dd8a10f466
The old polling message system is obsolete now that the worker messages are implemented. The old system was only used to clean up the persistent connection pool of a server.
482 lines
16 KiB
C++
482 lines
16 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/bsl11.
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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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#include <maxscale/cppdefs.hh>
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#include <memory>
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#include <tr1/unordered_map>
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#include <maxscale/platform.h>
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#include <maxscale/session.h>
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#include "messagequeue.hh"
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#include "poll.h"
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#include "worker.h"
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#include "workertask.hh"
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namespace maxscale
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{
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class Semaphore;
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struct WORKER_STATISTICS
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{
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WORKER_STATISTICS()
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{
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memset(this, 0, sizeof(WORKER_STATISTICS));
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}
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enum
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{
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MAXNFDS = 10,
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N_QUEUE_TIMES = 30
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};
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int64_t n_read; /*< Number of read events */
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int64_t n_write; /*< Number of write events */
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int64_t n_error; /*< Number of error events */
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int64_t n_hup; /*< Number of hangup events */
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int64_t n_accept; /*< Number of accept events */
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int64_t n_polls; /*< Number of poll cycles */
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int64_t n_pollev; /*< Number of polls returning events */
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int64_t n_nbpollev; /*< Number of polls returning events */
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int64_t n_fds[MAXNFDS]; /*< Number of wakeups with particular n_fds value */
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int64_t evq_length; /*< Event queue length */
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int64_t evq_max; /*< Maximum event queue length */
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int64_t blockingpolls; /*< Number of epoll_waits with a timeout specified */
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uint32_t qtimes[N_QUEUE_TIMES + 1];
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uint32_t exectimes[N_QUEUE_TIMES + 1];
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int64_t maxqtime;
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int64_t maxexectime;
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};
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class Worker : public MXS_WORKER
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, private MessageQueue::Handler
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, private MXS_POLL_DATA
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{
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Worker(const Worker&);
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Worker& operator = (const Worker&);
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public:
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typedef WORKER_STATISTICS STATISTICS;
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typedef WorkerTask Task;
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typedef WorkerDisposableTask DisposableTask;
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typedef std::tr1::unordered_map<uint32_t, MXS_SESSION*> SessionsById;
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enum state_t
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{
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STOPPED,
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IDLE,
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POLLING,
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PROCESSING,
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ZPROCESSING
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};
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enum execute_mode_t
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{
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EXECUTE_AUTO, /**< Execute tasks immediately */
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EXECUTE_QUEUED /**< Only queue tasks for execution */
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};
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/**
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* Initialize the worker mechanism.
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*
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* To be called once at process startup. This will cause as many workers
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* to be created as the number of threads defined.
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*
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* @return True if the initialization succeeded, false otherwise.
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*/
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static bool init();
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/**
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* Finalize the worker mechanism.
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*
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* To be called once at process shutdown. This will cause all workers
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* to be destroyed. When the function is called, no worker should be
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* running anymore.
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*/
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static void finish();
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/**
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* Returns the id of the worker
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*
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* @return The id of the worker.
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*/
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int id() const
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{
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return m_id;
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}
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/**
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* Returns the state of the worker.
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*
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* @return The current state.
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*
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* @attentions The state might have changed the moment after the function returns.
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*/
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state_t state() const
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{
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return m_state;
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}
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/**
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* Returns statistics for this worker.
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*
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* @return The worker specific statistics.
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*
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* @attentions The statistics may change at any time.
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*/
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const STATISTICS& statistics() const
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{
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return m_statistics;
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}
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/**
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* Returns statistics for all workers.
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*
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* @return Combined statistics.
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*
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* @attentions The statistics may no longer be accurate by the time it has
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* been returned. The returned values may also not represent a
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* 100% consistent set.
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*/
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static STATISTICS get_statistics();
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/**
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* Return a specific combined statistic value.
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*
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* @param what What to return.
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*
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* @return The corresponding value.
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*/
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static int64_t get_one_statistic(POLL_STAT what);
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/**
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* Add a file descriptor to the epoll instance of the worker.
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*
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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 pData The poll data associated with the descriptor:
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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 the worker.
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*
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* @attention The provided file descriptor must be non-blocking.
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* @attention @c pData must remain valid until the file descriptor is
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* removed from the worker.
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*
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* @return True, if the descriptor could be added, false otherwise.
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*/
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bool add_fd(int fd, uint32_t events, MXS_POLL_DATA* pData);
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/**
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* Add a file descriptor to the epoll instance shared between all workers.
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* Events occuring on the provided file descriptor will be handled by all
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* workers. This is primarily intended for listening sockets where the
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* only event is EPOLLIN, signaling that accept() can be used on the listening
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* socket for creating a connected socket to a client.
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*
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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 pData The poll data associated with the descriptor:
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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: 0
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*
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* @return True, if the descriptor could be added, false otherwise.
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*/
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static bool add_shared_fd(int fd, uint32_t events, MXS_POLL_DATA* pData);
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/**
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* Remove a file descriptor from the worker's epoll instance.
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*
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* @param fd The file descriptor to be removed.
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*
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* @return True on success, false on failure.
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*/
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bool remove_fd(int fd);
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/**
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* Remove a file descriptor from the epoll instance shared between all workers.
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*
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* @param fd The file descriptor to be removed.
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*
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* @return True on success, false on failure.
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*/
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static bool remove_shared_fd(int fd);
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/**
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* Main function of worker.
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*
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* The worker will run the poll loop, until it is told to shut down.
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*
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* @attention This function will run in the calling thread.
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*/
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void run();
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/**
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* Run worker in separate thread.
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*
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* This function will start a new thread, in which the `run`
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* function will be executed.
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*
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* @return True if the thread could be started, false otherwise.
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*/
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bool start();
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/**
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* Waits for the worker to finish.
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*/
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void join();
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/**
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* Initate shutdown of worker.
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*
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* @attention A call to this function will only initiate the shutdowm,
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* the worker will not have shut down when the function returns.
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*
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* @attention This function is signal safe.
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*/
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void shutdown();
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/**
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* Query whether worker should shutdown.
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*
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* @return True, if the worker should shut down, false otherwise.
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*/
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bool should_shutdown() const
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{
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return m_should_shutdown;
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}
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/**
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* Posts a task to a worker for execution.
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*
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* @param pTask The task to be executed.
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* @param pSem If non-NULL, will be posted once the task's `execute` return.
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* @param mode Execution mode
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*
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* @return True if the task could be posted (i.e. not executed), false otherwise.
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*
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* @attention The instance must remain valid for as long as it takes for the
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* task to be transferred to the worker and its `execute` function
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* to be called.
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*
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* The semaphore can be used for waiting for the task to be finished.
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*
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* @code
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* Semaphore sem;
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* MyTask task;
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*
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* pWorker->execute(&task, &sem);
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* sem.wait();
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*
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* MyResult& result = task.result();
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* @endcode
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*/
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bool post(Task* pTask, Semaphore* pSem = NULL, enum execute_mode_t mode = EXECUTE_AUTO);
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/**
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* Posts a task to a worker for execution.
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*
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* @param pTask The task to be executed.
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* @param mode Execution mode
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*
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* @return True if the task could be posted (i.e. not executed), false otherwise.
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*
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* @attention Once the task has been executed, it will be deleted.
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*/
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bool post(std::auto_ptr<DisposableTask> sTask, enum execute_mode_t mode = EXECUTE_AUTO);
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/**
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* Posts a task to all workers for execution.
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*
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* @param pTask The task to be executed.
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* @param pSem If non-NULL, will be posted once per worker when the task's
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* `execute` return.
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*
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* @return How many workers the task was posted to.
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*
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* @attention The very same task will be posted to all workers. The task
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* should either not have any sharable data or then it should
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* have data specific to each worker that can be accessed
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* without locks.
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*/
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static size_t broadcast(Task* pTask, Semaphore* pSem = NULL);
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/**
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* Posts a task to all workers for execution.
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*
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* @param pTask The task to be executed.
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*
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* @return How many workers the task was posted to.
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*
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* @attention The very same task will be posted to all workers. The task
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* should either not have any sharable data or then it should
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* have data specific to each worker that can be accessed
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* without locks.
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*
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* @attention Once the task has been executed by all workers, it will
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* be deleted.
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*/
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static size_t broadcast(std::auto_ptr<DisposableTask> sTask);
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/**
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* Executes a task on all workers in serial mode (the task is executed
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* on at most one worker thread at a time). When the function returns
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* the task has been executed on all workers.
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*
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* @param task The task to be executed.
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*
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* @return How many workers the task was posted to.
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*
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* @warning This function is extremely inefficient and will be slow compared
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* to the other functions. Only use this function when printing thread-specific
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* data to stdout.
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*/
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static size_t execute_serially(Task& task);
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/**
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* Executes a task on all workers concurrently and waits until all workers
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* are done. That is, when the function returns the task has been executed
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* by all workers.
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*
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* @param task The task to be executed.
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*
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* @return How many workers the task was posted to.
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*/
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static size_t execute_concurrently(Task& task);
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/**
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* Post a message to a worker.
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*
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* @param msg_id The message id.
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* @param arg1 Message specific first argument.
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* @param arg2 Message specific second argument.
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*
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* @return True if the message could be sent, false otherwise. If the message
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* posting fails, errno is set appropriately.
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*
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* @attention The return value tells *only* whether the message could be sent,
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* *not* that it has reached the worker.
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*
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* @attention This function is signal safe.
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*/
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bool post_message(uint32_t msg_id, intptr_t arg1, intptr_t arg2);
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/**
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* Broadcast a message to all worker.
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*
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* @param msg_id The message id.
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* @param arg1 Message specific first argument.
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* @param arg2 Message specific second argument.
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*
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* @return The number of messages posted; if less that ne number of workers
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* then some postings failed.
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*
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* @attention The return value tells *only* whether message could be posted,
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* *not* that it has reached the worker.
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*
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* @attentsion Exactly the same arguments are passed to all workers. Take that
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* into account if the passed data must be freed.
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*
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* @attention This function is signal safe.
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*/
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static size_t broadcast_message(uint32_t msg_id, intptr_t arg1, intptr_t arg2);
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/**
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* Initate shutdown of all workers.
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*
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* @attention A call to this function will only initiate the shutdowm,
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* the workers will not have shut down when the function returns.
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*
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* @attention This function is signal safe.
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*/
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static void shutdown_all();
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/**
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* Return the worker associated with the provided worker id.
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*
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* @param worker_id A worker id.
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*
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* @return The corresponding worker instance, or NULL if the id does
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* not correspond to a worker.
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*/
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static Worker* get(int worker_id);
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/**
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* Return the worker associated with the current thread.
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*
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* @return The worker instance, or NULL if the current thread does not have a worker.
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*/
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static Worker* get_current();
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/**
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* Return the worker id associated with the current thread.
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*
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* @return A worker instance, or -1 if the current thread does not have a worker.
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*/
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static int get_current_id();
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/**
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* Set the number of non-blocking poll cycles that will be done before
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* a blocking poll will take place.
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*
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* @param nbpolls Number of non-blocking polls to perform before blocking.
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*/
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static void set_nonblocking_polls(unsigned int nbpolls);
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/**
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* Maximum time to block in epoll_wait.
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*
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* @param maxwait Maximum wait time in millliseconds.
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*/
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static void set_maxwait(unsigned int maxwait);
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private:
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Worker(int id,
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int epoll_fd);
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virtual ~Worker();
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static Worker* create(int id, int epoll_listener_fd);
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bool post_disposable(DisposableTask* pTask, enum execute_mode_t mode = EXECUTE_AUTO);
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void handle_message(MessageQueue& queue, const MessageQueue::Message& msg); // override
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static void thread_main(void* arg);
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void poll_waitevents();
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static uint32_t epoll_instance_handler(struct mxs_poll_data* data, int wid, uint32_t events);
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uint32_t handle_epoll_events(uint32_t events);
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private:
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int m_id; /*< The id of the worker. */
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state_t m_state; /*< The state of the worker */
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int m_epoll_fd; /*< The epoll file descriptor. */
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STATISTICS m_statistics; /*< Worker statistics. */
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MessageQueue* m_pQueue; /*< The message queue of the worker. */
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THREAD m_thread; /*< The thread handle of the worker. */
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bool m_started; /*< Whether the thread has been started or not. */
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bool m_should_shutdown; /*< Whether shutdown should be performed. */
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bool m_shutdown_initiated; /*< Whether shutdown has been initated. */
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SessionsById m_sessions; /*< A mapping of session_id->MXS_SESSION. The map
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* should contain sessions exclusive to this
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* worker and not e.g. listener sessions. For now,
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* it's up to the protocol to decide whether a new
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* session is added to the map. */
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};
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}
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