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/*
* thread-pool.c
*
* A thread pool implementation
*
* Copyright © 2012-2021 Deutsches Elektronen-Synchrotron DESY,
* a research centre of the Helmholtz Association.
*
* Authors:
* 2010-2019 Thomas White <taw@physics.org>
*
* This file is part of CrystFEL.
*
* CrystFEL 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, either version 3 of the License, or
* (at your option) any later version.
*
* CrystFEL 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 CrystFEL. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <libcrystfel-config.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <assert.h>
#include "utils.h"
/** \file thread-pool.h */
/* --------------------------- Status label stuff --------------------------- */
static int use_status_labels = 0;
static pthread_key_t status_label_key;
struct worker_args
{
struct task_queue_range *tqr;
struct task_queue *tq;
int id;
};
signed int get_status_label()
{
int *cookie;
if ( !use_status_labels ) {
return -1;
}
cookie = pthread_getspecific(status_label_key);
return *cookie;
}
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_slot;
cookie_slot = malloc(sizeof(int));
*cookie_slot = w->id;
pthread_setspecific(status_label_key, cookie_slot);
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_slot);
return NULL;
}
/**
* \param n_threads The number of threads to run in parallel
* \param work The function to be called to do the work
* \param get_task The function which will determine the next unassigned task
* \param final The function which will be called to clean up after a task
* \param queue_args A pointer to any data required to determine the next task
* \param max Stop calling get_task after starting this number of jobs
* \param cpu_num Ignored
* \param cpu_groupsize Ignored
* \param cpu_offset Ignored
*
* \p get_task will be called every time a worker is idle. It returns either
* NULL, indicating that no further work is available, or a pointer which will
* be passed to \p work.
*
* \p final will be called once per image, and will be given both queue_args
* and the last task pointer.
*
* \p get_task and \p final will be called only under lock, and so do NOT need to
* be re-entrant or otherwise thread safe. 'work', of course, needs to be
* thread safe.
*
* Work will stop after \p max tasks have been processed whether get_task
* returned NULL or not. If \p max is zero, all tasks will be processed.
*
* \returns The number of tasks completed.
**/
int run_threads(int n_threads, TPWorkFunc work,
TPGetTaskFunc get_task, TPFinalFunc final,
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;
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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