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construct/include/ircd/db/prefetcher.h

102 lines
3.1 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_DB_PREFETCHER_H
namespace ircd::db
{
struct prefetcher extern *prefetcher;
}
struct ircd::db::prefetcher
{
struct ticker;
struct request;
using closure = std::function<bool (request &)>;
ctx::dock dock;
std::deque<request> queue;
std::unique_ptr<ticker> ticker;
ctx::context context;
size_t request_workers {0};
private:
void request_handle(request &);
size_t request_cleanup() noexcept;
void request_worker();
void handle();
void worker();
public:
size_t wait_pending();
size_t cancel(const closure &);
size_t cancel(database &); // Cancel all for db
size_t cancel(column &); // Cancel all for column
bool operator()(column &, const string_view &key, const gopts &);
prefetcher();
~prefetcher() noexcept;
};
struct ircd::db::prefetcher::request
{
using key_buf = char[208];
database *d {nullptr}; // database instance
uint32_t cid {0}; // column ID
uint32_t len {0}; // length of key
steady_point snd; // submitted by user
steady_point req; // request sent to database
steady_point fin; // result from database
key_buf key alignas(16); // key buffer
explicit operator string_view() const noexcept;
request(database &d, const column &c, const string_view &key) noexcept;
request() = default;
};
static_assert
(
sizeof(ircd::db::prefetcher::request) == 256,
"struct ircd::db::prefetcher::request fell out of alignment"
);
struct ircd::db::prefetcher::ticker
{
template<class T> using item = ircd::stats::item<T>;
// montonic event counts
item<uint64_t> queries; ///< All incoming user requests
item<uint64_t> rejects; ///< Queries which were ignored; already cached
item<uint64_t> request; ///< Prefetcher requests added to the queue
item<uint64_t> directs; ///< Direct dispatches to db::request pool
item<uint64_t> handles; ///< Incremented before dispatch to db::request
item<uint64_t> handled; ///< Incremented after dispatch to db::request
item<uint64_t> fetches; ///< Incremented before actual database operation
item<uint64_t> fetched; ///< Incremented after actual database operation
item<uint64_t> cancels; ///< Count of canceled operations
// throughput totals
item<uint64_t> fetched_bytes_key; ///< Total bytes of key data received
item<uint64_t> fetched_bytes_val; ///< Total bytes of value data received
// from last operation only
item<microseconds> last_snd_req; ///< duration request was queued here
item<microseconds> last_req_fin; ///< duration for database operation
// accumulated latency totals
item<microseconds> accum_snd_req;
item<microseconds> accum_req_fin;
ticker();
};