Add a configuration option to allow TTL-based expires on the slave

src/config.c

@@ -205,6 +205,10 @@ void loadServerConfigFromString(char *config) {
             if ((server.repl_serve_stale_data = yesnotoi(argv[1])) == -1) {
                 err = "argument must be 'yes' or 'no'"; goto loaderr;
             }
+        } else if (!strcasecmp(argv[0],"slave-allow-key-expires") && argc == 2) {
+            if ((server.slave_allow_key_expires = yesnotoi(argv[1])) == -1) {
+                err = "argument must be 'yes' or 'no'"; goto loaderr;
+            }
         } else if (!strcasecmp(argv[0],"slave-read-only") && argc == 2) {
             if ((server.repl_slave_ro = yesnotoi(argv[1])) == -1) {
                 err = "argument must be 'yes' or 'no'"; goto loaderr;
@@ -541,6 +545,11 @@ void configSetCommand(redisClient *c) {
 
         if (yn == -1) goto badfmt;
         server.repl_serve_stale_data = yn;
+    } else if (!strcasecmp(c->argv[2]->ptr,"slave-allow-key-expires")) {
+            int yn = yesnotoi(o->ptr);
+
+            if (yn == -1) goto badfmt;
+            server.slave_allow_key_expires = yn;
     } else if (!strcasecmp(c->argv[2]->ptr,"slave-read-only")) {
         int yn = yesnotoi(o->ptr);
 
@@ -761,6 +770,8 @@ void configGetCommand(redisClient *c) {
             server.aof_no_fsync_on_rewrite);
     config_get_bool_field("slave-serve-stale-data",
             server.repl_serve_stale_data);
+    config_get_bool_field("slave-allow-key-expires",
+            server.slave_allow_key_expires);
     config_get_bool_field("slave-read-only",
             server.repl_slave_ro);
     config_get_bool_field("stop-writes-on-bgsave-error",

src/db.c

@@ -493,7 +493,7 @@ int expireIfNeeded(redisDb *db, robj *key) {
      * Still we try to return the right information to the caller, 
      * that is, 0 if we think the key should be still valid, 1 if
      * we think the key is expired at this time. */
-    if (server.masterhost != NULL) {
+    if (server.masterhost != NULL && server.slave_allow_key_expires == 0) {
         return mstime() > when;
     }
 

src/redis.c

@@ -1171,6 +1171,7 @@ void initServerConfig() {
     server.repl_serve_stale_data = 1;
     server.repl_slave_ro = 1;
     server.repl_down_since = time(NULL);
+    server.slave_allow_key_expires = 0;
 
     /* Client output buffer limits */
     server.client_obuf_limits[REDIS_CLIENT_LIMIT_CLASS_NORMAL].hard_limit_bytes = 0;

src/redis.h

@@ -678,6 +678,7 @@ struct redisServer {
     /* Slave specific fields */
     char *masterauth;               /* AUTH with this password with master */
     char *masterhost;               /* Hostname of master */
+    int slave_allow_key_expires;    /* True if we allow keys to expire on the slave w/o relying on replication */
     int masterport;                 /* Port of master */
     int repl_ping_slave_period;     /* Master pings the salve every N seconds */
     int repl_timeout;               /* Timeout after N seconds of master idle */

tests/integration/replication-5.tcl

@@ -0,0 +1,51 @@
+start_server {tags {"repl"}} {
+    start_server {} {
+        r -1 config set slave-allow-key-expires yes
+
+        test {First server should have role slave after SLAVEOF} {
+            r -1 slaveof [srv 0 host] [srv 0 port]
+            after 1000
+            s -1 role
+        } {slave}
+
+        if {$::accurate} {set numops 50000} else {set numops 5000}
+
+        test {MASTER and SLAVE consistency with expire + allowed slave expires} {
+            createComplexDataset r $numops useexpire
+            after 4000 ;# Make sure everything expired before taking the digest
+            r keys *   ;# Force DEL syntesizing to slave
+            after 1000 ;# Wait another second. Now everything should be fine.
+            if {[r debug digest] ne [r -1 debug digest]} {
+                set csv1 [csvdump r]
+                set csv2 [csvdump {r -1}]
+                set fd [open /tmp/repldump1.txt w]
+                puts -nonewline $fd $csv1
+                close $fd
+                set fd [open /tmp/repldump2.txt w]
+                puts -nonewline $fd $csv2
+                close $fd
+                puts "Master - Slave inconsistency"
+                puts "Run diff -u against /tmp/repldump*.txt for more info"
+            }
+            assert_equal [r debug digest] [r -1 debug digest]
+        }
+
+        r -1 config set slave-read-only no
+
+        test {Keys should expire on the slave with slave-allow-key-expires=yes} {
+            r -1 set x bar
+            r -1 expire x 1
+            after 1500
+            list [r -1 get x] [r -1 exists x]
+        } {{} 0}
+
+        r -1 config set slave-allow-key-expires no
+
+        test {Keys should not expire on the slave with slave-allow-key-expires=yes} {
+            r -1 set x bar
+            r -1 expire x 1
+            after 1500
+            list [r -1 get x] [r -1 exists x]
+        } {bar 1}
+    }
+}

tests/test_helper.tcl

@@ -30,6 +30,7 @@ set ::all_tests {
     integration/replication-2
     integration/replication-3
     integration/replication-4
+    integration/replication-5
     integration/aof
     integration/rdb
     integration/convert-zipmap-hash-on-load