/*
 * threads.c:  Thread handles
 *
 * Author:
 *	Dick Porter (dick@ximian.com)
 *
 * (C) 2002-2006 Ximian, Inc.
 * Copyright 2003-2011 Novell, Inc (http://www.novell.com)
 * Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
 */

#include <config.h>
#include <stdio.h>
#include <glib.h>
#include <string.h>
#include <pthread.h>
#include <sched.h>
#include <sys/time.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>

#include <mono/io-layer/wapi.h>
#include <mono/io-layer/wapi-private.h>
#include <mono/io-layer/handles-private.h>
#include <mono/io-layer/thread-private.h>
#include <mono/io-layer/mutex-private.h>
#include <mono/io-layer/io-trace.h>

#include <mono/utils/mono-threads.h>
#include <mono/utils/atomic.h>
#include <mono/utils/mono-time.h>
#include <mono/utils/mono-once.h>
#include <mono/utils/mono-logger-internals.h>

#ifdef HAVE_VALGRIND_MEMCHECK_H
#include <valgrind/memcheck.h>
#endif

struct _WapiHandleOps _wapi_thread_ops = {
	NULL,				/* close */
	NULL,				/* signal */
	NULL,				/* own */
	NULL,				/* is_owned */
	NULL,				/* special_wait */
	NULL				/* prewait */
};
 
typedef enum {
	THREAD_PRIORITY_LOWEST = -2,
	THREAD_PRIORITY_BELOW_NORMAL = -1,
	THREAD_PRIORITY_NORMAL = 0,
	THREAD_PRIORITY_ABOVE_NORMAL = 1,
	THREAD_PRIORITY_HIGHEST = 2
} WapiThreadPriority;

static mono_once_t thread_ops_once = MONO_ONCE_INIT;

static void
thread_ops_init (void)
{
	_wapi_handle_register_capabilities (WAPI_HANDLE_THREAD,
					    WAPI_HANDLE_CAP_WAIT);
}

void
_wapi_thread_cleanup (void)
{
}

static gpointer
get_current_thread_handle (void)
{
	MonoThreadInfo *info;

	info = mono_thread_info_current ();
	g_assert (info);
	g_assert (info->handle);
	return info->handle;
}

static WapiHandle_thread*
lookup_thread (HANDLE handle)
{
	WapiHandle_thread *thread;
	gboolean ok;

	ok = _wapi_lookup_handle (handle, WAPI_HANDLE_THREAD,
							  (gpointer *)&thread);
	g_assert (ok);
	return thread;
}

static WapiHandle_thread*
get_current_thread (void)
{
	gpointer handle;

	handle = get_current_thread_handle ();
	return lookup_thread (handle);
}

void
wapi_thread_handle_set_exited (gpointer handle, guint32 exitstatus)
{
	WapiHandle_thread *thread_handle;
	int i, thr_ret;
	pid_t pid = _wapi_getpid ();
	pthread_t tid = pthread_self ();
	
	if (_wapi_handle_issignalled (handle) ||
	    _wapi_handle_type (handle) == WAPI_HANDLE_UNUSED) {
		/* We must have already deliberately finished with
		 * this thread, so don't do any more now
		 */
		return;
	}

	MONO_TRACE (G_LOG_LEVEL_DEBUG, MONO_TRACE_IO_LAYER, "%s: Thread %p terminating", __func__, handle);

	thread_handle = lookup_thread (handle);

	MONO_TRACE (G_LOG_LEVEL_DEBUG, MONO_TRACE_IO_LAYER, "%s: Thread %p abandoning held mutexes", __func__, handle);

	for (i = 0; i < thread_handle->owned_mutexes->len; i++) {
		gpointer mutex = g_ptr_array_index (thread_handle->owned_mutexes, i);

		_wapi_mutex_abandon (mutex, pid, tid);
		_wapi_thread_disown_mutex (mutex);
	}
	g_ptr_array_free (thread_handle->owned_mutexes, TRUE);
	
	thr_ret = _wapi_handle_lock_handle (handle);
	g_assert (thr_ret == 0);

	_wapi_handle_set_signal_state (handle, TRUE, TRUE);

	thr_ret = _wapi_handle_unlock_handle (handle);
	g_assert (thr_ret == 0);
	
	MONO_TRACE (G_LOG_LEVEL_DEBUG, MONO_TRACE_IO_LAYER, "%s: Recording thread handle %p id %ld status as %d",
		  __func__, handle, thread_handle->id, exitstatus);
	
	/* The thread is no longer active, so unref it */
	_wapi_handle_unref (handle);
}

/*
 * wapi_create_thread_handle:
 *
 *   Create a thread handle for the current thread.
 */
gpointer
wapi_create_thread_handle (void)
{
	WapiHandle_thread thread_handle = {0}, *thread;
	gpointer handle;

	mono_once (&thread_ops_once, thread_ops_init);

	thread_handle.owned_mutexes = g_ptr_array_new ();

	handle = _wapi_handle_new (WAPI_HANDLE_THREAD, &thread_handle);
	if (handle == _WAPI_HANDLE_INVALID) {
		g_warning ("%s: error creating thread handle", __func__);
		SetLastError (ERROR_GEN_FAILURE);
		
		return NULL;
	}

	thread = lookup_thread (handle);

	thread->id = pthread_self ();

	/*
	 * Hold a reference while the thread is active, because we use
	 * the handle to store thread exit information
	 */
	_wapi_handle_ref (handle);

	MONO_TRACE (G_LOG_LEVEL_DEBUG, MONO_TRACE_IO_LAYER, "%s: started thread id %ld", __func__, thread->id);
	
	return handle;
}

void
wapi_ref_thread_handle (gpointer handle)
{
	_wapi_handle_ref (handle);
}

gpointer
wapi_get_current_thread_handle (void)
{
	return get_current_thread_handle ();
}

gboolean
_wapi_thread_cur_apc_pending (void)
{
	return mono_thread_info_is_interrupt_state (mono_thread_info_current ());
}

void
_wapi_thread_own_mutex (gpointer mutex)
{
	WapiHandle_thread *thread;
	
	thread = get_current_thread ();

	_wapi_handle_ref (mutex);
	
	g_ptr_array_add (thread->owned_mutexes, mutex);
}

void
_wapi_thread_disown_mutex (gpointer mutex)
{
	WapiHandle_thread *thread;

	thread = get_current_thread ();

	_wapi_handle_unref (mutex);
	
	g_ptr_array_remove (thread->owned_mutexes, mutex);
}

/**
 * _wapi_thread_posix_priority_to_priority:
 *
 *   Convert a POSIX priority to a WapiThreadPriority.
 * sched_priority is a POSIX priority,
 * policy is the current scheduling policy
 */
static WapiThreadPriority 
_wapi_thread_posix_priority_to_priority (int sched_priority, int policy)
{
/* Necessary to get valid priority range */
#ifdef _POSIX_PRIORITY_SCHEDULING
	int max,
	    min,
	    i,
	    priority,
	    chunk;
	WapiThreadPriority priorities[] = {
		THREAD_PRIORITY_LOWEST,
		THREAD_PRIORITY_LOWEST,
		THREAD_PRIORITY_BELOW_NORMAL,
		THREAD_PRIORITY_NORMAL,
		THREAD_PRIORITY_ABOVE_NORMAL,
		THREAD_PRIORITY_HIGHEST,
		THREAD_PRIORITY_HIGHEST
	};
	    
	max = sched_get_priority_max (policy);
	min = sched_get_priority_min (policy);
	
	/* Partition priority range linearly, 
	   assign each partition a thread priority */
	if (max != min && 0 <= max && 0 <= min) {
		for (i=1, priority=min, chunk=(max-min)/7; 
		     i<6 && sched_priority > priority;
		     ++i) {
			priority += chunk;
		}
		
		if (max <= priority)
		{
			return (THREAD_PRIORITY_HIGHEST);
		}
		else
		{
			return (priorities[i-1]);
		}
	}
#endif

	return (THREAD_PRIORITY_NORMAL);
}

/**
 * _wapi_thread_priority_to_posix_priority:
 *
 *   Convert a WapiThreadPriority to a POSIX priority.
 * priority is a WapiThreadPriority,
 * policy is the current scheduling policy
 */
static int 
_wapi_thread_priority_to_posix_priority (WapiThreadPriority priority, int policy)
{
/* Necessary to get valid priority range */
#ifdef _POSIX_PRIORITY_SCHEDULING
	int max,
	    min,
	    posix_priority,
	    i;
	WapiThreadPriority priorities[] = {
		THREAD_PRIORITY_LOWEST,
		THREAD_PRIORITY_LOWEST,
		THREAD_PRIORITY_BELOW_NORMAL,
		THREAD_PRIORITY_NORMAL,
		THREAD_PRIORITY_ABOVE_NORMAL,
		THREAD_PRIORITY_HIGHEST,
		THREAD_PRIORITY_HIGHEST
	};
	
	max = sched_get_priority_max (policy);
	min = sched_get_priority_min (policy);

	/* Partition priority range linearly, 
	   numerically approximate matching ThreadPriority */
	if (max != min && 0 <= max && 0 <= min) {
		for (i=0; i<7; ++i) {
			if (priorities[i] == priority) {
				posix_priority = min + ((max-min)/7) * i;
				if (max < posix_priority)
				{
					return max;
				}
				else {
					return posix_priority;
				}
			}
		}
	}
#endif

	switch (policy) {
		case SCHED_FIFO:
		case SCHED_RR:
			return 50;
#ifdef SCHED_BATCH
		case SCHED_BATCH:
#endif
		case SCHED_OTHER:
			return 0;
		default:
			return -1;
	}
}

/**
 * GetThreadPriority:
 * @param handle: The thread handle to query.
 *
 * Gets the priority of the given thread.
 * @return: A MonoThreadPriority approximating the current POSIX 
 * thread priority, or THREAD_PRIORITY_NORMAL on error.
 */
gint32 
GetThreadPriority (gpointer handle)
{
	struct _WapiHandle_thread *thread_handle;
	int policy;
	struct sched_param param;
	gboolean ok = _wapi_lookup_handle (handle, WAPI_HANDLE_THREAD,
				  (gpointer *)&thread_handle);
				  
	if (ok == FALSE) {
		return (THREAD_PRIORITY_NORMAL);
	}
	
	switch (pthread_getschedparam (thread_handle->id, &policy, &param)) {
		case 0:
			return (_wapi_thread_posix_priority_to_priority (param.sched_priority, policy));
		case ESRCH:
			g_warning ("pthread_getschedparam: error looking up thread id %x", (gsize)thread_handle->id);
	}
	
	return (THREAD_PRIORITY_NORMAL);
}

/**
 * SetThreadPriority:
 * @param handle: The thread handle to query.
 * @param priority: The priority to give to the thread.
 *
 * Sets the priority of the given thread.
 * @return: TRUE on success, FALSE on failure or error.
 */
gboolean 
SetThreadPriority (gpointer handle, gint32 priority)
{
	struct _WapiHandle_thread *thread_handle;
	int policy,
	    posix_priority,
	    rv;
	struct sched_param param;
	gboolean ok = _wapi_lookup_handle (handle, WAPI_HANDLE_THREAD,
				  (gpointer *)&thread_handle);
				  
	if (ok == FALSE) {
		return ok;
	}
	
	rv = pthread_getschedparam (thread_handle->id, &policy, &param);
	if (rv) {
		if (ESRCH == rv)
			g_warning ("pthread_getschedparam: error looking up thread id %x", (gsize)thread_handle->id);
		return FALSE;
	}
	
	posix_priority =  _wapi_thread_priority_to_posix_priority (priority, policy);
	if (0 > posix_priority)
		return FALSE;
		
	param.sched_priority = posix_priority;
	switch (pthread_setschedparam (thread_handle->id, policy, &param)) {
		case 0:
			return TRUE;
		case ESRCH:
			g_warning ("pthread_setschedparam: error looking up thread id %x", (gsize)thread_handle->id);
			break;
		case ENOTSUP:
			g_warning ("%s: priority %d not supported", __func__, priority);
			break;
		case EPERM:
			g_warning ("%s: permission denied", __func__);
			break;
	}
	
	return FALSE;
}

char*
wapi_current_thread_desc (void)
{
	WapiHandle_thread *thread;
	gpointer thread_handle;
	int i;
	GString* text;
	char *res;

	thread_handle = get_current_thread_handle ();
	thread = lookup_thread (thread_handle);

	text = g_string_new (0);
	g_string_append_printf (text, "thread handle %p state : ", thread_handle);

	mono_thread_info_describe_interrupt_token (mono_thread_info_current (), text);

	g_string_append_printf (text, " owns (");
	for (i = 0; i < thread->owned_mutexes->len; i++)
		g_string_append_printf (text, i > 0 ? ", %p" : "%p", g_ptr_array_index (thread->owned_mutexes, i));
	g_string_append_printf (text, ")");

	res = text->str;
	g_string_free (text, FALSE);
	return res;
}