no copy in AddAndReadVector

Oneflow-Inc · Jun 10, 2022 · 6fafb4b · 6fafb4b
1 parent 4775c72
commit 6fafb4b
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/oneflow/core/common/add_and_read_vector.h b/oneflow/core/common/add_and_read_vector.h
@@ -42,15 +42,17 @@ class AddAndReadVector {
     CHECK_GE(index, 0);
     CHECK_LT(index, size_);
     int gran = GetGranularity(index + 1);
-    return granularity2vector_[gran].data()[index];
+    int offset = (1 << gran) - 1;
+    return granularity2vector_[gran].data()[index - offset];
   }
 
   // lock free.
   T& at(size_t index) {
     CHECK_GE(index, 0);
     CHECK_LT(index, size_);
     int gran = GetGranularity(index + 1);
-    return granularity2vector_[gran].data()[index];
+    int offset = (1 << gran) - 1;
+    return granularity2vector_[gran].data()[index - offset];
   }
 
   void push_back(const T& elem) {
@@ -61,7 +63,6 @@ class AddAndReadVector {
       CHECK_LT(next_granularity, N);
       CHECK_EQ(next_granularity, GetGranularity(size_ + 1));
       granularity2vector_[next_granularity].reserve(1 << next_granularity);
-      granularity2vector_[next_granularity] = granularity2vector_[granularity];
       granularity = next_granularity;
     } else if (granularity2vector_[granularity].size() > (1 << granularity)) {
       LOG(FATAL) << "fatal bug in AddAndReadVector::push_back";