Fix modernize-loop-convert warning reported by clang-tidy (#1112)

.clang-tidy

@@ -1,7 +1,7 @@
 # refer to https://clang.llvm.org/extra/clang-tidy/checks/list.html
 Checks: -*, clang-analyzer-core.*, clang-analyzer-cplusplus.*, clang-analyzer-deadcode.*, clang-analyzer-nullability.*, clang-analyzer-security.*, clang-analyzer-unix.*, clang-analyzer-valist.*, cppcoreguidelines-init-variables, cppcoreguidelines-macro-usage, cppcoreguidelines-interfaces-global-init, cppcoreguidelines-narrowing-conversions, cppcoreguidelines-no-malloc, cppcoreguidelines-prefer-member-initializer, cppcoreguidelines-special-member-functions, cppcoreguidelines-slicing, google-build-explicit-make-pair, google-default-arguments, google-explicit-constructor, modernize-avoid-bind, modernize-loop-convert, modernize-macro-to-enum, modernize-make-shared, modernize-make-unique, modernize-pass-by-value, modernize-redundant-void-arg, modernize-return-braced-init-list, modernize-use-auto, modernize-use-bool-literals, modernize-use-emplace, modernize-use-equals-default, modernize-use-equals-delete, modernize-use-nullptr, modernize-use-override, modernize-use-using, performance-faster-string-find, performance-for-range-copy, performance-implicit-conversion-in-loop, performance-inefficient-algorithm, performance-inefficient-vector-operation, performance-move-const-arg, performance-move-constructor-init, performance-no-automatic-move, performance-trivially-destructible, performance-type-promotion-in-math-fn, performance-unnecessary-copy-initialization, performance-unnecessary-value-param
 
-WarningsAsErrors: clang-analyzer-*, -clang-analyzer-security.insecureAPI.rand, cppcoreguidelines-interfaces-global-init, cppcoreguidelines-no-malloc, cppcoreguidelines-slicing, google-*, modernize-use-emplace, modernize-use-equals-default, modernize-use-equals-delete, performance-implicit-conversion-in-loop, performance-inefficient-algorithm, performance-move-constructor-init, performance-no-automatic-move, performance-trivially-destructible, performance-type-promotion-in-math-fn, performance-unnecessary-copy-initialization, modernize-use-bool-literals, performance-unnecessary-value-param, modernize-make-unique, performance-for-range-copy, performance-faster-string-find, modernize-redundant-void-arg, modernize-avoid-bind, modernize-use-auto, modernize-use-using, performance-inefficient-vector-operation, cppcoreguidelines-special-member-functions
+WarningsAsErrors: clang-analyzer-*, -clang-analyzer-security.insecureAPI.rand, cppcoreguidelines-interfaces-global-init, cppcoreguidelines-no-malloc, cppcoreguidelines-slicing, google-*, modernize-use-emplace, modernize-use-equals-default, modernize-use-equals-delete, performance-implicit-conversion-in-loop, performance-inefficient-algorithm, performance-move-constructor-init, performance-no-automatic-move, performance-trivially-destructible, performance-type-promotion-in-math-fn, performance-unnecessary-copy-initialization, modernize-use-bool-literals, performance-unnecessary-value-param, modernize-make-unique, performance-for-range-copy, performance-faster-string-find, modernize-redundant-void-arg, modernize-avoid-bind, modernize-use-auto, modernize-use-using, performance-inefficient-vector-operation, cppcoreguidelines-special-member-functions, modernize-loop-convert
 
 CheckOptions:
   - key:           cppcoreguidelines-special-member-functions.AllowSoleDefaultDtor

src/common/task_runner.cc

@@ -54,8 +54,8 @@ void TaskRunner::Stop() {
 }
 
 void TaskRunner::Join() {
-  for (size_t i = 0; i < threads_.size(); i++) {
-    if (threads_[i].joinable()) threads_[i].join();
+  for (auto &thread : threads_) {
+    if (thread.joinable()) thread.join();
   }
 }
 

src/stats/stats.cc

@@ -30,8 +30,8 @@ Stats::Stats() {
     im.last_sample_time = 0;
     im.last_sample_count = 0;
     im.idx = 0;
-    for (int j = 0; j < STATS_METRIC_SAMPLES; j++) {
-      im.samples[j] = 0;
+    for (uint64_t &sample : im.samples) {
+      sample = 0;
     }
     inst_metrics.push_back(im);
   }
@@ -105,6 +105,6 @@ void Stats::TrackInstantaneousMetric(int metric, uint64_t current_reading) {
 
 uint64_t Stats::GetInstantaneousMetric(int metric) {
   uint64_t sum = 0;
-  for (int j = 0; j < STATS_METRIC_SAMPLES; j++) sum += inst_metrics[metric].samples[j];
+  for (uint64_t sample : inst_metrics[metric].samples) sum += sample;
   return sum / STATS_METRIC_SAMPLES;
 }

src/storage/redis_db.cc

@@ -611,8 +611,8 @@ std::vector<std::string> *WriteBatchLogData::GetArguments() { return &args_; }
 
 std::string WriteBatchLogData::Encode() {
   std::string ret = std::to_string(type_);
-  for (size_t i = 0; i < args_.size(); i++) {
-    ret += " " + args_[i];
+  for (const auto &arg : args_) {
+    ret += " " + arg;
   }
   return ret;
 }

src/types/redis_set.cc

@@ -308,8 +308,8 @@ rocksdb::Status Set::Union(const std::vector<Slice> &keys, std::vector<std::stri
 
   std::map<std::string, bool> union_members;
   std::vector<std::string> target_members;
-  for (size_t i = 0; i < keys.size(); i++) {
-    auto s = Members(keys[i], &target_members);
+  for (const auto &key : keys) {
+    auto s = Members(key, &target_members);
     if (!s.ok()) return s;
     for (const auto &member : target_members) {
       union_members[member] = true;

src/types/redis_string.cc

@@ -134,11 +134,8 @@ std::vector<rocksdb::Status> String::MGet(const std::vector<Slice> &keys, std::v
   }
   std::vector<Slice> slice_keys;
   slice_keys.reserve(ns_keys.size());
-  // don't use range-based for loop here, coz the slice member
-  // would refer the address instead of copy the value, and use
-  // range-based for loop may cause all members refer to the same addr
-  for (size_t i = 0; i < ns_keys.size(); i++) {
-    slice_keys.emplace_back(ns_keys[i]);
+  for (const auto &ns_key : ns_keys) {
+    slice_keys.emplace_back(ns_key);
   }
   return getValues(slice_keys, values);
 }