Issue 5183 - Provide async interface for FileSystem

src/JsEngine.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 60 matching lines @@
   };
 }
 
 using namespace AdblockPlus;
 
 TimerPtr AdblockPlus::CreateDefaultTimer()
 {
   return TimerPtr(new DefaultTimer());
 }
 
+FileSystemPtr AdblockPlus::CreateDefaultFileSystem()
+{
+  return FileSystemPtr(new DefaultFileSystem(std::make_shared<DefaultFileSystemSync>()));
+}
+
 WebRequestPtr AdblockPlus::CreateDefaultWebRequest()
 {
   return WebRequestPtr(new DefaultWebRequest(std::make_shared<DefaultWebRequestSync>()));
 }
 
 AdblockPlus::ScopedV8Isolate::ScopedV8Isolate()
 {
   V8Initializer::Init();
   v8::Isolate::CreateParams isolateParams;
   isolateParams.array_buffer_allocator = v8::ArrayBuffer::Allocator::NewDefaultAllocator();
@@ skipping 39 matching lines @@
 void JsEngine::CallTimerTask(const JsWeakValuesID& timerParamsID)
 {
   auto timerParams = TakeJsValues(timerParamsID);
   JsValue callback = std::move(timerParams[0]);
 
   timerParams.erase(timerParams.begin()); // remove callback placeholder
   timerParams.erase(timerParams.begin()); // remove timeout param
   callback.Call(timerParams);
 }
 
-AdblockPlus::JsEngine::JsEngine(TimerPtr timer, WebRequestPtr webRequest)
-  : fileSystem(new DefaultFileSystem())
+AdblockPlus::JsEngine::JsEngine(TimerPtr timer, FileSystemPtr fileSystem,
+  WebRequestPtr webRequest)
+  : fileSystem(std::move(fileSystem))
   , logSystem(new DefaultLogSystem())
   , timer(std::move(timer))
   , webRequest(std::move(webRequest))
 {
 }
 
 AdblockPlus::JsEnginePtr AdblockPlus::JsEngine::New(const AppInfo& appInfo,
-  TimerPtr timer, WebRequestPtr webRequest)
+  TimerPtr timer, FileSystemPtr fileSystem, WebRequestPtr webRequest)
 {
-  JsEnginePtr result(new JsEngine(std::move(timer), std::move(webRequest)));
+  JsEnginePtr result(new JsEngine(std::move(timer),
+                                  std::move(fileSystem),
+                                  std::move(webRequest)));
 
   const v8::Locker locker(result->GetIsolate());
   const v8::Isolate::Scope isolateScope(result->GetIsolate());
   const v8::HandleScope handleScope(result->GetIsolate());
 
   result->context.reset(new v8::Global<v8::Context>(result->GetIsolate(),
     v8::Context::New(result->GetIsolate())));
   auto global = result->GetGlobalObject();
   AdblockPlus::GlobalJsObject::Setup(*result, appInfo, global);
   return result;
@@ skipping 142 matching lines @@
 
 AdblockPlus::JsValueList AdblockPlus::JsEngine::ConvertArguments(const v8::FunctionCallbackInfo<v8::Value>& arguments)
 {
   const JsContext context(*this);
   JsValueList list;
   for (int i = 0; i < arguments.Length(); i++)
     list.push_back(JsValue(shared_from_this(), arguments[i]));
   return list;
 }
 
-AdblockPlus::FileSystemPtr AdblockPlus::JsEngine::GetFileSystem() const
+AdblockPlus::FileSystemPtr AdblockPlus::JsEngine::GetAsyncFileSystem() const
 {
   return fileSystem;
 }
 
-void AdblockPlus::JsEngine::SetFileSystem(const AdblockPlus::FileSystemPtr& val)
+void AdblockPlus::JsEngine::SetFileSystem(const AdblockPlus::FileSystemSyncPtr& val)
 {
   if (!val)
     throw std::runtime_error("FileSystem cannot be null");
 
-  fileSystem = val;
+  fileSystemLegacy = val;

[sergei, 2017/07/05 10:03:21]

BTW, this `fileSystemLegacy` member is not used, so if the user sets it it will
have no effect. It seems the best option is to create async implementation with
injected `val`.

[hub, 2017/07/06 12:21:52]

We don't have a visibility of what filesystem has been created so we can't
simply recreate it. 

The few alternative I see are:
1. Add a method to IFileSystem to do this. We might need to address a few issues
in our own test though.
2. remove this method, but this would break API

One of these should happen.

[sergei, 2017/07/06 14:14:04]

I thought about removing of legacy member and setting 
fileSystem.reset(new DefaultFileSystem(val));

[hub, 2017/07/06 21:24:29]

Done.

 }
 
 void AdblockPlus::JsEngine::SetWebRequest(const AdblockPlus::WebRequestSharedPtr& val)
 {
   if (!val)
     throw std::runtime_error("WebRequest cannot be null");
 
   webRequestLegacy = val;
 }
 
@@ skipping 10 matching lines @@
   logSystem = val;
 }
 
 
 void AdblockPlus::JsEngine::SetGlobalProperty(const std::string& name,
                                               const AdblockPlus::JsValue& value)
 {
   auto global = GetGlobalObject();
   global.SetProperty(name, value);
 }