From 70bd1c94dee46dac0885831ccce3d1840388656e Mon Sep 17 00:00:00 2001
From: Tomas Mudrunka <tomas@mudrunka.cz>
Date: Thu, 1 Jul 2021 15:12:22 +0200
Subject: [PATCH] Priprava na vyhradni mod

---
 c/pthread_extra/pthread_extra.h     |  2 +
 c/pthread_extra/pthread_pause.c     | 57 +++++++++++++++++++++++++++--
 c/pthread_extra/pthread_user_data.c |  2 +-
 3 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/c/pthread_extra/pthread_extra.h b/c/pthread_extra/pthread_extra.h
index efba75e..ca5de70 100644
--- a/c/pthread_extra/pthread_extra.h
+++ b/c/pthread_extra/pthread_extra.h
@@ -24,6 +24,8 @@ typedef struct pthread_user_data_internal_t {
 } pthread_user_data_internal_t;
 
 pthread_user_data_internal_t* pthread_user_data_internal(pthread_t thread);
+int pthread_user_data_lock();
+int pthread_user_data_unlock();
 #endif //__PTHREAD_EXTRA_INTERNAL
 
 void** pthread_user_data_ptr(pthread_t thread);
diff --git a/c/pthread_extra/pthread_pause.c b/c/pthread_extra/pthread_pause.c
index c6b96f6..4107b38 100644
--- a/c/pthread_extra/pthread_pause.c
+++ b/c/pthread_extra/pthread_pause.c
@@ -12,10 +12,14 @@
 #include <assert.h>
 //#include <sys/time.h>
 
+///When this variable is nonzero, only referenced thread is allowed to run
+///Access has to be protected by pthread_user_data_lock()
+pthread_t pthread_pause_holder = 0;
+
 void pthread_pause_handler(const int signal, siginfo_t *info, void *ptr) {
 	(void)signal; (void)info; (void)ptr;
-	pthread_user_data_internal_t *td = (pthread_user_data_internal_t *)(info->si_value.sival_ptr);
-	(void)td;
+	int run = info->si_value.sival_int;
+	//(void)td;
 
 	//Do nothing when there are more signals pending (to cleanup the queue)
 	sigset_t pending;
@@ -30,7 +34,7 @@ void pthread_pause_handler(const int signal, siginfo_t *info, void *ptr) {
 	//printf("RCV: %p = %p\n", (void *)pthread_user_data_internal(pthread_self()), (void *)td);
 
 	//if(!pthread_user_data_internal(pthread_self())->running) {
-	if(!td->running) {
+	if(!run) {
 		sigsuspend(&sigset);
 	}
 }
@@ -75,6 +79,7 @@ void pthread_pause_disable() {
 	pthread_sigmask(SIG_BLOCK, &sigset, NULL);
 }
 
+/*
 int pthread_pause_reschedule(pthread_t thread) {
 	//Send signal to initiate pause handler
 	//printf("SND: %p\n", (void *)pthread_user_data_internal(thread));
@@ -84,6 +89,27 @@ int pthread_pause_reschedule(pthread_t thread) {
 		) == EAGAIN) usleep(1000);
 	return 0;
 }
+*/
+
+int pthread_pause_reschedule(pthread_t thread) {
+	//Decide if the thread should run
+
+	pthread_user_data_lock();
+	//Check if thread has running flag
+	int run = (pthread_user_data_internal(thread)->running);
+	//Check if privileged (single thread) mode is active
+	if((pthread_pause_holder != 0) && !pthread_equal(pthread_pause_holder, thread)) {
+		run = 0;
+	}
+	pthread_user_data_unlock();
+
+	//Send signal to initiate pause handler (keep trying while SigQueue is full)
+	//while(pthread_kill(thread, PTHREAD_XSIG_STOP) == EAGAIN) usleep(1000);
+	while(pthread_sigqueue(thread, PTHREAD_XSIG_STOP,
+		(const union sigval){.sival_int=run}
+		) == EAGAIN) usleep(1000);
+	return 0;
+}
 
 int pthread_extra_yield() {
 	//Yield to both schedulers
@@ -93,18 +119,39 @@ int pthread_extra_yield() {
 
 int pthread_pause(pthread_t thread) {
 	//Set thread as paused and notify it via signal (wait when queue full)
+	pthread_user_data_lock();
 	pthread_user_data_internal(thread)->running = 0;
+	pthread_user_data_unlock();
 	pthread_pause_reschedule(thread);
 	return 0;
 }
 
 int pthread_unpause(pthread_t thread) {
 	//Set thread as running and notify it via signal (wait when queue full)
+	pthread_user_data_lock();
 	pthread_user_data_internal(thread)->running = 1;
+	pthread_user_data_unlock();
 	pthread_pause_reschedule(thread);
 	return 0;
 }
 
+int pthread_pause_all() {
+	pthread_user_data_lock();
+	if(pthread_pause_holder!=0) assert(pthread_equal(pthread_pause_holder, pthread_self()));
+	pthread_pause_holder = pthread_self();
+	pthread_user_data_unlock();
+	//todo reschedule all
+	return 0;
+}
+
+int pthread_unpause_all() {
+	pthread_user_data_lock();
+	if(pthread_pause_holder!=0) assert(pthread_equal(pthread_pause_holder, pthread_self()));
+	pthread_pause_holder = 0;
+	pthread_user_data_unlock();
+	//todo reschedule
+	return 0;
+}
 
 
 // Wrappers ///////////////////////////////////////////////////////////
@@ -126,8 +173,10 @@ void *pthread_extra_thread_wrapper(void *arg) {
 	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_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
diff --git a/c/pthread_extra/pthread_user_data.c b/c/pthread_extra/pthread_user_data.c
index e0ba979..a1e1ebd 100644
--- a/c/pthread_extra/pthread_user_data.c
+++ b/c/pthread_extra/pthread_user_data.c
@@ -7,7 +7,7 @@
 //Static array with user data for all thread handles
 //TODO: perhaps use something more sophisticated like linked list?
 pthread_user_data_internal_t pthread_user_data[PTHREAD_XTHREADS_MAX+1] = {{.tid=PTHREAD_XNULL}};
-pthread_mutex_t pthread_user_data_mutex = PTHREAD_MUTEX_INITIALIZER;
+pthread_mutex_t pthread_user_data_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
 
 int pthread_user_data_lock() {
 	pthread_pause_disable();
-- 
2.30.2