feat(server): implement TOUCH command (#444)

Signed-off-by: Leonardo Mello <lsvmello@gmail.com>

Signed-off-by: Leonardo Mello <lsvmello@gmail.com>

CONTRIBUTORS.md

@@ -13,3 +13,4 @@
 * **[Ali-Akber Saifee](https://github.com/alisaifee)**
 * **[Elle Y](https://github.com/inohime)**
 * **[ATM SALEH](https://github.com/ATM-SALEH)**
+* **[Leonardo Mello](https://github.com/lsvmello)**

docs/api_status.md

@@ -202,8 +202,8 @@ with respect to Memcached and Redis APIs.
   - [ ] PFMERGE
 
 ### API 3
-- [ ] Generic Family
-  - [ ] TOUCH
+- [X] Generic Family
+  - [X] TOUCH
 - [X] HashSet Family
   - [X] HSTRLEN
 - [X] Server Family

src/server/generic_family.cc

@@ -1405,6 +1405,7 @@ void GenericFamily::Register(CommandRegistry* registry) {
             << CI{"PING", CO::FAST, -1, 0, 0, 0}.HFUNC(Ping)
             << CI{"ECHO", CO::LOADING | CO::FAST, 2, 0, 0, 0}.HFUNC(Echo)
             << CI{"EXISTS", CO::READONLY | CO::FAST, -2, 1, -1, 1}.HFUNC(Exists)
+            << CI{"TOUCH", CO::READONLY | CO::FAST, -2, 1, -1, 1}.HFUNC(Exists)
             << CI{"EXPIRE", CO::WRITE | CO::FAST, 3, 1, 1, 1}.HFUNC(Expire)
             << CI{"EXPIREAT", CO::WRITE | CO::FAST, 3, 1, 1, 1}.HFUNC(ExpireAt)
             << CI{"PERSIST", CO::WRITE | CO::FAST, 2, 1, 1, 1}.HFUNC(Persist)

src/server/generic_family.h

@@ -32,7 +32,6 @@ class GenericFamily {
   static OpResult<uint32_t> OpExists(const OpArgs& op_args, ArgSlice keys);
 
  private:
-
   static void Del(CmdArgList args, ConnectionContext* cntx);
   static void Ping(CmdArgList args, ConnectionContext* cntx);
   static void Exists(CmdArgList args, ConnectionContext* cntx);

src/server/generic_family_test.cc

@@ -94,6 +94,17 @@ TEST_F(GenericFamilyTest, Exists) {
   EXPECT_THAT(resp, IntArg(3));
 }
 
+TEST_F(GenericFamilyTest, Touch) {
+  RespExpr resp;
+
+  Run({"mset", "x", "0", "y", "1"});
+  resp = Run({"touch", "x", "y", "x"});
+  EXPECT_THAT(resp, IntArg(3));
+
+  resp = Run({"touch", "z", "x", "w"});
+  EXPECT_THAT(resp, IntArg(1));
+}
+
 TEST_F(GenericFamilyTest, Rename) {
   RespExpr resp;
   string b_val(32, 'b');