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100 lines
2.6 KiB
C++
100 lines
2.6 KiB
C++
/*
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* \brief Cross-plugin VFS environment
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* \author Emery Hemingway
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* \author Norman Feske
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* \date 2018-04-02
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*/
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/*
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* Copyright (C) 2018-2019 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _INCLUDE__VFS__ENV_H_
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#define _INCLUDE__VFS__ENV_H_
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#include <vfs/file_system.h>
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#include <vfs/remote_io.h>
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#include <base/allocator.h>
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#include <base/env.h>
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namespace Vfs { struct Env; }
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struct Vfs::Env : Interface
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{
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virtual Genode::Env &env() = 0;
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/**
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* Allocator for creating stuctures shared across open VFS handles
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*/
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virtual Genode::Allocator &alloc() = 0;
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/**
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* VFS root file system
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*/
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virtual File_system &root_dir() = 0;
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/**
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* Registry of deferred wakeups for plugins interacting with remote peers
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*/
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virtual Remote_io::Deferred_wakeups &deferred_wakeups() = 0;
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/**
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* Interface tailored for triggering and waiting for I/O
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*/
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struct Io : Interface, Genode::Noncopyable
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{
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/**
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* Trigger the deferred wakeup of remote peers
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*/
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virtual void commit() = 0;
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/**
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* Wakeup remote peers and wait for I/O progress
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*
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* This method is intended for implementing synchronous I/O.
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*/
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virtual void commit_and_wait() = 0;
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};
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virtual Io &io() = 0;
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/**
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* Interface for notifying the VFS user about possible progress
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*
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* This interface allows VFS plugins to prompt the potential unblocking of
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* the VFS user, e.g., continuing a write operation that was stalled
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* because of a saturated I/O buffer.
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*/
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struct User : Interface, Genode::Noncopyable
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{
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/**
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* Called whenever the VFS observes I/O
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*
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* Note that this method is usually called from the context of an
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* I/O signal handler. Hence, it must never execute application-level
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* code. Otherwise, unexpected nesting of application-level code might
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* occur, in particular if the application performs synchronous I/O
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* via 'wait_and_dispatch_one_io_signal()'.
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*
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* There are two recommended ways to safely implement this interface:
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*
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* The first option is to record the occurence of I/O for a later
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* application-level response by modifying a state variable.
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*
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* The second way is reflecting the condition to an application-level
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* signal handler by calling 'Signal_handler<T>::local_submit()'.
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* This way, the application-level signal handler is executed once
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* the component goes idle next time. This handler can then safely
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* enter application-level code.
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*/
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virtual void wakeup_vfs_user() = 0;
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};
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virtual User &user() = 0;
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};
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#endif /* _INCLUDE__VFS__ENV_H_ */
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