Implement convenience command deque-clear

CHANGELOG.md

 # Changelog
 All notable changes to this project will be documented in this file.
 
+## Unreleased
+- Add convenience command ``DEQUE-CLEAR``.
+
 ## 0.3.8 (2019-05-27)
 - Prevent elections from hanging on the TCP timeout when one of the member hosts
 is dropping packets, which could bring down an otherwise healthy cluster.

src/Commands.cc

@@ -92,6 +92,7 @@ struct cmdMapInit {
     redis_cmd_map["deque_push_back"] = {RedisCommand::DEQUE_PUSH_BACK, CommandType::WRITE};
     redis_cmd_map["deque_pop_back"] = {RedisCommand::DEQUE_POP_BACK, CommandType::WRITE};
     redis_cmd_map["deque_trim_front"] = {RedisCommand::DEQUE_TRIM_FRONT, CommandType::WRITE};
+    redis_cmd_map["deque_clear"] = {RedisCommand::DEQUE_CLEAR, CommandType::WRITE};
     redis_cmd_map["config_set"] = {RedisCommand::CONFIG_SET, CommandType::WRITE};
     redis_cmd_map["lhset"] = {RedisCommand::LHSET, CommandType::WRITE};
     redis_cmd_map["lhdel"] = {RedisCommand::LHDEL, CommandType::WRITE};

src/Commands.hh

@@ -93,6 +93,7 @@ enum class RedisCommand {
   DEQUE_TRIM_FRONT,
   DEQUE_LEN,
   DEQUE_SCAN_BACK,
+  DEQUE_CLEAR,
 
   RAW_SCAN,
   RAW_SCAN_TOMBSTONES,

src/Dispatcher.cc

@@ -300,6 +300,13 @@ RedisEncodedResponse RedisDispatcher::dispatchWrite(StagingArea &stagingArea, Re
       if(!st.ok()) return Formatter::fromStatus(st);
       return Formatter::integer(itemsRemoved);
     }
+    case RedisCommand::DEQUE_CLEAR: {
+      if(request.size() != 2) return errArgs(request);
+      int64_t itemsRemoved;
+      rocksdb::Status st = store.dequeTrimFront(stagingArea, request[1], "0", itemsRemoved);
+      if(!st.ok()) return Formatter::fromStatus(st);
+      return Formatter::integer(itemsRemoved);
+    }
     case RedisCommand::CONFIG_SET: {
       if(request.size() != 3) return errArgs(request);
       rocksdb::Status st = store.configSet(stagingArea, request[1], request[2]);

test/e2e.cc

@@ -842,6 +842,17 @@ TEST_F(Raft_e2e, DequeTrimming) {
   ASSERT_REPLY(tunnel(leaderID)->exec("del", "dq", "test"), 2);
 }
 
+TEST_F(Raft_e2e, DequeClear) {
+  spinup(0); spinup(1); spinup(2);
+  RETRY_ASSERT_TRUE(checkStateConsensus(0, 1, 2));
+  int leaderID = getServerID(state(0)->getSnapshot()->leader);
+
+  ASSERT_REPLY(tunnel(leaderID)->exec("deque-push-back", "dq", "1", "2", "3", "4"), 4);
+  ASSERT_REPLY(tunnel(leaderID)->exec("deque-clear", "dq"), 4);
+  ASSERT_REPLY(tunnel(leaderID)->exec("deque-len", "dq"), 0);
+  ASSERT_REPLY(tunnel(leaderID)->exec("set", "dq", "abc"), "OK");
+}
+
 TEST_F(Raft_e2e, replication_with_trimmed_journal) {
   spinup(0); spinup(1);
   RETRY_ASSERT_TRUE(checkStateConsensus(0, 1));