unsigned long)saddCommand},
+{"sremCommand", (unsigned long)sremCommand},
+{"smoveCommand", (unsigned long)smoveCommand},
+{"sismemberCommand", (unsigned long)sismemberCommand},
+{"scardCommand", (unsigned long)scardCommand},
+{"spopCommand", (unsigned long)spopCommand},
+{"sinterCommand", (unsigned long)sinterCommand},
+{"sinterstoreCommand", (unsigned long)sinterstoreCommand},
+{"sunionCommand", (unsigned long)sunionCommand},
+{"sunionstoreCommand", (unsigned long)sunionstoreCommand},
+{"sdiffCommand", (unsigned long)sdiffCommand},
+{"sdiffstoreCommand", (unsigned long)sdiffstoreCommand},
+{"syncCommand", (unsigned long)syncCommand},
+{"flushdbCommand", (unsigned long)flushdbCommand},
+{"flushallCommand", (unsigned long)flushallCommand},
+{"sortCommand", (unsigned long)sortCommand},
+{"lremCommand", (unsigned long)lremCommand},
+{"infoCommand", (unsigned long)infoCommand},
+{"mgetCommand", (unsigned long)mgetCommand},
+{"monitorCommand", (unsigned long)monitorCommand},
+{"expireCommand", (unsigned long)expireCommand},
+{"getSetCommand", (unsigned long)getSetCommand},
+{"ttlCommand", (unsigned long)ttlCommand},
+{"slaveofCommand", (unsigned long)slaveofCommand},
+{"debugCommand", (unsigned long)debugCommand},
+{"processCommand", (unsigned long)processCommand},
+{"setupSigSegvAction", (unsigned long)setupSigSegvAction},
+{"readQueryFromClient", (unsigned long)readQueryFromClient},
+{"rdbRemoveTempFile", (unsigned long)rdbRemoveTempFile},
+{NULL,0}
+};
+
+/* This function try to convert a pointer into a function name. It's used in
+ * oreder to provide a backtrace under segmentation fault that's able to
+ * display functions declared as static (otherwise the backtrace is useless). */
+static char *findFuncName(void *pointer, unsigned long *offset){
+    int i, ret = -1;
+    unsigned long off, minoff = 0;
+
+    /* Try to match against the Symbol with the smallest offset */
+    for (i=0; symsTable[i].pointer; i++) {
+        unsigned long lp = (unsigned long) pointer;
+
+        if (lp != (unsigned long)-1 && lp >= symsTable[i].pointer) {
+            off=lp-symsTable[i].pointer;
+            if (ret < 0 || off < minoff) {
+                minoff=off;
+                ret=i;
+            }
+        }
     }
+    if (ret == -1) return NULL;
+    *offset = minoff;
+    return symsTable[ret].name;
+}
+
+static void *getMcontextEip(ucontext_t *uc) {
+#if defined(__FreeBSD__)
+    return (void*) uc->uc_mcontext.mc_eip;
+#elif defined(__dietlibc__)
+    return (void*) uc->uc_mcontext.eip;
+#elif defined(__APPLE__) && !defined(MAC_OS_X_VERSION_10_6)
+    return (void*) uc->uc_mcontext->__ss.__eip;
+#elif defined(__APPLE__) && defined(MAC_OS_X_VERSION_10_6)
+  #ifdef _STRUCT_X86_THREAD_STATE64
+    return (void*) uc->uc_mcontext->__ss.__rip;
+  #else
+    return (void*) uc->uc_mcontext->__ss.__eip;
+  #endif 
+#elif defined(__i386__) || defined(__X86_64__) /* Linux x86 */
+    return (void*) uc->uc_mcontext.gregs[REG_EIP];
+#elif defined(__ia64__) /* Linux IA64 */
+    return (void*) uc->uc_mcontext.sc_ip;
+#else
+    return NULL;
+#endif
 }
 
+static void segvHandler(int sig, siginfo_t *info, void *secret) {
+    void *trace[100];
+    char **messages = NULL;
+    int i, trace_size = 0;
+    unsigned long offset=0;
+    time_t uptime = time(NULL)-server.stat_starttime;
+    ucontext_t *uc = (ucontext_t*) secret;
+    REDIS_NOTUSED(info);
+
+    redisLog(REDIS_WARNING,
+        "======= Ooops! Redis %s got signal: -%d- =======", REDIS_VERSION, sig);
+    redisLog(REDIS_WARNING, "%s", sdscatprintf(sdsempty(),
+        "redis_version:%s; "
+        "uptime_in_seconds:%d; "
+        "connected_clients:%d; "
+        "connected_slaves:%d; "
+        "used_memory:%zu; "
+        "changes_since_last_save:%lld; "
+        "bgsave_in_progress:%d; "
+        "last_save_time:%d; "
+        "total_connections_received:%lld; "
+        "total_commands_processed:%lld; "
+        "role:%s;"
+        ,REDIS_VERSION,
+        uptime,
+        listLength(server.clients)-listLength(server.slaves),
+        listLength(server.slaves),
+        server.usedmemory,
+        server.dirty,
+        server.bgsaveinprogress,
+        server.lastsave,
+        server.stat_numconnections,
+        server.stat_numcommands,
+        server.masterhost == NULL ? "master" : "slave"
+    ));
+    
+    trace_size = backtrace(trace, 100);
+    /* overwrite sigaction with caller's address */
+    if (getMcontextEip(uc) != NULL) {
+        trace[1] = getMcontextEip(uc);
+    }
+    messages = backtrace_symbols(trace, trace_size);
+
+    for (i=1; i<trace_size; ++i) {
+        char *fn = findFuncName(trace[i], &offset), *p;
+
+        p = strchr(messages[i],'+');
+        if (!fn || (p && ((unsigned long)strtol(p+1,NULL,10)) < offset)) {
+            redisLog(REDIS_WARNING,"%s", messages[i]);
+        } else {
+            redisLog(REDIS_WARNING,"%d redis-server %p %s + %d", i, trace[i], fn, (unsigned int)offset);
+        }
+    }
+    free(messages);
+    exit(0);
+}
+
+static void setupSigSegvAction(void) {
+    struct sigaction act;
+
+    sigemptyset (&act.sa_mask);
+    /* When the SA_SIGINFO flag is set in sa_flags then sa_sigaction
+     * is used. Otherwise, sa_handler is used */
+    act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND | SA_SIGINFO;
+    act.sa_sigaction = segvHandler;
+    sigaction (SIGSEGV, &act, NULL);
+    sigaction (SIGBUS, &act, NULL);
+    sigaction (SIGFPE, &act, NULL);
+    sigaction (SIGILL, &act, NULL);
+    sigaction (SIGBUS, &act, NULL);
+    return;
+}
+#else /* HAVE_BACKTRACE */
+static void setupSigSegvAction(void) {
+}
+#endif /* HAVE_BACKTRACE */
+
 /* =================================== Main! ================================ */
 
 #ifdef __linux__
@@ -4080,7 +4418,7 @@ int linuxOvercommitMemoryValue(void) {
 
 void linuxOvercommitMemoryWarning(void) {
     if (linuxOvercommitMemoryValue() == 0) {
-        redisLog(REDIS_WARNING,"WARNING overcommit_memory is set to 0! Background save may fail under low condition memory. To fix this issue add 'echo 1 > /proc/sys/vm/overcommit_memory' in your init scripts.");
+        redisLog(REDIS_WARNING,"WARNING overcommit_memory is set to 0! Background save may fail under low condition memory. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.");
     }
 }
 #endif /* __linux__ */
@@ -4110,10 +4448,6 @@ static void daemonize(void) {
 }
 
 int main(int argc, char **argv) {
-#ifdef __linux__
-    linuxOvercommitMemoryWarning();
-#endif
-
     initServerConfig();
     if (argc == 2) {
         ResetServerSaveParams();
@@ -4127,6 +4461,9 @@ int main(int argc, char **argv) {
     initServer();
     if (server.daemonize) daemonize();
     redisLog(REDIS_NOTICE,"Server started, Redis version " REDIS_VERSION);
+#ifdef __linux__
+    linuxOvercommitMemoryWarning();
+#endif
     if (rdbLoad(server.dbfilename) == REDIS_OK)
         redisLog(REDIS_NOTICE,"DB loaded from disk");
     if (aeCreateFileEvent(server.el, server.fd, AE_READABLE,