components/translate/content/common/cld_data_source.h

   1 // Copyright 2014 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 COMPONENTS_TRANSLATE_CONTENT_COMMON_CLD_DATA_SOURCE_H_
   6 #define COMPONENTS_TRANSLATE_CONTENT_COMMON_CLD_DATA_SOURCE_H_
   7
   8 #include <string>
   9
  10 #include "base/files/file_path.h"
  11 #include "base/macros.h"
  12 #include "base/synchronization/lock.h"
  13
  14 namespace component_updater {
  15   // For friend-class declaration, see private section at bottom of class.
  16   class CldComponentInstallerTest;
  17 }
  18
  19 namespace translate {
  20
  21 // Provides high-level functionality related to a CLD Data Source.
  22 class CldDataSource {
  23
  24  public:
  25   // Generally not used by Chromium code, but available for embedders to
  26   // configure additional data sources as subclasses.
  27   // Chromium code should use the getters (GetStaticDataSource(),
  28   // GetStandaloneDataSource(), and GetComponentDataSource()) and checkers
  29   // (IsUsingStaticDataSource(), IsUsingStandaloneDataSource() and
  30   // IsUsingComponentDataSource()) instead as appropriate.
  31   CldDataSource();
  32   virtual ~CldDataSource() {}
  33
  34   // Returns the symbolic name of the data source. In the Chromium
  35   // open-source tree, the following data sources exist:
  36   // static       uses the static_[browser|renderer]_cld_data_provider
  37   //              implementations.
  38   // standalone   uses the data_file_[browser|renderer]_cld_data_provider
  39   //              implementations.
  40   // component    also uses the data_file_[browser|renderer]_cld_data_provider
  41   //              implementations.
  42   //
  43   // Other implementations based upon Chromium may provide CLD differently and
  44   // may have other names.
  45   // This method is threadsafe.
  46   virtual std::string GetName();
  47
  48   // For data sources that support a separate CLD data file, configures the path
  49   // of that data file.
  50   //
  51   // The 'component' and 'standalone' data sources need this method to be called
  52   // in order to locate the CLD data on disk.
  53   // If the data source doesn't need or doesn't support such configuration, this
  54   // function is a no-op. This is the case for, e.g., the static data source.
  55   // This method is threadsafe.
  56   virtual void SetCldDataFilePath(const base::FilePath& path);
  57
  58   // Returns the path most recently set by SetCldDataFilePath. The initial value
  59   // prior to any such call is the empty path. If the data source doesn't
  60   // support a data file, returns the empty path.
  61   // This method is threadsafe.
  62   virtual base::FilePath GetCldDataFilePath();
  63
  64   // Sets the default data source for this process, i.e. the data source to be
  65   // used unless the embedder calls Set(CldDatasource*). This is the method
  66   // that normal (i.e., non-test) Chromium code should use; embedders can and
  67   // should use the unconditional Set(CldDataSource*) method instead. If a
  68   // default data source has already been set, this method does nothing.
  69   static void SetDefault(CldDataSource* data_source);
  70
  71   // Unconditionally sets the data source for this process, overwriting any
  72   // previously-configured default. Normal Chromium code should never use this
  73   // method; it is provided for embedders to inject a data source from outside
  74   // of the Chromium code base. Test code can also use this method to force the
  75   // runtime to have a desired behavior.
  76   static void Set(CldDataSource* data_source);
  77
  78   // Returns the data source for this process. Guaranteed to never be null.
  79   // If no instance has been set, this returns the same object obtained by
  80   // calling GetStaticDataSource(), which is always safe but may fail to
  81   // function if the CLD data is not *actually* statically linked.
  82   static CldDataSource* Get();
  83
  84   // Fetch the global instance of the "static" data source.
  85   // Only use to call SetDefault(CldDataSource*) or Set(CldDataSource*).
  86   static CldDataSource* GetStaticDataSource();
  87
  88   // Returns true if and only if the data source returned by Get() is the
  89   // "static" data source.
  90   static bool IsUsingStaticDataSource();
  91
  92   // Fetch the global instance of the "standalone" data source.
  93   // Only use to call SetDefault(CldDataSource*) or Set(CldDataSource*).
  94   static CldDataSource* GetStandaloneDataSource();
  95
  96   // Returns true if and only if the data source returned by Get() is the
  97   // "static" data source.
  98   static bool IsUsingStandaloneDataSource();
  99
 100   // Fetch the global instance of the "component" data source.
 101   // Only use to call SetDefault(CldDataSource*) or Set(CldDataSource*).
 102   static CldDataSource* GetComponentDataSource();
 103
 104   // Returns true if and only if the data source returned by Get() is the
 105   // "static" data source.
 106   static bool IsUsingComponentDataSource();
 107
 108  private:
 109   friend class component_updater::CldComponentInstallerTest;
 110
 111   // For unit test code ONLY. Under normal circumstances the calls to
 112   // SetCldDataFilePath() and GetCldDataFilePath() have a DHECK intended to
 113   // perform a sanity check on the runtime CLD data source configuration; no
 114   // production code should be calling SetCldDataFilePath() or
 115   // GetCldDataFilePath() unless the "component" or "standalone" data source is
 116   // being used. Unit tests will generally be built with the "static" data
 117   // source, and this method allows tests to bypass the DCHECK for testing
 118   // purposes.
 119   //
 120   // Unit tests that use this function should use it in SetUp(), and then call
 121   // EnableSanityChecksForTest() in TearDown() for maximum safety.
 122   static void DisableSanityChecksForTest();
 123
 124   // This method [re-]enables the sanity check disabled by
 125   // DisableSanityChecksForTest().
 126   static void EnableSanityChecksForTest();
 127
 128   base::FilePath m_cached_filepath;  // Guarded by m_file_lock
 129   base::Lock m_file_lock;  // Guards m_cached_filepath
 130
 131   DISALLOW_COPY_AND_ASSIGN(CldDataSource);
 132 };
 133
 134 }  // namespace translate
 135 #endif  // COMPONENTS_TRANSLATE_CONTENT_COMMON_CLD_DATA_SOURCE_H_