cc/RateLimiter.h

   1 // Copyright 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef RateLimiter_h
   6 #define RateLimiter_h
   7
   8 #if USE(ACCELERATED_COMPOSITING)
   9
  10 #include <wtf/PassRefPtr.h>
  11 #include <wtf/RefCounted.h>
  12
  13 namespace WebKit {
  14 class WebGraphicsContext3D;
  15 }
  16
  17 namespace WebCore {
  18
  19 class RateLimiterClient {
  20 public:
  21     virtual void rateLimit() = 0;
  22 };
  23
  24 // A RateLimiter can be used to make sure that a single context does not dominate all execution time.
  25 // To use, construct a RateLimiter class around the context and call start() whenever calls are made on the
  26 // context outside of normal flow control. RateLimiter will block if the context is too far ahead of the
  27 // compositor.
  28 class RateLimiter : public RefCounted<RateLimiter> {
  29 public:
  30     static PassRefPtr<RateLimiter> create(WebKit::WebGraphicsContext3D*, RateLimiterClient*);
  31     ~RateLimiter();
  32
  33     void start();
  34
  35     // Context and client will not be accessed after stop().
  36     void stop();
  37
  38 private:
  39     RateLimiter(WebKit::WebGraphicsContext3D*, RateLimiterClient*);
  40
  41     class Task;
  42     friend class Task;
  43     void rateLimitContext();
  44
  45     WebKit::WebGraphicsContext3D* m_context;
  46     bool m_active;
  47     RateLimiterClient *m_client;
  48 };
  49
  50 }
  51 #endif // USE(ACCELERATED_COMPOSITING)
  52
  53 #endif