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/*
* Copyright (C) 2016, 2017 "IoT.bzh"
* Author José Bollo <jose.bollo@iot.bzh>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define _GNU_SOURCE
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <time.h>
#include <sys/syscall.h>
#include <pthread.h>
#include <errno.h>
#include <assert.h>
#include <systemd/sd-event.h>
#include "jobs.h"
#include "sig-monitor.h"
#include "verbose.h"
#if 0
#define _alert_ "do you really want to remove monitoring?"
#define sig_monitor_init_timeouts() ((void)0)
#define sig_monitor_clean_timeouts() ((void)0)
#define sig_monitor(to,cb,arg) (cb(0,arg))
#endif
/** Internal shortcut for callback */
typedef void (*job_cb_t)(int, void*, void *, void*);
/** Description of a pending job */
struct job
{
struct job *next; /**< link to the next job enqueued */
void *group; /**< group of the request */
job_cb_t callback; /**< processing callback */
void *arg1; /**< first arg */
void *arg2; /**< second arg */
void *arg3; /**< third arg */
int timeout; /**< timeout in second for processing the request */
unsigned blocked: 1; /**< is an other request blocking this one ? */
unsigned dropped: 1; /**< is removed ? */
};
/** Description of handled event loops */
struct events
{
struct events *next;
struct sd_event *event;
unsigned runs: 1;
};
/** Description of threads */
struct thread
{
struct thread *next; /**< next thread of the list */
struct thread *upper; /**< upper same thread */
struct job *job; /**< currently processed job */
struct events *events; /**< currently processed job */
pthread_t tid; /**< the thread id */
unsigned stop: 1; /**< stop requested */
unsigned lowered: 1; /**< has a lower same thread */
unsigned waits: 1; /**< is waiting? */
};
/* synchronisation of threads */
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
/* count allowed, started and waiting threads */
static int allowed = 0; /** allowed count of threads */
static int started = 0; /** started count of threads */
static int waiting = 0; /** waiting count of threads */
static int remains = 0; /** allowed count of waiting jobs */
static int nevents = 0; /** count of events */
/* list of threads */
static struct thread *threads;
static _Thread_local struct thread *current;
/* queue of pending jobs */
static struct job *first_job;
static struct events *first_events;
static struct job *free_jobs;
/**
* Create a new job with the given parameters
* @param group the group of the job
* @param timeout the timeout of the job (0 if none)
* @param callback the function that achieves the job
* @param arg1 the first argument of the callback
* @param arg2 the second argument of the callback
* @param arg3 the third argument of the callback
* @return the created job unblock or NULL when no more memory
*/
static struct job *job_create(
void *group,
int timeout,
job_cb_t callback,
void *arg1,
void *arg2,
void *arg3)
{
struct job *job;
/* try recyle existing job */
job = free_jobs;
if (job)
free_jobs = job->next;
else {
/* allocation without blocking */
pthread_mutex_unlock(&mutex);
job = malloc(sizeof *job);
pthread_mutex_lock(&mutex);
if (!job) {
errno = -ENOMEM;
goto end;
}
}
/* initialises the job */
job->group = group;
job->timeout = timeout;
job->callback = callback;
job->arg1 = arg1;
job->arg2 = arg2;
job->arg3 = arg3;
job->blocked = 0;
job->dropped = 0;
end:
return job;
}
/**
* Adds 'job' at the end of the list of jobs, marking it
* as blocked if an other job with the same group is pending.
* @param job the job to add
*/
static void job_add(struct job *job)
{
void *group;
struct job *ijob, **pjob;
/* prepare to add */
group = job->group;
job->next = NULL;
/* search end and blockers */
pjob = &first_job;
ijob = first_job;
while (ijob) {
if (group && ijob->group == group)
job->blocked = 1;
pjob = &ijob->next;
ijob = ijob->next;
}
/* queue the jobs */
*pjob = job;
}
/**
* Get the next job to process or NULL if none.
* @return the first job that isn't blocked or NULL
*/
static inline struct job *job_get()
{
struct job *job = first_job;
while (job && job->blocked)
job = job->next;
return job;
}
/**
* Get the next events to process or NULL if none.
* @return the first events that isn't running or NULL
*/
static inline struct events *events_get()
{
struct events *events = first_events;
while (events && events->runs)
events = events->next;
return events;
}
/**
* Releases the processed 'job': removes it
* from the list of jobs and unblock the first
* pending job of the same group if any.
* @param job the job to release
*/
static inline void job_release(struct job *job)
{
struct job *ijob, **pjob;
void *group;
/* first unqueue the job */
pjob = &first_job;
ijob = first_job;
while (ijob != job) {
pjob = &ijob->next;
ijob = ijob->next;
}
*pjob = job->next;
/* then unblock jobs of the same group */
group = job->group;
if (group) {
ijob = job->next;
while (ijob && ijob->group != group)
ijob = ijob->next;
if (ijob)
ijob->blocked = 0;
}
/* recycle the job */
job->next = free_jobs;
free_jobs = job;
}
/**
* Monitored normal callback for a job.
* This function is called by the monitor
* to run the job when the safe environment
* is set.
* @param signum 0 on normal flow or the number
* of the signal that interrupted the normal
* flow
* @param arg the job to run
*/
static void job_call(int signum, void *arg)
{
struct job *job = arg;
job->callback(signum, job->arg1, job->arg2, job->arg3);
}
/**
* Monitored cancel callback for a job.
* This function is called by the monitor
* to cancel the job when the safe environment
* is set.
* @param signum 0 on normal flow or the number
* of the signal that interrupted the normal
* flow, isn't used
* @param arg the job to run
*/
static void job_cancel(int signum, void *arg)
{
job_call(SIGABRT, arg);
}
/**
* Monitored normal callback for events.
* This function is called by the monitor
* to run the event loop when the safe environment
* is set.
* @param signum 0 on normal flow or the number
* of the signal that interrupted the normal
* flow
* @param arg the events to run
*/
static void events_call(int signum, void *arg)
{
struct events *events = arg;
if (!signum)
sd_event_run(events->event, (uint64_t) -1);
}
/**
* Main processing loop of threads processing jobs.
* The loop must be called with the mutex locked
* and it returns with the mutex locked.
* @param me the description of the thread to use
* TODO: how are timeout handled when reentering?
*/
static void thread_run(volatile struct thread *me)
{
struct thread **prv;
struct job *job;
struct events *events;
/* initialize description of itself and link it in the list */
me->tid = pthread_self();
me->stop = 0;
me->lowered = 0;
me->waits = 0;
me->upper = current;
if (current)
current->lowered = 1;
else
sig_monitor_init_timeouts();
current = (struct thread*)me;
me->next = threads;
threads = (struct thread*)me;
started++;
NOTICE("job thread starting %d(/%d) %s", started, allowed, me->upper ? "child" : "parent");
/* loop until stopped */
me->events = NULL;
while (!me->stop) {
/* get a job */
job = job_get(first_job);
if (job) {
/* prepare running the job */
remains++; /* increases count of job that can wait */
job->blocked = 1; /* mark job as blocked */
me->job = job; /* record the job (only for terminate) */
/* run the job */
pthread_mutex_unlock(&mutex);
sig_monitor(job->timeout, job_call, job);
pthread_mutex_lock(&mutex);
/* release the run job */
job_release(job);
/* release event if any */
events = me->events;
if (events) {
events->runs = 0;
me->events = NULL;
}
} else {
/* no job, check events */
events = events_get();
if (events) {
/* run the events */
events->runs = 1;
me->events = events;
pthread_mutex_unlock(&mutex);
sig_monitor(0, events_call, events);
pthread_mutex_lock(&mutex);
events->runs = 0;
me->events = NULL;
} else {
/* no job and not events */
waiting++;
me->waits = 1;
pthread_cond_wait(&cond, &mutex);
me->waits = 0;
waiting--;
}
}
}
NOTICE("job thread stoping %d(/%d) %s", started, allowed, me->upper ? "child" : "parent");
/* unlink the current thread and cleanup */
started--;
prv = &threads;
while (*prv != me)
prv = &(*prv)->next;
*prv = me->next;
current = me->upper;
if (current)
current->lowered = 0;
else
sig_monitor_clean_timeouts();
}
/**
* Entry point for created threads.
* @param data not used
* @return NULL
*/
static void *thread_main(void *data)
{
struct thread me;
pthread_mutex_lock(&mutex);
thread_run(&me);
pthread_mutex_unlock(&mutex);
return NULL;
}
/**
* Starts a new thread
* @return 0 in case of success or -1 in case of error
*/
static int start_one_thread()
{
pthread_t tid;
int rc;
rc = pthread_create(&tid, NULL, thread_main, NULL);
if (rc != 0) {
/* errno = rc; */
WARNING("not able to start thread: %m");
rc = -1;
}
return rc;
}
/**
* Queues a new asynchronous job represented by 'callback'
* for the 'group' and the 'timeout'.
* Jobs are queued FIFO and are possibly executed in parallel
* concurrently except for job of the same group that are
* executed sequentially in FIFO order.
* @param group The group of the job or NULL when no group.
* @param timeout The maximum execution time in seconds of the job
* or 0 for unlimited time.
* @param callback The function to execute for achieving the job.
* Its first parameter is either 0 on normal flow
* or the signal number that broke the normal flow.
* @return 0 in case of success or -1 in case of error
*/
int jobs_queue0(
void *group,
int timeout,
void (*callback)(int signum))
{
return jobs_queue3(group, timeout, (job_cb_t)callback, NULL, NULL, NULL);
}
/**
* Queues a new asynchronous job represented by 'callback' and 'arg1'
* for the 'group' and the 'timeout'.
* Jobs are queued FIFO and are possibly executed in parallel
* concurrently except for job of the same group that are
* executed sequentially in FIFO order.
* @param group The group of the job or NULL when no group.
* @param timeout The maximum execution time in seconds of the job
* or 0 for unlimited time.
* @param callback The function to execute for achieving the job.
* Its first parameter is either 0 on normal flow
* or the signal number that broke the normal flow.
* The remaining parameter is the parameter 'arg1'
* given here.
* @param arg1 The second argument for 'callback'
* @return 0 in case of success or -1 in case of error
*/
int jobs_queue(
void *group,
int timeout,
void (*callback)(int, void*),
void *arg)
{
return jobs_queue3(group, timeout, (job_cb_t)callback, arg, NULL, NULL);
}
/**
* Queues a new asynchronous job represented by 'callback' and 'arg[12]'
* for the 'group' and the 'timeout'.
* Jobs are queued FIFO and are possibly executed in parallel
* concurrently except for job of the same group that are
* executed sequentially in FIFO order.
* @param group The group of the job or NULL when no group.
* @param timeout The maximum execution time in seconds of the job
* or 0 for unlimited time.
* @param callback The function to execute for achieving the job.
* Its first parameter is either 0 on normal flow
* or the signal number that broke the normal flow.
* The remaining parameters are the parameters 'arg[12]'
* given here.
* @param arg1 The second argument for 'callback'
* @param arg2 The third argument for 'callback'
* @return 0 in case of success or -1 in case of error
*/
int jobs_queue2(
void *group,
int timeout,
void (*callback)(int, void*, void*),
void *arg1,
void *arg2)
{
return jobs_queue3(group, timeout, (job_cb_t)callback, arg1, arg2, NULL);
}
/**
* Queues a new asynchronous job represented by 'callback' and 'arg[123]'
* for the 'group' and the 'timeout'.
* Jobs are queued FIFO and are possibly executed in parallel
* concurrently except for job of the same group that are
* executed sequentially in FIFO order.
* @param group The group of the job or NULL when no group.
* @param timeout The maximum execution time in seconds of the job
* or 0 for unlimited time.
* @param callback The function to execute for achieving the job.
* Its first parameter is either 0 on normal flow
* or the signal number that broke the normal flow.
* The remaining parameters are the parameters 'arg[123]'
* given here.
* @param arg1 The second argument for 'callback'
* @param arg2 The third argument for 'callback'
* @param arg3 The forth argument for 'callback'
* @return 0 in case of success or -1 in case of error
*/
int jobs_queue3(
void *group,
int timeout,
void (*callback)(int, void*, void *, void*),
void *arg1,
void *arg2,
void *arg3)
{
const char *info;
struct job *job;
int rc;
pthread_mutex_lock(&mutex);
/* allocates the job */
job = job_create(group, timeout, callback, arg1, arg2, arg3);
if (!job) {
errno = ENOMEM;
info = "out of memory";
goto error;
}
/* check availability */
if (remains == 0) {
errno = EBUSY;
info = "too many jobs";
goto error2;
}
/* start a thread if needed */
if (waiting == 0 && started < allowed) {
/* all threads are busy and a new can be started */
rc = start_one_thread();
if (rc < 0 && started == 0) {
info = "can't start first thread";
goto error2;
}
}
/* queues the job */
remains--;
job_add(job);
/* signal an existing job */
pthread_cond_signal(&cond);
pthread_mutex_unlock(&mutex);
return 0;
error2:
job->next = free_jobs;
free_jobs = job;
error:
ERROR("can't process job with threads: %s, %m", info);
pthread_mutex_unlock(&mutex);
return -1;
}
/**
* Enter a synchronisation point: activates the job given by 'callback'
* @param group the gro
*/
int jobs_enter(
void *group,
int timeout,
void (*callback)(int signum, void *closure, struct jobloop *jobloop),
void *closure)
{
struct job *job;
struct thread me;
pthread_mutex_lock(&mutex);
/* allocates the job */
job = job_create(group, timeout, (job_cb_t)callback, closure, &me, NULL);
if (!job) {
ERROR("out of memory");
errno = ENOMEM;
pthread_mutex_unlock(&mutex);
return -1;
}
/* queues the job */
job_add(job);
/* run until stopped */
thread_run(&me);
pthread_mutex_unlock(&mutex);
return 0;
}
int jobs_leave(struct jobloop *jobloop)
{
struct thread *t;
pthread_mutex_lock(&mutex);
t = threads;
while (t && t != (struct thread*)jobloop)
t = t->next;
if (!t) {
errno = EINVAL;
} else {
t->stop = 1;
if (t->waits)
pthread_cond_broadcast(&cond);
}
pthread_mutex_unlock(&mutex);
return -!t;
}
/**
* Gets a sd_event item for the current thread.
* @return a sd_event or NULL in case of error
*/
struct sd_event *jobs_get_sd_event()
{
struct events *events;
struct thread *me;
int rc;
pthread_mutex_lock(&mutex);
/* search events on stack */
me = current;
while (me && !me->events)
me = me->upper;
if (me)
/* return the stacked events */
events = me->events;
else {
/* search an available events */
events = events_get();
if (!events) {
/* not found, check if creation possible */
if (nevents >= allowed) {
ERROR("not possible to add a new event");
events = NULL;
} else {
events = malloc(sizeof *events);
if (events && (rc = sd_event_new(&events->event)) >= 0) {
if (nevents < started || start_one_thread() >= 0) {
events->runs = 0;
events->next = first_events;
first_events = events;
} else {
ERROR("can't start thread for events");
sd_event_unref(events->event);
free(events);
events = NULL;
}
} else {
if (!events) {
ERROR("out of memory");
errno = ENOMEM;
} else {
free(events);
ERROR("creation of sd_event failed: %m");
events = NULL;
errno = -rc;
}
}
}
}
if (events) {
/* */
me = current;
if (me) {
events->runs = 1;
me->events = events;
} else {
WARNING("event returned for unknown thread!");
}
}
}
pthread_mutex_unlock(&mutex);
return events ? events->event : NULL;
}
/**
* Enter the jobs processing loop.
* @param allowed_count Maximum count of thread for jobs including this one
* @param start_count Count of thread to start now, must be lower.
* @param waiter_count Maximum count of jobs that can be waiting.
* @param start The start routine to activate (can't be NULL)
* @return 0 in case of success or -1 in case of error.
*/
int jobs_start(int allowed_count, int start_count, int waiter_count, void (*start)())
{
int rc, launched;
struct thread me;
struct job *job;
assert(allowed_count >= 1);
assert(start_count >= 0);
assert(waiter_count > 0);
assert(start_count <= allowed_count);
rc = -1;
pthread_mutex_lock(&mutex);
/* check whether already running */
if (current || allowed) {
ERROR("thread already started");
errno = EINVAL;
goto error;
}
/* start */
if (sig_monitor_init() < 0) {
ERROR("failed to initialise signal handlers");
goto error;
}
/* records the allowed count */
allowed = allowed_count;
started = 0;
waiting = 0;
remains = waiter_count;
/* start at least one thread */
launched = 0;
while ((launched + 1) < start_count) {
if (start_one_thread() != 0) {
ERROR("Not all threads can be started");
goto error;
}
launched++;
}
/* queue the start job */
job = job_create(NULL, 0, (job_cb_t)start, NULL, NULL, NULL);
if (!job) {
ERROR("out of memory");
errno = ENOMEM;
goto error;
}
job_add(job);
remains--;
/* run until end */
thread_run(&me);
rc = 0;
error:
pthread_mutex_unlock(&mutex);
return rc;
}
/**
* Terminate all the threads and cancel all pending jobs.
*/
void jobs_terminate()
{
struct job *job, *head, *tail;
pthread_t me, *others;
struct thread *t;
int count;
/* how am i? */
me = pthread_self();
/* request all threads to stop */
pthread_mutex_lock(&mutex);
allowed = 0;
/* count the number of threads */
count = 0;
t = threads;
while (t) {
if (!t->upper && !pthread_equal(t->tid, me))
count++;
t = t->next;
}
/* fill the array of threads */
others = alloca(count * sizeof *others);
count = 0;
t = threads;
while (t) {
if (!t->upper && !pthread_equal(t->tid, me))
others[count++] = t->tid;
t = t->next;
}
/* stops the threads */
t = threads;
while (t) {
t->stop = 1;
t = t->next;
}
/* wait the threads */
pthread_cond_broadcast(&cond);
pthread_mutex_unlock(&mutex);
while (count)
pthread_join(others[--count], NULL);
pthread_mutex_lock(&mutex);
/* cancel pending jobs of other threads */
remains = 0;
head = first_job;
first_job = NULL;
tail = NULL;
while (head) {
/* unlink the job */
job = head;
head = job->next;
/* search if job is stacked for current */
t = current;
while (t && t->job != job)
t = t->upper;
if (t) {
/* yes, relink it at end */
if (tail)
tail->next = job;
else
first_job = job;
tail = job;
job->next = NULL;
} else {
/* no cancel the job */
pthread_mutex_unlock(&mutex);
sig_monitor(0, job_cancel, job);
free(job);
pthread_mutex_lock(&mutex);
}
}
pthread_mutex_unlock(&mutex);
}
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