Rewritten commands are logged as their original command (#8006)

* Rewritten commands are logged as their original command

Co-authored-by: Madelyn Olson <madelyneolson@gmail.com>

src/networking.c

@@ -139,6 +139,8 @@ client *createClient(connection *conn) {
     c->argc = 0;
     c->argv = NULL;
     c->argv_len_sum = 0;
+    c->original_argc = 0;
+    c->original_argv = NULL;
     c->cmd = c->lastcmd = NULL;
     c->multibulklen = 0;
     c->bulklen = -1;
@@ -1065,6 +1067,17 @@ void acceptUnixHandler(aeEventLoop *el, int fd, void *privdata, int mask) {
     }
 }
 
+void freeClientOriginalArgv(client *c) {
+    /* We didn't rewrite this client */
+    if (!c->original_argv) return;
+
+    for (int j = 0; j < c->original_argc; j++)
+        decrRefCount(c->original_argv[j]);
+    zfree(c->original_argv);
+    c->original_argv = NULL;
+    c->original_argc = 0;
+}
+
 static void freeClientArgv(client *c) {
     int j;
     for (j = 0; j < c->argc; j++)
@@ -1246,6 +1259,7 @@ void freeClient(client *c) {
     /* Free data structures. */
     listRelease(c->reply);
     freeClientArgv(c);
+    freeClientOriginalArgv(c);
 
     /* Unlink the client: this will close the socket, remove the I/O
      * handlers, and remove references of the client from different
@@ -2765,6 +2779,19 @@ void securityWarningCommand(client *c) {
     freeClientAsync(c);
 }
 
+/* Keep track of the original command arguments so that we can generate
+ * an accurate slowlog entry after the command has been executed. */
+static void retainOriginalCommandVector(client *c) {
+    /* We already rewrote this command, so don't rewrite it again */
+    if (c->original_argv) return;
+    c->original_argc = c->argc;
+    c->original_argv = zmalloc(sizeof(robj*)*(c->argc));
+    for (int j = 0; j < c->argc; j++) {
+        c->original_argv[j] = c->argv[j];
+        incrRefCount(c->argv[j]);
+    }
+}
+
 /* Rewrite the command vector of the client. All the new objects ref count
  * is incremented. The old command vector is freed, and the old objects
  * ref count is decremented. */
@@ -2782,26 +2809,14 @@ void rewriteClientCommandVector(client *c, int argc, ...) {
         argv[j] = a;
         incrRefCount(a);
     }
-    /* We free the objects in the original vector at the end, so we are
-     * sure that if the same objects are reused in the new vector the
-     * refcount gets incremented before it gets decremented. */
-    for (j = 0; j < c->argc; j++) decrRefCount(c->argv[j]);
-    zfree(c->argv);
-    /* Replace argv and argc with our new versions. */
-    c->argv = argv;
-    c->argc = argc;
-    c->argv_len_sum = 0;
-    for (j = 0; j < c->argc; j++)
-        if (c->argv[j])
-            c->argv_len_sum += getStringObjectLen(c->argv[j]);
-    c->cmd = lookupCommandOrOriginal(c->argv[0]->ptr);
-    serverAssertWithInfo(c,NULL,c->cmd != NULL);
+    replaceClientCommandVector(c, argc, argv);
     va_end(ap);
 }
 
 /* Completely replace the client command vector with the provided one. */
 void replaceClientCommandVector(client *c, int argc, robj **argv) {
     int j;
+    retainOriginalCommandVector(c);
     freeClientArgv(c);
     zfree(c->argv);
     c->argv = argv;
@@ -2827,7 +2842,7 @@ void replaceClientCommandVector(client *c, int argc, robj **argv) {
  *    free the no longer used objects on c->argv. */
 void rewriteClientCommandArgument(client *c, int i, robj *newval) {
     robj *oldval;
-
+    retainOriginalCommandVector(c);
     if (i >= c->argc) {
         c->argv = zrealloc(c->argv,sizeof(robj*)*(i+1));
         c->argc = i+1;

src/server.c

@@ -3467,8 +3467,13 @@ void call(client *c, int flags) {
         char *latency_event = (c->cmd->flags & CMD_FAST) ?
                               "fast-command" : "command";
         latencyAddSampleIfNeeded(latency_event,duration/1000);
-        slowlogPushEntryIfNeeded(c,c->argv,c->argc,duration);
+        /* If command argument vector was rewritten, use the original
+         * arguments. */
+        robj **argv = c->original_argv ? c->original_argv : c->argv;
+        int argc = c->original_argv ? c->original_argc : c->argc;
+        slowlogPushEntryIfNeeded(c,argv,argc,duration);
     }
+    freeClientOriginalArgv(c);
 
     if (flags & CMD_CALL_STATS) {
         /* use the real command that was executed (cmd and lastamc) may be

src/server.h

@@ -808,6 +808,8 @@ typedef struct client {
     size_t querybuf_peak;   /* Recent (100ms or more) peak of querybuf size. */
     int argc;               /* Num of arguments of current command. */
     robj **argv;            /* Arguments of current command. */
+    int original_argc;      /* Num of arguments of original command if arguments were rewritten. */
+    robj **original_argv;   /* Arguments of original command if arguments were rewritten. */
     size_t argv_len_sum;    /* Sum of lengths of objects in argv list. */
     struct redisCommand *cmd, *lastcmd;  /* Last command executed. */
     user *user;             /* User associated with this connection. If the
@@ -1668,6 +1670,7 @@ void closeTimedoutClients(void);
 void freeClient(client *c);
 void freeClientAsync(client *c);
 void resetClient(client *c);
+void freeClientOriginalArgv(client *c);
 void sendReplyToClient(connection *conn);
 void *addReplyDeferredLen(client *c);
 void setDeferredArrayLen(client *c, void *node, long length);

tests/unit/slowlog.tcl

@@ -41,6 +41,41 @@ start_server {tags {"slowlog"} overrides {slowlog-log-slower-than 1000000}} {
         assert_equal {foobar} [lindex $e 5]
     }
 
+    test {SLOWLOG - Rewritten commands are logged as their original command} {
+        r config set slowlog-log-slower-than 0
+
+        # Test rewriting client arguments
+        r sadd set a b c d e
+        r slowlog reset
+
+        # SPOP is rewritten as DEL when all keys are removed
+        r spop set 10
+        assert_equal {spop set 10} [lindex [lindex [r slowlog get] 0] 3]
+
+        # Test replacing client arguments
+        r slowlog reset
+
+        # GEOADD is replicated as ZADD
+        r geoadd cool-cities -122.33207 47.60621 Seattle
+        assert_equal {geoadd cool-cities -122.33207 47.60621 Seattle} [lindex [lindex [r slowlog get] 0] 3]
+
+        # Test replacing a single command argument
+        r set A 5
+        r slowlog reset
+        
+        # GETSET is replicated as SET
+        r getset a 5
+        assert_equal {getset a 5} [lindex [lindex [r slowlog get] 0] 3]
+
+        # INCRBYFLOAT calls rewrite multiple times, so it's a special case
+        r set A 0
+        r slowlog reset
+        
+        # INCRBYFLOAT is replicated as SET
+        r INCRBYFLOAT A 1.0
+        assert_equal {INCRBYFLOAT A 1.0} [lindex [lindex [r slowlog get] 0] 3]
+    }
+
     test {SLOWLOG - commands with too many arguments are trimmed} {
         r config set slowlog-log-slower-than 0
         r slowlog reset