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MYSQL-15: Implement server-side statement timeout support
Introduce an implementation of per-thread timers. The API can be used to create one-shot timers that use a monotonically increasing clock as the timing base. A timer expires in a given amount of time (in milliseconds) from when the timer is armed. Upon timer expiration, a given callback function is invoked in a separate thread. Timers can also be cancelled (disarmed) and provide an indication of the state (signaled or non-signaled) of the timer at the time of cancellation. The timer API is currently only implemented on Linux and Mac OS X.
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Davi Arnaut
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Feb 29, 2012
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,69 @@ | ||
| /* Copyright (c) 2012, Twitter, Inc. All rights reserved. | ||
| This program 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 of the License. | ||
| 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. */ | ||
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| #ifndef MY_TIMER_H | ||
| #define MY_TIMER_H | ||
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| #include "my_global.h" /* C_MODE_START, C_MODE_END */ | ||
| #include "my_config.h" /* HAVE_*_TIMERS */ | ||
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| /* POSIX timers API. */ | ||
| #ifdef HAVE_POSIX_TIMERS | ||
| # include <time.h> /* timer_t */ | ||
| typedef timer_t os_timer_t; | ||
| #elif HAVE_KQUEUE_TIMERS | ||
| # include <sys/types.h> /* uintptr_t */ | ||
| typedef uintptr_t os_timer_t; | ||
| #endif | ||
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| /* Whether timer API is implemented. */ | ||
| #ifdef HAVE_MY_TIMER | ||
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| C_MODE_START | ||
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| typedef struct st_my_timer my_timer_t; | ||
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| /** Non-copyable timer object. */ | ||
| struct st_my_timer | ||
| { | ||
| /** Timer ID used to identify the timer in timer requests. */ | ||
| os_timer_t id; | ||
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| /** Timer expiration notification function. */ | ||
| void (*notify_function)(my_timer_t *); | ||
| }; | ||
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| /* Initialize internal components. */ | ||
| int my_timer_init_ext(void); | ||
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| /* Release any resources acquired. */ | ||
| void my_timer_deinit(void); | ||
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| /* Create a timer object. */ | ||
| int my_timer_create(my_timer_t *timer); | ||
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| /* Set the time (in milliseconds) until the next expiration of the timer. */ | ||
| int my_timer_set(my_timer_t *timer, unsigned long time); | ||
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| /* Reset the time until the next expiration of the timer. */ | ||
| int my_timer_reset(my_timer_t *timer, bool *state); | ||
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| /* Delete a timer object. */ | ||
| void my_timer_delete(my_timer_t *timer); | ||
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| C_MODE_END | ||
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| #endif /* HAVE_MY_TIMER */ | ||
| #endif /* MY_TIMER_H */ |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,219 @@ | ||
| /* Copyright (c) 2012, Twitter, Inc. All rights reserved. | ||
| This program 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 of the License. | ||
| 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. */ | ||
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| #include "my_timer.h" /* my_timer_t */ | ||
| #include "my_pthread.h" /* my_thread_init, my_thread_end */ | ||
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| #include <sys/types.h> | ||
| #include <sys/event.h> | ||
| #include <sys/time.h> | ||
| #include <assert.h> | ||
| #include <errno.h> | ||
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| static int kq_fd= -1; | ||
| static pthread_t thread; | ||
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| /** | ||
| Timer expiration notification thread. | ||
| @param arg Unused. | ||
| */ | ||
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| static void * | ||
| timer_notify_thread(void *arg __attribute__((unused))) | ||
| { | ||
| my_timer_t *timer; | ||
| struct kevent kev; | ||
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| my_thread_init(); | ||
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| while (1) | ||
| { | ||
| if (kevent(kq_fd, NULL, 0, &kev, 1, NULL) < 0) | ||
| continue; | ||
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| if (kev.filter == EVFILT_TIMER) | ||
| { | ||
| timer= kev.udata; | ||
| assert(timer->id == kev.ident); | ||
| timer->notify_function(timer); | ||
| } | ||
| else if (kev.filter == EVFILT_USER) | ||
| break; | ||
| } | ||
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| my_thread_end(); | ||
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| return NULL; | ||
| } | ||
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| /** | ||
| Create a helper thread to dispatch timer expiration notifications. | ||
| @return On success, 0. On error, -1 is returned. | ||
| */ | ||
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| static int | ||
| start_helper_thread(void) | ||
| { | ||
| struct kevent kev; | ||
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| EV_SET(&kev, 0, EVFILT_USER, EV_ADD, 0, 0, 0); | ||
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| if (kevent(kq_fd, &kev, 1, NULL, 0, NULL) < 0) | ||
| return -1; | ||
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| return pthread_create(&thread, NULL, timer_notify_thread, NULL); | ||
| } | ||
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| /** | ||
| Initialize internal components. | ||
| @return On success, 0. | ||
| On error, -1 is returned, and errno is set to indicate the error. | ||
| */ | ||
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| int | ||
| my_timer_init_ext(void) | ||
| { | ||
| int rc; | ||
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| /* Create a file descriptor for event notification. */ | ||
| if ((kq_fd= kqueue()) < 0) | ||
| return -1; | ||
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| /* Create a helper thread. */ | ||
| if ((rc= start_helper_thread())) | ||
| close(kq_fd); | ||
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| return rc; | ||
| } | ||
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| /** | ||
| Release any resources that were allocated as part of initialization. | ||
| */ | ||
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| void | ||
| my_timer_deinit(void) | ||
| { | ||
| struct kevent kev; | ||
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| EV_SET(&kev, 0, EVFILT_USER, 0, NOTE_TRIGGER, 0, 0); | ||
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| /* There's not much to do if triggering the event fails. */ | ||
| if (kevent(kq_fd, &kev, 1, NULL, 0, NULL) > -1) | ||
| pthread_join(thread, NULL); | ||
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| close(kq_fd); | ||
| } | ||
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| /** | ||
| Create a timer object. | ||
| @param timer Timer object. | ||
| @return On success, 0. | ||
| On error, -1 is returned, and errno is set to indicate the error. | ||
| */ | ||
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| int | ||
| my_timer_create(my_timer_t *timer) | ||
| { | ||
| assert(kq_fd >= 0); | ||
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| timer->id= (uintptr_t) timer; | ||
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| return 0; | ||
| } | ||
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| /** | ||
| Set the time until the next expiration of the timer. | ||
| @param timer Timer object. | ||
| @param time Amount of time (in milliseconds) before the timer expires. | ||
| @return On success, 0. | ||
| On error, -1 is returned, and errno is set to indicate the error. | ||
| */ | ||
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| int | ||
| my_timer_set(my_timer_t *timer, unsigned long time) | ||
| { | ||
| struct kevent kev; | ||
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| EV_SET(&kev, timer->id, EVFILT_TIMER, EV_ADD | EV_ONESHOT, 0, time, timer); | ||
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| return kevent(kq_fd, &kev, 1, NULL, 0, NULL); | ||
| } | ||
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| /** | ||
| Reset the time until the next expiration of the timer. | ||
| @param timer Timer object. | ||
| @param state The state of the timer at the time of cancellation, either | ||
| signaled (false) or nonsignaled (true). | ||
| @return On success, 0. | ||
| On error, -1 is returned, and errno is set to indicate the error. | ||
| */ | ||
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| int | ||
| my_timer_reset(my_timer_t *timer, bool *state) | ||
| { | ||
| int status; | ||
| struct kevent kev; | ||
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| EV_SET(&kev, timer->id, EVFILT_TIMER, EV_DELETE, 0, 0, NULL); | ||
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| status= kevent(kq_fd, &kev, 1, NULL, 0, NULL); | ||
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| /* | ||
| If the event was retrieved from the kqueue (at which point we | ||
| consider it to be signaled), the timer was automatically deleted. | ||
| */ | ||
| if (!status) | ||
| *state= 1; | ||
| else if (errno == ENOENT) | ||
| { | ||
| *state= 0; | ||
| status= 0; | ||
| } | ||
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| return status; | ||
| } | ||
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| /** | ||
| Delete a timer object. | ||
| @param timer Timer object. | ||
| */ | ||
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| void | ||
| my_timer_delete(my_timer_t *timer) | ||
| { | ||
| struct kevent kev; | ||
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| EV_SET(&kev, timer->id, EVFILT_TIMER, EV_DELETE, 0, 0, NULL); | ||
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| kevent(kq_fd, &kev, 1, NULL, 0, NULL); | ||
| } | ||
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