Avoid flush all redis db in kvrocks2redis (apache#498)

In the kvrocks2redis tool, when kvrocks sends data to Redis, it will flush
the whole target redis by using the FLUSHALL command. We shouldn't do that,
we just need to clear the target DB.

In addition, modify the comments in the configuration file to make it more
accessible. And based on the output of cpplint, fixed the nonstandard header file.

Author: caipengbo

tools/kvrocks2redis/config.cc

@@ -1,17 +1,14 @@
 #include "config.h"
-#include <fcntl.h>
-#include <string.h>
+
 #include <strings.h>
-#include <glog/logging.h>
 #include <rocksdb/env.h>
 
 #include <fstream>
 #include <iostream>
-#include <sstream>
+#include <utility>
 #include <vector>
 
 #include "../../src/util.h"
-#include "../../src/status.h"
 #include "../../src/config.h"
 
 namespace Kvrocks2redis {

tools/kvrocks2redis/kvrocks2redis.conf

@@ -1,24 +1,22 @@
 ################################ GENERAL #####################################
 
-# The value should be INFO, WARNING, ERROR, FATAL
-# default is INFO
+# The value should be INFO, WARNING, ERROR, FATAL.
+#
+# Default is INFO
 loglevel INFO
 
 # By default kvrocks2redis does not run as a daemon. Use 'yes' if you need it.
 # Note that kvrocks2redis will write a pid file in /var/run/kvrocks2redis.pid when daemonized.
 daemonize no
 
-# The working directory
-#
-# The kvrocks node db directory
+# The kvrocks working directory.
 # Note that you must specify a directory here, not a file name.
 data-dir ./data
 
-# Intermediate files are output to this directory when the kvrocks2redis program runs
-#
+# Intermediate files are output to this directory when the kvrocks2redis program runs.
 output-dir ./
 
-# Sync kvrocks node. Use the node's Psync command to get the newest wal raw write_batch
+# Sync kvrocks node. Use the node's Psync command to get the newest wal raw write_batch.
 #
 # kvrocks <kvrocks_ip> <kvrocks_port> [<kvrocks_auth>]
 kvrocks 127.0.0.1 6666
@@ -29,7 +27,9 @@ kvrocks 127.0.0.1 6666
 cluster-enable yes
 
 ################################ NAMESPACE AND Sync Target Redis #####################################
-# namespace.{namespace} <redis_ip> <redis_port> [<auth> <db_number>]
-# 
-# Default db_number is 0
+# Synchronize the specified namespace data to the specified Redis DB.
+# Warning: It will flush the target redis DB data.
+#
+# namespace.{namespace} <redis_ip> <redis_port> [<redis_auth> <redis_db_number>]
+# Default redis_db_number is 0
 namespace.__namespace 127.0.0.1 6379

tools/kvrocks2redis/parser.cc

@@ -1,11 +1,10 @@
 #include "parser.h"
 
-#include <memory>
-
 #include <glog/logging.h>
 #include <rocksdb/write_batch.h>
 
-#include "../../src/redis_bitmap.h"
+#include <memory>
+
 #include "../../src/redis_slot.h"
 #include "../../src/redis_reply.h"
 

tools/kvrocks2redis/redis_writer.cc

@@ -39,16 +39,15 @@ Status RedisWriter::Write(const std::string &ns, const std::vector<std::string>
   return Status::OK();
 }
 
-Status RedisWriter::FlushAll(const std::string &ns) {
-  auto s = Writer::FlushAll(ns);
+Status RedisWriter::FlushDB(const std::string &ns) {
+  auto s = Writer::FlushDB(ns);
   if (!s.IsOK()) {
     return s;
   }
 
   updateNextOffset(ns, 0);
 
-  //Warning: this will flush all redis data
-  s = Write(ns, {Redis::Command2RESP({"FLUSHALL"})});
+  s = Write(ns, {Redis::Command2RESP({"FLUSHDB"})});
   if (!s.IsOK()) return s;
 
   return Status::OK();

tools/kvrocks2redis/redis_writer.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <glog/logging.h>
+#include <map>
 #include <string>
 #include <vector>
 #include <thread>
@@ -12,7 +13,7 @@ class RedisWriter : public Writer {
   explicit RedisWriter(Kvrocks2redis::Config *config);
   ~RedisWriter();
   Status Write(const std::string &ns, const std::vector<std::string> &aofs) override;
-  Status FlushAll(const std::string &ns) override;
+  Status FlushDB(const std::string &ns) override;
 
   void Stop() override;
 

tools/kvrocks2redis/sync.cc

@@ -189,9 +189,9 @@ Status Sync::incrementBatchLoop() {
 void Sync::parseKVFromLocalStorage() {
   LOG(INFO) << "[kvrocks2redis] Start parsing kv from the local storage";
   for (const auto &iter : config_->tokens) {
-    auto s = writer_->FlushAll(iter.first);
+    auto s = writer_->FlushDB(iter.first);
     if (!s.IsOK()) {
-      LOG(ERROR) << "[kvrocks2redis] Failed to flush all in namespace: " << iter.first
+      LOG(ERROR) << "[kvrocks2redis] Failed to flush target redis db in namespace: " << iter.first
                  << ", encounter error: " << s.Msg();
       return;
     }

tools/kvrocks2redis/writer.cc

@@ -21,7 +21,7 @@ Status Writer::Write(const std::string &ns, const std::vector<std::string> &aofs
   return Status::OK();
 }
 
-Status Writer::FlushAll(const std::string &ns) {
+Status Writer::FlushDB(const std::string &ns) {
   auto s = GetAofFd(ns, true);
   if (!s.IsOK()) {
     return Status(Status::NotOK, s.Msg());

tools/kvrocks2redis/writer.h

@@ -14,7 +14,7 @@ class Writer {
   explicit Writer(Kvrocks2redis::Config *config) : config_(config) {}
   ~Writer();
   virtual Status Write(const std::string &ns, const std::vector<std::string> &aofs);
-  virtual Status FlushAll(const std::string &ns);
+  virtual Status FlushDB(const std::string &ns);
   virtual void Stop() {}
   Status OpenAofFile(const std::string &ns, bool truncate);
   Status GetAofFd(const std::string &ns, bool truncate = false);