Supplements of guideline of compilation on macOS with make and clean up some code

README.md

@@ -47,7 +47,7 @@ sudo yum install -y epel-release && sudo yum install -y git gcc gcc-c++ make sna
 sudo apt-get install gcc g++ make libsnappy-dev autoconf automake libtool which libgtest-dev
 
 # MACOSX
-brew install snappy googletest
+brew install autoconf automake libtool snappy googletest
 ```
 
 It is as simple as:

src/cron.cc

@@ -29,7 +29,7 @@ Status Cron::SetScheduleTime(const std::vector<std::string> &args) {
     if (!s.IsOK()) {
       return Status(Status::NotOK, "time expression format error : " + s.Msg());
     }
-    new_schedulers.push_back(st);
+    new_schedulers.emplace_back(std::move(st));
   }
   schedulers_ = std::move(new_schedulers);
   return Status::OK();

src/redis_cmd.cc

@@ -1239,7 +1239,7 @@ class CommandHMSet : public Commander {
     Redis::Hash hash_db(svr->storage_, conn->GetNamespace());
     std::vector<FieldValue> field_values;
     for (unsigned int i = 2; i < args_.size(); i += 2) {
-      field_values.push_back(FieldValue{args_[i], args_[i + 1]});
+      field_values.emplace_back(FieldValue{args_[i], args_[i + 1]});
     }
     rocksdb::Status s = hash_db.MSet(args_[1], field_values, false, &ret);
     if (!s.ok()) {

src/redis_db.cc

@@ -365,6 +365,9 @@ rocksdb::Status Database::FindKeyRangeWithPrefix(const std::string &prefix,
   if (cf_handle == nullptr) {
     cf_handle = metadata_cf_handle_;
   }
+  if (prefix.empty()) {
+    return rocksdb::Status::NotFound();
+  }
   begin->clear();
   end->clear();
 
@@ -383,10 +386,8 @@ rocksdb::Status Database::FindKeyRangeWithPrefix(const std::string &prefix,
   // it's ok to increase the last char in prefix as the boundary of the prefix
   // while we limit the namespace last char shouldn't be larger than 128.
   std::string next_prefix = prefix;
-  char last_char = next_prefix.back();
-  last_char++;
-  next_prefix.pop_back();
-  next_prefix.push_back(last_char);
+  auto prefix_size = prefix.size();
+  next_prefix[prefix_size - 1] ++;
   iter->SeekForPrev(next_prefix);
   int max_prev_limit = 128;  // prevent unpredicted long while loop
   int i = 0;
@@ -475,7 +476,7 @@ std::string WriteBatchLogData::Encode() {
 }
 
 Status WriteBatchLogData::Decode(const rocksdb::Slice &blob) {
-  std::string log_data = blob.ToString();
+  const std::string& log_data = blob.ToString();
   std::vector<std::string> args;
   Util::Split(log_data, " ", &args);
   type_ = static_cast<RedisType >(std::stoi(args[0]));

src/redis_hash.cc

@@ -168,14 +168,14 @@ rocksdb::Status Hash::MGet(const Slice &user_key,
 rocksdb::Status Hash::Set(const Slice &user_key, const Slice &field, const Slice &value, int *ret) {
   FieldValue fv = {field.ToString(), value.ToString()};
   std::vector<FieldValue> fvs;
-  fvs.push_back(fv);
+  fvs.emplace_back(std::move(fv));
   return MSet(user_key, fvs, false, ret);
 }
 
 rocksdb::Status Hash::SetNX(const Slice &user_key, const Slice &field, Slice value, int *ret) {
   FieldValue fv = {field.ToString(), value.ToString()};
   std::vector<FieldValue> fvs;
-  fvs.push_back(fv);
+  fvs.emplace_back(std::move(fv));
   return MSet(user_key, fvs, true, ret);
 }
 

src/util.cc

@@ -157,7 +157,6 @@ Status SockConnect(std::string host, uint32_t port, int *fd, uint64_t conn_timeo
       return Status(Status::NotOK, strerror(errno));
     }
     SockSetTcpNoDelay(*fd, 1);
-    SockSetTcpNoDelay(*fd, 1);
   }
   if (timeout > 0) {
     struct timeval tv;