zircon/system/ulib/fs/include/fs/synchronous-vfs.h

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#pragma once

#ifndef __Fuchsia__
#error "Fuchsia-only header"
#endif

#include <lib/async/cpp/task.h>
#include <fbl/intrusive_double_list.h>
#include <fbl/function.h>
#include <fbl/unique_ptr.h>
#include <fs/connection.h>
#include <fs/vfs.h>

namespace fs {

// A specialization of |Vfs| which tears down all active connections when it
// is destroyed.
//
// This class is NOT thread-safe and it must be used with a
// single-threaded asynchronous dispatcher.
//
// Additionally, this class must only be used with Vnode implementations
// that do not defer completion of operations; "deferred callback" closures
// must be invoked before returning "ERR_DISPATCHER_ASYNC".
//
// It is safe to shutdown the dispatch loop before destroying the
// SynchronousVfs object.
class SynchronousVfs : public Vfs {
public:
    SynchronousVfs();
    SynchronousVfs(async_dispatcher_t* dispatcher);

    // The SynchronousVfs destructor terminates all open
    // connections.
    ~SynchronousVfs() override;

private:
    // Synchronously drop all connections managed by the VFS.
    //
    // Invokes |handler| once when all connections are destroyed.
    // It is safe to delete SynchronousVfs from within the closure.
    void Shutdown(ShutdownCallback handler) override;

    void RegisterConnection(fbl::unique_ptr<Connection> connection) final;
    void UnregisterConnection(Connection* connection) final;
    bool IsTerminating() const final;

    fbl::DoublyLinkedList<fbl::unique_ptr<Connection>> connections_;
    bool is_shutting_down_;
};

} // namespace fs