/*
 * mono-threads-posix.c: Low-level threading, posix version
 *
 * Author:
 *	Rodrigo Kumpera (kumpera@gmail.com)
 *
 * (C) 2011 Novell, Inc
 */

#include <config.h>

/* For pthread_main_np, pthread_get_stackaddr_np and pthread_get_stacksize_np */
#if defined (__MACH__)
#define _DARWIN_C_SOURCE 1
#endif

#include <mono/utils/mono-threads.h>
#include <mono/utils/mono-coop-semaphore.h>
#include <mono/metadata/gc-internals.h>
#include <mono/utils/mono-threads-debug.h>

#include <errno.h>

#if defined(PLATFORM_ANDROID) && !defined(TARGET_ARM64) && !defined(TARGET_AMD64)
#define USE_TKILL_ON_ANDROID 1
#endif

#ifdef USE_TKILL_ON_ANDROID
extern int tkill (pid_t tid, int signal);
#endif

#if defined(_POSIX_VERSION) || defined(__native_client__)

#include <pthread.h>

#include <sys/resource.h>

int
mono_threads_platform_create_thread (MonoThreadStart thread_fn, gpointer thread_data, gsize* const stack_size, MonoNativeThreadId *out_tid)
{
	pthread_attr_t attr;
	pthread_t thread;
	int policy;
	struct sched_param param;
	gint res;
	gsize set_stack_size;
	size_t min_size;

	res = pthread_attr_init (&attr);
	g_assert (!res);

	if (stack_size)
		set_stack_size = *stack_size;
	else
		set_stack_size = 0;

#ifdef HAVE_PTHREAD_ATTR_SETSTACKSIZE
	if (set_stack_size == 0) {
#if HAVE_VALGRIND_MEMCHECK_H
		if (RUNNING_ON_VALGRIND)
			set_stack_size = 1 << 20;
		else
			set_stack_size = (SIZEOF_VOID_P / 4) * 1024 * 1024;
#else
		set_stack_size = (SIZEOF_VOID_P / 4) * 1024 * 1024;
#endif
	}

#ifdef PTHREAD_STACK_MIN
	if (set_stack_size < PTHREAD_STACK_MIN)
		set_stack_size = PTHREAD_STACK_MIN;
#endif

	res = pthread_attr_setstacksize (&attr, set_stack_size);
	g_assert (!res);
#endif /* HAVE_PTHREAD_ATTR_SETSTACKSIZE */

	memset (&param, 0, sizeof (param));

	res = pthread_attr_getschedpolicy (&attr, &policy);
	if (res != 0)
		g_error ("%s: pthread_attr_getschedpolicy failed, error: \"%s\" (%d)", g_strerror (res), res);

#ifdef _POSIX_PRIORITY_SCHEDULING
	int max, min;

	/* Necessary to get valid priority range */

	min = sched_get_priority_min (policy);
	max = sched_get_priority_max (policy);

	if (max > 0 && min >= 0 && max > min)
		param.sched_priority = (max - min) / 2 + min;
	else
#endif
	{
		switch (policy) {
		case SCHED_FIFO:
		case SCHED_RR:
			param.sched_priority = 50;
			break;
#ifdef SCHED_BATCH
		case SCHED_BATCH:
#endif
		case SCHED_OTHER:
			param.sched_priority = 0;
			break;
		default:
			g_error ("%s: unknown policy %d", __func__, policy);
		}
	}

	res = pthread_attr_setschedparam (&attr, &param);
	if (res != 0)
		g_error ("%s: pthread_attr_setschedparam failed, error: \"%s\" (%d)", g_strerror (res), res);

	if (stack_size) {
		res = pthread_attr_getstacksize (&attr, &min_size);
		if (res != 0)
			g_error ("%s: pthread_attr_getstacksize failed, error: \"%s\" (%d)", g_strerror (res), res);
		else
			*stack_size = min_size;
	}

	/* Actually start the thread */
	res = mono_gc_pthread_create (&thread, &attr, (gpointer (*)(gpointer)) thread_fn, thread_data);
	if (res)
		return -1;

	if (out_tid)
		*out_tid = thread;

	return 0;
}

void
mono_threads_platform_init (void)
{
}

gboolean
mono_threads_platform_in_critical_region (MonoNativeThreadId tid)
{
	return FALSE;
}

gboolean
mono_threads_platform_yield (void)
{
	return sched_yield () == 0;
}

void
mono_threads_platform_exit (gsize exit_code)
{
	pthread_exit ((gpointer) exit_code);
}

int
mono_threads_get_max_stack_size (void)
{
	struct rlimit lim;

	/* If getrlimit fails, we don't enforce any limits. */
	if (getrlimit (RLIMIT_STACK, &lim))
		return INT_MAX;
	/* rlim_t is an unsigned long long on 64bits OSX but we want an int response. */
	if (lim.rlim_max > (rlim_t)INT_MAX)
		return INT_MAX;
	return (int)lim.rlim_max;
}

int
mono_threads_pthread_kill (MonoThreadInfo *info, int signum)
{
	THREADS_SUSPEND_DEBUG ("sending signal %d to %p[%p]\n", signum, info, mono_thread_info_get_tid (info));
#ifdef USE_TKILL_ON_ANDROID
	int result, old_errno = errno;
	result = tkill (info->native_handle, signum);
	if (result < 0) {
		result = errno;
		errno = old_errno;
	}
	return result;
#elif defined(__native_client__)
	/* Workaround pthread_kill abort() in NaCl glibc. */
	return 0;
#elif !defined(HAVE_PTHREAD_KILL)
	g_error ("pthread_kill() is not supported by this platform");
#else
	return pthread_kill (mono_thread_info_get_tid (info), signum);
#endif
}

MonoNativeThreadId
mono_native_thread_id_get (void)
{
	return pthread_self ();
}

gboolean
mono_native_thread_id_equals (MonoNativeThreadId id1, MonoNativeThreadId id2)
{
	return pthread_equal (id1, id2);
}

/*
 * mono_native_thread_create:
 *
 *   Low level thread creation function without any GC wrappers.
 */
gboolean
mono_native_thread_create (MonoNativeThreadId *tid, gpointer func, gpointer arg)
{
	return pthread_create (tid, NULL, (void *(*)(void *)) func, arg) == 0;
}

void
mono_native_thread_set_name (MonoNativeThreadId tid, const char *name)
{
#ifdef __MACH__
	/*
	 * We can't set the thread name for other threads, but we can at least make
	 * it work for threads that try to change their own name.
	 */
	if (tid != mono_native_thread_id_get ())
		return;

	if (!name) {
		pthread_setname_np ("");
	} else {
		char n [63];

		strncpy (n, name, 63);
		n [62] = '\0';
		pthread_setname_np (n);
	}
#elif defined (__NetBSD__)
	if (!name) {
		pthread_setname_np (tid, "%s", (void*)"");
	} else {
		char n [PTHREAD_MAX_NAMELEN_NP];

		strncpy (n, name, PTHREAD_MAX_NAMELEN_NP);
		n [PTHREAD_MAX_NAMELEN_NP - 1] = '\0';
		pthread_setname_np (tid, "%s", (void*)n);
	}
#elif defined (HAVE_PTHREAD_SETNAME_NP)
	if (!name) {
		pthread_setname_np (tid, "");
	} else {
		char n [16];

		strncpy (n, name, 16);
		n [15] = '\0';
		pthread_setname_np (tid, n);
	}
#endif
}

gboolean
mono_native_thread_join (MonoNativeThreadId tid)
{
	void *res;

	return !pthread_join (tid, &res);
}

#endif /* defined(_POSIX_VERSION) || defined(__native_client__) */

#if defined(USE_POSIX_BACKEND)

gboolean
mono_threads_suspend_begin_async_suspend (MonoThreadInfo *info, gboolean interrupt_kernel)
{
	int sig = interrupt_kernel ? mono_threads_suspend_get_abort_signal () :  mono_threads_suspend_get_suspend_signal ();

	if (!mono_threads_pthread_kill (info, sig)) {
		mono_threads_add_to_pending_operation_set (info);
		return TRUE;
	}
	return FALSE;
}

gboolean
mono_threads_suspend_check_suspend_result (MonoThreadInfo *info)
{
	return info->suspend_can_continue;
}

/*
This begins async resume. This function must do the following:

- Install an async target if one was requested.
- Notify the target to resume.
*/
gboolean
mono_threads_suspend_begin_async_resume (MonoThreadInfo *info)
{
	int sig = mono_threads_suspend_get_restart_signal ();

	if (!mono_threads_pthread_kill (info, sig)) {
		mono_threads_add_to_pending_operation_set (info);
		return TRUE;
	}
	return FALSE;
}

void
mono_threads_suspend_abort_syscall (MonoThreadInfo *info)
{
	/* We signal a thread to break it from the current syscall.
	 * This signal should not be interpreted as a suspend request. */
	info->syscall_break_signal = TRUE;
	if (mono_threads_pthread_kill (info, mono_threads_suspend_get_abort_signal ()) == 0) {
		mono_threads_add_to_pending_operation_set (info);
	}
}

gboolean
mono_threads_suspend_needs_abort_syscall (void)
{
	return TRUE;
}

void
mono_threads_suspend_register (MonoThreadInfo *info)
{
#if defined (PLATFORM_ANDROID)
	info->native_handle = gettid ();
#endif
}

void
mono_threads_suspend_free (MonoThreadInfo *info)
{
}

void
mono_threads_suspend_init (void)
{
}

#endif /* defined(USE_POSIX_BACKEND) */