Issue 5183 - Provide async interface for FileSystem

src/DefaultFileSystem.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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <AdblockPlus/DefaultFileSystem.h>
 #include <cstdio>
 #include <cstring>
 #include <fstream>
+#include <sstream>
 #include <stdexcept>
+#include <thread>
 
 #include <sys/types.h>
 
 #ifdef _WIN32
 #include <windows.h>
 #include <Shlobj.h>
 #include <Shlwapi.h>
 #else
 #include <sys/stat.h>
 #include <cerrno>
@@ skipping 26 matching lines @@
 #else
   // POSIX systems: assume that file system encoding is UTF-8 and just use the
   // file paths as they are.
   std::string NormalizePath(const std::string& path)
   {
     return path;
   }
 #endif
 }
 
-FileSystem::IOBuffer
-DefaultFileSystem::Read(const std::string& path) const
+IFileSystem::IOBuffer
+DefaultFileSystemSync::Read(const std::string& path) const

[sergei, 2017/07/07 13:41:01]

It's actually not our coding style, but I think it's fine. I would even like to
have such coding style (return value on a separate line for a function
implementation).

 {
   std::ifstream file(NormalizePath(path).c_str(), std::ios_base::binary);
   if (file.fail())
     throw RuntimeErrorWithErrno("Failed to open " + path);
 
   file.seekg(0, std::ios_base::end);
   auto dataSize = file.tellg();
   file.seekg(0, std::ios_base::beg);
 
-  IOBuffer data(dataSize);
+  IFileSystem::IOBuffer data(dataSize);
   file.read(reinterpret_cast<std::ifstream::char_type*>(data.data()),
             data.size());
   return data;
 }
 
-void DefaultFileSystem::Write(const std::string& path,
-                              const IOBuffer& data)
+void DefaultFileSystemSync::Write(const std::string& path,
+                              const IFileSystem::IOBuffer& data)
 {
   std::ofstream file(NormalizePath(path).c_str(), std::ios_base::out | std::ios_base::binary);
   file.write(reinterpret_cast<const std::ofstream::char_type*>(data.data()),
              data.size());
 }
 
-void DefaultFileSystem::Move(const std::string& fromPath,
-                             const std::string& toPath)
+void DefaultFileSystemSync::Move(const std::string& fromPath,
+                                 const std::string& toPath)
 {
   if (rename(NormalizePath(fromPath).c_str(), NormalizePath(toPath).c_str()))
     throw RuntimeErrorWithErrno("Failed to move " + fromPath + " to " + toPath);
 }
 
-void DefaultFileSystem::Remove(const std::string& path)
+void DefaultFileSystemSync::Remove(const std::string& path)
 {
   if (remove(NormalizePath(path).c_str()))
     throw RuntimeErrorWithErrno("Failed to remove " + path);
 }
 
-FileSystem::StatResult DefaultFileSystem::Stat(const std::string& path) const
+IFileSystem::StatResult DefaultFileSystemSync::Stat(const std::string& path) const
 {
-  FileSystem::StatResult result;
+  IFileSystem::StatResult result;
 #ifdef WIN32
   WIN32_FILE_ATTRIBUTE_DATA data;
   if (!GetFileAttributesExW(NormalizePath(path).c_str(), GetFileExInfoStandard, &data))
   {
     DWORD err = GetLastError();
     if (err == ERROR_FILE_NOT_FOUND ||
         err == ERROR_PATH_NOT_FOUND ||
         err == ERROR_INVALID_DRIVE)
     {
       return result;
@@ skipping 43 matching lines @@
 #if _POSIX_C_SOURCE >= 200809L
   result.lastModified = static_cast<int64_t>(nativeStat.st_mtim.tv_sec) * MSEC_IN_SEC
                       +  static_cast<int64_t>(nativeStat.st_mtim.tv_nsec) / NSEC_IN_MSEC;
 #else
   result.lastModified = static_cast<int64_t>(nativeStat.st_mtime) * MSEC_IN_SEC;
 #endif
   return result;
 #endif
 }
 
-std::string DefaultFileSystem::Resolve(const std::string& path) const
+std::string DefaultFileSystemSync::Resolve(const std::string& path) const
 {
   if (basePath == "")
   {
     return path;
   }
   else
   {
 #ifdef _WIN32
   if (PathIsRelative(NormalizePath(path).c_str()))
 #else
   if (path.length() && *path.begin() != PATH_SEPARATOR)
 #endif
     {
       return basePath + PATH_SEPARATOR + path;
     }
     else
     {
       return path;
     }
   }
 }
 
-void DefaultFileSystem::SetBasePath(const std::string& path)
+void DefaultFileSystemSync::SetBasePath(const std::string& path)
 {
   basePath = path;
 
   if (*basePath.rbegin() == PATH_SEPARATOR)
   {
     basePath.resize(basePath.size() - 1);
   }
 }
 
+DefaultFileSystem::DefaultFileSystem(const FileSystemSyncPtr& syncImpl)
+  : syncImpl(syncImpl)
+{
+}
+
+void DefaultFileSystem::Read(const std::string& path,
+                             const ReadCallback& callback) const
+{
+  auto impl = syncImpl;
+  std::thread([impl, path, callback]
+  {
+    std::string error;
+    try
+    {
+      auto data = impl->Read(path);
+      callback(std::move(data), error);
+      return;
+    }
+    catch (std::exception& e)
+    {
+      error = e.what();
+    }
+    catch (...)
+    {
+      error =  "Unknown error while reading from " + path;
+    }
+    callback(IOBuffer(), error);
+  }).detach();
+}
+
+void DefaultFileSystem::Write(const std::string& path,
+                              const IOBuffer& data,
+                              const Callback& callback)
+{
+  auto impl = syncImpl;
+  std::thread([impl, path, data, callback]
+  {
+    std::string error;
+    try
+    {
+      impl->Write(path, data);
+    }
+    catch (std::exception& e)
+    {
+      error = e.what();
+    }
+    catch (...)
+    {
+      error = "Unknown error while writing to " + path;
+    }
+    callback(error);
+  }).detach();
+}
+
+void DefaultFileSystem::Move(const std::string& fromPath,
+                             const std::string& toPath,
+                             const Callback& callback)
+{
+  auto impl = syncImpl;
+  std::thread([impl, fromPath, toPath, callback]
+  {
+    std::string error;
+    try
+    {
+      impl->Move(fromPath, toPath);
+    }
+    catch (std::exception& e)
+    {
+      error = e.what();
+    }
+    catch (...)
+    {
+      error = "Unknown error while moving " + fromPath + " to " + toPath;
+    }
+    callback(error);
+  }).detach();
+}
+
+void DefaultFileSystem::Remove(const std::string& path,
+                               const Callback& callback)
+{
+  auto impl = syncImpl;
+  std::thread([impl, path, callback]
+  {
+    std::string error;
+    try
+    {
+      impl->Remove(path);
+    }
+    catch (std::exception& e)
+    {
+      error = e.what();
+    }
+    catch (...)
+    {
+      error = "Unknown error while removing " + path;
+    }
+    callback(error);
+  }).detach();
+}
+
+void DefaultFileSystem::Stat(const std::string& path,
+                             const StatCallback& callback) const
+{
+  auto impl = syncImpl;
+  std::thread([impl, path, callback]
+  {
+    std::string error;
+    try
+    {
+      auto result = impl->Stat(path);
+      callback(result, error);
+      return;
+    }
+    catch (std::exception& e)
+    {
+      error = e.what();
+    }
+    catch (...)
+    {
+      error = "Unknown error while calling stat on " + path;
+    }
+    callback(StatResult(), error);
+  }).detach();
+}
+
+std::string DefaultFileSystem::Resolve(const std::string& path) const
+{
+  return syncImpl->Resolve(path);
+}