MaxScale/server/core/poll.cc
Markus Mäkelä b33f464eea
MXS-1506: Make heartbeat reads atomic
The old hkheartbeat variable was changed to the mxs_clock() function that
simply wraps an atomic load of the variable. This allows it to be
correctly read by MaxScale as well as opening up the possibility of
converting the value load to a relaxed memory order read.

Renamed the header and associated macros. Removed inclusion of the
heartbeat header from the housekeeper header and added it to the files
that were missing it.
2018-04-10 15:29:29 +03:00

416 lines
11 KiB
C++

/*
* Copyright (c) 2016 MariaDB Corporation Ab
*
* Use of this software is governed by the Business Source License included
* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
*
* Change Date: 2020-01-01
*
* On the date above, in accordance with the Business Source License, use
* of this software will be governed by version 2 or later of the General
* Public License.
*/
/**
* @file poll.c - Abstraction of the epoll functionality
*/
#include <maxscale/poll.h>
#include <errno.h>
#include <inttypes.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <mysql.h>
#include <sys/epoll.h>
#include <maxscale/alloc.h>
#include <maxscale/atomic.h>
#include <maxscale/config.h>
#include <maxscale/clock.h>
#include <maxscale/platform.h>
#include <maxscale/server.h>
#include <maxscale/statistics.h>
#include "internal/poll.h"
#include "internal/worker.hh"
using maxscale::Worker;
static int n_threads; /*< Number of threads */
/**
* Initialise the polling system we are using for the gateway.
*
* In this case we are using the Linux epoll mechanism
*/
void
poll_init()
{
n_threads = config_threadcount();
}
static bool add_fd_to_worker(int wid, int fd, uint32_t events, MXS_POLL_DATA* data)
{
ss_dassert((wid >= 0) && (wid <= n_threads));
Worker* worker = Worker::get(wid);
ss_dassert(worker);
return worker->add_fd(fd, events, data);
}
static bool add_fd_to_workers(int fd, uint32_t events, MXS_POLL_DATA* data)
{
bool rv = true;
int thread_id = data->thread.id;
rv = Worker::add_shared_fd(fd, events, data);
if (rv)
{
// The DCB will appear on the list of the calling thread.
int wid = Worker::get_current_id();
if (wid == -1)
{
// TODO: Listeners are created before the workers have been started.
// TODO: Hence the returned id will be -1. We change it to 0, which in
// TODO: practice will mean that they will end up on the Worker running
// TODO: in the main thread. This needs to be sorted out.
wid = 0;
}
data->thread.id = wid;
}
else
{
// Restore the situation.
data->thread.id = thread_id;
}
return rv;
}
bool poll_add_fd_to_worker(int wid, int fd, uint32_t events, MXS_POLL_DATA* data)
{
bool rv;
if (wid == MXS_WORKER_ALL)
{
rv = add_fd_to_workers(fd, events, data);
}
else
{
ss_dassert((wid >= 0) && (wid < n_threads));
rv = add_fd_to_worker(wid, fd, events, data);
}
return rv;
}
static bool remove_fd_from_worker(int wid, int fd)
{
ss_dassert((wid >= 0) && (wid < n_threads));
Worker* worker = Worker::get(wid);
ss_dassert(worker);
return worker->remove_fd(fd);
}
static bool remove_fd_from_workers(int fd)
{
return Worker::remove_shared_fd(fd);
}
bool poll_remove_fd_from_worker(int wid, int fd)
{
bool rv;
if (wid == MXS_WORKER_ALL)
{
rv = remove_fd_from_workers(fd);
}
else
{
rv = remove_fd_from_worker(wid, fd);
}
return rv;
}
/**
* Set the number of non-blocking poll cycles that will be done before
* a blocking poll will take place. Whenever an event arrives on a thread
* or the thread sees a pending event to execute it will reset it's
* poll_spin coutn to zero and will then poll with a 0 timeout until the
* poll_spin value is greater than the value set here.
*
* @param nbpolls Number of non-block polls to perform before blocking
*/
void
poll_set_nonblocking_polls(unsigned int nbpolls)
{
Worker::set_nonblocking_polls(nbpolls);
}
/**
* Set the maximum amount of time, in milliseconds, the polling thread
* will block before it will wake and check the event queue for work
* that may have been added by another thread.
*
* @param maxwait Maximum wait time in milliseconds
*/
void
poll_set_maxwait(unsigned int maxwait)
{
Worker::set_maxwait(maxwait);
}
/**
* Display an entry from the spinlock statistics data
*
* @param dcb The DCB to print to
* @param desc Description of the statistic
* @param value The statistic value
*/
static void
spin_reporter(void *dcb, char *desc, int value)
{
dcb_printf((DCB *)dcb, "\t%-40s %d\n", desc, value);
}
/**
* Debug routine to print the polling statistics
*
* @param dcb DCB to print to
*/
void
dprintPollStats(DCB *dcb)
{
int i;
Worker::STATISTICS s = Worker::get_statistics();
dcb_printf(dcb, "\nPoll Statistics.\n\n");
dcb_printf(dcb, "No. of epoll cycles: %" PRId64 "\n", s.n_polls);
dcb_printf(dcb, "No. of epoll cycles with wait: %" PRId64 "\n", s.blockingpolls);
dcb_printf(dcb, "No. of epoll calls returning events: %" PRId64 "\n", s.n_pollev);
dcb_printf(dcb, "No. of non-blocking calls returning events: %" PRId64 "\n", s.n_nbpollev);
dcb_printf(dcb, "No. of read events: %" PRId64 "\n", s.n_read);
dcb_printf(dcb, "No. of write events: %" PRId64 "\n", s.n_write);
dcb_printf(dcb, "No. of error events: %" PRId64 "\n", s.n_error);
dcb_printf(dcb, "No. of hangup events: %" PRId64 "\n", s.n_hup);
dcb_printf(dcb, "No. of accept events: %" PRId64 "\n", s.n_accept);
dcb_printf(dcb, "Total event queue length: %" PRId64 "\n", s.evq_length);
dcb_printf(dcb, "Average event queue length: %" PRId64 "\n", s.evq_length);
dcb_printf(dcb, "Maximum event queue length: %" PRId64 "\n", s.evq_max);
dcb_printf(dcb, "No of poll completions with descriptors\n");
dcb_printf(dcb, "\tNo. of descriptors\tNo. of poll completions.\n");
for (i = 0; i < Worker::STATISTICS::MAXNFDS - 1; i++)
{
dcb_printf(dcb, "\t%2d\t\t\t%" PRId64 "\n", i + 1, s.n_fds[i]);
}
dcb_printf(dcb, "\t>= %d\t\t\t%" PRId64 "\n",
Worker::STATISTICS::MAXNFDS, s.n_fds[Worker::STATISTICS::MAXNFDS - 1]);
}
/**
* Print the thread status for all the polling threads
*
* @param dcb The DCB to send the thread status data
*/
void
dShowThreads(DCB *dcb)
{
dcb_printf(dcb, "Polling Threads.\n\n");
dcb_printf(dcb, " ID | State | #descriptors (curr) | #descriptors (tot) | Load (1s) | Load (1m) | Load (1h) |\n");
dcb_printf(dcb, "----+------------+---------------------+---------------------+-----------+-----------+-----------+\n");
for (int i = 0; i < n_threads; i++)
{
Worker* worker = Worker::get(i);
ss_dassert(worker);
const char *state = "Unknown";
switch (worker->state())
{
case Worker::STOPPED:
state = "Stopped";
break;
case Worker::IDLE:
state = "Idle";
break;
case Worker::POLLING:
state = "Polling";
break;
case Worker::PROCESSING:
state = "Processing";
break;
case Worker::ZPROCESSING:
state = "Collecting";
break;
default:
ss_dassert(!true);
}
uint32_t nCurrent;
uint64_t nTotal;
worker->get_descriptor_counts(&nCurrent, &nTotal);
dcb_printf(dcb, " %2d | %10s | %19" PRIu32 " | %19" PRIu64 " | %9d | %9d | %9d |\n",
i, state, nCurrent, nTotal,
worker->load(Worker::Load::ONE_SECOND),
worker->load(Worker::Load::ONE_MINUTE),
worker->load(Worker::Load::ONE_HOUR));
}
}
/**
* Print the event queue statistics
*
* @param pdcb The DCB to print the event queue to
*/
void
dShowEventStats(DCB *pdcb)
{
int i;
Worker::STATISTICS s = Worker::get_statistics();
dcb_printf(pdcb, "\nEvent statistics.\n");
dcb_printf(pdcb, "Maximum queue time: %3" PRId64 "00ms\n", s.maxqtime);
dcb_printf(pdcb, "Maximum execution time: %3" PRId64 "00ms\n", s.maxexectime);
dcb_printf(pdcb, "Maximum event queue length: %3" PRId64 "\n", s.evq_max);
dcb_printf(pdcb, "Average event queue length: %3" PRId64 "\n", s.evq_length);
dcb_printf(pdcb, "\n");
dcb_printf(pdcb, " | Number of events\n");
dcb_printf(pdcb, "Duration | Queued | Executed\n");
dcb_printf(pdcb, "---------------+------------+-----------\n");
dcb_printf(pdcb, " < 100ms | %-10d | %-10d\n", s.qtimes[0], s.exectimes[0]);
for (i = 1; i < Worker::STATISTICS::N_QUEUE_TIMES; i++)
{
dcb_printf(pdcb, " %2d00 - %2d00ms | %-10d | %-10d\n", i, i + 1, s.qtimes[i], s.exectimes[i]);
}
dcb_printf(pdcb, " > %2d00ms | %-10d | %-10d\n", Worker::STATISTICS::N_QUEUE_TIMES,
s.qtimes[Worker::STATISTICS::N_QUEUE_TIMES], s.exectimes[Worker::STATISTICS::N_QUEUE_TIMES]);
}
/**
* Return a poll statistic from the polling subsystem
*
* @param what The required statistic
* @return The value of that statistic
*/
int64_t
poll_get_stat(POLL_STAT what)
{
return Worker::get_one_statistic(what);
}
namespace
{
struct EVENT_TIMES_CB_DATA
{
int rowno;
Worker::STATISTICS* stats;
};
}
/**
* Provide a row to the result set that defines the event queue statistics
*
* @param set The result set
* @param data The index of the row to send
* @return The next row or NULL
*/
static RESULT_ROW *
eventTimesRowCallback(RESULTSET *set, void *v)
{
EVENT_TIMES_CB_DATA* data = (EVENT_TIMES_CB_DATA*)v;
char buf[40];
RESULT_ROW *row;
if (data->rowno >= Worker::STATISTICS::N_QUEUE_TIMES)
{
MXS_FREE(data);
return NULL;
}
row = resultset_make_row(set);
if (data->rowno == 0)
{
resultset_row_set(row, 0, "< 100ms");
}
else if (data->rowno == Worker::STATISTICS::N_QUEUE_TIMES - 1)
{
snprintf(buf, 39, "> %2d00ms", Worker::STATISTICS::N_QUEUE_TIMES);
buf[39] = '\0';
resultset_row_set(row, 0, buf);
}
else
{
snprintf(buf, 39, "%2d00 - %2d00ms", data->rowno, data->rowno + 1);
buf[39] = '\0';
resultset_row_set(row, 0, buf);
}
snprintf(buf, 39, "%u", data->stats->qtimes[data->rowno]);
buf[39] = '\0';
resultset_row_set(row, 1, buf);
snprintf(buf, 39, "%u", data->stats->exectimes[data->rowno]);
buf[39] = '\0';
resultset_row_set(row, 2, buf);
data->rowno++;
return row;
}
/**
* Return a result set that has the current set of services in it
*
* @return A Result set
*/
RESULTSET *
eventTimesGetList()
{
RESULTSET *set;
EVENT_TIMES_CB_DATA *data;
if ((data = (EVENT_TIMES_CB_DATA*)MXS_MALLOC(sizeof(EVENT_TIMES_CB_DATA))) == NULL)
{
return NULL;
}
Worker::STATISTICS s = Worker::get_statistics();
data->rowno = 0;
data->stats = &s;
if ((set = resultset_create(eventTimesRowCallback, data)) == NULL)
{
MXS_FREE(data);
return NULL;
}
resultset_add_column(set, "Duration", 20, COL_TYPE_VARCHAR);
resultset_add_column(set, "No. Events Queued", 12, COL_TYPE_VARCHAR);
resultset_add_column(set, "No. Events Executed", 12, COL_TYPE_VARCHAR);
return set;
}