tools/gn/loader.h

   1 // Copyright (c) 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 TOOLS_GN_LOADER_H_
   6 #define TOOLS_GN_LOADER_H_
   7
   8 #include <map>
   9 #include <set>
  10
  11 #include "base/callback.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "tools/gn/label.h"
  14 #include "tools/gn/scope.h"
  15
  16 namespace base {
  17 class MessageLoop;
  18 }
  19
  20 class BuildSettings;
  21 class Settings;
  22 class SourceFile;
  23 class Toolchain;
  24
  25 // The loader manages execution of the different build files. It receives
  26 // requests (normally from the Builder) when new references are found, and also
  27 // manages loading the build config files.
  28 //
  29 // This loader class is abstract so it can be mocked out for testing the
  30 // Builder.
  31 class Loader : public base::RefCountedThreadSafe<Loader> {
  32  public:
  33   Loader();
  34
  35   // Loads the given file in the conext of the given toolchain. The initial
  36   // call to this (the one that actually starts the generation) should have an
  37   // empty toolchain name, which will trigger the load of the default build
  38   // config.
  39   virtual void Load(const SourceFile& file,
  40                     const Label& toolchain_name) = 0;
  41
  42   // Notification that the given toolchain has loaded. This will unblock files
  43   // waiting on this definition.
  44   virtual void ToolchainLoaded(const Toolchain* toolchain) = 0;
  45
  46   // Returns the label of the default toolchain.
  47   virtual Label GetDefaultToolchain() const = 0;
  48
  49   // Returns information about the toolchain with the given label. Will return
  50   // false if we haven't processed this toolchain yet.
  51   virtual const Settings* GetToolchainSettings(const Label& label) const = 0;
  52
  53   // Helper function that extracts the file and toolchain name from the given
  54   // label, and calls Load().
  55   void Load(const Label& label);
  56
  57   // Returns the build file that the given label references.
  58   static SourceFile BuildFileForLabel(const Label& label);
  59
  60   // When processing the default build config, we want to capture the argument
  61   // of set_default_build_config. The implementation of that function uses this
  62   // constant as a property key to get the Label* out of the scope where the
  63   // label should be stored.
  64   static const void* kDefaultToolchainKey;
  65
  66  protected:
  67   friend class base::RefCountedThreadSafe<Loader>;
  68   virtual ~Loader();
  69 };
  70
  71 class LoaderImpl : public Loader {
  72  public:
  73   // Callback to emulate InputFileManager::AsyncLoadFile.
  74   typedef base::Callback<bool(const LocationRange&,
  75                               const BuildSettings*,
  76                               const SourceFile&,
  77                               const base::Callback<void(const ParseNode*)>&,
  78                               Err*)> AsyncLoadFileCallback;
  79
  80   LoaderImpl(const BuildSettings* build_settings);
  81
  82   // Loader implementation.
  83   virtual void Load(const SourceFile& file,
  84                     const Label& toolchain_name) OVERRIDE;
  85   virtual void ToolchainLoaded(const Toolchain* toolchain) OVERRIDE;
  86   virtual Label GetDefaultToolchain() const OVERRIDE;
  87   virtual const Settings* GetToolchainSettings(
  88       const Label& label) const OVERRIDE;
  89
  90   // Sets the message loop corresponding to the main thread. By default this
  91   // class will use the thread active during construction, but there is not
  92   // a message loop active during construction all the time.
  93   void set_main_loop(base::MessageLoop* loop) { main_loop_ = loop; }
  94
  95   // The complete callback is called whenever there are no more pending loads.
  96   // Called on the main thread only. This may be called more than once if the
  97   // queue is drained, but then more stuff gets added.
  98   void set_complete_callback(const base::Closure& cb) {
  99     complete_callback_ = cb;
 100   }
 101
 102   // This callback is used when the loader finds it wants to load a file.
 103   void set_async_load_file(const AsyncLoadFileCallback& cb) {
 104     async_load_file_ = cb;
 105   }
 106
 107   const Label& default_toolchain_label() const {
 108     return default_toolchain_label_;
 109   }
 110
 111  private:
 112   struct LoadID;
 113   struct ToolchainRecord;
 114
 115   virtual ~LoaderImpl();
 116
 117   // Schedules the input file manager to load the given file.
 118   void ScheduleLoadFile(const Settings* settings,
 119                         const SourceFile& file);
 120   void ScheduleLoadBuildConfig(
 121       Settings* settings,
 122       const Scope::KeyValueMap& toolchain_overrides);
 123
 124   // Runs the given file on the background thread. These are called by the
 125   // input file manager.
 126   void BackgroundLoadFile(const Settings* settings,
 127                           const SourceFile& file_name,
 128                           const ParseNode* root);
 129   void BackgroundLoadBuildConfig(
 130       Settings* settings,
 131       const Scope::KeyValueMap& toolchain_overrides,
 132       const ParseNode* root);
 133
 134   // Posted to the main thread when any file other than a build config file
 135   // file has completed running.
 136   void DidLoadFile();
 137
 138   // Posted to the main thread when any build config file has completed
 139   // running. The label should be the name of the toolchain.
 140   //
 141   // If there is no defauled toolchain loaded yet, we'll assume that the first
 142   // call to this indicates to the default toolchain, and this function will
 143   // set the default toolchain name to the given label.
 144   void DidLoadBuildConfig(const Label& label);
 145
 146   // Decrements the pending_loads_ variable and issues the complete callback if
 147   // necessary.
 148   void DecrementPendingLoads();
 149
 150   // Forwards to the appropriate location to load the file.
 151   bool AsyncLoadFile(const LocationRange& origin,
 152                      const BuildSettings* build_settings,
 153                      const SourceFile& file_name,
 154                      const base::Callback<void(const ParseNode*)>& callback,
 155                      Err* err);
 156
 157   base::MessageLoop* main_loop_;
 158
 159   int pending_loads_;
 160   base::Closure complete_callback_;
 161
 162   // When non-null, use this callback instead of the InputFileManager for
 163   // mocking purposes.
 164   AsyncLoadFileCallback async_load_file_;
 165
 166   typedef std::set<LoadID> LoadIDSet;
 167   LoadIDSet invocations_;
 168
 169   const BuildSettings* build_settings_;
 170   Label default_toolchain_label_;
 171
 172   // Records for the build config file loads.
 173   // Owning pointers.
 174   typedef std::map<Label, ToolchainRecord*> ToolchainRecordMap;
 175   ToolchainRecordMap toolchain_records_;
 176 };
 177
 178 #endif  // TOOLS_GN_LOADER_H_