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/*
* thread-pool.c
*
* A thread pool implementation
*
* (c) 2006-2011 Thomas White <taw@physics.org>
*
* Part of CrystFEL - crystallography with a FEL
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <assert.h>
#ifdef HAVE_CPU_AFFINITY
#include <sched.h>
#endif
#include "utils.h"
/* ------------------------------ CPU affinity ------------------------------ */
#ifdef HAVE_CPU_AFFINITY
static void set_affinity(int n, int cpu_num, int cpu_groupsize, int cpu_offset)
{
cpu_set_t c;
int group;
int n_cpu_groups;
int i;
if ( cpu_num == 0 ) return;
CPU_ZERO(&c);
/* Work out which group this thread belongs to */
group = (n / cpu_groupsize) + cpu_offset;
/* Work out which CPUs should be used for this group */
n_cpu_groups = cpu_num / cpu_groupsize;
group = group % n_cpu_groups;
/* Set flags */
for ( i=0; i<cpu_groupsize; i++ ) {
int cpu = cpu_groupsize*group + i;
CPU_SET(cpu, &c);
}
if ( sched_setaffinity(0, sizeof(cpu_set_t), &c) ) {
/* Cannot use ERROR() just yet */
fprintf(stderr, "%i: Failed to set CPU affinity.\n", n);
}
}
#else /* HAVE_CPU_AFFINITY */
static void set_affinity(int n, int cpu_num, int cpu_groupsize, int cpu_offset)
{
/* Do absolutely nothing */
}
#endif /* HAVE_CPU_AFFINITY */
/* --------------------------- Status label stuff --------------------------- */
static int use_status_labels = 0;
static pthread_key_t status_label_key;
pthread_mutex_t stderr_lock = PTHREAD_MUTEX_INITIALIZER;
struct worker_args
{
struct task_queue_range *tqr;
struct task_queue *tq;
int id;
int cpu_num;
int cpu_groupsize;
int cpu_offset;
};
signed int get_status_label()
{
int *cookie;
if ( !use_status_labels ) {
return -1;
}
cookie = pthread_getspecific(status_label_key);
return *cookie;
}
/* ---------------------------- Custom get_task() --------------------------- */
struct task_queue
{
pthread_mutex_t lock;
int n_started;
int n_completed;
int max;
void *(*get_task)(void *);
void (*finalise)(void *, void *);
void *queue_args;
void (*work)(void *, int);
};
static void *task_worker(void *pargsv)
{
struct worker_args *w = pargsv;
struct task_queue *q = w->tq;
int *cookie;
set_affinity(w->id, w->cpu_num, w->cpu_groupsize, w->cpu_offset);
cookie = malloc(sizeof(int));
*cookie = w->id;
pthread_setspecific(status_label_key, cookie);
free(w);
do {
void *task;
int cookie;
/* Get a task */
pthread_mutex_lock(&q->lock);
if ( (q->max) && (q->n_started >= q->max) ) {
pthread_mutex_unlock(&q->lock);
break;
}
task = q->get_task(q->queue_args);
/* No more tasks? */
if ( task == NULL ) {
pthread_mutex_unlock(&q->lock);
break;
}
q->n_started++;
pthread_mutex_unlock(&q->lock);
cookie = *(int *)pthread_getspecific(status_label_key);
q->work(task, cookie);
/* Update totals etc */
pthread_mutex_lock(&q->lock);
q->n_completed++;
if ( q->finalise ) {
q->finalise(q->queue_args, task);
}
pthread_mutex_unlock(&q->lock);
} while ( 1 );
free(cookie);
return NULL;
}
int run_threads(int n_threads, void (*work)(void *, int),
void *(*get_task)(void *), void (*final)(void *, void *),
void *queue_args, int max,
int cpu_num, int cpu_groupsize, int cpu_offset)
{
pthread_t *workers;
int i;
struct task_queue q;
pthread_key_create(&status_label_key, NULL);
workers = malloc(n_threads * sizeof(pthread_t));
pthread_mutex_init(&q.lock, NULL);
q.work = work;
q.get_task = get_task;
q.finalise = final;
q.queue_args = queue_args;
q.n_started = 0;
q.n_completed = 0;
q.max = max;
/* Now it's safe to start using the status labels */
if ( n_threads > 1 ) use_status_labels = 1;
/* Start threads */
for ( i=0; i<n_threads; i++ ) {
struct worker_args *w;
w = malloc(sizeof(struct worker_args));
w->tq = &q;
w->tqr = NULL;
w->id = i;
w->cpu_num = cpu_num;
w->cpu_groupsize = cpu_groupsize;
w->cpu_offset = cpu_offset;
if ( pthread_create(&workers[i], NULL, task_worker, w) ) {
/* Not ERROR() here */
fprintf(stderr, "Couldn't start thread %i\n", i);
n_threads = i;
break;
}
}
/* Join threads */
for ( i=0; i<n_threads; i++ ) {
pthread_join(workers[i], NULL);
}
use_status_labels = 0;
free(workers);
return q.n_completed;
}
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