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      1 /*
      2  * Copyright 2016 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef SkUrlDataManager_DEFINED
      9 #define SkUrlDataManager_DEFINED
     10 
     11 #include "SkChecksum.h"
     12 #include "SkData.h"
     13 #include "SkString.h"
     14 #include "SkTDynamicHash.h"
     15 
     16 /*
     17  * A simple class which allows clients to add opaque data types, and returns a url where this data
     18  * will be hosted.  Its up to the owner of this class to actually serve the data.
     19  */
     20 bool operator==(const SkData& a, const SkData& b);
     21 
     22 class UrlDataManager {
     23 public:
     24     UrlDataManager(SkString rootUrl);
     25     ~UrlDataManager() { this->reset(); }
     26 
     27     /*
     28      * Adds a data blob to the cache with a particular content type.  UrlDataManager will hash
     29      * the blob data to ensure uniqueness
     30      */
     31     SkString addData(SkData*, const char* contentType);
     32 
     33     struct UrlData : public SkRefCnt {
     34         SkString fUrl;
     35         SkString fContentType;
     36         SkAutoTUnref<SkData> fData;
     37     };
     38 
     39     /*
     40      * returns the UrlData object which should be hosted at 'url'
     41      */
     42     UrlData* getDataFromUrl(SkString url) {
     43         return fUrlLookup.find(url);
     44     }
     45     void reset();
     46 
     47 private:
     48     struct LookupTrait {
     49         // We use the data as a hash, this is not really optimal but is fine until proven otherwise
     50         static const SkData& GetKey(const UrlData& data) {
     51             return *data.fData.get();
     52         }
     53 
     54         static uint32_t Hash(const SkData& key) {
     55             return SkChecksum::Murmur3(key.bytes(), key.size());
     56         }
     57     };
     58 
     59     struct ReverseLookupTrait {
     60         static const SkString& GetKey(const UrlData& data) {
     61             return data.fUrl;
     62         }
     63 
     64         static uint32_t Hash(const SkString& key) {
     65             return SkChecksum::Murmur3(key.c_str(), strlen(key.c_str()));
     66         }
     67     };
     68 
     69 
     70     SkString fRootUrl;
     71     SkTDynamicHash<UrlData, SkData, LookupTrait> fCache;
     72     SkTDynamicHash<UrlData, SkString, ReverseLookupTrait> fUrlLookup;
     73     uint32_t fDataId;
     74 };
     75 
     76 #endif
     77