parkinglot benchmark

[folly.git] / folly / ProducerConsumerQueue.h

diff --git a/folly/ProducerConsumerQueue.h b/folly/ProducerConsumerQueue.h
index 12f2bf427c33ce9485ac393d42097f6b1a1a1741..57d41cca84b9599604bbca4581b3cf862b423fe2 100644 (file)
--- a/folly/ProducerConsumerQueue.h
+++ b/folly/ProducerConsumerQueue.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 Facebook, Inc.
+ * Copyright 2012-present Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,7 +35,7 @@ namespace folly {
  * ProducerConsumerQueue is a one producer and one consumer queue
  * without locks.
  */
-template<class T>
+template <class T>
 struct ProducerConsumerQueue {
   typedef T value_type;
 
@@ -77,7 +77,7 @@ struct ProducerConsumerQueue {
     std::free(records_);
   }
 
-  template<class ...Args>
+  template <class... Args>
   bool write(Args&&... recordArgs) {
     auto const currentWrite = writeIndex_.load(std::memory_order_relaxed);
     auto nextRecord = currentWrite + 1;
@@ -167,15 +167,22 @@ struct ProducerConsumerQueue {
     return ret;
   }
 
-private:
- char pad0_[CacheLocality::kFalseSharingRange];
- const uint32_t size_;
- T* const records_;
+  // maximum number of items in the queue.
+  size_t capacity() const {
+    return size_ - 1;
+  }
+
+ private:
+  char pad0_[hardware_destructive_interference_size];
+  const uint32_t size_;
+  T* const records_;
 
- FOLLY_ALIGN_TO_AVOID_FALSE_SHARING std::atomic<unsigned int> readIndex_;
- FOLLY_ALIGN_TO_AVOID_FALSE_SHARING std::atomic<unsigned int> writeIndex_;
+  alignas(hardware_destructive_interference_size)
+      std::atomic<unsigned int> readIndex_;
+  alignas(hardware_destructive_interference_size)
+      std::atomic<unsigned int> writeIndex_;
 
- char pad1_[CacheLocality::kFalseSharingRange - sizeof(writeIndex_)];
+  char pad1_[hardware_destructive_interference_size - sizeof(writeIndex_)];
 };
 
-}
+} // namespace folly