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   // 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_