X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=folly%2FProducerConsumerQueue.h;h=9ebe65acb46c66dbef1f9ab33e77e07fd968bdeb;hb=719b2df9d1996283acaac1d13476bcbc7da42154;hp=69f3fd5a79019f7daeae66b6806a7df404708934;hpb=321542683a01c3f334047531e9b487f047129775;p=folly.git

diff --git a/folly/ProducerConsumerQueue.h b/folly/ProducerConsumerQueue.h
index 69f3fd5a..9ebe65ac 100644
--- a/folly/ProducerConsumerQueue.h
+++ b/folly/ProducerConsumerQueue.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 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 {
 
 /*
@@ -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