fix: add switch for RTC cache read

conf/pika.conf

@@ -18,11 +18,16 @@ rocksdb-periodic-second : 86400 * 3;
 # Master's run-id
 # master-run-id :
 
-# The number of threads for running Pika.
+# The number of Net-worker threads in Pika.
 # It's not recommended to set this value exceeds
 # the number of CPU cores on the deployment server.
 thread-num : 1
 
+# use Net worker thread to read redis Cache for [Get, HGet] command,
+# which can significantly improve QPS and reduce latency when cache hit rate is high
+# default value is "yes", set it to "no" if you wanna disable it
+rtc-cache-read : yes
+
 # Size of the thread pool, The threads within this pool
 # are dedicated to handling user requests.
 thread-pool-size : 12

include/pika_client_conn.h

@@ -59,6 +59,7 @@ class PikaClientConn : public net::RedisConn {
     std::shared_ptr<std::string> resp_ptr;
     LogOffset offset;
     std::string db_name;
+    bool cache_miss_in_rtc_;
   };
 
   struct TxnStateBitMask {
@@ -78,7 +79,7 @@ class PikaClientConn : public net::RedisConn {
   void ProcessRedisCmds(const std::vector<net::RedisCmdArgsType>& argvs, bool async, std::string* response) override;
 
   bool ReadCmdInCache(const net::RedisCmdArgsType& argv, const std::string& opt);
-  void BatchExecRedisCmd(const std::vector<net::RedisCmdArgsType>& argvs);
+  void BatchExecRedisCmd(const std::vector<net::RedisCmdArgsType>& argvs, bool cache_miss_in_rtc);
   int DealMessage(const net::RedisCmdArgsType& argv, std::string* response) override { return 0; }
   static void DoBackgroundTask(void* arg);
 
@@ -136,12 +137,12 @@ class PikaClientConn : public net::RedisConn {
   std::shared_ptr<User> user_;
 
   std::shared_ptr<Cmd> DoCmd(const PikaCmdArgsType& argv, const std::string& opt,
-                             const std::shared_ptr<std::string>& resp_ptr);
+                             const std::shared_ptr<std::string>& resp_ptr, bool cache_miss_in_rtc);
 
   void ProcessSlowlog(const PikaCmdArgsType& argv, uint64_t do_duration);
   void ProcessMonitor(const PikaCmdArgsType& argv);
 
-  void ExecRedisCmd(const PikaCmdArgsType& argv, std::shared_ptr<std::string>& resp_ptr);
+  void ExecRedisCmd(const PikaCmdArgsType& argv, std::shared_ptr<std::string>& resp_ptr, bool cache_miss_in_rtc);
   void TryWriteResp();
 };
 

include/pika_command.h

@@ -575,6 +575,9 @@ class Cmd : public std::enable_shared_from_this<Cmd> {
   uint32_t GetCmdId() const { return cmdId_; };
   bool CheckArg(uint64_t num) const;
 
+  bool IsCacheMissedInRtc() const;
+  void SetCacheMissedInRtc(bool value);
+
  protected:
   // enable copy, used default copy
   // Cmd(const Cmd&);
@@ -603,6 +606,7 @@ class Cmd : public std::enable_shared_from_this<Cmd> {
   uint64_t do_duration_ = 0;
   uint32_t cmdId_ = 0;
   uint32_t aclCategory_ = 0;
+  bool cache_missed_in_rtc_{false};
 
  private:
   virtual void DoInitial() = 0;

include/pika_conf.h

@@ -468,6 +468,7 @@ class PikaConf : public pstd::BaseConf {
 
   // Immutable config items, we don't use lock.
   bool daemonize() { return daemonize_; }
+  bool rtc_cache_read_enabled() { return rtc_cache_read_enabled_; }
   std::string pidfile() { return pidfile_; }
   int binlog_file_size() { return binlog_file_size_; }
   std::vector<rocksdb::CompressionType> compression_per_level();
@@ -930,6 +931,7 @@ class PikaConf : public pstd::BaseConf {
   int level0_file_num_compaction_trigger_ = 4;
   int64_t max_client_response_size_ = 0;
   bool daemonize_ = false;
+  bool rtc_cache_read_enabled_ = false;
   int timeout_ = 0;
   std::string server_id_;
   std::string run_id_;

src/pika_client_conn.cc

@@ -36,7 +36,7 @@ PikaClientConn::PikaClientConn(int fd, const std::string& ip_port, net::Thread*
 }
 
 std::shared_ptr<Cmd> PikaClientConn::DoCmd(const PikaCmdArgsType& argv, const std::string& opt,
-                                           const std::shared_ptr<std::string>& resp_ptr) {
+                                           const std::shared_ptr<std::string>& resp_ptr, bool cache_miss_in_rtc) {
   // Get command info
   std::shared_ptr<Cmd> c_ptr = g_pika_cmd_table_manager->GetCmd(opt);
   if (!c_ptr) {
@@ -47,6 +47,7 @@ std::shared_ptr<Cmd> PikaClientConn::DoCmd(const PikaCmdArgsType& argv, const st
     }
     return tmp_ptr;
   }
+  c_ptr->SetCacheMissedInRtc(cache_miss_in_rtc);
   c_ptr->SetConn(shared_from_this());
   c_ptr->SetResp(resp_ptr);
 
@@ -273,6 +274,7 @@ void PikaClientConn::ProcessRedisCmds(const std::vector<net::RedisCmdArgsType>&
   time_stat_->Reset();
   if (async) {
     auto arg = new BgTaskArg();
+    arg->cache_miss_in_rtc_ = false;
     arg->redis_cmds = argvs;
     time_stat_->enqueue_ts_ = time_stat_->before_queue_ts_ = pstd::NowMicros();
     arg->conn_ptr = std::dynamic_pointer_cast<PikaClientConn>(shared_from_this());
@@ -288,21 +290,23 @@ void PikaClientConn::ProcessRedisCmds(const std::vector<net::RedisCmdArgsType>&
     bool is_admin_cmd = g_pika_conf->is_admin_cmd(opt);
 
     //we don't intercept pipeline batch (argvs.size() > 1)
-    if (argvs.size() == 1 && IsInterceptedByRTC(opt) &&
+    if (g_pika_conf->rtc_cache_read_enabled() &&
+        argvs.size() == 1 && IsInterceptedByRTC(opt) &&
         PIKA_CACHE_NONE != g_pika_conf->cache_mode() &&
         !IsInTxn()) {
       // read in cache
       if (ReadCmdInCache(argvs[0], opt)) {
         delete arg;
         return;
       }
+      arg->cache_miss_in_rtc_ = true;
       time_stat_->before_queue_ts_ = pstd::NowMicros();
     }
 
     g_pika_server->ScheduleClientPool(&DoBackgroundTask, arg, is_slow_cmd, is_admin_cmd);
     return;
   }
-  BatchExecRedisCmd(argvs);
+  BatchExecRedisCmd(argvs, false);
 }
 
 void PikaClientConn::DoBackgroundTask(void* arg) {
@@ -320,15 +324,15 @@ void PikaClientConn::DoBackgroundTask(void* arg) {
     }
   }
 
-  conn_ptr->BatchExecRedisCmd(bg_arg->redis_cmds);
+  conn_ptr->BatchExecRedisCmd(bg_arg->redis_cmds, bg_arg->cache_miss_in_rtc_);
 }
 
-void PikaClientConn::BatchExecRedisCmd(const std::vector<net::RedisCmdArgsType>& argvs) {
+void PikaClientConn::BatchExecRedisCmd(const std::vector<net::RedisCmdArgsType>& argvs, bool cache_miss_in_rtc) {
   resp_num.store(static_cast<int32_t>(argvs.size()));
   for (const auto& argv : argvs) {
     std::shared_ptr<std::string> resp_ptr = std::make_shared<std::string>();
     resp_array.push_back(resp_ptr);
-    ExecRedisCmd(argv, resp_ptr);
+    ExecRedisCmd(argv, resp_ptr, cache_miss_in_rtc);
   }
   time_stat_->process_done_ts_ = pstd::NowMicros();
   TryWriteResp();
@@ -363,9 +367,6 @@ bool PikaClientConn::ReadCmdInCache(const net::RedisCmdArgsType& argv, const std
     return false;
   }
   //only read command(Get, HGet) will reach here, no need of record lock
-  if (c_ptr->db_->cache()->CacheStatus() != PIKA_CACHE_STATUS_OK) {
-    return false;
-  }
   bool read_status = c_ptr->DoReadCommandInCache();
   auto cmdstat_map = g_pika_cmd_table_manager->GetCommandStatMap();
   resp_num--;
@@ -508,7 +509,8 @@ void PikaClientConn::ExitTxn() {
   }
 }
 
-void PikaClientConn::ExecRedisCmd(const PikaCmdArgsType& argv, std::shared_ptr<std::string>& resp_ptr) {
+void PikaClientConn::ExecRedisCmd(const PikaCmdArgsType& argv, std::shared_ptr<std::string>& resp_ptr,
+                                  bool cache_miss_in_rtc) {
   // get opt
   std::string opt = argv[0];
   pstd::StringToLower(opt);
@@ -519,7 +521,7 @@ void PikaClientConn::ExecRedisCmd(const PikaCmdArgsType& argv, std::shared_ptr<s
     }
   }
 
-  std::shared_ptr<Cmd> cmd_ptr = DoCmd(argv, opt, resp_ptr);
+  std::shared_ptr<Cmd> cmd_ptr = DoCmd(argv, opt, resp_ptr, cache_miss_in_rtc);
   *resp_ptr = std::move(cmd_ptr->res().message());
   resp_num--;
 }

src/pika_command.cc

@@ -828,7 +828,7 @@ Cmd* GetCmdFromDB(const std::string& opt, const CmdTable& cmd_table) {
 bool Cmd::CheckArg(uint64_t num) const { return !((arity_ > 0 && num != arity_) || (arity_ < 0 && num < -arity_)); }
 
 Cmd::Cmd(std::string name, int arity, uint32_t flag, uint32_t aclCategory)
-    : name_(std::move(name)), arity_(arity), flag_(flag), aclCategory_(aclCategory) {
+    : name_(std::move(name)), arity_(arity), flag_(flag), aclCategory_(aclCategory), cache_missed_in_rtc_(false) {
 }
 
 void Cmd::Initial(const PikaCmdArgsType& argv, const std::string& db_name) {
@@ -891,10 +891,12 @@ void Cmd::DoCommand(const HintKeys& hint_keys) {
   if (IsNeedCacheDo()
       && PIKA_CACHE_NONE != g_pika_conf->cache_mode()
       && db_->cache()->CacheStatus() == PIKA_CACHE_STATUS_OK) {
-    if (IsNeedReadCache()) {
+    if (!cache_missed_in_rtc_
+        && IsNeedReadCache()) {
       ReadCache();
     }
-    if (is_read() && res().CacheMiss()) {
+    if (is_read()
+        && (res().CacheMiss() || cache_missed_in_rtc_)) {
       pstd::lock::MultiScopeRecordLock record_lock(db_->LockMgr(), current_key());
       DoThroughDB();
       if (IsNeedUpdateCache()) {
@@ -1064,3 +1066,5 @@ void Cmd::SetResp(const std::shared_ptr<std::string>& resp) { resp_ = resp; }
 std::shared_ptr<std::string> Cmd::GetResp() { return resp_.lock(); }
 
 void Cmd::SetStage(CmdStage stage) { stage_ = stage; }
+bool Cmd::IsCacheMissedInRtc() const { return cache_missed_in_rtc_; }
+void Cmd::SetCacheMissedInRtc(bool value) { cache_missed_in_rtc_ = value; }

src/pika_conf.cc

@@ -541,6 +541,11 @@ int PikaConf::Load() {
   GetConfStr("daemonize", &dmz);
   daemonize_ = dmz == "yes";
 
+  // read redis cache in Net worker threads
+  std::string rtc_enabled;
+  GetConfStr("rtc-cache-read", &rtc_enabled);
+  rtc_cache_read_enabled_ = rtc_enabled != "no";
+
   // binlog
   std::string wb;
   GetConfStr("write-binlog", &wb);