folly copyright 2015 -> copyright 2016

[folly.git] / folly / experimental / LockFreeRingBuffer.h

diff --git a/folly/experimental/LockFreeRingBuffer.h b/folly/experimental/LockFreeRingBuffer.h
index 0a2d10f3eaaa48659a412584670687cb7789c5e7..5411112d0f7bf37c6b50ef963c1319c5a24533a6 100644 (file)
--- a/folly/experimental/LockFreeRingBuffer.h
+++ b/folly/experimental/LockFreeRingBuffer.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 Facebook, Inc.
+ * Copyright 2016 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -70,16 +70,24 @@ public:
   struct Cursor {
     explicit Cursor(uint64_t initialTicket) noexcept : ticket(initialTicket) {}
 
-    void moveForward(uint64_t steps = 1) noexcept {
+    /// Returns true if this cursor now points to a different
+    /// write, false otherwise.
+    bool moveForward(uint64_t steps = 1) noexcept {
+      uint64_t prevTicket = ticket;
       ticket += steps;
+      return prevTicket != ticket;
     }
 
-    void moveBackward(uint64_t steps = 1) noexcept {
+    /// Returns true if this cursor now points to a previous
+    /// write, false otherwise.
+    bool moveBackward(uint64_t steps = 1) noexcept {
+      uint64_t prevTicket = ticket;
       if (steps > ticket) {
         ticket = 0;
       } else {
         ticket -= steps;
       }
+      return prevTicket != ticket;
     }
 
   protected: // for test visibility reasons