Fix class member shadowing in folly::ProducerConsumerQueue

[folly.git] / folly / ProducerConsumerQueue.h

diff --git a/folly/ProducerConsumerQueue.h b/folly/ProducerConsumerQueue.h
index fedc2c7429c8467b779332702b3631e61efe8d83..d0bf3ec8c3436976a9fe95927f815d7919cf051b 100644 (file)
--- a/folly/ProducerConsumerQueue.h
+++ b/folly/ProducerConsumerQueue.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,16 +17,18 @@
 // @author Bo Hu (bhu@fb.com)
 // @author Jordan DeLong (delong.j@fb.com)
 
-#ifndef PRODUCER_CONSUMER_QUEUE_H_
-#define PRODUCER_CONSUMER_QUEUE_H_
+#pragma once
 
 #include <atomic>
 #include <cassert>
 #include <cstdlib>
+#include <memory>
 #include <stdexcept>
 #include <type_traits>
 #include <utility>
 
+#include <folly/detail/CacheLocality.h>
+
 namespace folly {
 
 /*
@@ -62,12 +64,12 @@ struct ProducerConsumerQueue {
     // (No real synchronization needed at destructor time: only one
     // thread can be doing this.)
     if (!std::is_trivially_destructible<T>::value) {
-      size_t read = readIndex_;
-      size_t end = writeIndex_;
-      while (read != end) {
-        records_[read].~T();
-        if (++read == size_) {
-          read = 0;
+      size_t readIndex = readIndex_;
+      size_t endIndex = writeIndex_;
+      while (readIndex != endIndex) {
+        records_[readIndex].~T();
+        if (++readIndex == size_) {
+          readIndex = 0;
         }
       }
     }
@@ -135,16 +137,16 @@ struct ProducerConsumerQueue {
   }
 
   bool isEmpty() const {
-   return readIndex_.load(std::memory_order_consume) ==
-         writeIndex_.load(std::memory_order_consume);
+    return readIndex_.load(std::memory_order_acquire) ==
+        writeIndex_.load(std::memory_order_acquire);
   }
 
   bool isFull() const {
-    auto nextRecord = writeIndex_.load(std::memory_order_consume) + 1;
+    auto nextRecord = writeIndex_.load(std::memory_order_acquire) + 1;
     if (nextRecord == size_) {
       nextRecord = 0;
     }
-    if (nextRecord != readIndex_.load(std::memory_order_consume)) {
+    if (nextRecord != readIndex_.load(std::memory_order_acquire)) {
       return false;
     }
     // queue is full
@@ -157,8 +159,8 @@ struct ProducerConsumerQueue {
   //   be removing items concurrently).
   // * It is undefined to call this from any other thread.
   size_t sizeGuess() const {
-    int ret = writeIndex_.load(std::memory_order_consume) -
-              readIndex_.load(std::memory_order_consume);
+    int ret = writeIndex_.load(std::memory_order_acquire) -
+        readIndex_.load(std::memory_order_acquire);
     if (ret < 0) {
       ret += size_;
     }
@@ -166,13 +168,14 @@ struct ProducerConsumerQueue {
   }
 
 private:
+  char pad0_[detail::CacheLocality::kFalseSharingRange];
   const uint32_t size_;
   T* const records_;
 
-  std::atomic<unsigned int> readIndex_;
-  std::atomic<unsigned int> writeIndex_;
+  FOLLY_ALIGN_TO_AVOID_FALSE_SHARING std::atomic<unsigned int> readIndex_;
+  FOLLY_ALIGN_TO_AVOID_FALSE_SHARING std::atomic<unsigned int> writeIndex_;
+
+  char pad1_[detail::CacheLocality::kFalseSharingRange - sizeof(writeIndex_)];
 };
 
 }
-
-#endif