text: /*
   * threadpool.c: global thread pool
   *
   * Authors:
   *   Dietmar Maurer (dietmar@ximian.com)
   *   Gonzalo Paniagua Javier (gonzalo@ximian.com)
   *
   * Copyright 2001-2003 Ximian, Inc (http://www.ximian.com)
   * Copyright 2004-2009 Novell, Inc (http://www.novell.com)
   */
  
  #include <config.h>
  #include <glib.h>
  
  #define THREADS_PER_CPU	10 /* 20 + THREADS_PER_CPU * number of CPUs */
  #define THREAD_EXIT_TIMEOUT 1000
  #define INITIAL_QUEUE_LENGTH 128
  
  #include <mono/metadata/domain-internals.h>
  #include <mono/metadata/tabledefs.h>
  #include <mono/metadata/threads.h>
  #include <mono/metadata/threads-types.h>
  #include <mono/metadata/threadpool-internals.h>
  #include <mono/metadata/exception.h>
  #include <mono/metadata/file-io.h>
  #include <mono/metadata/monitor.h>
  #include <mono/metadata/mono-mlist.h>
  #include <mono/metadata/marshal.h>
  #include <mono/metadata/socket-io.h>
  #include <mono/io-layer/io-layer.h>
  #include <mono/metadata/gc-internal.h>
  #include <mono/utils/mono-time.h>
  #include <mono/utils/mono-proclib.h>
  #include <errno.h>
  #ifdef HAVE_SYS_TIME_H
  #include <sys/time.h>
  #endif
  #include <sys/types.h>
  #include <fcntl.h>
  #ifdef HAVE_UNISTD_H
  #include <unistd.h>
  #endif
  #include <string.h>
  #ifdef HAVE_SYS_SOCKET_H
  #include <sys/socket.h>
  #endif
  #include <mono/utils/mono-poll.h>
  #ifdef HAVE_EPOLL
  #include <sys/epoll.h>
  #endif
  
  #ifndef DISABLE_SOCKETS
  #include "mono/io-layer/socket-wrappers.h"
  #endif
  
  #include "threadpool.h"
  
  #define THREAD_WANTS_A_BREAK(t) ((t->state & (ThreadState_StopRequested | \
  						ThreadState_SuspendRequested)) != 0)
  
  #define THREAD_ABORT_REQUESTED(t) ((t->state & ThreadState_AbortRequested) != 0)
  
  #undef EPOLL_DEBUG
  
  /* maximum number of worker threads */
  static int mono_max_worker_threads;
  static int mono_min_worker_threads;
  static int mono_io_max_worker_threads;
  static int mono_io_min_worker_threads;
  
  /* current number of worker threads */
  static int mono_worker_threads = 0;
  static int io_worker_threads = 0;
  
  /* current number of busy threads */
  static int busy_worker_threads = 0;
  static int busy_io_worker_threads;
  
  /* mono_thread_pool_init called */
  static int tp_inited;
  /* started idle threads */
  static int tp_idle_started;
  
  static CRITICAL_SECTION ares_lock;
  static CRITICAL_SECTION io_queue_lock;
  static int pending_io_items;
  
  typedef struct {
  	CRITICAL_SECTION io_lock; /* access to sock_to_state */
  	int inited;
  	int pipe [2];
  	MonoGHashTable *sock_to_state;
  
  	HANDLE new_sem; /* access to newpfd and write side of the pipe */
  	mono_pollfd *newpfd;
  	gboolean epoll_disabled;
  #ifdef HAVE_EPOLL
  	int epollfd;
  #endif
  } SocketIOData;
  
  static SocketIOData socket_io_data;
  
  /* we append a job */
  static HANDLE job_added;
  static HANDLE io_job_added;
  
  /* Keep in sync with the System.MonoAsyncCall class which provides GC tracking */
  typedef struct {
  	MonoObject         object;
  	MonoMethodMessage *msg;
  	MonoMethod        *cb_method;
  	MonoDelegate      *cb_target;
  	MonoObject        *state;
  	MonoObject        *res;
  	MonoArray         *out_args;
  	/* This is a HANDLE, we use guint64 so the managed object layout remains constant */
  	guint64           wait_event;
  } ASyncCall;
  
  typedef struct {
  	MonoArray *array;
  	int first_elem;
  	int next_elem;
  } TPQueue;
  
  static void async_invoke_thread (gpointer data);
  static void append_job (CRITICAL_SECTION *cs, TPQueue *list, MonoObject *ar);
  static void start_thread_or_queue (MonoAsyncResult *ares);
  static void start_tpthread (MonoAsyncResult *ares);
  static void mono_async_invoke (MonoAsyncResult *ares);
  static MonoObject* dequeue_job (CRITICAL_SECTION *cs, TPQueue *list);
  static void free_queue (TPQueue *list);
  
  static TPQueue async_call_queue = {NULL, 0, 0};
  static TPQueue async_io_queue = {NULL, 0, 0};
  
  static MonoClass *async_call_klass;
  static MonoClass *socket_async_call_klass;
  static MonoClass *process_async_call_klass;
  
  /* Hooks */
  static MonoThreadPoolFunc tp_start_func;
  static MonoThreadPoolFunc tp_finish_func;
  static gpointer tp_hooks_user_data;
  static MonoThreadPoolItemFunc tp_item_begin_func;
  static MonoThreadPoolItemFunc tp_item_end_func;
  static gpointer tp_item_user_data;
  
  #define INIT_POLLFD(a, b, c) {(a)->fd = b; (a)->events = c; (a)->revents = 0;}
  enum {
  	AIO_OP_FIRST,
  	AIO_OP_ACCEPT = 0,
  	AIO_OP_CONNECT,
  	AIO_OP_RECEIVE,
  	AIO_OP_RECEIVEFROM,
  	AIO_OP_SEND,
  	AIO_OP_SENDTO,
  	AIO_OP_RECV_JUST_CALLBACK,
  	AIO_OP_SEND_JUST_CALLBACK,
  	AIO_OP_READPIPE,
  	AIO_OP_LAST
  };
  
  #ifdef DISABLE_SOCKETS
  #define socket_io_cleanup(x)
  #else
  static void
  socket_io_cleanup (SocketIOData *data)
  {
  	gint release;
  
  	if (data->inited == 0)
  		return;
  
  	EnterCriticalSection (&data->io_lock);
  	data->inited = 0;
  #ifdef PLATFORM_WIN32
  	closesocket (data->pipe [0]);
  	closesocket (data->pipe [1]);
  #else
  	close (data->pipe [0]);
  	close (data->pipe [1]);
  #endif
  	data->pipe [0] = -1;
  	data->pipe [1] = -1;
  	if (data->new_sem)
  		CloseHandle (data->new_sem);
  	data->new_sem = NULL;
  	mono_g_hash_table_destroy (data->sock_to_state);
  	data->sock_to_state = NULL;
  	free_queue (&async_io_queue);
  	release = (gint) InterlockedCompareExchange (&io_worker_threads, 0, -1);
  	if (io_job_added)
  		ReleaseSemaphore (io_job_added, release, NULL);
  	g_free (data->newpfd);
  	data->newpfd = NULL;
  #ifdef HAVE_EPOLL
  	if (FALSE == data->epoll_disabled)
  		close (data->epollfd);
  #endif
  	LeaveCriticalSection (&data->io_lock);
  }
  
  static int
  get_event_from_state (MonoSocketAsyncResult *state)
  {
  	switch (state->operation) {
  	case AIO_OP_ACCEPT:
  	case AIO_OP_RECEIVE:
  	case AIO_OP_RECV_JUST_CALLBACK:
  	case AIO_OP_RECEIVEFROM:
  	case AIO_OP_READPIPE:
  		return MONO_POLLIN;
  	case AIO_OP_SEND:
  	case AIO_OP_SEND_JUST_CALLBACK:
  	case AIO_OP_SENDTO:
  	case AIO_OP_CONNECT:
  		return MONO_POLLOUT;
  	default: /* Should never happen */
  		g_print ("get_event_from_state: unknown value in switch!!!\n");
  		return 0;
  	}
  }
  
  static int
  get_events_from_list (MonoMList *list)
  {
  	MonoSocketAsyncResult *state;
  	int events = 0;
  
  	while (list && (state = (MonoSocketAsyncResult *)mono_mlist_get_data (list))) {
  		events |= get_event_from_state (state);
  		list = mono_mlist_next (list);
  	}
  
  	return events;
  }
  
  #define ICALL_RECV(x)	ves_icall_System_Net_Sockets_Socket_Receive_internal (\
  				(SOCKET)(gssize)x->handle, x->buffer, x->offset, x->size,\
  				 x->socket_flags, &x->error);
  
  #define ICALL_SEND(x)	ves_icall_System_Net_Sockets_Socket_Send_internal (\
  				(SOCKET)(gssize)x->handle, x->buffer, x->offset, x->size,\
  				 x->socket_flags, &x->error);
  
  #endif /* !DISABLE_SOCKETS */
  
  static void
  unregister_job (MonoAsyncResult *obj)
  {
  }
  
  static void
  threadpool_jobs_inc (MonoObject *obj)
  {
  	if (obj)
  		InterlockedIncrement (&obj->vtable->domain->threadpool_jobs);
  }
  
  static gboolean
  threadpool_jobs_dec (MonoObject *obj)
  {
  	MonoDomain *domain = obj->vtable->domain;
  	int remaining_jobs = InterlockedDecrement (&domain->threadpool_jobs);
  	if (remaining_jobs == 0 && domain->cleanup_semaphore) {
  		ReleaseSemaphore (domain->cleanup_semaphore, 1, NULL);
  		return TRUE;
  	}
  	return FALSE;
  }
  
  #ifndef DISABLE_SOCKETS
  static void
  async_invoke_io_thread (gpointer data)
  {
  	MonoDomain *domain;
  	MonoThread *thread;
  	const gchar *version;
  	int workers_io, min_io;
  
  	thread = mono_thread_current ();
   	if (tp_start_func)
   		tp_start_func (tp_hooks_user_data);
  
  	version = mono_get_runtime_info ()->framework_version;
  	for (;;) {
  		MonoSocketAsyncResult *state;
  		MonoAsyncResult *ar;
  
  		state = (MonoSocketAsyncResult *) data;
  		if (state) {
  			InterlockedDecrement (&pending_io_items);
  			ar = state->ares;
  			switch (state->operation) {
  			case AIO_OP_RECEIVE:
  				state->total = ICALL_RECV (state);
  				break;
  			case AIO_OP_SEND:
  				state->total = ICALL_SEND (state);
  				break;
  			}
  
  			/* worker threads invokes methods in different domains,
  			 * so we need to set the right domain here */
  			domain = ((MonoObject *)ar)->vtable->domain;
  
  			g_assert (domain);
  
  			if (domain->state == MONO_APPDOMAIN_UNLOADED || domain->state == MONO_APPDOMAIN_UNLOADING) {
  				threadpool_jobs_dec ((MonoObject *)ar);
  				unregister_job (ar);
  				data = NULL;
  			} else {
  				mono_thread_push_appdomain_ref (domain);
  				if (threadpool_jobs_dec ((MonoObject *)ar)) {
  					unregister_job (ar);
  					data = NULL;
  					mono_thread_pop_appdomain_ref ();
  					continue;
  				}
  				if (mono_domain_set (domain, FALSE)) {
  					/* ASyncCall *ac; */
  
  					if (tp_item_begin_func)
  						tp_item_begin_func (tp_item_user_data);
  					mono_async_invoke (ar);
  					if (tp_item_end_func)
  						tp_item_end_func (tp_item_user_data);
  					/*
  					ac = (ASyncCall *) ar->object_data;
  					if (ac->msg->exc != NULL)
  						mono_unhandled_exception (ac->msg->exc);
  					*/
  					mono_domain_set (mono_get_root_domain (), TRUE);
  				}
  				mono_thread_pop_appdomain_ref ();
  				InterlockedDecrement (&busy_io_worker_threads);
  				/* If the callee changes the background status, set it back to TRUE */
  				if (*version != '1' && !mono_thread_test_state (thread , ThreadState_Background))
  					ves_icall_System_Threading_Thread_SetState (thread, ThreadState_Background);
  			}
  		}
  
  		data = dequeue_job (&io_queue_lock, &async_io_queue);
  	
  		if (!data && !mono_runtime_is_shutting_down() && !THREAD_ABORT_REQUESTED(thread)) {
  			guint32 wr;
  			int timeout = THREAD_EXIT_TIMEOUT;
  			guint32 start_time = mono_msec_ticks ();
  			
  			do {
  				wr = WaitForSingleObjectEx (io_job_added, (guint32)timeout, TRUE);
  				if (THREAD_WANTS_A_BREAK (thread))
  					mono_thread_interruption_checkpoint ();
  			
  				timeout -= mono_msec_ticks () - start_time;
  			
  				if (wr != WAIT_TIMEOUT && wr != WAIT_IO_COMPLETION)
  					data = dequeue_job (&io_queue_lock, &async_io_queue);
  			}
  			while (!data && timeout > 0 && !mono_runtime_is_shutting_down() && !THREAD_ABORT_REQUESTED(thread));
  		}
  
  		if (!data) {
  			workers_io = (int) InterlockedCompareExchange (&io_worker_threads, 0, -1); 
  			min_io = (int) InterlockedCompareExchange (&mono_io_min_worker_threads, 0, -1); 
  	
  			while (!data && workers_io <= min_io && !mono_runtime_is_shutting_down() && !THREAD_ABORT_REQUESTED(thread)) {
  				WaitForSingleObjectEx (io_job_added, INFINITE, TRUE);
  				if (THREAD_WANTS_A_BREAK (thread))
  					mono_thread_interruption_checkpoint ();
  			
  				data = dequeue_job (&io_queue_lock, &async_io_queue);
  				workers_io = (int) InterlockedCompareExchange (&io_worker_threads, 0, -1); 
  				min_io = (int) InterlockedCompareExchange (&mono_io_min_worker_threads, 0, -1); 
  			}
  		}
  	
  		if (!data) {
  			InterlockedDecrement (&io_worker_threads);
   			if (tp_finish_func)
   				tp_finish_func (tp_hooks_user_data);
  			return;
  		}
  		
  		InterlockedIncrement (&busy_io_worker_threads);
  	}
  
  	g_assert_not_reached ();
  }
  
  static void
  start_io_thread_or_queue (MonoSocketAsyncResult *ares)
  {
  	int busy, worker;
  
  	busy = (int) InterlockedCompareExchange (&busy_io_worker_threads, 0, -1);
  	worker = (int) InterlockedCompareExchange (&io_worker_threads, 0, -1); 
  	if (worker <= ++busy &&
  	    worker < mono_io_max_worker_threads) {
  		InterlockedIncrement (&busy_io_worker_threads);
  		InterlockedIncrement (&io_worker_threads);
  		threadpool_jobs_inc ((MonoObject *)ares);
  		mono_thread_create_internal (mono_get_root_domain (), async_invoke_io_thread, ares, TRUE);
  	} else {
  		append_job (&io_queue_lock, &async_io_queue, (MonoObject*)ares);
  		ReleaseSemaphore (io_job_added, 1, NULL);
  	}
  }
  
  static MonoMList *
  process_io_event (MonoMList *list, int event)
  {
  	MonoSocketAsyncResult *state;
  	MonoMList *oldlist;
  
  	oldlist = list;
  	state = NULL;
  	while (list) {
  		state = (MonoSocketAsyncResult *) mono_mlist_get_data (list);
  		if (get_event_from_state (state) == event)
  			break;
  		
  		list = mono_mlist_next (list);
  	}
  
  	if (list != NULL) {
  		oldlist = mono_mlist_remove_item (oldlist, list);
  #ifdef EPOLL_DEBUG
  		g_print ("Dispatching event %d on socket %d\n", event, state->handle);
  #endif
  		if (!(mono_object_domain (state)->state == MONO_APPDOMAIN_UNLOADING || mono_object_domain (state)->state == MONO_APPDOMAIN_UNLOADED)) {
  			InterlockedIncrement (&pending_io_items);
  			start_io_thread_or_queue (state);
  		}
  	}
  
  	return oldlist;
  }
  
  static int
  mark_bad_fds (mono_pollfd *pfds, int nfds)
  {
  	int i, ret;
  	mono_pollfd *pfd;
  	int count = 0;
  
  	for (i = 0; i < nfds; i++) {
  		pfd = &pfds [i];
  		if (pfd->fd == -1)
  			continue;
  
  		ret = mono_poll (pfd, 1, 0);
  		if (ret == -1 && errno == EBADF) {
  			pfd->revents |= MONO_POLLNVAL;
  			count++;
  		} else if (ret == 1) {
  			count++;
  		}
  	}
  
  	return count;
  }
  
  static void
  socket_io_poll_main (gpointer p)
  {
  #define INITIAL_POLLFD_SIZE	1024
  #define POLL_ERRORS (MONO_POLLERR | MONO_POLLHUP | MONO_POLLNVAL)
  	SocketIOData *data = p;
  	mono_pollfd *pfds;
  	gint maxfd = 1;
  	gint allocated;
  	gint i;
  	MonoThread *thread;
  
  	thread = mono_thread_current ();
  
  	allocated = INITIAL_POLLFD_SIZE;
  	pfds = g_new0 (mono_pollfd, allocated);
  	INIT_POLLFD (pfds, data->pipe [0], MONO_POLLIN);
  	for (i = 1; i < allocated; i++)
  		INIT_POLLFD (&pfds [i], -1, 0);
  
  	while (1) {
  		int nsock = 0;
  		mono_pollfd *pfd;
  		char one [1];
  		MonoMList *list;
  
  		do {
  			if (nsock == -1) {
  				if (THREAD_WANTS_A_BREAK (thread))
  					mono_thread_interruption_checkpoint ();
  			}
  
  			nsock = mono_poll (pfds, maxfd, -1);
  		} while (nsock == -1 && errno == EINTR);
  
  		/* 
  		 * Apart from EINTR, we only check EBADF, for the rest:
  		 *  EINVAL: mono_poll() 'protects' us from descriptor
  		 *      numbers above the limit if using select() by marking
  		 *      then as MONO_POLLERR.  If a system poll() is being
  		 *      used, the number of descriptor we're passing will not
  		 *      be over sysconf(_SC_OPEN_MAX), as the error would have
  		 *      happened when opening.
  		 *
  		 *  EFAULT: we own the memory pointed by pfds.
  		 *  ENOMEM: we're doomed anyway
  		 *
  		 */
  
  		if (nsock == -1 && errno == EBADF) {
  			pfds->revents = 0; /* Just in case... */
  			nsock = mark_bad_fds (pfds, maxfd);
  		}
  
  		if ((pfds->revents & POLL_ERRORS) != 0) {
  			/* We're supposed to die now, as the pipe has been closed */
  			g_free (pfds);
  			socket_io_cleanup (data);
  			return;
  		}
  
  		/* Got a new socket */
  		if ((pfds->revents & MONO_POLLIN) != 0) {
  			int nread;
  
  			for (i = 1; i < allocated; i++) {
  				pfd = &pfds [i];
  				if (pfd->fd == -1 || data->newpfd == NULL ||
  				    pfd->fd == data->newpfd->fd)
  					break;
  			}
  
  			if (i == allocated) {
  				mono_pollfd *oldfd;
  
  				oldfd = pfds;
  				i = allocated;
  				allocated = allocated * 2;
  				pfds = g_renew (mono_pollfd, oldfd, allocated);
  				g_free (oldfd);
  				for (; i < allocated; i++)
  					INIT_POLLFD (&pfds [i], -1, 0);
  			}
  #ifndef PLATFORM_WIN32
  			nread = read (data->pipe [0], one, 1);
  #else
  			nread = recv ((SOCKET) data->pipe [0], one, 1, 0);
  #endif
  			if (nread <= 0) {
  				g_free (pfds);
  				return; /* we're closed */
  			}
  
  			INIT_POLLFD (&pfds [i], data->newpfd->fd, data->newpfd->events);
  			ReleaseSemaphore (data->new_sem, 1, NULL);
  			if (i >= maxfd)
  				maxfd = i + 1;
  			nsock--;
  		}
  
  		if (nsock == 0)
  			continue;
  
  		EnterCriticalSection (&data->io_lock);
  		if (data->inited == 0) {
  			g_free (pfds);
  			LeaveCriticalSection (&data->io_lock);
  			return; /* cleanup called */
  		}
  
  		for (i = 1; i < maxfd && nsock > 0; i++) {
  			pfd = &pfds [i];
  			if (pfd->fd == -1 || pfd->revents == 0)
  				continue;
  
  			nsock--;
  			list = mono_g_hash_table_lookup (data->sock_to_state, GINT_TO_POINTER (pfd->fd));
  			if (list != NULL && (pfd->revents & (MONO_POLLIN | POLL_ERRORS)) != 0) {
  				list = process_io_event (list, MONO_POLLIN);
  			}
  
  			if (list != NULL && (pfd->revents & (MONO_POLLOUT | POLL_ERRORS)) != 0) {
  				list = process_io_event (list, MONO_POLLOUT);
  			}
  
  			if (list != NULL) {
  				mono_g_hash_table_replace (data->sock_to_state, GINT_TO_POINTER (pfd->fd), list);
  				pfd->events = get_events_from_list (list);
  			} else {
  				mono_g_hash_table_remove (data->sock_to_state, GINT_TO_POINTER (pfd->fd));
  				pfd->fd = -1;
  				if (i == maxfd - 1)
  					maxfd--;
  			}
  		}
  		LeaveCriticalSection (&data->io_lock);
  	}
  }
  
  #ifdef HAVE_EPOLL
  #define EPOLL_ERRORS (EPOLLERR | EPOLLHUP)
  static void
  socket_io_epoll_main (gpointer p)
  {
  	SocketIOData *data;
  	int epollfd;
  	MonoThread *thread;
  	struct epoll_event *events, *evt;
  	const int nevents = 512;
  	int ready = 0, i;
  
  	data = p;
  	epollfd = data->epollfd;
  	thread = mono_thread_current ();
  	events = g_new0 (struct epoll_event, nevents);
  
  	while (1) {
  		do {
  			if (ready == -1) {
  				if (THREAD_WANTS_A_BREAK (thread))
  					mono_thread_interruption_checkpoint ();
  			}
  #ifdef EPOLL_DEBUG
  			g_print ("epoll_wait init\n");
  #endif
  			ready = epoll_wait (epollfd, events, nevents, -1);
  #ifdef EPOLL_DEBUG
  			{
  			int err = errno;
  			g_print ("epoll_wait end with %d ready sockets (%d %s).\n", ready, err, (err) ? g_strerror (err) : "");
  			errno = err;
  			}
  #endif
  		} while (ready == -1 && errno == EINTR);
  
  		if (ready == -1) {
  			int err = errno;
  			g_free (events);
  			if (err != EBADF)
  				g_warning ("epoll_wait: %d %s\n", err, g_strerror (err));
  
  			close (epollfd);
  			return;
  		}
  
  		EnterCriticalSection (&data->io_lock);
  		if (data->inited == 0) {
  #ifdef EPOLL_DEBUG
  			g_print ("data->inited == 0\n");
  #endif
  			g_free (events);
  			close (epollfd);
  			return; /* cleanup called */
  		}
  
  		for (i = 0; i < ready; i++) {
  			int fd;
  			MonoMList *list;
  
  			evt = &events [i];
  			fd = evt->data.fd;
  			list = mono_g_hash_table_lookup (data->sock_to_state, GINT_TO_POINTER (fd));
  #ifdef EPOLL_DEBUG
  			g_print ("Event %d on %d list length: %d\n", evt->events, fd, mono_mlist_length (list));
  #endif
  			if (list != NULL && (evt->events & (EPOLLIN | EPOLL_ERRORS)) != 0) {
  				list = process_io_event (list, MONO_POLLIN);
  			}
  
  			if (list != NULL && (evt->events & (EPOLLOUT | EPOLL_ERRORS)) != 0) {
  				list = process_io_event (list, MONO_POLLOUT);
  			}
  
  			if (list != NULL) {
  				mono_g_hash_table_replace (data->sock_to_state, GINT_TO_POINTER (fd), list);
  				evt->events = get_events_from_list (list);
  #ifdef EPOLL_DEBUG
  				g_print ("MOD %d to %d\n", fd, evt->events);
  #endif
  				if (epoll_ctl (epollfd, EPOLL_CTL_MOD, fd, evt)) {
  					if (epoll_ctl (epollfd, EPOLL_CTL_ADD, fd, evt) == -1) {
  #ifdef EPOLL_DEBUG
  						int err = errno;
  						g_message ("epoll_ctl(MOD): %d %s fd: %d events: %d", err, g_strerror (err), fd, evt->events);
  						errno = err;
  #endif
  					}
  				}
  			} else {
  				mono_g_hash_table_remove (data->sock_to_state, GINT_TO_POINTER (fd));
  #ifdef EPOLL_DEBUG
  				g_print ("DEL %d\n", fd);
  #endif
  				epoll_ctl (epollfd, EPOLL_CTL_DEL, fd, evt);
  			}
  		}
  		LeaveCriticalSection (&data->io_lock);
  	}
  }
  #endif
  
  /*
   * select/poll wake up when a socket is closed, but epoll just removes
   * the socket from its internal list without notification.
   */
  void
  mono_thread_pool_remove_socket (int sock)
  {
  	MonoMList *list, *next;
  	MonoSocketAsyncResult *state;
  
  	if (socket_io_data.inited == FALSE)
  		return;
  
  	EnterCriticalSection (&socket_io_data.io_lock);
  	list = mono_g_hash_table_lookup (socket_io_data.sock_to_state, GINT_TO_POINTER (sock));
  	if (list) {
  		mono_g_hash_table_remove (socket_io_data.sock_to_state, GINT_TO_POINTER (sock));
  	}
  	LeaveCriticalSection (&socket_io_data.io_lock);
  	
  	while (list) {
  		state = (MonoSocketAsyncResult *) mono_mlist_get_data (list);
  		if (state->operation == AIO_OP_RECEIVE)
  			state->operation = AIO_OP_RECV_JUST_CALLBACK;
  		else if (state->operation == AIO_OP_SEND)
  			state->operation = AIO_OP_SEND_JUST_CALLBACK;
  
  		next = mono_mlist_remove_item (list, list);
  		list = process_io_event (list, MONO_POLLIN);
  		if (list)
  			process_io_event (list, MONO_POLLOUT);
  
  		list = next;
  	}
  }
  
  #ifdef PLATFORM_WIN32
  static DWORD WINAPI
  connect_hack (LPVOID x)
  {
  	struct sockaddr_in *addr = (struct sockaddr_in *) x;
  	int count = 0;
  
  	while (connect ((SOCKET) socket_io_data.pipe [1], (SOCKADDR *) addr, sizeof (struct sockaddr_in))) {
  		Sleep (500);
  		if (++count > 3) {
  			g_warning ("Error initializing async. sockets %d.\n", WSAGetLastError ());
  			g_assert (WSAGetLastError ());
  		}
  	}
  }
  #endif
  
  static void
  socket_io_init (SocketIOData *data)
  {
  #ifdef PLATFORM_WIN32
  	struct sockaddr_in server;
  	struct sockaddr_in client;
  	SOCKET srv;
  	int len;
  	HANDLE connect_handle;
  #endif
  	int inited;
  
  	inited = InterlockedCompareExchange (&data->inited, -1, -1);
  	if (inited == 1)
  		return;
  
  	EnterCriticalSection (&data->io_lock);
  	inited = InterlockedCompareExchange (&data->inited, -1, -1);
  	if (inited == 1) {
  		LeaveCriticalSection (&data->io_lock);
  		return;
  	}
  
  #ifdef HAVE_EPOLL
  	data->epoll_disabled = (g_getenv ("MONO_DISABLE_AIO") != NULL);
  	if (FALSE == data->epoll_disabled) {
  		data->epollfd = epoll_create (256);
  		data->epoll_disabled = (data->epollfd == -1);
  		if (data->epoll_disabled && g_getenv ("MONO_DEBUG"))
  			g_message ("epoll_create() failed. Using plain poll().");
  	} else {
  		data->epollfd = -1;
  	}
  #else
  	data->epoll_disabled = TRUE;
  #endif
  
  #ifndef PLATFORM_WIN32
  	if (data->epoll_disabled) {
  		if (pipe (data->pipe) != 0) {
  			int err = errno;
  			perror ("mono");
  			g_assert (err);
  		}
  	} else {
  		data->pipe [0] = -1;
  		data->pipe [1] = -1;
  	}
  #else
  	srv = socket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
  	g_assert (srv != INVALID_SOCKET);
  	data->pipe [1] = socket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
  	g_assert (data->pipe [1] != INVALID_SOCKET);
  
  	server.sin_family = AF_INET;
  	server.sin_addr.s_addr = inet_addr ("127.0.0.1");
  	server.sin_port = 0;
  	if (bind (srv, (SOCKADDR *) &server, sizeof (server))) {
  		g_print ("%d\n", WSAGetLastError ());
  		g_assert (1 != 0);
  	}
  
  	len = sizeof (server);
  	getsockname (srv, (SOCKADDR *) &server, &len);
  	listen (srv, 1);
  	connect_handle = mono_create_thread (NULL, 0, connect_hack, &server, 0, NULL);
  	len = sizeof (server);
  	data->pipe [0] = accept (srv, (SOCKADDR *) &client, &len);
  	g_assert (data->pipe [0] != INVALID_SOCKET);
  	closesocket (srv);
  	WaitForSingleObject (connect_handle, INFINITE);
  	CloseHandle (connect_handle);
  #endif
  	data->sock_to_state = mono_g_hash_table_new_type (g_direct_hash, g_direct_equal, MONO_HASH_VALUE_GC);
  
  	if (data->epoll_disabled) {
  		data->new_sem = CreateSemaphore (NULL, 1, 1, NULL);
  		g_assert (data->new_sem != NULL);
  	}
  	io_job_added = CreateSemaphore (NULL, 0, 0x7fffffff, NULL);
  	g_assert (io_job_added != NULL);
  	if (data->epoll_disabled) {
  		mono_thread_create_internal (mono_get_root_domain (), socket_io_poll_main, data, TRUE);
  	}
  #ifdef HAVE_EPOLL
  	else {
  		mono_thread_create_internal (mono_get_root_domain (), socket_io_epoll_main, data, TRUE);
  	}
  #endif
  	InterlockedCompareExchange (&data->inited, 1, 0);
  	LeaveCriticalSection (&data->io_lock);
  }
  
  static void
  socket_io_add_poll (MonoSocketAsyncResult *state)
  {
  	int events;
  	char msg [1];
  	MonoMList *list;
  	SocketIOData *data = &socket_io_data;
  	int w;
  
  #if defined(PLATFORM_MACOSX) || defined(PLATFORM_BSD) || defined(PLATFORM_WIN32) || defined(PLATFORM_SOLARIS)
  	/* select() for connect() does not work well on the Mac. Bug #75436. */
  	/* Bug #77637 for the BSD 6 case */
  	/* Bug #78888 for the Windows case */
  	if (state->operation == AIO_OP_CONNECT && state->blocking == TRUE) {
  		start_io_thread_or_queue (state);
  		return;
  	}
  #endif
  	WaitForSingleObject (data->new_sem, INFINITE);
  	if (data->newpfd == NULL)
  		data->newpfd = g_new0 (mono_pollfd, 1);
  
  	EnterCriticalSection (&data->io_lock);
  	/* FIXME: 64 bit issue: handle can be a pointer on windows? */
  	list = mono_g_hash_table_lookup (data->sock_to_state, GINT_TO_POINTER (state->handle));
  	if (list == NULL) {
  		list = mono_mlist_alloc ((MonoObject*)state);
  	} else {
  		list = mono_mlist_append (list, (MonoObject*)state);
  	}
  
  	events = get_events_from_list (list);
  	INIT_POLLFD (data->newpfd, GPOINTER_TO_INT (state->handle), events);
  	mono_g_hash_table_replace (data->sock_to_state, GINT_TO_POINTER (state->handle), list);
  	LeaveCriticalSection (&data->io_lock);
  	*msg = (char) state->operation;
  #ifndef PLATFORM_WIN32
  	w = write (data->pipe [1], msg, 1);
  	w = w;
  #else
  	send ((SOCKET) data->pipe [1], msg, 1, 0);
  #endif
  }
  
  #ifdef HAVE_EPOLL
  static gboolean
  socket_io_add_epoll (MonoSocketAsyncResult *state)
  {
  	MonoMList *list;
  	SocketIOData *data = &socket_io_data;
  	struct epoll_event event;
  	int epoll_op, ievt;
  	int fd;
  
  	memset (&event, 0, sizeof (struct epoll_event));
  	fd = GPOINTER_TO_INT (state->handle);
  	EnterCriticalSection (&data->io_lock);
  	list = mono_g_hash_table_lookup (data->sock_to_state, GINT_TO_POINTER (fd));
  	if (list == NULL) {
  		list = mono_mlist_alloc ((MonoObject*)state);
  		epoll_op = EPOLL_CTL_ADD;
  	} else {
  		list = mono_mlist_append (list, (MonoObject*)state);
  		epoll_op = EPOLL_CTL_MOD;
  	}
  
  	ievt = get_events_from_list (list);
  	if ((ievt & MONO_POLLIN) != 0)
  		event.events |= EPOLLIN;
  	if ((ievt & MONO_POLLOUT) != 0)
  		event.events |= EPOLLOUT;
  
  	mono_g_hash_table_replace (data->sock_to_state, state->handle, list);
  	event.data.fd = fd;
  #ifdef EPOLL_DEBUG
  	g_print ("%s %d with %d\n", epoll_op == EPOLL_CTL_ADD ? "ADD" : "MOD", fd, event.events);
  #endif
  	if (epoll_ctl (data->epollfd, epoll_op, fd, &event) == -1) {
  		int err = errno;
  		if (epoll_op == EPOLL_CTL_ADD && err == EEXIST) {
  			epoll_op = EPOLL_CTL_MOD;
  			if (epoll_ctl (data->epollfd, epoll_op, fd, &event) == -1) {
  				g_message ("epoll_ctl(MOD): %d %s\n", err, g_strerror (err));
  			}
  		}
  	}
  
  	LeaveCriticalSection (&data->io_lock);
  	return TRUE;
  }
  #endif
  
  static void
  socket_io_add (MonoAsyncResult *ares, MonoSocketAsyncResult *state)
  {
  	socket_io_init (&socket_io_data);
  	MONO_OBJECT_SETREF (state, ares, ares);
  #ifdef HAVE_EPOLL
  	if (socket_io_data.epoll_disabled == FALSE) {
  		if (socket_io_add_epoll (state))
  			return;
  	}
  #endif
  	socket_io_add_poll (state);
  }
  
  static gboolean
  socket_io_filter (MonoObject *target, MonoObject *state)
  {
  	gint op;
  	MonoSocketAsyncResult *sock_res = (MonoSocketAsyncResult *) state;
  	MonoClass *klass;
  
  	if (target == NULL || state == NULL)
  		return FALSE;
  
  	if (socket_async_call_klass == NULL) {
  		klass = target->vtable->klass;
  		/* Check if it's SocketAsyncCall in System.Net.Sockets
  		 * FIXME: check the assembly is signed correctly for extra care
  		 */
  		if (klass->name [0] == 'S' && strcmp (klass->name, "SocketAsyncCall") == 0 
  				&& strcmp (mono_image_get_name (klass->image), "System") == 0
  				&& klass->nested_in && strcmp (klass->nested_in->name, "Socket") == 0)
  			socket_async_call_klass = klass;
  	}
  
  	if (process_async_call_klass == NULL) {
  		klass = target->vtable->klass;
  		/* Check if it's AsyncReadHandler in System.Diagnostics.Process
  		 * FIXME: check the assembly is signed correctly for extra care
  		 */
  		if (klass->name [0] == 'A' && strcmp (klass->name, "AsyncReadHandler") == 0 
  				&& strcmp (mono_image_get_name (klass->image), "System") == 0
  				&& klass->nested_in && strcmp (klass->nested_in->name, "Process") == 0)
  			process_async_call_klass = klass;
  	}
  	/* return both when socket_async_call_klass has not been seen yet and when
  	 * the object is not an instance of the class.
  	 */
  	if (target->vtable->klass != socket_async_call_klass && target->vtable->klass != process_async_call_klass)
  		return FALSE;
  
  	op = sock_res->operation;
  	if (op < AIO_OP_FIRST || op >= AIO_OP_LAST)
  		return FALSE;
  
  	return TRUE;
  }
  #endif /* !DISABLE_SOCKETS */
  
  static void
  mono_async_invoke (MonoAsyncResult *ares)
  {
  	ASyncCall *ac = (ASyncCall *)ares->object_data;
  	MonoThread *thread = NULL;
  	MonoObject *res, *exc = NULL;
  	MonoArray *out_args = NULL;
  
  	if (ares->execution_context) {
  		/* use captured ExecutionContext (if available) */
  		thread = mono_thread_current ();
  		MONO_OBJECT_SETREF (ares, original_context, mono_thread_get_execution_context ());
  		mono_thread_set_execution_context (ares->execution_context);
  	} else {
  		ares->original_context = NULL;
  	}
  
  	ac->msg->exc = NULL;
  	res = mono_message_invoke (ares->async_delegate, ac->msg, &exc, &out_args);
  	MONO_OBJECT_SETREF (ac, res, res);
  	MONO_OBJECT_SETREF (ac, msg->exc, exc);
  	MONO_OBJECT_SETREF (ac, out_args, out_args);
  
  	ares->completed = 1;
  
  	/* call async callback if cb_method != null*/
  	if (ac->cb_method) {
  		MonoObject *exc = NULL;
  		void *pa = &ares;
  		mono_runtime_invoke (ac->cb_method, ac->cb_target, pa, &exc);
  		/* 'exc' will be the previous ac->msg->exc if not NULL and not
  		 * catched. If catched, this will be set to NULL and the
  		 * exception will not be printed. */
  		MONO_OBJECT_SETREF (ac->msg, exc, exc);
  	}
  
  	/* restore original thread execution context if flow isn't suppressed, i.e. non null */
  	if (ares->original_context) {
  		mono_thread_set_execution_context (ares->original_context);
  		ares->original_context = NULL;
  	}
  
  	/* notify listeners */
  	mono_monitor_enter ((MonoObject *) ares);
  	if (ares->handle != NULL) {
  		ac->wait_event = (gsize) mono_wait_handle_get_handle ((MonoWaitHandle *) ares->handle);
  		SetEvent ((gpointer)(gsize)ac->wait_event);
  	}
  	mono_monitor_exit ((MonoObject *) ares);
  	if (ares->gchandle) {
  		mono_gchandle_free (ares->gchandle);
  		ares->gchandle = 0;
  	}
  }
  
  static void
  start_idle_threads (MonoAsyncResult *data)
  {
  	int needed;
  	int existing;
  
  	needed = (int) InterlockedCompareExchange (&mono_min_worker_threads, 0, -1); 
  	do {
  		existing = (int) InterlockedCompareExchange (&mono_worker_threads, 0, -1); 
  		if ((needed - existing) > 0) {
  			start_tpthread (data);
  			if (data) 
  				threadpool_jobs_dec ((MonoObject*)data);
  			data = NULL;
  			SleepEx (500, TRUE);
  		}
  	} while ((needed - existing) > 0);
  
  	/* If we don't start any thread here, make sure 'data' is processed. */
  	if (data != NULL) {
  		start_thread_or_queue (data);
  		threadpool_jobs_dec ((MonoObject*)data);
  	}
  }
  
  static void
  start_tpthread (MonoAsyncResult *data)
  {
  	InterlockedIncrement (&mono_worker_threads);
  	InterlockedIncrement (&busy_worker_threads);
  	threadpool_jobs_inc ((MonoObject *)data);
  	mono_thread_create_internal (mono_get_root_domain (), async_invoke_thread, data, TRUE);
  }
  
  void
  mono_thread_pool_init ()
  {
  	int threads_per_cpu = THREADS_PER_CPU;
  	int cpu_count;
  
  	if ((int) InterlockedCompareExchange (&tp_inited, 1, 0) == 1)
  		return;
  
  	MONO_GC_REGISTER_ROOT (socket_io_data.sock_to_state);
  	InitializeCriticalSection (&socket_io_data.io_lock);
  	InitializeCriticalSection (&ares_lock);
  	InitializeCriticalSection (&io_queue_lock);
  	job_added = CreateSemaphore (NULL, 0, 0x7fffffff, NULL);
  	g_assert (job_added != NULL);
  	if (g_getenv ("MONO_THREADS_PER_CPU") != NULL) {
  		threads_per_cpu = atoi (g_getenv ("MONO_THREADS_PER_CPU"));
  		if (threads_per_cpu <= 0)
  			threads_per_cpu = THREADS_PER_CPU;
  	}
  
  	cpu_count = mono_cpu_count ();
  	mono_max_worker_threads = 20 + threads_per_cpu * cpu_count;
  	mono_min_worker_threads = cpu_count; /* 1 idle thread per cpu */
  	mono_io_max_worker_threads = mono_max_worker_threads / 2;
  	if (mono_io_max_worker_threads < 16)
  		mono_io_max_worker_threads = 16;
  	mono_io_min_worker_threads = cpu_count;
  
  	async_call_klass = mono_class_from_name (mono_defaults.corlib, "System", "MonoAsyncCall");
  	g_assert (async_call_klass);
  }
  
  MonoAsyncResult *
  mono_thread_pool_add (MonoObject *target, MonoMethodMessage *msg, MonoDelegate *async_callback,
  		      MonoObject *state)
  {
  	MonoDomain *domain = mono_domain_get ();
  	MonoAsyncResult *ares;
  	ASyncCall *ac;
  
  	ac = (ASyncCall*)mono_object_new (mono_domain_get (), async_call_klass);
  	MONO_OBJECT_SETREF (ac, msg, msg);
  	MONO_OBJECT_SETREF (ac, state, state);
  
  	if (async_callback) {
  		ac->cb_method = mono_get_delegate_invoke (((MonoObject *)async_callback)->vtable->klass);
  		MONO_OBJECT_SETREF (ac, cb_target, async_callback);
  	}
  
  	ares = mono_async_result_new (domain, NULL, ac->state, NULL, (MonoObject*)ac);
  	MONO_OBJECT_SETREF (ares, async_delegate, target);
  	// It seems like garbage collect likes to nuke ares inappropriately. The handle prevents this.
  	ares->gchandle = mono_gchandle_new (ares, FALSE);
  
  	EnterCriticalSection (&ares_lock);
  	if (domain->state == MONO_APPDOMAIN_UNLOADED || domain->state == MONO_APPDOMAIN_UNLOADING) {
  		LeaveCriticalSection (&ares_lock);
  		return ares;
  	}
  	LeaveCriticalSection (&ares_lock);
  
  #ifndef DISABLE_SOCKETS
  	if (socket_io_filter (target, state)) {
  		socket_io_add (ares, (MonoSocketAsyncResult *) state);
  		return ares;
  	}
  #endif
  	
  	start_thread_or_queue (ares);
  	return ares;
  }
  
  static void
  start_thread_or_queue (MonoAsyncResult *ares)
  {
  	int busy, worker;
  
  	if ((int) InterlockedCompareExchange (&tp_idle_started, 1, 0) == 0) {
  		threadpool_jobs_inc ((MonoObject*)ares);
  		mono_thread_create_internal (mono_get_root_domain (), start_idle_threads, ares, TRUE);
  		return;
  	}
  
  	busy = (int) InterlockedCompareExchange (&busy_worker_threads, 0, -1);
  	worker = (int) InterlockedCompareExchange (&mono_worker_threads, 0, -1); 
  	if (worker <= ++busy &&
  	    worker < mono_max_worker_threads) {
  		start_tpthread (ares);
  	} else {
  		append_job (&mono_delegate_section, &async_call_queue, (MonoObject*)ares);
  		ReleaseSemaphore (job_added, 1, NULL);
  	}
  }
  
  MonoObject *
  mono_thread_pool_finish (MonoAsyncResult *ares, MonoArray **out_args, MonoObject **exc)
  {
  	ASyncCall *ac;
  
  	*exc = NULL;
  	*out_args = NULL;
  
  	/* check if already finished */
  	mono_monitor_enter ((MonoObject *) ares);
  	
  	if (ares->endinvoke_called) {
  		*exc = (MonoObject *)mono_exception_from_name (mono_defaults.corlib, "System", 
  					      "InvalidOperationException");
  		mono_monitor_exit ((MonoObject *) ares);
  		return NULL;
  	}
  
  	ares->endinvoke_called = 1;
  	ac = (ASyncCall *)ares->object_data;
  
  	g_assert (ac != NULL);
  
  	/* wait until we are really finished */
  	if (!ares->completed) {
  		if (ares->handle == NULL) {
  			ac->wait_event = (gsize)CreateEvent (NULL, TRUE, FALSE, NULL);
  			g_assert(ac->wait_event != 0);
  			MONO_OBJECT_SETREF (ares, handle, (MonoObject *) mono_wait_handle_new (mono_object_domain (ares), (gpointer)(gsize)ac->wait_event));
  		}
  		mono_monitor_exit ((MonoObject *) ares);
  		WaitForSingleObjectEx ((gpointer)(gsize)ac->wait_event, INFINITE, TRUE);
  	} else {
  		mono_monitor_exit ((MonoObject *) ares);
  	}
  
  	*exc = ac->msg->exc; /* FIXME: GC add write barrier */
  	*out_args = ac->out_args;
  
  	return ac->res;
  }
  
  void
  mono_thread_pool_cleanup (void)
  {
  	gint release;
  
  	EnterCriticalSection (&mono_delegate_section);
  	free_queue (&async_call_queue);
  	release = (gint) InterlockedCompareExchange (&mono_worker_threads, 0, -1);
  	LeaveCriticalSection (&mono_delegate_section);
  	if (job_added)
  		ReleaseSemaphore (job_added, release, NULL);
  
  	socket_io_cleanup (&socket_io_data);
  }
  
  static void
  null_array (MonoArray *a, int first, int last)
  {
  	/* We must null the old array because it might
  	   contain cross-appdomain references, which
  	   will crash the GC when the domains are
  	   unloaded. */
  	memset (mono_array_addr (a, MonoObject*, first), 0, sizeof (MonoObject*) * (last - first));
  }
  
  static void
  append_job (CRITICAL_SECTION *cs, TPQueue *list, MonoObject *ar)
  {
  	if (mono_runtime_is_shutting_down())
  		return;
  
  	threadpool_jobs_inc (ar); 
  
  	EnterCriticalSection (cs);
  	if (ar->vtable->domain->state == MONO_APPDOMAIN_UNLOADING ||
  			ar->vtable->domain->state == MONO_APPDOMAIN_UNLOADED) {
  		LeaveCriticalSection (cs);
  		return;
  	}
  	if (list->array && (list->next_elem < mono_array_length (list->array))) {
  		mono_array_setref (list->array, list->next_elem, ar);
  		list->next_elem++;
  		LeaveCriticalSection (cs);
  		return;
  	}
  	if (!list->array) {
  		MONO_GC_REGISTER_ROOT (list->array);
  		list->array = mono_array_new_cached (mono_get_root_domain (), mono_defaults.object_class, INITIAL_QUEUE_LENGTH);
  	} else {
  		int count = list->next_elem - list->first_elem;
  		/* slide the array or create a larger one if it's full */
  		if (list->first_elem) {
  			mono_array_memcpy_refs (list->array, 0, list->array, list->first_elem, count);
  			null_array (list->array, count, list->next_elem);
  		} else {
  			MonoArray *olda = list->array;
  			MonoArray *newa = mono_array_new_cached (mono_get_root_domain (), mono_defaults.object_class, mono_array_length (list->array) * 2);
  			mono_array_memcpy_refs (newa, 0, list->array, list->first_elem, count);
  			list->array = newa;
  			null_array (olda, list->first_elem, list->next_elem);
  		}
  		list->first_elem = 0;
  		list->next_elem = count;
  	}
  	mono_array_setref (list->array, list->next_elem, ar);
  	list->next_elem++;
  	LeaveCriticalSection (cs);
  }
  
  
  static void
  clear_queue (CRITICAL_SECTION *cs, TPQueue *list, MonoDomain *domain)
  {
  	int i, count = 0;
  	EnterCriticalSection (cs);
  	/*remove*/
  	for (i = list->first_elem; i < list->next_elem; ++i) {
  		MonoObject *obj = mono_array_get (list->array, MonoObject*, i);
  		if (obj->vtable->domain == domain) {
  			threadpool_jobs_dec (obj);
  			unregister_job ((MonoAsyncResult*)obj);
  
  			mono_array_set (list->array, MonoObject*, i, NULL);
  			++count;
  		}
  	}
  	/*compact*/
  	if (count) {
  		int idx = 0;
  		for (i = list->first_elem; i < list->next_elem; ++i) {
  			MonoObject *obj = mono_array_get (list->array, MonoObject*, i);
  			if (obj)
  				mono_array_set (list->array, MonoObject*, idx++, obj);
  		}
  		list->first_elem = 0;
  		list->next_elem = count;
  	}
  	LeaveCriticalSection (cs);
  }
  
  /*
   * Clean up the threadpool of all domain jobs.
   * Can only be called as part of the domain unloading process as
   * it will wait for all jobs to be visible to the interruption code. 
   */
  gboolean
  mono_thread_pool_remove_domain_jobs (MonoDomain *domain, int timeout)
  {
  	HANDLE sem_handle;
  	int result = TRUE;
  	guint32 start_time = 0;
  
  	g_assert (domain->state == MONO_APPDOMAIN_UNLOADING);
  
  	clear_queue (&mono_delegate_section, &async_call_queue, domain);
  	clear_queue (&io_queue_lock, &async_io_queue, domain);
  
  	/*
  	 * There might be some threads out that could be about to execute stuff from the given domain.
  	 * We avoid that by setting up a semaphore to be pulsed by the thread that reaches zero.
  	 */
  	sem_handle = CreateSemaphore (NULL, 0, 1, NULL);
  	
  	domain->cleanup_semaphore = sem_handle;
  	/*
  	 * The memory barrier here is required to have global ordering between assigning to cleanup_semaphone
  	 * and reading threadpool_jobs.
  	 * Otherwise this thread could read a stale version of threadpool_jobs and wait forever.
  	 */
  	mono_memory_write_barrier ();
  
  	if (domain->threadpool_jobs && timeout != -1)
  		start_time = mono_msec_ticks ();
  	while (domain->threadpool_jobs) {
  		WaitForSingleObject (sem_handle, timeout);
  		if (timeout != -1 && (mono_msec_ticks () - start_time) > timeout) {
  			result = FALSE;
  			break;
  		}
  	}
  
  	domain->cleanup_semaphore = NULL;
  	CloseHandle (sem_handle);
  	return result;
  }
  
  
  static MonoObject*
  dequeue_job (CRITICAL_SECTION *cs, TPQueue *list)
  {
  	MonoObject *ar;
  	int count;
  
  	EnterCriticalSection (cs);
  	if (!list->array || list->first_elem == list->next_elem) {
  		LeaveCriticalSection (cs);
  		return NULL;
  	}
  	ar = mono_array_get (list->array, MonoObject*, list->first_elem);
  	mono_array_setref (list->array, list->first_elem, NULL);
  	list->first_elem++;
  	count = list->next_elem - list->first_elem;
  	/* reduce the size of the array if it's mostly empty */
  	if (mono_array_length (list->array) > INITIAL_QUEUE_LENGTH && count < (mono_array_length (list->array) / 3)) {
  		MonoArray *olda = list->array;
  		MonoArray *newa = mono_array_new_cached (mono_get_root_domain (), mono_defaults.object_class, mono_array_length (list->array) / 2);
  		mono_array_memcpy_refs (newa, 0, list->array, list->first_elem, count);
  		list->array = newa;
  		null_array (olda, list->first_elem, list->next_elem);
  		list->first_elem = 0;
  		list->next_elem = count;
  	}
  	LeaveCriticalSection (cs);
  
  	return ar;
  }
  
  static void
  free_queue (TPQueue *list)
  {
  	if (list->array)
  		null_array (list->array, list->first_elem, list->next_elem);
  	list->array = NULL;
  	list->first_elem = list->next_elem = 0;
  }
  
  static void
  async_invoke_thread (gpointer data)
  {
  	MonoDomain *domain;
  	MonoThread *thread;
  	int workers, min;
  	const gchar *version;
   
  	thread = mono_thread_current ();
   	if (tp_start_func)
   		tp_start_func (tp_hooks_user_data);
  
  	version = mono_get_runtime_info ()->framework_version;
  	for (;;) {
  		MonoAsyncResult *ar;
  
  		ar = (MonoAsyncResult *) data;
  		if (ar) {
  			/* worker threads invokes methods in different domains,
  			 * so we need to set the right domain here */
  			domain = ((MonoObject *)ar)->vtable->domain;
  
  			g_assert (domain);
  
  			if (domain->state == MONO_APPDOMAIN_UNLOADED || domain->state == MONO_APPDOMAIN_UNLOADING) {
  				threadpool_jobs_dec ((MonoObject *)ar);
  				unregister_job (ar);
  				data = NULL;
  			} else {
  				mono_thread_push_appdomain_ref (domain);
  				if (threadpool_jobs_dec ((MonoObject *)ar)) {
  					unregister_job (ar);
  					data = NULL;
  					mono_thread_pop_appdomain_ref ();
  					continue;
  				}
  
  				if (mono_domain_set (domain, FALSE)) {
  					/* ASyncCall *ac; */
  
  					if (tp_item_begin_func)
  						tp_item_begin_func (tp_item_user_data);
  					mono_async_invoke (ar);
  					if (tp_item_end_func)
  						tp_item_end_func (tp_item_user_data);
  					/*
  					ac = (ASyncCall *) ar->object_data;
  					if (ac->msg->exc != NULL)
  						mono_unhandled_exception (ac->msg->exc);
  					*/
  					mono_domain_set (mono_get_root_domain (), TRUE);
  				}
  				mono_thread_pop_appdomain_ref ();
  				InterlockedDecrement (&busy_worker_threads);
  				/* If the callee changes the background status, set it back to TRUE */
  				if (*version != '1' && !mono_thread_test_state (thread , ThreadState_Background))
  					ves_icall_System_Threading_Thread_SetState (thread, ThreadState_Background);
  			}
  		}
  
  		data = dequeue_job (&mono_delegate_section, &async_call_queue);
  
  		if (!data && !mono_runtime_is_shutting_down() && !THREAD_ABORT_REQUESTED(thread)) {
  			guint32 wr;
  			int timeout = THREAD_EXIT_TIMEOUT;
  			guint32 start_time = mono_msec_ticks ();
  			
  			do {
  				wr = WaitForSingleObjectEx (job_added, (guint32)timeout, TRUE);
  				if (THREAD_WANTS_A_BREAK (thread))
  					mono_thread_interruption_checkpoint ();
  			
  				timeout -= mono_msec_ticks () - start_time;
  			
  				if (wr != WAIT_TIMEOUT && wr != WAIT_IO_COMPLETION)
  					data = dequeue_job (&mono_delegate_section, &async_call_queue);
  			}
  			while (!mono_runtime_is_shutting_down() && !data && timeout > 0 && !THREAD_ABORT_REQUESTED(thread));
  		}
  
  		if (!data) {
  			workers = (int) InterlockedCompareExchange (&mono_worker_threads, 0, -1); 
  			min = (int) InterlockedCompareExchange (&mono_min_worker_threads, 0, -1); 
  	
  			while (!mono_runtime_is_shutting_down() && !data && workers <= min && !THREAD_ABORT_REQUESTED(thread)) {
  				WaitForSingleObjectEx (job_added, INFINITE, TRUE);
  				if (THREAD_WANTS_A_BREAK (thread))
  					mono_thread_interruption_checkpoint ();
  			
  				data = dequeue_job (&mono_delegate_section, &async_call_queue);
  				workers = (int) InterlockedCompareExchange (&mono_worker_threads, 0, -1); 
  				min = (int) InterlockedCompareExchange (&mono_min_worker_threads, 0, -1); 
  			}
  		}
  	
  		if (!data) {
  			InterlockedDecrement (&mono_worker_threads);
   			if (tp_finish_func)
   				tp_finish_func (tp_hooks_user_data);
  			return;
  		}
  		
  		InterlockedIncrement (&busy_worker_threads);
  	}
  
  	g_assert_not_reached ();
  }
  
  void
  ves_icall_System_Threading_ThreadPool_GetAvailableThreads (gint *workerThreads, gint *completionPortThreads)
  {
  	gint busy, busy_io;
  
  	MONO_ARCH_SAVE_REGS;
  
  	busy = (gint) InterlockedCompareExchange (&busy_worker_threads, 0, -1);
  	busy_io = (gint) InterlockedCompareExchange (&busy_io_worker_threads, 0, -1);
  	*workerThreads = mono_max_worker_threads - busy;
  	*completionPortThreads = mono_io_max_worker_threads - busy_io;
  }
  
  void
  ves_icall_System_Threading_ThreadPool_GetMaxThreads (gint *workerThreads, gint *completionPortThreads)
  {
  	MONO_ARCH_SAVE_REGS;
  
  	*workerThreads = mono_max_worker_threads;
  	*completionPortThreads = mono_io_max_worker_threads;
  }
  
  void
  ves_icall_System_Threading_ThreadPool_GetMinThreads (gint *workerThreads, gint *completionPortThreads)
  {
  	gint workers, workers_io;
  
  	MONO_ARCH_SAVE_REGS;
  
  	workers = (gint) InterlockedCompareExchange (&mono_min_worker_threads, 0, -1);
  	workers_io = (gint) InterlockedCompareExchange (&mono_io_min_worker_threads, 0, -1);
  
  	*workerThreads = workers;
  	*completionPortThreads = workers_io;
  }
  
  MonoBoolean
  ves_icall_System_Threading_ThreadPool_SetMinThreads (gint workerThreads, gint completionPortThreads)
  {
  	int max_threads;
  	int max_io_threads;
  
  	MONO_ARCH_SAVE_REGS;
  
  	max_threads = InterlockedCompareExchange (&mono_max_worker_threads, -1, -1);
  	if (workerThreads <= 0 || workerThreads > max_threads)
  		return FALSE;
  
  	max_io_threads = InterlockedCompareExchange (&mono_io_max_worker_threads, -1, -1);
  	if (completionPortThreads <= 0 || completionPortThreads > max_io_threads)
  		return FALSE;
  
  	InterlockedExchange (&mono_min_worker_threads, workerThreads);
  	InterlockedExchange (&mono_io_min_worker_threads, completionPortThreads);
  	mono_thread_create_internal (mono_get_root_domain (), start_idle_threads, NULL, TRUE);
  	return TRUE;
  }
  
  MonoBoolean
  ves_icall_System_Threading_ThreadPool_SetMaxThreads (gint workerThreads, gint completionPortThreads)
  {
  	gint32 min_threads;
  	gint32 min_io_threads;
  	gint32 cpu_count;
  
  	MONO_ARCH_SAVE_REGS;
  
  	cpu_count = mono_cpu_count ();
  	min_threads = InterlockedCompareExchange (&mono_min_worker_threads, -1, -1);
  	if (workerThreads < min_threads || workerThreads < cpu_count)
  		return FALSE;
  
  	/* We don't really have the concept of completion ports. Do we care here? */
  	min_io_threads = InterlockedCompareExchange (&mono_io_min_worker_threads, -1, -1);
  	if (completionPortThreads < min_io_threads || completionPortThreads < cpu_count)
  		return FALSE;
  
  	InterlockedExchange (&mono_max_worker_threads, workerThreads);
  	InterlockedExchange (&mono_io_max_worker_threads, completionPortThreads);
  	return TRUE;
  }
  
  /**
   * mono_install_threadpool_thread_hooks
   * @start_func: the function to be called right after a new threadpool thread is created. Can be NULL.
   * @finish_func: the function to be called right before a thredpool thread is exiting. Can be NULL.
   * @user_data: argument passed to @start_func and @finish_func.
   *
   * @start_fun will be called right after a threadpool thread is created and @finish_func right before a threadpool thread exits.
   * The calls will be made from the thread itself.
   */
  void
  mono_install_threadpool_thread_hooks (MonoThreadPoolFunc start_func, MonoThreadPoolFunc finish_func, gpointer user_data)
  {
  	tp_start_func = start_func;
  	tp_finish_func = finish_func;
  	tp_hooks_user_data = user_data;
  }
  
  /**
   * mono_install_threadpool_item_hooks
   * @begin_func: the function to be called before a threadpool work item processing starts.
   * @end_func: the function to be called after a threadpool work item is finished.
   * @user_data: argument passed to @begin_func and @end_func.
   *
   * The calls will be made from the thread itself and from the same AppDomain
   * where the work item was executed.
   *
   */
  void
  mono_install_threadpool_item_hooks (MonoThreadPoolItemFunc begin_func, MonoThreadPoolItemFunc end_func, gpointer user_data)
  {
  	tp_item_begin_func = begin_func;
  	tp_item_end_func = end_func;
  	tp_item_user_data = user_data;
  }
  
  