RequestContext support

[folly.git] / folly / Arena.h

diff --git a/folly/Arena.h b/folly/Arena.h
index 2b93aa344547fd658cb0a3477a3c3d7c826498ef..00caa947abba291e2bdc07e1e3b7318ed7ff1bba 100644 (file)
--- a/folly/Arena.h
+++ b/folly/Arena.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 Facebook, Inc.
+ * Copyright 2015 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -84,7 +84,8 @@ class Arena {
     size = roundUp(size);
     bytesUsed_ += size;
 
-    if (LIKELY(end_ - ptr_ >= size)) {
+    assert(ptr_ <= end_);
+    if (LIKELY((size_t)(end_ - ptr_) >= size)) {
       // Fast path: there's enough room in the current block
       char* r = ptr_;
       ptr_ += size;
@@ -118,7 +119,6 @@ class Arena {
     return bytesUsed_;
   }
 
- private:
   // not copyable
   Arena(const Arena&) = delete;
   Arena& operator=(const Arena&) = delete;
@@ -127,6 +127,7 @@ class Arena {
   Arena(Arena&&) = default;
   Arena& operator=(Arena&&) = default;
 
+ private:
   struct Block;
   typedef boost::intrusive::slist_member_hook<
     boost::intrusive::tag<Arena>> BlockLink;
@@ -147,9 +148,9 @@ class Arena {
     }
 
    private:
-    Block() { }
-    ~Block() { }
-  } __attribute__((aligned));
+    Block() = default;
+    ~Block() = default;
+  } __attribute__((__aligned__));
   // This should be alignas(std::max_align_t) but neither alignas nor
   // max_align_t are supported by gcc 4.6.2.
 
@@ -157,6 +158,7 @@ class Arena {
   static constexpr size_t kDefaultMinBlockSize = 4096 - sizeof(Block);
   static constexpr size_t kNoSizeLimit = 0;
   static constexpr size_t kDefaultMaxAlign = alignof(Block);
+  static constexpr size_t kBlockOverhead = sizeof(Block);
 
  private:
   bool isAligned(uintptr_t address) const {