bb6e0767cc
MXS_WORKER is an abstraction of a worker aka worker thread. It has a pipe whose read descriptor is added to the worker/thread specific poll set and a write descriptor used for sending messages to the worker. The worker exposes a function mxs_worker_post_message using which messages can be sent to the worker. These messages can be sent from any thread but will be delivered on the thread dedicated for the worker. To illustrate how it works, maxadmin has been provided with a new command "ping workers" that sends a message to every worker, which then logs a message to the log. Additional refactoring are needed, since there currently are overlaps and undesirable interactions between the poll mechanism, the thread mechanism and the worker mechanism. This is visible currently, for instance, by it not being possible to shut down MaxScale. The reason is that the workers should be shut down first, then the poll mechanism and finally the threads. The shutdown need to be arranged so that a shutdown message is sent to the workers who then cause the polling loop to exit, which will cause the threads to exit. That can be arranged cleanly by making poll_waitevents() a "method" of the worker, which implies that the poll set becomes a "member variable" of the worker. To be continued.
99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
#pragma once
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/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl.
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*
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* Change Date: 2019-07-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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/**
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* @file poll_basic.h The Descriptor Control Block
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*/
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#include <maxscale/cdefs.h>
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#include <sys/epoll.h>
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typedef enum mxs_poll_action
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{
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MXS_POLL_NOP = 0x00,
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MXS_POLL_ACCEPT = 0x01,
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MXS_POLL_READ = 0x02,
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MXS_POLL_WRITE = 0x04,
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MXS_POLL_HUP = 0x08,
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MXS_POLL_ERROR = 0x10,
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} mxs_poll_action_t;
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typedef struct mxs_poll_data
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{
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/** Pointer to function that knows how to handle events for this particular
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* 'struct mxs_poll_data' structure.
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*
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* @param data The `mxs_poll_data` instance that contained this pointer.
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* @param wid The worker thread id.
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* @param events The epoll events.
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*
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* @return A combination of mxs_poll_action_t enumeration values.
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*/
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uint32_t (*handler)(struct mxs_poll_data *data, int wid, uint32_t events);
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struct
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{
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/**
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* The id of the worker thread
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*/
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int id;
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} thread;
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} MXS_POLL_DATA;
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/**
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* A file descriptor should be added to the poll set of all workers.
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*/
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#define MXS_WORKER_ALL -1
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/**
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* A file descriptor should be added to the poll set of some worker.
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*/
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#define MXS_WORKER_ANY -2
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/**
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* Add a file descriptor with associated data to the poll set.
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*
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* @param wid `MXS_WORKER_ALL` if the file descriptor should be added to the
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* poll set of all workers, `MXS_WORKER_ANY` if the file descriptor
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* should be added to some worker, otherwise the id of a worker.
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* @param fd The file descriptor to be added.
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* @param events Mask of epoll event types.
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* @param data The structure containing the file descriptor to be
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* added.
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*
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* data->handler : Handler that knows how to deal with events
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* for this particular type of 'struct mxs_poll_data'.
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* data->thread.id: Will be updated by `poll_add_fd_to_worker`.
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*
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* @attention If the descriptor should be added to all workers, then the worker
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* thread id will be 0.
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*
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* @attention The provided file descriptor *must* be non-blocking.
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*
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* @return 0 on success, non-zero on failure.
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*/
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int poll_add_fd_to_worker(int wid, int fd, uint32_t events, MXS_POLL_DATA* data);
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/**
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* Remove a file descriptor from a poll set.
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*
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* @param wid `MXS_WORKER_ALL` if the file descriptor should be removed from
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* the poll set of all workers; otherwise the id of a worker.
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* @param fd The file descriptor to be removed.
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*
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* @return 0 on success, non-zero on failure.
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*/
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int poll_remove_fd_from_worker(int wid, int fd);
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