Initial commit of sync engine code to browser/sync....

chrome/browser/sync/notifier/base/fastalloc.h

+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_SYNC_NOTIFIER_BASE_FASTALLOC_H_
+#define CHROME_BROWSER_SYNC_NOTIFIER_BASE_FASTALLOC_H_
+
+#include <assert.h>
+
+namespace notifier {
+
+template<class T, size_t Size>
+class FastAlloc {
+ public:
+  FastAlloc() : buffer_(NULL), size_(0) { };
+  ~FastAlloc() { freeBuffer(); }
+  T* get_buffer(size_t size) {
+    if (size_ != 0) {
+      // We only allow one call to get_buffer. This makes the logic here
+      // simpler, and the user has to worry less about someone else calling
+      // get_buffer again on the same FastAlloc object and invalidating the
+      // memory they were using.
+      assert(false && "get_buffer may one be called once");
+      return NULL;
+    }
+
+    if (size <= Size) {
+      buffer_ = internal_buffer_;
+    } else {
+      buffer_ = new T[size];
+    }
+
+    if (buffer_ != NULL) {
+      size_ = size;
+    }
+    return buffer_;
+  }
+
+ private:
+  void freeBuffer() {
+#ifdef DEBUG
+    memset(buffer_, 0xCC, size_ * sizeof(T));
+#endif
+
+    if (buffer_ != NULL && buffer_ != internal_buffer_) {
+      delete[] buffer_;
+    }
+    buffer_ = NULL;
+    size_ = 0;
+  }
+
+  T* buffer_;
+  T internal_buffer_[Size];
+  size_t size_;
+};
+
+}
+
+#endif  // CHROME_BROWSER_SYNC_NOTIFIER_BASE_FASTALLOC_H_