chrome/browser/feedback/system_logs/system_logs_fetcher_base.h

   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   // |source_name| provides a descriptive identifier for debugging.
  33   explicit SystemLogsSource(const std::string& source_name);
  34   virtual ~SystemLogsSource();
  35
  36   // Fetches data and passes it by to the callback
  37   virtual void Fetch(const SysLogsSourceCallback& callback) = 0;
  38
  39   const std::string& source_name() const { return source_name_; }
  40
  41  private:
  42   std::string source_name_;
  43 };
  44
  45 // The SystemLogsFetcherBaseBase specifies an interface for LogFetcher classes.
  46 // Derived LogFetcher classes aggregate the logs from a list of SystemLogSource
  47 // classes.
  48 //
  49 // EXAMPLE:
  50 // class Example {
  51 //  public:
  52 //   void ProcessLogs(SystemLogsResponse* response) {
  53 //      //do something with the logs
  54 //   }
  55 //   void GetLogs() {
  56 //     SystemLogsFetcherBase* fetcher = new SystemLogsFetcherBase();
  57 //     fetcher->Fetch(base::Bind(&Example::ProcessLogs, this));
  58 //   }
  59 class SystemLogsFetcherBase
  60     : public base::SupportsWeakPtr<SystemLogsFetcherBase> {
  61  public:
  62   SystemLogsFetcherBase();
  63   ~SystemLogsFetcherBase();
  64
  65   void Fetch(const SysLogsFetcherCallback& callback);
  66
  67  protected:
  68   // Callback passed to all the data sources. It merges the |data| it receives
  69   // into response_. When all the data sources have responded, it deletes their
  70   // objects and returns the response to the callback_. After this it
  71   // deletes this instance of the object.
  72   void AddResponse(const std::string& source_name,
  73                    SystemLogsResponse* response);
  74
  75   ScopedVector<SystemLogsSource> data_sources_;
  76   SysLogsFetcherCallback callback_;
  77
  78   scoped_ptr<SystemLogsResponse> response_;  // The actual response data.
  79   size_t num_pending_requests_;   // The number of callbacks it should get.
  80
  81  private:
  82
  83   DISALLOW_COPY_AND_ASSIGN(SystemLogsFetcherBase);
  84 };
  85
  86 }  // namespace system_logs
  87
  88 #endif  // CHROME_BROWSER_FEEDBACK_SYSTEM_LOGS_SYSTEM_LOGS_FETCHER_BASE_H_