467 lines
19 KiB
C++
467 lines
19 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 <vector>
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#include "mutation.hh"
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#include "clustering_key_filter.hh"
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#include "core/future.hh"
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#include "core/future-util.hh"
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#include "core/do_with.hh"
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#include "tracing/trace_state.hh"
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// A mutation_reader is an object which allows iterating on mutations: invoke
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// the function to get a future for the next mutation, with an unset optional
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// marking the end of iteration. After calling mutation_reader's operator(),
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// caller must keep the object alive until the returned future is fulfilled.
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//
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// streamed_mutation object emitted by mutation_reader remains valid after the
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// destruction of the mutation_reader.
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//
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// Asking mutation_reader for another streamed_mutation (i.e. invoking
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// mutation_reader::operator()) invalidates all streamed_mutation objects
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// previously produced by that reader.
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//
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// The mutations returned have strictly monotonically increasing keys. Two
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// consecutive mutations never have equal keys.
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//
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// TODO: When iterating over mutations, we don't need a schema_ptr for every
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// single one as it is normally the same for all of them. So "mutation" might
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// not be the optimal object to use here.
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class mutation_reader final {
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public:
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class impl {
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public:
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virtual ~impl() {}
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virtual future<streamed_mutation_opt> operator()() = 0;
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virtual future<> fast_forward_to(const dht::partition_range&) {
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throw std::bad_function_call();
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}
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};
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private:
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class null_impl final : public impl {
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public:
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virtual future<streamed_mutation_opt> operator()() override { throw std::bad_function_call(); }
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};
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private:
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std::unique_ptr<impl> _impl;
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public:
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mutation_reader(std::unique_ptr<impl> impl) noexcept : _impl(std::move(impl)) {}
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mutation_reader() : mutation_reader(std::make_unique<null_impl>()) {}
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mutation_reader(mutation_reader&&) = default;
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mutation_reader(const mutation_reader&) = delete;
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mutation_reader& operator=(mutation_reader&&) = default;
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mutation_reader& operator=(const mutation_reader&) = delete;
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future<streamed_mutation_opt> operator()() { return _impl->operator()(); }
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// Changes the range of partitions to pr. The range can only be moved
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// forwards. pr.begin() needs to be larger than pr.end() of the previousl
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// used range (i.e. either the initial one passed to the constructor or a
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// previous fast forward target).
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// pr needs to be valid until the reader is destroyed or fast_forward_to()
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// is called again.
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future<> fast_forward_to(const dht::partition_range& pr) { return _impl->fast_forward_to(pr); }
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};
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// Impl: derived from mutation_reader::impl; Args/args: arguments for Impl's constructor
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template <typename Impl, typename... Args>
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inline
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mutation_reader
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make_mutation_reader(Args&&... args) {
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return mutation_reader(std::make_unique<Impl>(std::forward<Args>(args)...));
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}
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// Combines multiple mutation_readers into one.
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class combined_mutation_reader : public mutation_reader::impl {
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std::vector<mutation_reader> _readers;
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std::vector<mutation_reader*> _all_readers;
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struct mutation_and_reader {
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streamed_mutation m;
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mutation_reader* read;
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bool operator<(const mutation_and_reader& other) const {
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return read < other.read;
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}
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struct less_compare {
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bool operator()(const mutation_and_reader& a, mutation_reader* b) const {
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return a.read < b;
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}
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bool operator()(mutation_reader* a, const mutation_and_reader& b) const {
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return a < b.read;
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}
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bool operator()(const mutation_and_reader& a, const mutation_and_reader& b) const {
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return a < b;
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}
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};
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};
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std::vector<mutation_and_reader> _ptables;
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// comparison function for std::make_heap()/std::push_heap()
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static bool heap_compare(const mutation_and_reader& a, const mutation_and_reader& b) {
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auto&& s = a.m.schema();
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// order of comparison is inverted, because heaps produce greatest value first
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return b.m.decorated_key().less_compare(*s, a.m.decorated_key());
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}
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std::vector<streamed_mutation> _current;
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std::vector<mutation_reader*> _next;
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private:
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future<> prepare_next();
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// Produces next mutation or disengaged optional if there are no more.
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future<streamed_mutation_opt> next();
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protected:
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combined_mutation_reader() = default;
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void init_mutation_reader_set(std::vector<mutation_reader*>);
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future<> fast_forward_to(std::vector<mutation_reader*> to_add, std::vector<mutation_reader*> to_remove, const dht::partition_range& pr);
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public:
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combined_mutation_reader(std::vector<mutation_reader> readers);
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virtual future<streamed_mutation_opt> operator()() override;
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virtual future<> fast_forward_to(const dht::partition_range& pr) override;
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};
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// Creates a mutation reader which combines data return by supplied readers.
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// Returns mutation of the same schema only when all readers return mutations
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// of the same schema.
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mutation_reader make_combined_reader(std::vector<mutation_reader>);
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mutation_reader make_combined_reader(mutation_reader&& a, mutation_reader&& b);
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// reads from the input readers, in order
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mutation_reader make_reader_returning(mutation);
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mutation_reader make_reader_returning(streamed_mutation);
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mutation_reader make_reader_returning_many(std::vector<mutation>,
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const query::partition_slice& slice = query::full_slice,
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streamed_mutation::forwarding fwd = streamed_mutation::forwarding::no);
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mutation_reader make_reader_returning_many(std::vector<mutation>, const dht::partition_range&);
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mutation_reader make_reader_returning_many(std::vector<streamed_mutation>);
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mutation_reader make_empty_reader();
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struct restricted_mutation_reader_config {
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semaphore* sem = nullptr;
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std::chrono::nanoseconds timeout = {};
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size_t max_queue_length = std::numeric_limits<size_t>::max();
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std::function<void ()> raise_queue_overloaded_exception = default_raise_queue_overloaded_exception;
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static void default_raise_queue_overloaded_exception() {
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throw std::runtime_error("restricted mutation reader queue overload");
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}
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};
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// Restricts a given `mutation_reader` to a concurrency limited according to settings in
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// a restricted_mutation_reader_config. These settings include a semaphore for limiting the number
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// of active concurrent readers, a timeout for inactive readers, and a maximum queue size for
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// inactive readers.
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mutation_reader make_restricted_reader(const restricted_mutation_reader_config& config, unsigned weight, mutation_reader&& base);
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/*
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template<typename T>
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concept bool StreamedMutationFilter() {
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return requires(T t, const streamed_mutation& sm) {
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{ t(sm) } -> bool;
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};
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}
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*/
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template <typename MutationFilter>
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class filtering_reader : public mutation_reader::impl {
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mutation_reader _rd;
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MutationFilter _filter;
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streamed_mutation_opt _current;
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static_assert(std::is_same<bool, std::result_of_t<MutationFilter(const streamed_mutation&)>>::value, "bad MutationFilter signature");
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public:
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filtering_reader(mutation_reader rd, MutationFilter&& filter)
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: _rd(std::move(rd)), _filter(std::forward<MutationFilter>(filter)) {
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}
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virtual future<streamed_mutation_opt> operator()() override {\
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return repeat([this] {
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return _rd().then([this] (streamed_mutation_opt&& mo) mutable {
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if (!mo) {
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_current = std::move(mo);
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return stop_iteration::yes;
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} else {
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if (_filter(*mo)) {
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_current = std::move(mo);
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return stop_iteration::yes;
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}
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return stop_iteration::no;
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}
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});
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}).then([this] {
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return make_ready_future<streamed_mutation_opt>(std::move(_current));
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});
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};
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virtual future<> fast_forward_to(const dht::partition_range& pr) override {
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return _rd.fast_forward_to(pr);
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}
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};
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// Creates a mutation_reader wrapper which creates a new stream of mutations
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// with some mutations removed from the original stream.
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// MutationFilter is a callable which decides which mutations are dropped. It
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// accepts mutation const& and returns a bool. The mutation stays in the
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// stream if and only if the filter returns true.
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template <typename MutationFilter>
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mutation_reader make_filtering_reader(mutation_reader rd, MutationFilter&& filter) {
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return make_mutation_reader<filtering_reader<MutationFilter>>(std::move(rd), std::forward<MutationFilter>(filter));
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}
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// Calls the consumer for each element of the reader's stream until end of stream
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// is reached or the consumer requests iteration to stop by returning stop_iteration::yes.
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// The consumer should accept mutation as the argument and return stop_iteration.
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// The returned future<> resolves when consumption ends.
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template <typename Consumer>
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inline
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future<> consume(mutation_reader& reader, Consumer consumer) {
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static_assert(std::is_same<future<stop_iteration>, futurize_t<std::result_of_t<Consumer(mutation&&)>>>::value, "bad Consumer signature");
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using futurator = futurize<std::result_of_t<Consumer(mutation&&)>>;
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return do_with(std::move(consumer), [&reader] (Consumer& c) -> future<> {
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return repeat([&reader, &c] () {
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return reader().then([] (auto sm) {
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return mutation_from_streamed_mutation(std::move(sm));
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}).then([&c] (mutation_opt&& mo) -> future<stop_iteration> {
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if (!mo) {
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return make_ready_future<stop_iteration>(stop_iteration::yes);
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}
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return futurator::apply(c, std::move(*mo));
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});
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});
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});
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}
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// mutation_source represents source of data in mutation form. The data source
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// can be queried multiple times and in parallel. For each query it returns
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// independent mutation_reader.
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// The reader returns mutations having all the same schema, the one passed
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// when invoking the source.
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class mutation_source {
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using partition_range = const dht::partition_range&;
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using io_priority = const io_priority_class&;
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using func_type = std::function<mutation_reader(schema_ptr,
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partition_range,
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const query::partition_slice&,
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io_priority,
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tracing::trace_state_ptr,
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streamed_mutation::forwarding
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)>;
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// We could have our own version of std::function<> that is nothrow
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// move constructible and save some indirection and allocation.
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// Probably not worth the effort though.
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std::unique_ptr<func_type> _fn;
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private:
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mutation_source() = default;
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explicit operator bool() const { return bool(_fn); }
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friend class optimized_optional<mutation_source>;
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public:
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mutation_source(func_type fn) : _fn(std::make_unique<func_type>(std::move(fn))) {}
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mutation_source(std::function<mutation_reader(schema_ptr, partition_range, const query::partition_slice&, io_priority)> fn)
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: _fn(std::make_unique<func_type>([fn = std::move(fn)] (schema_ptr s, partition_range range, const query::partition_slice& slice, io_priority pc, tracing::trace_state_ptr, streamed_mutation::forwarding) {
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return fn(s, range, slice, pc);
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})) {}
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mutation_source(std::function<mutation_reader(schema_ptr, partition_range, const query::partition_slice&)> fn)
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: _fn(std::make_unique<func_type>([fn = std::move(fn)] (schema_ptr s, partition_range range, const query::partition_slice& slice, io_priority, tracing::trace_state_ptr, streamed_mutation::forwarding) {
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return fn(s, range, slice);
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})) {}
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mutation_source(std::function<mutation_reader(schema_ptr, partition_range range)> fn)
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: _fn(std::make_unique<func_type>([fn = std::move(fn)] (schema_ptr s, partition_range range, const query::partition_slice&, io_priority, tracing::trace_state_ptr, streamed_mutation::forwarding) {
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return fn(s, range);
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})) {}
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mutation_source(const mutation_source& other)
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: _fn(std::make_unique<func_type>(*other._fn)) { }
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mutation_source& operator=(const mutation_source& other) {
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_fn = std::make_unique<func_type>(*other._fn);
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return *this;
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}
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mutation_source(mutation_source&&) = default;
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mutation_source& operator=(mutation_source&&) = default;
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// Creates a new reader.
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//
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// All parameters captured by reference must remain live as long as returned
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// mutation_reader or streamed_mutation obtained through it are alive.
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mutation_reader operator()(schema_ptr s,
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partition_range range = query::full_partition_range,
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const query::partition_slice& slice = query::full_slice,
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io_priority pc = default_priority_class(),
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tracing::trace_state_ptr trace_state = nullptr,
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streamed_mutation::forwarding fwd = streamed_mutation::forwarding::no) const
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{
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return (*_fn)(std::move(s), range, slice, pc, std::move(trace_state), fwd);
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}
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};
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template<>
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struct move_constructor_disengages<mutation_source> {
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enum { value = true };
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};
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using mutation_source_opt = optimized_optional<mutation_source>;
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/// A partition_presence_checker quickly returns whether a key is known not to exist
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/// in a data source (it may return false positives, but not false negatives).
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enum class partition_presence_checker_result {
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definitely_doesnt_exist,
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maybe_exists
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};
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using partition_presence_checker = std::function<partition_presence_checker_result (const dht::decorated_key& key)>;
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inline
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partition_presence_checker make_default_partition_presence_checker() {
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return [] (const dht::decorated_key&) { return partition_presence_checker_result::maybe_exists; };
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}
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template<typename Consumer>
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future<stop_iteration> do_consume_streamed_mutation_flattened(streamed_mutation& sm, Consumer& c)
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{
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do {
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if (sm.is_buffer_empty()) {
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if (sm.is_end_of_stream()) {
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break;
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}
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auto f = sm.fill_buffer();
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if (!f.available()) {
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return f.then([&] { return do_consume_streamed_mutation_flattened(sm, c); });
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}
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f.get();
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} else {
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if (sm.pop_mutation_fragment().consume(c) == stop_iteration::yes) {
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break;
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}
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}
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} while (true);
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return make_ready_future<stop_iteration>(c.consume_end_of_partition());
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}
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/*
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template<typename T>
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concept bool FlattenedConsumer() {
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return StreamedMutationConsumer() && requires(T obj, const dht::decorated_key& dk) {
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obj.consume_new_partition(dk);
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obj.consume_end_of_partition();
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};
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}
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*/
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template<typename FlattenedConsumer>
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auto consume_flattened(mutation_reader mr, FlattenedConsumer&& c, bool reverse_mutations = false)
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{
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return do_with(std::move(mr), std::move(c), stdx::optional<streamed_mutation>(), [reverse_mutations] (auto& mr, auto& c, auto& sm) {
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return repeat([&, reverse_mutations] {
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return mr().then([&, reverse_mutations] (auto smopt) {
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if (!smopt) {
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return make_ready_future<stop_iteration>(stop_iteration::yes);
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}
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if (!reverse_mutations) {
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sm.emplace(std::move(*smopt));
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} else {
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sm.emplace(reverse_streamed_mutation(std::move(*smopt)));
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}
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c.consume_new_partition(sm->decorated_key());
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if (sm->partition_tombstone()) {
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c.consume(sm->partition_tombstone());
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}
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return do_consume_streamed_mutation_flattened(*sm, c);
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});
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}).then([&] {
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return c.consume_end_of_stream();
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});
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});
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}
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/*
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template<typename T>
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concept bool StreamedMutationFilter() {
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return requires(T obj, const streamed_mutation& sm) {
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{ filter(sm); } -> bool;
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};
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}
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*/
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// This version of consume_flattened() must be run inside a thread and
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// guarantees that all FlattenedConsumer functions will also be called in the same thread
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// context.
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template<typename FlattenedConsumer, typename StreamedMutationFilter>
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auto consume_flattened_in_thread(mutation_reader& mr, FlattenedConsumer& c, StreamedMutationFilter&& filter)
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{
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while (true) {
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auto smopt = mr().get0();
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if (!smopt) {
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break;
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}
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auto& sm = *smopt;
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if (!filter(sm)) {
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continue;
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}
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c.consume_new_partition(sm.decorated_key());
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if (sm.partition_tombstone()) {
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c.consume(sm.partition_tombstone());
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}
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do {
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if (sm.is_buffer_empty()) {
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if (sm.is_end_of_stream()) {
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break;
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}
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sm.fill_buffer().get0();
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} else {
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if (sm.pop_mutation_fragment().consume(c) == stop_iteration::yes) {
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break;
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}
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}
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} while (true);
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if (c.consume_end_of_partition() == stop_iteration::yes) {
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break;
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}
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}
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return c.consume_end_of_stream();
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}
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template<typename FlattenedConsumer>
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auto consume_flattened_in_thread(mutation_reader& mr, FlattenedConsumer& c)
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{
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return consume_flattened_in_thread(mr, c, [] (auto&&) { return true; });
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}
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// Adapts a non-movable FlattenedConsumer to a movable one.
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template<typename FlattenedConsumer>
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class stable_flattened_mutations_consumer {
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std::unique_ptr<FlattenedConsumer> _ptr;
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public:
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stable_flattened_mutations_consumer(std::unique_ptr<FlattenedConsumer> ptr) : _ptr(std::move(ptr)) {}
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auto consume_new_partition(const dht::decorated_key& dk) { return _ptr->consume_new_partition(dk); }
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auto consume(tombstone t) { return _ptr->consume(t); }
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auto consume(static_row&& sr) { return _ptr->consume(std::move(sr)); }
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auto consume(clustering_row&& cr) { return _ptr->consume(std::move(cr)); }
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auto consume(range_tombstone&& rt) { return _ptr->consume(std::move(rt)); }
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auto consume_end_of_partition() { return _ptr->consume_end_of_partition(); }
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auto consume_end_of_stream() { return _ptr->consume_end_of_stream(); }
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};
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template<typename FlattenedConsumer, typename... Args>
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stable_flattened_mutations_consumer<FlattenedConsumer> make_stable_flattened_mutations_consumer(Args&&... args) {
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return { std::make_unique<FlattenedConsumer>(std::forward<Args>(args)...) };
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}
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// Requires ranges to be sorted and disjoint.
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mutation_reader
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make_multi_range_reader(schema_ptr s, mutation_source source, const dht::partition_range_vector& ranges,
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const query::partition_slice& slice, const io_priority_class& pc = default_priority_class(),
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tracing::trace_state_ptr trace_state = nullptr, streamed_mutation::forwarding fwd = streamed_mutation::forwarding::no);
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