0f41ef1b84
Also add comments about the expected signature of IndexConsumer Signed-off-by: Glauber Costa <glauber@scylladb.com>
130 lines
4.0 KiB
C++
130 lines
4.0 KiB
C++
/*
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* Copyright (C) 2015 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "sstables.hh"
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#include "consumer.hh"
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namespace sstables {
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class index_consumer {
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uint64_t max_quantity;
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public:
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index_list indexes;
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index_consumer(uint64_t q) : max_quantity(q) {
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indexes.reserve(q);
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}
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bool should_continue() {
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return indexes.size() < max_quantity;
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}
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void consume_entry(index_entry&& ie) {
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indexes.push_back(std::move(ie));
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}
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};
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// IndexConsumer is a concept that implements:
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//
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// bool should_continue();
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// void consume_entry(index_entry&& ie);
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template <class IndexConsumer>
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class index_consume_entry_context: public data_consumer::continuous_data_consumer<index_consume_entry_context<IndexConsumer>> {
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using proceed = data_consumer::proceed;
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using continuous_data_consumer = data_consumer::continuous_data_consumer<index_consume_entry_context<IndexConsumer>>;
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private:
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IndexConsumer& _consumer;
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enum class state {
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START,
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KEY_SIZE,
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KEY_BYTES,
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POSITION,
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PROMOTED_SIZE,
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PROMOTED_BYTES,
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CONSUME_ENTRY,
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} _state = state::START;
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temporary_buffer<char> _key;
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temporary_buffer<char> _promoted;
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public:
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void verify_end_state() {
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}
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bool non_consuming() const {
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return ((_state == state::CONSUME_ENTRY) || (_state == state::START) ||
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((_state == state::PROMOTED_BYTES) && (continuous_data_consumer::_prestate == continuous_data_consumer::prestate::NONE)));
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}
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proceed process_state(temporary_buffer<char>& data) {
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switch (_state) {
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// START comes first, to make the handling of the 0-quantity case simpler
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case state::START:
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if (!_consumer.should_continue()) {
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return proceed::no;
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}
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_state = state::KEY_SIZE;
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break;
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case state::KEY_SIZE:
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if (this->read_16(data) != continuous_data_consumer::read_status::ready) {
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_state = state::KEY_BYTES;
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break;
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}
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case state::KEY_BYTES:
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if (this->read_bytes(data, this->_u16, _key) != continuous_data_consumer::read_status::ready) {
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_state = state::POSITION;
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break;
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}
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case state::POSITION:
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if (this->read_64(data) != continuous_data_consumer::read_status::ready) {
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_state = state::PROMOTED_SIZE;
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break;
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}
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case state::PROMOTED_SIZE:
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if (this->read_32(data) != continuous_data_consumer::read_status::ready) {
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_state = state::PROMOTED_BYTES;
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break;
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}
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case state::PROMOTED_BYTES:
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if (this->read_bytes(data, this->_u32, _promoted) != continuous_data_consumer::read_status::ready) {
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_state = state::CONSUME_ENTRY;
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break;
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}
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case state::CONSUME_ENTRY:
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_consumer.consume_entry(index_entry(std::move(_key), this->_u64, std::move(_promoted)));
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_state = state::START;
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break;
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default:
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throw malformed_sstable_exception("unknown state");
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}
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return proceed::yes;
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}
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index_consume_entry_context(IndexConsumer& consumer,
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input_stream<char>&& input, uint64_t maxlen)
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: continuous_data_consumer(std::move(input), maxlen)
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, _consumer(consumer)
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{}
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};
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}
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