Don't use RingBuffer.push_front

Author: szegedi

bindings/buffer.hh

@@ -4,9 +4,9 @@ namespace dd {
 template <class T>
 class RingBuffer {
  public:
-  explicit RingBuffer(size_t size)
-      : buffer(std::make_unique<T[]>(size)),
-        capacity_(size),
+  explicit RingBuffer(size_t capacity)
+      : buffer(std::make_unique<T[]>(capacity)),
+        capacity_(capacity),
         size_(0),
         back_index_(0),
         front_index_(0) {}
@@ -37,24 +37,6 @@ class RingBuffer {
     }
   }
 
-  template <typename T2>
-  void push_front(T2&& t) {
-    if (full()) {
-      if (empty()) {
-        return;
-      }
-      // overwrite buffer head
-      decrement(front_index_);
-      buffer[front_index_] = std::forward<T2>(t);
-      // move buffer head
-      back_index_ = front_index_;
-    } else {
-      decrement(front_index_);
-      buffer[front_index_] = std::forward<T2>(t);
-      ++size_;
-    }
-  }
-
   T pop_front() {
     auto idx = front_index_;
     increment(front_index_);

bindings/profilers/wall.cc

@@ -304,13 +304,11 @@ bool isIdleSample(const CpuProfileNode* sample) {
 LabelSetsByNode WallProfiler::GetLabelSetsByNode(CpuProfile* profile) {
   LabelSetsByNode labelSetsByNode;
 
-  if (contexts.empty() || profile->GetSamplesCount() == 0) {
+  auto sampleCount = profile->GetSamplesCount();
+  if (contexts.empty() || sampleCount == 0) {
     return labelSetsByNode;
   }
   auto isolate = Isolate::GetCurrent();
-  SampleContext sampleContext = contexts.pop_front();
-
-  auto sampleCount = profile->GetSamplesCount();
 
   for (int i = 0; i < sampleCount; i++) {
     auto sample = profile->GetSample(i);
@@ -324,12 +322,13 @@ LabelSetsByNode WallProfiler::GetLabelSetsByNode(CpuProfile* profile) {
     // to it in time, and stop as soon as it sees a context that's too recent
     // for this sample.
     for (;;) {
+      auto& sampleContext = contexts.front();
       if (sampleContext.time_to < sampleTimestamp) {
         // Current sample context is too old, discard it and fetch the next one.
+        contexts.pop_front();
         if (contexts.empty()) {
           return labelSetsByNode;
         }
-        sampleContext = contexts.pop_front();
       } else if (sampleContext.time_from > sampleTimestamp) {
         // Current sample context is too recent, we'll try to match it to the
         // next sample.
@@ -349,17 +348,14 @@ LabelSetsByNode WallProfiler::GetLabelSetsByNode(CpuProfile* profile) {
               array, array->Length(), sampleContext.labels.get()->Get(isolate));
         }
         // Sample context was consumed, fetch the next one
+        contexts.pop_front();
         if (contexts.empty()) {
           return labelSetsByNode;
         }
-        sampleContext = contexts.pop_front();
         break;  // don't match more than one context to one sample
       }
     }
   }
-  // Push the last popped sample context back into the ring to be used by the
-  // next profile
-  contexts.push_front(std::move(sampleContext));
   return labelSetsByNode;
 }