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310 lines
7.8 KiB
C++
310 lines
7.8 KiB
C++
/*
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* \brief Stream of block-operation requests
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* \author Norman Feske
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* \date 2018-12-17
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*/
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/*
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* Copyright (C) 2018 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__BLOCK__REQUEST_STREAM_H_
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#define _INCLUDE__BLOCK__REQUEST_STREAM_H_
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/* Genode includes */
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#include <block_session/block_session.h>
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#include <packet_stream_tx/rpc_object.h>
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#include <block/request.h>
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namespace Block { struct Request_stream; }
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class Block::Request_stream : Genode::Noncopyable
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{
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public:
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struct Block_size { Genode::size_t value; };
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struct Align_log2 { Genode::size_t value; };
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/**
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* Interface for accessing the content of a 'Request'
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*
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* The 'Payload' is separate from 'Request_stream' to allow its use
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* as argument without exposing the entirely of the 'Request_stream'
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* to the called code.
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*/
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class Payload : Noncopyable
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{
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private:
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friend class Request_stream;
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Genode::addr_t const _base;
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Genode::size_t const _size;
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Block::Session::Info const _info;
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/**
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* Return pointer to the first byte of the request content
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*/
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void *_request_ptr(Block::Request request) const
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{
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return (void *)(_base + request.offset);
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}
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/**
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* Return request size in bytes
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*/
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Genode::size_t _request_size(Block::Request const &request) const
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{
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return request.operation.count * _info.block_size;
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}
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bool _valid_range_and_alignment(Block::Request const &request) const
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{
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/* local address of the last byte of the request */
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Genode::addr_t const request_end = _base + request.offset
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+ _request_size(request) - 1;
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/* check for integer overflow and zero-sized request */
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if (request_end <= _base)
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return false;
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/* check for upper bound */
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if (request_end > _base + _size - 1)
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return false;
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/* check for proper alignment */
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if (!Genode::aligned(request.offset, _info.align_log2))
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return false;
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return true;
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}
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Payload(Genode::addr_t base, Genode::size_t size,
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Block::Session::Info info)
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:
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_base(base), _size(size), _info(info)
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{ }
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public:
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/**
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* Call functor 'fn' with the pointer and size of the 'request'
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* content as arguments
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*
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* If the request does not carry any payload, 'fn' is not
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* called.
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*/
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template <typename FN>
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void with_content(Block::Request request, FN const &fn) const
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{
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if (_valid_range_and_alignment(request))
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fn(_request_ptr(request), _request_size(request));
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}
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};
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private:
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Block::Session::Info const _info;
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Packet_stream_tx::Rpc_object<Block::Session::Tx> _tx;
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typedef Genode::Packet_stream_sink<Block::Session::Tx_policy> Tx_sink;
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Payload const _payload;
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public:
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Request_stream(Genode::Region_map &rm,
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Genode::Dataspace_capability ds,
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Genode::Entrypoint &ep,
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Genode::Signal_context_capability sigh,
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Block::Session::Info const info)
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:
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_info(info),
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_tx(ds, rm, ep.rpc_ep()),
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_payload(_tx.sink()->ds_local_base(), _tx.sink()->ds_size(), info)
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{
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_tx.sigh_ready_to_ack(sigh);
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_tx.sigh_packet_avail(sigh);
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}
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virtual ~Request_stream()
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{
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_tx.sigh_ready_to_ack(Genode::Signal_context_capability());
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_tx.sigh_packet_avail(Genode::Signal_context_capability());
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}
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Genode::Capability<Block::Session::Tx> tx_cap() { return _tx.cap(); }
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Block::Session::Info info() const { return _info; }
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/**
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* Call functor 'fn' with 'Payload' interface as argument
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*
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* The 'Payload' interface allows the functor to access the content
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* of a request by calling 'Payload::with_content'.
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*/
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template <typename FN>
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void with_payload(FN const &fn) const { fn(_payload); }
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/**
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* Call functor 'fn' with the pointer and size to the 'request' content
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*
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* This is a wrapper for 'Payload::with_content'. It is convenient
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* in situations where the 'Payload' interface does not need to be
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* propagated as argument.
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*/
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template <typename FN>
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void with_content(Request const &request, FN const &fn) const
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{
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_payload.with_content(request, fn);
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}
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enum class Response { ACCEPTED, REJECTED, RETRY };
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/**
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* Call functor 'fn' for each pending request, with its packet as argument
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*
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* The boolean return value of the functor expresses whether the request
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* was accepted or not. If it was accepted, the request is removed from the
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* packet stream. If the request could not be accepted, the iteration
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* aborts and the request packet stays in the packet stream.
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*/
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template <typename FN>
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void with_requests(FN const &fn)
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{
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Tx_sink &tx_sink = *_tx.sink();
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using namespace Genode;
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for (;;) {
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if (!tx_sink.packet_avail())
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return;
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typedef Block::Packet_descriptor Packet_descriptor;
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Packet_descriptor const packet = tx_sink.peek_packet();
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bool const packet_valid = tx_sink.packet_valid(packet)
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&& (packet.offset() >= 0);
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Operation operation { .type = packet.operation_type(),
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.block_number = packet.block_number(),
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.count = packet.block_count() };
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Request request { .operation = operation,
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.success = false,
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.offset = packet.offset(),
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.tag = packet.tag() };
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Response const response = packet_valid
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? fn(request)
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: Response::REJECTED;
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bool progress = false;
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switch (response) {
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case Response::REJECTED:
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/*
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* Acknowledge rejected packet if there is enough room in
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* the acknowledgement queue. Otherwise, the rejected
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* packet stays in the request queue and is evaluated
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* again.
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*/
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if (tx_sink.ack_slots_free()) {
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(void)tx_sink.try_get_packet();
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tx_sink.try_ack_packet(packet);
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progress = true;
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}
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break;
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case Response::ACCEPTED:
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(void)tx_sink.try_get_packet();
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progress = true;
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break;
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case Response::RETRY:
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break;
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}
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/*
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* Stop iterating of no request-queue elements can be consumed.
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*/
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if (!progress)
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break;
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}
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}
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class Ack : Noncopyable
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{
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private:
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friend class Request_stream;
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Tx_sink &_tx_sink;
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bool _submitted = false;
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Genode::size_t const _block_size;
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Ack(Tx_sink &tx_sink, Genode::size_t block_size)
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: _tx_sink(tx_sink), _block_size(block_size) { }
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public:
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void submit(Block::Request request)
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{
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if (_submitted) {
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Genode::warning("attempt to ack the same packet twice");
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return;
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}
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typedef Block::Packet_descriptor Packet_descriptor;
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Packet_descriptor::Payload
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payload { .offset = request.offset,
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.bytes = request.operation.count * _block_size };
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Packet_descriptor packet(request.operation, payload, request.tag);
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packet.succeeded(request.success);
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_tx_sink.try_ack_packet(packet);
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_submitted = true;
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}
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};
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/**
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* Try to submit acknowledgement packets
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*
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* The method repeatedly calls the functor 'fn' with an 'Ack' reference,
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* which provides an interface to 'submit' one acknowledgement. The
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* iteration stops when the acknowledgement queue is fully populated or if
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* the functor does not call 'Ack::submit'.
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*/
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template <typename FN>
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void try_acknowledge(FN const &fn)
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{
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Tx_sink &tx_sink = *_tx.sink();
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while (tx_sink.ack_slots_free()) {
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Ack ack(tx_sink, _payload._info.block_size);
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fn(ack);
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if (!ack._submitted)
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break;
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}
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}
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void wakeup_client_if_needed() { _tx.sink()->wakeup(); }
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};
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#endif /* _INCLUDE__BLOCK__REQUEST_STREAM_H_ */
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