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// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_LEVELDB_LEVELDB_MOJO_PROXY_H_
#define COMPONENTS_LEVELDB_LEVELDB_MOJO_PROXY_H_
#include <map>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "base/callback_forward.h"
#include "base/files/file.h"
#include "base/memory/ref_counted.h"
#include "base/synchronization/waitable_event.h"
#include "components/filesystem/public/interfaces/directory.mojom.h"
namespace base {
class SingleThreadTaskRunner;
}
namespace leveldb {
// A proxy for thread safe access to Mojo objects from multiple threads.
//
// MojoEnv is an object passed to the LevelDB implementation which can be
// called from multiple threads. Mojo pipes are bound to a single
// thread. Because of this mismatch, we create a proxy object which will
// redirect calls to the thread which owns the Mojo pipe, sends and receives
// messages.
//
// All public methods can be accessed from any thread.
class LevelDBMojoProxy : public base::RefCountedThreadSafe<LevelDBMojoProxy> {
public:
explicit LevelDBMojoProxy(
scoped_refptr<base::SingleThreadTaskRunner> task_runner);
// A private struct to hide the underlying file that holds the lock from our
// callers, forcing them to go through our LockFile()/UnlockFile() interface
// so that they don't try to use the underlying pointer from an unsafe thread.
struct OpaqueLock;
// A private struct to hide the underlying root directory that we're
// operating in. LevelDBMojoProxy will want to own all the directory
// pointers, so while opening a database, we pass the directory to the thread
// it will be operated on.
struct OpaqueDir;
// Passes ownership of a |directory| to the other thread, giving a reference
// handle back to the caller.
OpaqueDir* RegisterDirectory(filesystem::mojom::DirectoryPtr directory);
void UnregisterDirectory(OpaqueDir* dir);
// Synchronously calls Directory.OpenFileHandle().
base::File OpenFileHandle(OpaqueDir* dir,
const std::string& name,
uint32_t open_flags);
// Synchronously syncs |directory_|.
filesystem::mojom::FileError SyncDirectory(OpaqueDir* dir,
const std::string& name);
// Synchronously checks whether |name| exists.
bool FileExists(OpaqueDir* dir, const std::string& name);
// Synchronously returns the filenames of all files in |path|.
filesystem::mojom::FileError GetChildren(OpaqueDir* dir,
const std::string& path,
std::vector<std::string>* result);
// Synchronously deletes |path|.
filesystem::mojom::FileError Delete(OpaqueDir* dir,
const std::string& path,
uint32_t delete_flags);
// Synchronously creates |path|.
filesystem::mojom::FileError CreateDir(OpaqueDir* dir,
const std::string& path);
// Synchronously gets the size of a file.
filesystem::mojom::FileError GetFileSize(OpaqueDir* dir,
const std::string& path,
uint64_t* file_size);
// Synchronously renames a file.
filesystem::mojom::FileError RenameFile(OpaqueDir* dir,
const std::string& old_path,
const std::string& new_path);
// Synchronously locks a file. Returns both the file return code, and if OK,
// an opaque object to the lock to enforce going through this interface to
// unlock the file so that unlocking happens on the correct thread.
std::pair<filesystem::mojom::FileError, OpaqueLock*> LockFile(
OpaqueDir* dir,
const std::string& path);
// Unlocks a file. LevelDBMojoProxy takes ownership of lock. (We don't make
// this a scoped_ptr because exporting the ctor/dtor for this struct publicly
// defeats the purpose of the struct.)
filesystem::mojom::FileError UnlockFile(OpaqueLock* lock);
private:
friend class base::RefCountedThreadSafe<LevelDBMojoProxy>;
~LevelDBMojoProxy();
void RunInternal(const base::Closure& task);
void DoOnOtherThread(const base::Closure& c, base::WaitableEvent* event);
// Implementation methods of the public interface. Depending on whether they
// were called from the thread that |task_runner_| is, these might be run
// on the current thread or through PostTask().
void RegisterDirectoryImpl(
mojo::InterfacePtrInfo<filesystem::mojom::Directory> directory_info,
OpaqueDir** out_dir);
void UnregisterDirectoryImpl(OpaqueDir* dir);
void OpenFileHandleImpl(OpaqueDir* dir,
std::string name,
uint32_t open_flags,
base::File* out_file);
void SyncDirectoryImpl(OpaqueDir* dir,
std::string name,
filesystem::mojom::FileError* out_error);
void FileExistsImpl(OpaqueDir* dir,
std::string name,
bool* exists);
void GetChildrenImpl(OpaqueDir* dir,
std::string name,
std::vector<std::string>* contents,
filesystem::mojom::FileError* out_error);
void DeleteImpl(OpaqueDir* dir,
std::string name,
uint32_t delete_flags,
filesystem::mojom::FileError* out_error);
void CreateDirImpl(OpaqueDir* dir,
std::string name,
filesystem::mojom::FileError* out_error);
void GetFileSizeImpl(OpaqueDir* dir,
const std::string& path,
uint64_t* file_size,
filesystem::mojom::FileError* out_error);
void RenameFileImpl(OpaqueDir* dir,
const std::string& old_path,
const std::string& new_path,
filesystem::mojom::FileError* out_error);
void LockFileImpl(OpaqueDir* dir,
const std::string& path,
filesystem::mojom::FileError* out_error,
OpaqueLock** out_lock);
void UnlockFileImpl(std::unique_ptr<OpaqueLock> lock,
filesystem::mojom::FileError* out_error);
// The task runner which represents the thread that all mojo objects are
// bound to.
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
int outstanding_opaque_dirs_;
DISALLOW_COPY_AND_ASSIGN(LevelDBMojoProxy);
};
} // namespace leveldb
#endif // COMPONENTS_LEVELDB_LEVELDB_MOJO_PROXY_H_
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