Add DELIFEQ command

src/commands.def

@@ -10459,6 +10459,31 @@ struct COMMAND_ARG DECRBY_Args[] = {
 {MAKE_ARG("decrement",ARG_TYPE_INTEGER,-1,NULL,NULL,NULL,CMD_ARG_NONE,0,NULL)},
 };
 
+/********** DELIFEQ ********************/
+
+#ifndef SKIP_CMD_HISTORY_TABLE
+/* DELIFEQ history */
+#define DELIFEQ_History NULL
+#endif
+
+#ifndef SKIP_CMD_TIPS_TABLE
+/* DELIFEQ tips */
+#define DELIFEQ_Tips NULL
+#endif
+
+#ifndef SKIP_CMD_KEY_SPECS_TABLE
+/* DELIFEQ key specs */
+keySpec DELIFEQ_Keyspecs[1] = {
+{NULL,CMD_KEY_RM|CMD_KEY_ACCESS|CMD_KEY_DELETE,KSPEC_BS_INDEX,.bs.index={1},KSPEC_FK_RANGE,.fk.range={0,1,0}}
+};
+#endif
+
+/* DELIFEQ argument table */
+struct COMMAND_ARG DELIFEQ_Args[] = {
+{MAKE_ARG("key",ARG_TYPE_KEY,0,NULL,NULL,NULL,CMD_ARG_NONE,0,NULL)},
+{MAKE_ARG("value",ARG_TYPE_STRING,-1,NULL,NULL,NULL,CMD_ARG_NONE,0,NULL)},
+};
+
 /********** GET ********************/
 
 #ifndef SKIP_CMD_HISTORY_TABLE
@@ -11316,6 +11341,7 @@ struct COMMAND_STRUCT serverCommandTable[] = {
 {MAKE_CMD("append","Appends a string to the value of a key. Creates the key if it doesn't exist.","O(1). The amortized time complexity is O(1) assuming the appended value is small and the already present value is of any size, since the dynamic string library used by the server will double the free space available on every reallocation.","2.0.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,APPEND_History,0,APPEND_Tips,0,appendCommand,3,CMD_WRITE|CMD_DENYOOM|CMD_FAST,ACL_CATEGORY_STRING,APPEND_Keyspecs,1,NULL,2),.args=APPEND_Args},
 {MAKE_CMD("decr","Decrements the integer value of a key by one. Uses 0 as initial value if the key doesn't exist.","O(1)","1.0.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,DECR_History,0,DECR_Tips,0,decrCommand,2,CMD_WRITE|CMD_DENYOOM|CMD_FAST,ACL_CATEGORY_STRING,DECR_Keyspecs,1,NULL,1),.args=DECR_Args},
 {MAKE_CMD("decrby","Decrements a number from the integer value of a key. Uses 0 as initial value if the key doesn't exist.","O(1)","1.0.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,DECRBY_History,0,DECRBY_Tips,0,decrbyCommand,3,CMD_WRITE|CMD_DENYOOM|CMD_FAST,ACL_CATEGORY_STRING,DECRBY_Keyspecs,1,NULL,2),.args=DECRBY_Args},
+{MAKE_CMD("delifeq","Delete key if value matches string.","O(1)","9.0.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,DELIFEQ_History,0,DELIFEQ_Tips,0,delifeqCommand,3,CMD_WRITE,ACL_CATEGORY_STRING,DELIFEQ_Keyspecs,1,NULL,2),.args=DELIFEQ_Args},
 {MAKE_CMD("get","Returns the string value of a key.","O(1)","1.0.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,GET_History,0,GET_Tips,0,getCommand,2,CMD_READONLY|CMD_FAST,ACL_CATEGORY_STRING,GET_Keyspecs,1,NULL,1),.args=GET_Args},
 {MAKE_CMD("getdel","Returns the string value of a key after deleting the key.","O(1)","6.2.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,GETDEL_History,0,GETDEL_Tips,0,getdelCommand,2,CMD_WRITE|CMD_FAST,ACL_CATEGORY_STRING,GETDEL_Keyspecs,1,NULL,1),.args=GETDEL_Args},
 {MAKE_CMD("getex","Returns the string value of a key after setting its expiration time.","O(1)","6.2.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,GETEX_History,0,GETEX_Tips,0,getexCommand,-2,CMD_WRITE|CMD_FAST,ACL_CATEGORY_STRING,GETEX_Keyspecs,1,NULL,2),.args=GETEX_Args},

src/commands/delifeq.json

@@ -0,0 +1,60 @@
+{
+    "DELIFEQ": {
+        "summary": "Delete key if value matches string.",
+        "complexity": "O(1)",
+        "group": "string",
+        "since": "9.0.0",
+        "arity": 3,
+        "function": "delifeqCommand",
+        "command_flags": [
+            "WRITE"
+        ],
+        "acl_categories": [
+            "STRING"
+        ],
+        "key_specs": [
+            {
+                "flags": [
+                    "RM",
+                    "ACCESS",
+                    "DELETE"
+                ],
+                "begin_search": {
+                    "index": {
+                        "pos": 1
+                    }
+                },
+                "find_keys": {
+                    "range": {
+                        "lastkey": 0,
+                        "step": 1,
+                        "limit": 0
+                    }
+                }
+            }
+        ],
+        "reply_schema": {
+            "oneOf": [
+                {
+                    "description": "The key was not deleted.",
+                    "const": 0
+                },
+                {
+                    "description": "The key was deleted.",
+                    "const": 1
+                }
+            ]
+        },
+        "arguments": [
+          {
+              "name": "key",
+              "type": "key",
+              "key_spec_index": 0
+          },
+          {
+              "name": "value",
+              "type": "string"
+          }
+        ]
+    }
+}

src/server.h

@@ -3628,6 +3628,7 @@ void setCommand(client *c);
 void setnxCommand(client *c);
 void setexCommand(client *c);
 void psetexCommand(client *c);
+void delifeqCommand(client *c);
 void getCommand(client *c);
 void getexCommand(client *c);
 void getdelCommand(client *c);

src/t_string.c

@@ -384,6 +384,32 @@ void psetexCommand(client *c) {
     setGenericCommand(c, OBJ_PX | OBJ_ARGV3, c->argv[1], c->argv[3], c->argv[2], UNIT_MILLISECONDS, NULL, NULL, NULL);
 }
 
+void delifeqCommand(client *c) {
+    robj *existing_value = lookupKeyWrite(c->db, c->argv[1]);
+
+    if (existing_value == NULL) {
+        addReplyLongLong(c, 0);
+        return;
+    }
+
+    if (checkType(c, existing_value, OBJ_STRING)) {
+        /* Error reply already sent */
+        return;
+    }
+
+    if (compareStringObjects(existing_value, c->argv[2]) != 0) {
+        addReplyLongLong(c, 0);
+        return;
+    }
+
+    if (!dbSyncDelete(c->db, c->argv[1])) {
+        addReplyLongLong(c, 0);
+        return;
+    }
+
+    addReplyLongLong(c, 1);
+}
+
 int getGenericCommand(client *c) {
     robj *o;
 

tests/unit/type/string.tcl

@@ -756,6 +756,27 @@ if {[string match {*jemalloc*} [s mem_allocator]]} {
         lappend res [r get bar]
     } {12 12}
 
+    test {DELIFEQ non-existing key} {
+        r del foo
+        assert_equal 0 [r delifeq foo "test"]
+    }
+
+    test {DELIFEQ existing key, matching value} {
+        r set foo "test"
+        assert_equal 1 [r delifeq foo "test"]
+    }
+
+    test {DELIFEQ existing key, non-matching value} {
+        r set foo "nope"
+        assert_equal 0 [r delifeq foo "test"]
+    }
+
+    test {DELIFEQ existing key, non-string value} {
+        r del foo
+        r sadd foo "test"
+        assert_error "WRONGTYPE*" {r delifeq foo "test"}
+    }
+
 if {[string match {*jemalloc*} [s mem_allocator]]} {
     test {Memory usage of embedded string value} {
         # Check that we can fit 9 bytes of key + value into a 32 byte