253 lines
6.2 KiB
C
253 lines
6.2 KiB
C
/*
|
|
* This file is distributed as part of the SkySQL Gateway. It is free
|
|
* software: you can redistribute it and/or modify it under the terms of the
|
|
* GNU General Public License as published by the Free Software Foundation,
|
|
* version 2.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
|
|
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
|
|
* details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along with
|
|
* this program; if not, write to the Free Software Foundation, Inc., 51
|
|
* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*
|
|
* Copyright SkySQL Ab 2013
|
|
*/
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <stdlib.h>
|
|
#include <sys/epoll.h>
|
|
#include <poll.h>
|
|
#include <dcb.h>
|
|
#include <atomic.h>
|
|
#include <gwbitmask.h>
|
|
|
|
/**
|
|
* @file poll.c - Abstraction of the epoll functionality
|
|
*
|
|
* @verbatim
|
|
* Revision History
|
|
*
|
|
* Date Who Description
|
|
* 19/06/13 Mark Riddoch Initial implementation
|
|
* 28/06/13 Mark Riddoch Added poll mask support and DCB
|
|
* zombie management
|
|
*
|
|
* @endverbatim
|
|
*/
|
|
|
|
static int epoll_fd = -1; /**< The epoll file descriptor */
|
|
static int shutdown = 0; /**< Flag the shutdown of the poll subsystem */
|
|
static GWBITMASK poll_mask;
|
|
/**
|
|
* The polling statistics
|
|
*/
|
|
static struct {
|
|
int n_read; /**< Number of read events */
|
|
int n_write; /**< Number of write events */
|
|
int n_error; /**< Number of error events */
|
|
int n_hup; /**< Number of hangup events */
|
|
int n_accept; /**< Number of accept events */
|
|
int n_polls; /**< Number of poll cycles */
|
|
} pollStats;
|
|
|
|
|
|
/**
|
|
* Initialise the polling system we are using for the gateway.
|
|
*
|
|
* In this case we are using the Linux epoll mechanism
|
|
*/
|
|
void
|
|
poll_init()
|
|
{
|
|
if (epoll_fd != -1)
|
|
return;
|
|
if ((epoll_fd = epoll_create(MAX_EVENTS)) == -1)
|
|
{
|
|
perror("epoll_create");
|
|
exit(-1);
|
|
}
|
|
memset(&pollStats, 0, sizeof(pollStats));
|
|
bitmask_init(&poll_mask);
|
|
}
|
|
|
|
/**
|
|
* Add a DCB to the set of descriptors within the polling
|
|
* environment.
|
|
*
|
|
* @param dcb The descriptor to add to the poll
|
|
* @return -1 on error or 0 on success
|
|
*/
|
|
int
|
|
poll_add_dcb(DCB *dcb)
|
|
{
|
|
struct epoll_event ev;
|
|
|
|
ev.events = EPOLLIN | EPOLLOUT | EPOLLET;
|
|
ev.data.ptr = dcb;
|
|
|
|
return epoll_ctl(epoll_fd, EPOLL_CTL_ADD, dcb->fd, &ev);
|
|
|
|
}
|
|
|
|
/**
|
|
* Remove a descriptor from the set of descriptors within the
|
|
* polling environment.
|
|
*
|
|
* @param dcb The descriptor to remove
|
|
* @return -1 on error or 0 on success
|
|
*/
|
|
int
|
|
poll_remove_dcb(DCB *dcb)
|
|
{
|
|
struct epoll_event ev;
|
|
|
|
return epoll_ctl(epoll_fd, EPOLL_CTL_DEL, dcb->fd, &ev);
|
|
}
|
|
|
|
#define BLOCKINGPOLL 0 /* Set BLOCKING POLL to 1 if using a single thread and to make
|
|
* debugging easier.
|
|
*/
|
|
/**
|
|
* The main polling loop
|
|
*
|
|
* This routine does the polling and despatches of IO events
|
|
* to the DCB's. It may be called either directly or as the entry point
|
|
* of a polling thread within the gateway.
|
|
*
|
|
* The routine will loop as long as the variable "shutdown" is set to zero,
|
|
* setting this to a non-zero value will cause the polling loop to return.
|
|
*
|
|
* There are two options for the polling, a debug option that is only useful if
|
|
* you have a single thread. This blocks in epoll_wait until an event occurs.
|
|
*
|
|
* The non-debug option does an epoll with a time out. This allows the checking of
|
|
* shutdown value to be checked in all threads. The algorithm for polling in this
|
|
* mode is to do a poll with no-wait, if no events are detected then the poll is
|
|
* repeated with a time out. This allows for a quick check before making the call
|
|
* with timeout. The call with the timeout differs in that the Linux scheduler may
|
|
* deschedule a process if a timeout is included, but will not do this if a 0 timeout
|
|
* value is given. this improves performance when the gateway is under heavy load.
|
|
*
|
|
* @param arg The thread ID passed as a void * to satisfy the threading package
|
|
*/
|
|
void
|
|
poll_waitevents(void *arg)
|
|
{
|
|
struct epoll_event events[MAX_EVENTS];
|
|
int i, nfds;
|
|
int thread_id = (int)arg;
|
|
|
|
/* Add this thread to the bitmask of running polling threads */
|
|
bitmask_set(&poll_mask, thread_id);
|
|
while (1)
|
|
{
|
|
#if BLOCKINGPOLL
|
|
if ((nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, -1)) == -1)
|
|
{
|
|
}
|
|
#else
|
|
if ((nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, 0)) == -1)
|
|
{
|
|
}
|
|
else if (nfds == 0)
|
|
{
|
|
if ((nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, EPOLL_TIMEOUT)) == -1)
|
|
{
|
|
}
|
|
}
|
|
#endif
|
|
if (nfds > 0)
|
|
{
|
|
atomic_add(&pollStats.n_polls, 1);
|
|
for (i = 0; i < nfds; i++)
|
|
{
|
|
DCB *dcb = (DCB *)events[i].data.ptr;
|
|
__uint32_t ev = events[i].events;
|
|
|
|
if (DCB_ISZOMBIE(dcb))
|
|
continue;
|
|
|
|
if (ev & EPOLLERR)
|
|
{
|
|
atomic_add(&pollStats.n_error, 1);
|
|
dcb->func.error(dcb);
|
|
if (DCB_ISZOMBIE(dcb))
|
|
continue;
|
|
}
|
|
if (ev & EPOLLHUP)
|
|
{
|
|
atomic_add(&pollStats.n_hup, 1);
|
|
dcb->func.hangup(dcb);
|
|
if (DCB_ISZOMBIE(dcb))
|
|
continue;
|
|
}
|
|
if (ev & EPOLLOUT)
|
|
{
|
|
atomic_add(&pollStats.n_write, 1);
|
|
dcb->func.write_ready(dcb);
|
|
}
|
|
if (ev & EPOLLIN)
|
|
{
|
|
if (dcb->state == DCB_STATE_LISTENING)
|
|
{
|
|
atomic_add(&pollStats.n_accept, 1);
|
|
dcb->func.accept(dcb);
|
|
}
|
|
else
|
|
{
|
|
atomic_add(&pollStats.n_read, 1);
|
|
dcb->func.read(dcb);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
dcb_process_zombies(thread_id);
|
|
if (shutdown)
|
|
{
|
|
/* Remove this thread from the bitmask of running polling threads */
|
|
bitmask_clear(&poll_mask, thread_id);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Shutdown the polling loop
|
|
*/
|
|
void
|
|
poll_shutdown()
|
|
{
|
|
shutdown = 1;
|
|
}
|
|
|
|
/**
|
|
* Return the bitmask of polling threads
|
|
*
|
|
* @return The bitmask of the running polling threads
|
|
*/
|
|
GWBITMASK *
|
|
poll_bitmask()
|
|
{
|
|
return &poll_mask;
|
|
}
|
|
|
|
/**
|
|
* Debug routine to print the polling statistics
|
|
*
|
|
* @param dcb DCB to print to
|
|
*/
|
|
void
|
|
dprintPollStats(DCB *dcb)
|
|
{
|
|
dcb_printf(dcb, "Number of epoll cycles: %d\n", pollStats.n_polls);
|
|
dcb_printf(dcb, "Number of read events: %d\n", pollStats.n_read);
|
|
dcb_printf(dcb, "Number of write events: %d\n", pollStats.n_write);
|
|
dcb_printf(dcb, "Number of error events: %d\n", pollStats.n_error);
|
|
dcb_printf(dcb, "Number of hangup events: %d\n", pollStats.n_hup);
|
|
dcb_printf(dcb, "Number of accept events: %d\n", pollStats.n_accept);
|
|
}
|