1 // Copyright 2014 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 ANDROID_WEBVIEW_BROWSER_GLOBAL_TILE_MANAGER_H_ 6 #define ANDROID_WEBVIEW_BROWSER_GLOBAL_TILE_MANAGER_H_ 7 8 #include <list> 9 #include "base/basictypes.h" 10 #include "base/lazy_instance.h" 11 #include "base/sequence_checker.h" 12 #include "base/synchronization/lock.h" 13 #include "content/public/browser/android/synchronous_compositor.h" 14 15 namespace android_webview { 16 17 class GlobalTileManagerClient; 18 19 // A global tile manager that keeps track of the number of tile resources. Each 20 // tile needs file descriptors (typically 2) and there is a soft limit of 1024 21 // file descriptors per Android process. The GlobalTileManager does not keep 22 // track of how many tiles each individual view is actually using. The purpose 23 // of GlobalTileManager is to behave gracefully (as in not crashing) when the 24 // embedder of webview creates a lot of webviews and draw them at the same time. 25 class GlobalTileManager { 26 private: 27 typedef std::list<GlobalTileManagerClient*> ListType; 28 29 public: 30 typedef ListType::iterator Key; 31 static GlobalTileManager* GetInstance(); 32 33 void SetTileLimit(size_t num_tiles_limit); 34 35 // Requests the |new_num_of_tiles| from the available global pool. Calls 36 // GlobalTileManagerClient.SetNumTiles after the manager determines how many 37 // tiles are available for the client. If the number of tiles left is not 38 // enough to satisfy the request, the manager will evict tiles allocated to 39 // other clients. 40 void RequestTiles(content::SynchronousCompositorMemoryPolicy new_policy, 41 Key key); 42 43 Key PushBack(GlobalTileManagerClient* client); 44 45 // |key| must be already in manager. Move the tile manager client 46 // corresponding to |key| to most recent. This function should be called after 47 // RequestTiles. 48 void DidUse(Key key); 49 50 void Remove(Key key); 51 52 private: 53 friend struct base::DefaultLazyInstanceTraits<GlobalTileManager>; 54 GlobalTileManager(); 55 ~GlobalTileManager(); 56 57 // Continues evicting the inactive views until freeing up at least amount of 58 // tiles specified by |desired_num_tiles| to draw a view specified by |key|, 59 // or until all inactive views have been evicted. Returns the amount of 60 // memory that was actually evicted. This function is called when a 61 // request cannot be satisfied. 62 size_t Evict(size_t desired_num_tiles, Key key); 63 64 // Check that the sum of all client's tiles is equal to 65 // total_allocated_tiles_. 66 bool IsConsistent() const; 67 68 size_t num_tiles_limit_; 69 70 size_t total_allocated_tiles_; 71 ListType mru_list_; 72 base::SequenceChecker sequence_checker_; 73 74 DISALLOW_COPY_AND_ASSIGN(GlobalTileManager); 75 }; 76 77 } // namespace android_webview 78 79 #endif // ANDROID_WEBVIEW_BROWSER_GLOBAL_TILE_MANAGER_H_ 80