X-Git-Url: http://git.harvie.cz/?a=blobdiff_plain;f=c%2Fpthread_extra%2Fpthread_pause.c;h=950d6fa26954ffdbf5d42ad9fcec3a27fd3e860b;hb=46a7758b58eeff9b507e6e173b03b7fd909e22c3;hp=309016c289c3001159a7c94b9201dda47606c5e3;hpb=a8e71e8fffa0159f06b2c469fb2d3dfd8222b306;p=mirrors%2FPrograms.git

diff --git a/c/pthread_extra/pthread_pause.c b/c/pthread_extra/pthread_pause.c
index 309016c..950d6fa 100644
--- a/c/pthread_extra/pthread_pause.c
+++ b/c/pthread_extra/pthread_pause.c
@@ -1,19 +1,250 @@
+#define __PTHREAD_EXTRA_INTERNAL
+
 #include <pthread.h>
 #include <pthread_extra.h>
 #include <signal.h>
+#include <semaphore.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/resource.h>
+//#include <sys/siginfo.h>
+//#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+//#include <sys/time.h>
+
+//Mutex that ensures proper serialization of (un)pause calls
+//pthread_mutex_t pthread_pause_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
 
-void pthread_unpause_handler() {
-	//NOP
+//Semaphore that ensures proper serialization of (un)pause signals
+sem_t pthread_pause_sem;
+//Once control to init the semaphore (and possibly other stuff)
+pthread_once_t pthread_pause_once_ctrl = PTHREAD_ONCE_INIT;
+void pthread_pause_once(void) {
+	sem_init(&pthread_pause_sem, 0, 1);
 }
+void pthread_pause_init() { pthread_once(&pthread_pause_once_ctrl, &pthread_pause_once); }
 
-void pthread_pause_handler() {
-	sigset_t sigset;
-	sigfillset(&sigset);
-	sigdelset(&sigset, PTHREAD_XSIG_CONT);
-	sigsuspend(&sigset);
+///When this variable is nonzero, only referenced thread is allowed to run
+///Access has to be protected by pthread_user_data_lock() and pthread_pause_sem;
+pthread_t pthread_pause_holder = PTHREAD_XNULL;
+
+void pthread_pause_handler(const int signal, siginfo_t *info, void *ptr) {
+	(void)signal; (void)info; (void)ptr;
+	int run = info->si_value.sival_int;
+	//(void)td;
+
+	//Post semaphore to confirm that signal is handled
+	sem_post(&pthread_pause_sem);
+
+	//Keep waiting for signals until we are supposed to be running
+	if(!run) {
+		sigset_t sigset;
+		sigfillset(&sigset);
+		sigdelset(&sigset, PTHREAD_XSIG_STOP);
+		sigsuspend(&sigset);
+	}
 }
 
 void pthread_pause_enable() {
-	signal(PTHREAD_XSIG_STOP, pthread_pause_handler);
-	signal(PTHREAD_XSIG_CONT, pthread_unpause_handler);
+	pthread_pause_init(); //Make sure semaphore is init'd
+
+	//Nesting signals too deep is not good for stack
+	//You can get runtime stats using following command:
+	//grep -i sig /proc/$(pgrep binary)/status
+	//struct rlimit sigq = {.rlim_cur = 32, .rlim_max=32};
+	//setrlimit(RLIMIT_SIGPENDING, &sigq);
+
+	//Prepare signal mask
+	sigset_t sigset;
+	sigemptyset(&sigset);
+	sigaddset(&sigset, PTHREAD_XSIG_STOP);
+
+	//Setup signal handler
+	//signal(PTHREAD_XSIG_STOP, pthread_pause_handler);
+	const struct sigaction pause_sa = {
+		.sa_sigaction = pthread_pause_handler,
+		.sa_mask = sigset,
+		.sa_flags = SA_SIGINFO | SA_RESTART,
+		.sa_restorer = NULL
+	};
+
+	sigaction(PTHREAD_XSIG_STOP, &pause_sa, NULL);
+
+	//Unblock signal
+	pthread_sigmask(SIG_UNBLOCK, &sigset, NULL);
+
+	//Add thread to internal registry
+	pthread_user_data_internal(pthread_self()); //Only now, when signals are unblocked!
+}
+
+void pthread_pause_disable() {
+	//pthread_user_data_lock();
+	pthread_pause_init(); //Make sure semaphore is init'd
+
+	//Add thread to internal registry
+	//pthread_user_data_internal(pthread_self()); //DEADLOCKS!
+
+	//Block signal
+	sigset_t sigset;
+	sigemptyset(&sigset);
+	sigaddset(&sigset, PTHREAD_XSIG_STOP);
+
+	//Make sure all signals are dispatched before we block them
+	//Maybe not a good idea, causes DEADLOCKS!
+	//sem_wait(&pthread_pause_sem);
+	pthread_sigmask(SIG_BLOCK, &sigset, NULL);
+	//sem_post(&pthread_pause_sem);
+
+	//pthread_user_data_unlock();
+}
+
+/*
+int pthread_pause_reschedule(pthread_t thread) {
+	//Send signal to initiate pause handler
+	//printf("SND: %p\n", (void *)pthread_user_data_internal(thread));
+	//while(pthread_kill(thread, PTHREAD_XSIG_STOP) == EAGAIN) usleep(1000);
+	while(pthread_sigqueue(thread, PTHREAD_XSIG_STOP,
+		(const union sigval){.sival_ptr=pthread_user_data_internal(thread)}
+		) == EAGAIN) usleep(1000);
+	return 0;
+}
+*/
+
+int pthread_pause_reschedule(pthread_t thread) {
+	//Decide if the thread should run and signal it
+	pthread_user_data_lock();
+
+	//Wait for semaphore which means signal queue is empty
+	pthread_pause_init(); //Make sure semaphore is init'd
+	sem_wait(&pthread_pause_sem);
+
+	//Only call this if you already acquired pthread_pause_sem semaphore!!!!
+	//Otherwise call pthread_pause_reschedule()
+
+	//Check if thread has running flag
+	int run = (pthread_user_data_internal(thread)->running);
+	//Check if privileged (single thread) mode is active
+	if(!pthread_equal(pthread_pause_holder, PTHREAD_XNULL) && !pthread_equal(pthread_pause_holder, thread)) {
+		run = 0;
+	}
+
+	//Send signal to initiate pause handler (keep trying while SigQueue is full)
+	//while(pthread_kill(thread, PTHREAD_XSIG_STOP) == EAGAIN) usleep(1000);
+	//printf("Sched %lu = %d (self: %lu, lck: %lu)\n", thread, run, pthread_self(), pthread_pause_holder);
+	while(pthread_sigqueue(thread, PTHREAD_XSIG_STOP,
+		(const union sigval){.sival_int=run}
+		) == EAGAIN) usleep(1000);
+
+	//Wait for signal to be delivered
+	sem_wait(&pthread_pause_sem);
+	sem_post(&pthread_pause_sem);
+	pthread_user_data_unlock();
+
+	return 0;
+}
+
+int pthread_extra_yield() {
+	//Yield to both schedulers
+	pthread_pause_reschedule(pthread_self());
+	return pthread_yield();
+}
+
+///Sanity check to be sure there are no race conditions
+inline void pthread_pause_assert_owner() {
+	if(!pthread_equal(pthread_pause_holder,PTHREAD_XNULL))
+		assert(pthread_equal(pthread_pause_holder, pthread_self()));
+}
+
+///Pause specified thread (block until it is paused)
+int pthread_pause(pthread_t thread) {
+	pthread_user_data_lock();
+	pthread_pause_assert_owner();
+	//if(!pthread_equal(pthread_pause_holder,PTHREAD_XNULL)) assert(pthread_equal(pthread_pause_holder, pthread_self()));
+	//Set thread as paused and notify it via signal (wait when queue full)
+	pthread_user_data_internal(thread)->running = 0;
+	pthread_pause_reschedule(thread);
+	pthread_user_data_unlock();
+	return 0;
+}
+
+///UnPause specified thread (block until it is unpaused)
+int pthread_unpause(pthread_t thread) {
+	pthread_user_data_lock();
+	pthread_pause_assert_owner();
+	//Set thread as running and notify it via signal (wait when queue full)
+	pthread_user_data_internal(thread)->running = 1;
+	pthread_pause_reschedule(thread);
+	pthread_user_data_unlock();
+	return 0;
+}
+
+///Enter exclusive mode by pausing everyone else
+int pthread_pause_all() {
+	//printf("Pause ALL\n");
+	pthread_user_data_lock();
+	//printf("Pause ALL+\n");
+	//printf("Pause %p == %p\n", (void *)pthread_pause_holder, (void *)pthread_self());
+	pthread_pause_assert_owner();
+	pthread_pause_holder = pthread_self();
+	pthread_user_data_internal_iterate(&pthread_pause_reschedule, NULL);
+	//printf("Pause ALL!\n");
+	pthread_user_data_unlock();
+	return 0;
+}
+
+///Leave exclusive mode by unpausing everyone else
+int pthread_unpause_all() {
+	//printf("UnPause ALL\n");
+	pthread_user_data_lock();
+	//printf("UnPause ALL+\n");
+	pthread_pause_assert_owner();
+	pthread_pause_holder = PTHREAD_XNULL;
+	pthread_user_data_internal_iterate(&pthread_pause_reschedule, NULL);
+	//printf("UnPause ALL!\n");
+	pthread_user_data_unlock();
+	return 0;
+}
+
+
+// Wrappers ///////////////////////////////////////////////////////////
+
+
+typedef struct pthread_extra_wrapper_t {
+	void *(*start_routine)(void *);
+	void *restrict arg;
+} pthread_extra_wrapper_t;
+
+void *pthread_extra_thread_wrapper(void *arg) {
+	pthread_extra_wrapper_t task = *((pthread_extra_wrapper_t*)arg);
+	free(arg);
+
+	pthread_pause_enable();
+
+	//Register new thread to user data structure
+	//pthread_user_data_internal(pthread_self()); //Perhaps already done in pthread_extra_yield() and pthread_pause_enable()??
+
+	//TODO: user_data should do this automaticaly?
+	pthread_cleanup_push(pthread_user_data_cleanup, (void *)pthread_self());
+
+	//Check if we should be running according to pthread_pause sub-scheduler
+	//pthread_pause_reschedule(pthread_self());
+	pthread_extra_yield();
+
+	//Run actual task
+	return task.start_routine(task.arg);
+
+	pthread_cleanup_pop(1); //Needed by pthread_cleanup_push() macro
+}
+
+int pthread_extra_create(pthread_t *restrict thread,
+                          const pthread_attr_t *restrict attr,
+                          void *(*start_routine)(void *),
+                          void *restrict arg) {
+
+	pthread_extra_wrapper_t *task = malloc(sizeof(pthread_extra_wrapper_t));
+	assert(task != NULL);
+	task->start_routine=start_routine;
+	task->arg=arg;
+	return pthread_create(thread, attr, pthread_extra_thread_wrapper, task);
 }