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| 1 // Copyright (c) 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 WEBKIT_GLUE_DEFER_STRATEGY_H_ |
| 6 #define WEBKIT_GLUE_DEFER_STRATEGY_H_ |
| 7 |
| 8 #include "base/singleton.h" |
| 9 |
| 10 namespace webkit_glue { |
| 11 |
| 12 class BufferedResourceLoader; |
| 13 |
| 14 class DeferStrategy { |
| 15 public: |
| 16 // Checks to see if loader should defer loading based on its state. |
| 17 // Defers loader if needed. |
| 18 // Returns true deferring was enabled, false otherwise. |
| 19 virtual bool EnableDeferIfNeeded(BufferedResourceLoader* loader) const = 0; |
| 20 |
| 21 // Checks to see if loader should stop deferring based on its state. |
| 22 // Disables deferring if needed. |
| 23 // Returns true deferring was disabled, false otherwise. |
| 24 virtual bool DisableDeferIfNeeded(BufferedResourceLoader* loader) const = 0; |
| 25 |
| 26 // Returns true if this strategy will ever allow resource deferring. This is |
| 27 // used by BufferedResourceLoader to determine how much data should be |
| 28 // stored in its in-memory buffer. |
| 29 virtual bool AllowsDeferring() const { return true; }; |
| 30 |
| 31 // Toggles the defer settings for the resource loader. |
| 32 // Returns true if defer setting was toggled, false otherwise. |
| 33 static bool ToggleDefer(BufferedResourceLoader* loader); |
| 34 }; |
| 35 |
| 36 // Never defer resource loading; keep buffering until all data has been |
| 37 // received. |
| 38 class NeverDeferStrategy : public DeferStrategy { |
| 39 public: |
| 40 static NeverDeferStrategy* GetInstance(); |
| 41 virtual bool EnableDeferIfNeeded(BufferedResourceLoader* loader) const; |
| 42 virtual bool DisableDeferIfNeeded(BufferedResourceLoader* loader) const; |
| 43 virtual bool AllowsDeferring() const { return false; }; |
| 44 }; |
| 45 |
| 46 // Buffer up until a threshold determined by the resource loader. |
| 47 class ThresholdDeferStrategy : public DeferStrategy { |
| 48 public: |
| 49 static ThresholdDeferStrategy* GetInstance(); |
| 50 virtual bool EnableDeferIfNeeded(BufferedResourceLoader* loader) const; |
| 51 virtual bool DisableDeferIfNeeded(BufferedResourceLoader* loader) const; |
| 52 }; |
| 53 |
| 54 // Buffer only what is requested by the read requests on the loader. |
| 55 class ReadThenDeferStrategy : public DeferStrategy { |
| 56 public: |
| 57 static ReadThenDeferStrategy* GetInstance(); |
| 58 virtual bool EnableDeferIfNeeded(BufferedResourceLoader* loader) const; |
| 59 virtual bool DisableDeferIfNeeded(BufferedResourceLoader* loader) const; |
| 60 }; |
| 61 |
| 62 }; |
| 63 |
| 64 #endif // WEBKIT_GLUE_DEFER_STRATEGY_H_ |
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