| // Copyright 2014 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 ANDROID_WEBVIEW_BROWSER_GLOBAL_TILE_MANAGER_H_ |
| #define ANDROID_WEBVIEW_BROWSER_GLOBAL_TILE_MANAGER_H_ |
| |
| #include <list> |
| #include "base/basictypes.h" |
| #include "base/lazy_instance.h" |
| #include "base/sequence_checker.h" |
| #include "base/synchronization/lock.h" |
| |
| namespace android_webview { |
| |
| class GlobalTileManagerClient; |
| |
| // A global tile manager that keeps track of the number of tile resources. Each |
| // tile needs file descriptors (typically 2) and there is a soft limit of 1024 |
| // file descriptors per Android process. The GlobalTileManager does not keep |
| // track of how many tiles each individual view is actually using. The purpose |
| // of GlobalTileManager is to behave gracefully (as in not crashing) when the |
| // embedder of webview creates a lot of webviews and draw them at the same time. |
| class GlobalTileManager { |
| private: |
| typedef std::list<GlobalTileManagerClient*> ListType; |
| |
| public: |
| typedef ListType::iterator Key; |
| static GlobalTileManager* GetInstance(); |
| |
| void SetTileLimit(size_t num_tiles_limit); |
| |
| // Requests the |num_of_tiles| from the available global pool. Calls |
| // GlobalTileManagerClient.SetNumTiles after the manager determines how many |
| // tiles are available for the client. If the number of tiles left is not |
| // enough to satisfy the request, the manager will evict tiles allocated to |
| // other clients. |
| void RequestTiles(size_t new_num_of_tiles, Key key); |
| |
| Key PushBack(GlobalTileManagerClient* client); |
| |
| // |key| must be already in manager. Move the tile manager client |
| // corresponding to |key| to most recent. This function should be called after |
| // RequestTiles. |
| void DidUse(Key key); |
| |
| void Remove(Key key); |
| |
| private: |
| friend struct base::DefaultLazyInstanceTraits<GlobalTileManager>; |
| GlobalTileManager(); |
| ~GlobalTileManager(); |
| |
| // Continues evicting the inactive views until freeing up at least amount of |
| // tiles specified by |desired_num_tiles| to draw a view specified by |key|, |
| // or until all inactive views have been evicted. Returns the amount of |
| // memory that was actually evicted. This function is called when a |
| // request cannot be satisfied. |
| size_t Evict(size_t desired_num_tiles, Key key); |
| |
| // Check that the sum of all client's tiles is equal to |
| // total_allocated_tiles_. |
| bool IsConsistent() const; |
| |
| size_t num_tiles_limit_; |
| |
| size_t total_allocated_tiles_; |
| ListType mru_list_; |
| base::SequenceChecker sequence_checker_; |
| |
| DISALLOW_COPY_AND_ASSIGN(GlobalTileManager); |
| }; |
| |
| } // namespace android_webview |
| |
| #endif // ANDROID_WEBVIEW_BROWSER_GLOBAL_TILE_MANAGER_H_ |