chrome/browser/ui/app_list/search/common/webservice_cache.cc

   1 // Copyright 2013 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 #include "chrome/browser/ui/app_list/search/common/webservice_cache.h"
   6
   7 #include "base/strings/string_number_conversions.h"
   8 #include "base/values.h"
   9 #include "content/public/browser/browser_context.h"
  10 #include "content/public/browser/browser_thread.h"
  11
  12 namespace app_list {
  13 namespace {
  14
  15 const unsigned int kWebserviceCacheMaxSize = 1000;
  16 const unsigned int kWebserviceCacheTimeLimitInMinutes = 1;
  17
  18 const char kKeyResultTime[] = "time";
  19 const char kKeyResult[] = "result";
  20
  21 const char kWebstoreQueryPrefix[] = "webstore:";
  22 const char kPeopleQueryPrefix[] = "people:";
  23
  24 }  // namespace
  25
  26 void WebserviceCache::CacheDeletor::operator()(const Payload& payload) {
  27   delete payload.result;
  28 }
  29
  30 WebserviceCache::WebserviceCache(content::BrowserContext* context)
  31     : cache_(Cache::NO_AUTO_EVICT),
  32       cache_loaded_(false) {
  33   const char kStoreDataFileName[] = "Webservice Search Cache";
  34   const base::FilePath data_file =
  35       context->GetPath().AppendASCII(kStoreDataFileName);
  36   data_store_ = new DictionaryDataStore(
  37       data_file, content::BrowserThread::GetBlockingPool());
  38   data_store_->Load(base::Bind(&WebserviceCache::OnCacheLoaded, AsWeakPtr()));
  39 }
  40
  41 WebserviceCache::~WebserviceCache() {
  42 }
  43
  44 const CacheResult WebserviceCache::Get(QueryType type,
  45                                        const std::string& query) {
  46   std::string typed_query = PrependType(type, query);
  47   Cache::iterator iter = cache_.Get(typed_query);
  48   if (iter != cache_.end()) {
  49     if (base::Time::Now() - iter->second.time <=
  50         base::TimeDelta::FromMinutes(kWebserviceCacheTimeLimitInMinutes)) {
  51       return std::make_pair(FRESH, iter->second.result);
  52     } else {
  53       return std::make_pair(STALE, iter->second.result);
  54     }
  55   }
  56   return std::make_pair(STALE, static_cast<base::DictionaryValue*>(NULL));
  57 }
  58
  59 void WebserviceCache::Put(QueryType type,
  60                           const std::string& query,
  61                           scoped_ptr<base::DictionaryValue> result) {
  62   if (result) {
  63     std::string typed_query = PrependType(type, query);
  64     Payload payload(base::Time::Now(), result.release());
  65
  66     cache_.Put(typed_query, payload);
  67     // If the cache isn't loaded yet, we're fine with losing queries since
  68     // a 1000 entry cache should load really quickly so the chance of a user
  69     // already having typed a 3 character search before the cache has loaded is
  70     // very unlikely.
  71     if (cache_loaded_) {
  72       data_store_->cached_dict()->Set(typed_query, DictFromPayload(payload));
  73       data_store_->ScheduleWrite();
  74       if (cache_.size() > kWebserviceCacheMaxSize)
  75         TrimCache();
  76     }
  77   }
  78 }
  79
  80 void WebserviceCache::OnCacheLoaded(scoped_ptr<base::DictionaryValue>) {
  81   if (!data_store_->cached_dict())
  82     return;
  83
  84   std::vector<std::string> cleanup_keys;
  85   for (base::DictionaryValue::Iterator it(*data_store_->cached_dict());
  86       !it.IsAtEnd();
  87       it.Advance()) {
  88     const base::DictionaryValue* payload_dict;
  89     Payload payload;
  90     if (!it.value().GetAsDictionary(&payload_dict) ||
  91         !payload_dict ||
  92         !PayloadFromDict(payload_dict, &payload)) {
  93       // In case we don't have a valid payload associated with a given query,
  94       // clean up that query from our data store.
  95       cleanup_keys.push_back(it.key());
  96       continue;
  97     }
  98     cache_.Put(it.key(), payload);
  99   }
 100
 101   if (!cleanup_keys.empty()) {
 102     for (size_t i = 0; i < cleanup_keys.size(); ++i)
 103       data_store_->cached_dict()->Remove(cleanup_keys[i], NULL);
 104     data_store_->ScheduleWrite();
 105   }
 106   cache_loaded_ = true;
 107 }
 108
 109 bool WebserviceCache::PayloadFromDict(const base::DictionaryValue* dict,
 110                                       Payload* payload) {
 111   std::string time_string;
 112   if (!dict->GetString(kKeyResultTime, &time_string))
 113     return false;
 114   const base::DictionaryValue* result;
 115   if (!dict->GetDictionary(kKeyResult, &result))
 116     return false;
 117
 118   int64 time_val;
 119   base::StringToInt64(time_string, &time_val);
 120
 121   // The result dictionary will be owned by the cache, hence create a copy
 122   // instead of returning the original reference. The new dictionary will be
 123   // owned by our MRU cache.
 124   *payload = Payload(base::Time::FromInternalValue(time_val),
 125                      result->DeepCopy());
 126   return true;
 127 }
 128
 129 base::DictionaryValue* WebserviceCache::DictFromPayload(
 130     const Payload& payload) {
 131   base::DictionaryValue* dict = new base::DictionaryValue();
 132   dict->SetString(kKeyResultTime, base::Int64ToString(
 133       payload.time.ToInternalValue()));
 134   // The payload will still keep ownership of it's result dict, hence put a
 135   // a copy of the result dictionary here. This dictionary will be owned by
 136   // data_store_->cached_dict().
 137   dict->Set(kKeyResult, payload.result->DeepCopy());
 138
 139   return dict;
 140 }
 141
 142 void WebserviceCache::TrimCache() {
 143   for (Cache::size_type i = cache_.size(); i > kWebserviceCacheMaxSize; i--) {
 144     Cache::reverse_iterator rbegin = cache_.rbegin();
 145     data_store_->cached_dict()->Remove(rbegin->first, NULL);
 146     cache_.Erase(rbegin);
 147   }
 148   data_store_->ScheduleWrite();
 149 }
 150
 151 std::string WebserviceCache::PrependType(
 152     QueryType type, const std::string& query) {
 153   switch (type) {
 154     case WEBSTORE:
 155       return kWebstoreQueryPrefix + query;
 156     case PEOPLE:
 157       return kPeopleQueryPrefix + query;
 158     default:
 159       return query;
 160   }
 161 }
 162
 163 }  // namespace app_list