Page Speed Optimization Libraries  1.5.27.2
net/instaweb/util/public/cache_interface.h
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00001 /*
00002  * Copyright 2010 Google Inc.
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *      http:///www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00018 
00019 #ifndef NET_INSTAWEB_UTIL_PUBLIC_CACHE_INTERFACE_H_
00020 #define NET_INSTAWEB_UTIL_PUBLIC_CACHE_INTERFACE_H_
00021 
00022 #include <vector>
00023 
00024 #include "base/logging.h"
00025 #include "net/instaweb/util/public/basictypes.h"
00026 #include "net/instaweb/util/public/shared_string.h"
00027 #include "net/instaweb/util/public/string.h"
00028 
00029 namespace net_instaweb {
00030 
00032 class CacheInterface {
00033  public:
00034   enum KeyState {
00035     kAvailable = 0,     
00036     kNotFound = 1,      
00037     kOverload = 2,      
00038     kNetworkError = 3,  
00039     kTimeout = 4,       
00040   };
00041 
00042   class Callback {
00043    public:
00044     virtual ~Callback();
00045     SharedString* value() { return &value_; }
00046 
00050     bool DelegatedValidateCandidate(const GoogleString& key, KeyState state) {
00051       return ValidateCandidate(key, state);
00052     }
00053 
00054     void DelegatedDone(KeyState state) {
00055       Done(state);
00056     }
00057 
00058    protected:
00059     friend class CacheInterface;
00060 
00074     virtual bool ValidateCandidate(const GoogleString& key,
00075                                    KeyState state) { return true; }
00076 
00083     virtual void Done(KeyState state) = 0;
00084 
00085    private:
00086     SharedString value_;
00087   };
00088 
00091   class SynchronousCallback : public Callback {
00092    public:
00093     SynchronousCallback() { Reset(); }
00094 
00095     bool called() const { return called_; }
00096     KeyState state() const { return state_; }
00098 
00099     void Reset() {
00100       called_ = false;
00101       state_ = CacheInterface::kNotFound;
00102       SharedString empty;
00103       *value() = empty;
00104     }
00105 
00106     virtual void Done(CacheInterface::KeyState state) {
00107       called_ = true;
00108       state_ = state;
00109     }
00110 
00111    private:
00112     bool called_;
00113     CacheInterface::KeyState state_;
00114 
00115     DISALLOW_COPY_AND_ASSIGN(SynchronousCallback);
00116   };
00117 
00119   struct KeyCallback {
00120     KeyCallback(const GoogleString& k, Callback* c) : key(k), callback(c) {}
00121     GoogleString key;
00122     Callback* callback;
00123   };
00124   typedef std::vector<KeyCallback> MultiGetRequest;
00125 
00126   CacheInterface();
00127   virtual ~CacheInterface();
00128 
00135   virtual void Get(const GoogleString& key, Callback* callback) = 0;
00136 
00144   virtual void MultiGet(MultiGetRequest* request);
00145 
00149   virtual void Put(const GoogleString& key, SharedString* value) = 0;
00150   virtual void Delete(const GoogleString& key) = 0;
00151 
00155   void PutSwappingString(const GoogleString& key, GoogleString* value) {
00156     SharedString shared_string;
00157     shared_string.SwapWithString(value);
00158     Put(key, &shared_string);
00159   }
00160 
00166   virtual GoogleString Name() const = 0;
00167 
00171   virtual CacheInterface* Backend();
00172 
00175   virtual bool IsBlocking() const = 0;
00176 
00183   virtual bool IsHealthy() const = 0;
00184 
00189   virtual void ShutDown() = 0;
00190 
00204   virtual bool MustEncodeKeyInValueOnPut() const { return false; }
00205 
00209   virtual void PutWithKeyInValue(const GoogleString& key,
00210                                  SharedString* key_and_value) {
00211     CHECK(false);
00212   }
00213 
00214  protected:
00216   void ValidateAndReportResult(const GoogleString& key, KeyState state,
00217                                Callback* callback);
00218 
00221   void ReportMultiGetNotFound(MultiGetRequest* request);
00222 };
00223 
00224 }  
00225 
00226 #endif  ///< NET_INSTAWEB_UTIL_PUBLIC_CACHE_INTERFACE_H_
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