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      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 #ifndef CHROME_BROWSER_FEEDBACK_SYSTEM_LOGS_SYSTEM_LOGS_FETCHER_BASE_H_
      6 #define CHROME_BROWSER_FEEDBACK_SYSTEM_LOGS_SYSTEM_LOGS_FETCHER_BASE_H_
      7 
      8 #include <map>
      9 #include <string>
     10 
     11 #include "base/callback.h"
     12 #include "base/memory/scoped_vector.h"
     13 #include "base/memory/weak_ptr.h"
     14 
     15 namespace system_logs {
     16 
     17 typedef std::map<std::string, std::string> SystemLogsResponse;
     18 
     19 // Callback that the data sources use to return data.
     20 typedef base::Callback<void(SystemLogsResponse* response)>
     21     SysLogsSourceCallback;
     22 
     23 // Callback that the SystemLogsFetcherBase uses to return data.
     24 typedef base::Callback<void(scoped_ptr<SystemLogsResponse> response)>
     25     SysLogsFetcherCallback;
     26 
     27 // The SystemLogsSource provides a interface for the data sources that
     28 // the SystemLogsFetcherBase class uses to fetch logs and other
     29 // information.
     30 class SystemLogsSource {
     31  public:
     32   // Fetches data and passes it by to the callback
     33   virtual void Fetch(const SysLogsSourceCallback& callback) = 0;
     34   virtual ~SystemLogsSource() {}
     35 };
     36 
     37 // The SystemLogsFetcherBaseBase specifies an interface for LogFetcher classes.
     38 // Derived LogFetcher classes aggregate the logs from a list of SystemLogSource
     39 // classes.
     40 //
     41 // EXAMPLE:
     42 // class Example {
     43 //  public:
     44 //   void ProcessLogs(SystemLogsResponse* response) {
     45 //      //do something with the logs
     46 //   }
     47 //   void GetLogs() {
     48 //     SystemLogsFetcherBase* fetcher = new SystemLogsFetcherBase();
     49 //     fetcher->Fetch(base::Bind(&Example::ProcessLogs, this));
     50 //   }
     51 class SystemLogsFetcherBase
     52     : public base::SupportsWeakPtr<SystemLogsFetcherBase> {
     53  public:
     54   SystemLogsFetcherBase();
     55   ~SystemLogsFetcherBase();
     56 
     57   void Fetch(const SysLogsFetcherCallback& callback);
     58 
     59  protected:
     60   // Callback passed to all the data sources. It merges the |data| it receives
     61   // into response_. When all the data sources have responded, it deletes their
     62   // objects and returns the response to the callback_. After this it
     63   // deletes this instance of the object.
     64   void AddResponse(SystemLogsResponse* response);
     65 
     66   ScopedVector<SystemLogsSource> data_sources_;
     67   SysLogsFetcherCallback callback_;
     68 
     69   scoped_ptr<SystemLogsResponse> response_;  // The actual response data.
     70   size_t num_pending_requests_;   // The number of callbacks it should get.
     71 
     72  private:
     73 
     74   DISALLOW_COPY_AND_ASSIGN(SystemLogsFetcherBase);
     75 };
     76 
     77 }  // namespace system_logs
     78 
     79 #endif  // CHROME_BROWSER_FEEDBACK_SYSTEM_LOGS_SYSTEM_LOGS_FETCHER_BASE_H_
     80