172 lines
3.7 KiB
C++
172 lines
3.7 KiB
C++
/*
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* \brief Backend for end points of synchronous interprocess communication
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* \author Martin Stein
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* \author Stefan Kalkowski
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* \date 2012-11-30
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*/
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/*
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* Copyright (C) 2012-2019 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 _CORE__KERNEL__IPC_NODE_H_
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#define _CORE__KERNEL__IPC_NODE_H_
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/* Genode includes */
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#include <util/fifo.h>
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namespace Kernel
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{
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class Thread;
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/**
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* Backend for end points of synchronous interprocess communication
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*/
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class Ipc_node;
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}
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class Kernel::Ipc_node
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{
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private:
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using Queue_item = Genode::Fifo_element<Ipc_node>;
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using Queue = Genode::Fifo<Queue_item>;
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enum State
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{
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INACTIVE = 1,
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AWAIT_REPLY = 2,
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AWAIT_REQUEST = 3,
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};
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Thread &_thread;
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Queue_item _request_queue_item { *this };
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State _state { INACTIVE };
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Ipc_node *_caller { nullptr };
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Ipc_node *_callee { nullptr };
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bool _help { false };
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Queue _request_queue { };
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/**
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* Buffer next request from request queue in 'r' to handle it
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*/
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void _receive_request(Ipc_node &caller);
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/**
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* Receive a given reply if one is expected
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*/
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void _receive_reply(Ipc_node &callee);
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/**
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* Insert 'r' into request queue, buffer it if we were waiting for it
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*/
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void _announce_request(Ipc_node &node);
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/**
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* Cancel all requests in request queue
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*/
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void _cancel_request_queue();
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/**
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* Cancel request in outgoing buffer
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*/
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void _cancel_outbuf_request();
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/**
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* Cancel request in incoming buffer
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*/
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void _cancel_inbuf_request();
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/**
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* A request 'r' in inbuf or request queue was cancelled by sender
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*/
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void _announced_request_cancelled(Ipc_node &node);
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/**
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* The request in the outbuf was cancelled by receiver
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*/
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void _outbuf_request_cancelled();
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/**
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* Return wether we are the source of a helping relationship
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*/
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bool _helps_outbuf_dst();
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/**
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* Make the class noncopyable because it has pointer members
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*/
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Ipc_node(const Ipc_node&) = delete;
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/**
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* Make the class noncopyable because it has pointer members
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*/
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const Ipc_node& operator=(const Ipc_node&) = delete;
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public:
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/**
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* Destructor
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*/
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~Ipc_node();
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/**
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* Constructor
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*/
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Ipc_node(Thread &thread);
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/**
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* Send a request and wait for the according reply
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*
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* \param callee targeted IPC node
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* \param help wether the request implies a helping relationship
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*/
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bool can_send_request();
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void send_request(Ipc_node &callee,
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bool help);
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/**
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* Return root destination of the helping-relation tree we are in
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*/
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Thread &helping_sink();
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/**
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* Call function 'f' of type 'void (Ipc_node *)' for each helper
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*/
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template <typename F> void for_each_helper(F f)
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{
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/* if we have a helper in the receive buffer, call 'f' for it */
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if (_caller && _caller->_help) f(_caller->_thread);
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/* call 'f' for each helper in our request queue */
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_request_queue.for_each([f] (Queue_item &item) {
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Ipc_node &node { item.object() };
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if (node._help) f(node._thread);
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});
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}
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/**
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* Wait until a request has arrived and load it for handling
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*
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* \return wether a request could be received already
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*/
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bool can_await_request();
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void await_request();
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/**
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* Reply to last request if there's any
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*/
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void send_reply();
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/**
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* If IPC node waits, cancel '_outbuf' to stop waiting
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*/
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void cancel_waiting();
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bool awaits_request() const { return _state == AWAIT_REQUEST; }
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};
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#endif /* _CORE__KERNEL__IPC_NODE_H_ */
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