2006-07-20 Dick Porter <dick@ximian.com>
[mono.git] / mono / metadata / threadpool.c
index 2b1f904c104961e36003c8f06825a823e17fe1c1..a7f7c04f54e6d4a87223171e98f49bbf6ab60c23 100644 (file)
 #ifdef PLATFORM_WIN32
 #define WINVER 0x0500
 #define _WIN32_WINNT 0x0500
-#define THREADS_PER_CPU        25
-#else
-#define THREADS_PER_CPU        50
 #endif
 
+#define THREADS_PER_CPU        5 /* 20 + THREADS_PER_CPU * number of CPUs */
+
 #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 <string.h>
 
 #include <mono/utils/mono-poll.h>
+#ifdef HAVE_EPOLL
+#include <sys/epoll.h>
+#endif
+
+#include "mono/io-layer/socket-wrappers.h"
 
 #include "threadpool.h"
 
+#define THREAD_WANTS_A_BREAK(t) ((t->state & (ThreadState_StopRequested | \
+                                               ThreadState_SuspendRequested)) != 0)
+
+#undef EPOLL_DEBUG
+
 /* maximum number of worker threads */
-int mono_max_worker_threads = THREADS_PER_CPU;
-static int mono_min_worker_threads = 0;
+static int mono_max_worker_threads;
+static int mono_min_worker_threads;
+static int mono_io_max_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;
@@ -59,6 +72,8 @@ static int tp_inited;
 static MonoGHashTable *ares_htable = NULL;
 
 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 */
@@ -68,59 +83,92 @@ typedef struct {
 
        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;
-       HANDLE             wait_event;
        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;
 
 static void async_invoke_thread (gpointer data);
-static void append_job (MonoAsyncResult *ar);
+static void append_job (CRITICAL_SECTION *cs, GList **plist, gpointer ar);
 static void start_thread_or_queue (MonoAsyncResult *ares);
+static void mono_async_invoke (MonoAsyncResult *ares);
+static gpointer dequeue_job (CRITICAL_SECTION *cs, GList **plist);
 
 static GList *async_call_queue = NULL;
+static GList *async_io_queue = NULL;
 
+static MonoClass *async_call_klass;
 static MonoClass *socket_async_call_klass;
 
 #define INIT_POLLFD(a, b, c) {(a)->fd = b; (a)->events = c; (a)->revents = 0;}
 enum {
-       AIO_FIRST,
-       AIO_ACCEPT = 0,
-       AIO_CONNECT,
-       AIO_RECEIVE,
-       AIO_RECEIVEFROM,
-       AIO_SEND,
-       AIO_SENDTO,
-       AIO_LAST
+       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_LAST
 };
 
 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]);
-       data->pipe [0] = -1;
        close (data->pipe [1]);
+#endif
+       data->pipe [0] = -1;
        data->pipe [1] = -1;
-       CloseHandle (data->new_sem);
+       if (data->new_sem)
+               CloseHandle (data->new_sem);
        data->new_sem = NULL;
        g_hash_table_destroy (data->sock_to_state);
        data->sock_to_state = NULL;
+       g_list_free (async_io_queue);
+       async_io_queue = NULL;
+       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);
 }
 
@@ -128,16 +176,18 @@ static int
 get_event_from_state (MonoSocketAsyncResult *state)
 {
        switch (state->operation) {
-       case AIO_ACCEPT:
-       case AIO_RECEIVE:
-       case AIO_RECEIVEFROM:
+       case AIO_OP_ACCEPT:
+       case AIO_OP_RECEIVE:
+       case AIO_OP_RECV_JUST_CALLBACK:
+       case AIO_OP_RECEIVEFROM:
                return MONO_POLLIN;
-       case AIO_SEND:
-       case AIO_SENDTO:
-       case AIO_CONNECT:
+       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 ("socket_io_add: unknown value in switch!!!\n");
+               g_print ("get_event_from_state: unknown value in switch!!!\n");
                return 0;
        }
 }
@@ -157,6 +207,116 @@ get_events_from_list (GSList *list)
        return events;
 }
 
+#define ICALL_RECV(x)  ves_icall_System_Net_Sockets_Socket_Receive_internal (\
+                               (SOCKET) 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) x->handle, x->buffer, x->offset, x->size,\
+                                x->socket_flags, &x->error);
+
+static void
+async_invoke_io_thread (gpointer data)
+{
+       MonoDomain *domain;
+       MonoThread *thread;
+       thread = mono_thread_current ();
+       thread->threadpool_thread = TRUE;
+       ves_icall_System_Threading_Thread_SetState (thread, ThreadState_Background);
+
+       for (;;) {
+               MonoSocketAsyncResult *state;
+               MonoAsyncResult *ar;
+
+               state = (MonoSocketAsyncResult *) data;
+               if (state) {
+                       InterlockedDecrement (&pending_io_items);
+                       ar = state->ares;
+                       /* worker threads invokes methods in different domains,
+                        * so we need to set the right domain here */
+                       switch (state->operation) {
+                       case AIO_OP_RECEIVE:
+                               state->total = ICALL_RECV (state);
+                               break;
+                       case AIO_OP_SEND:
+                               state->total = ICALL_SEND (state);
+                               break;
+                       }
+
+                       domain = ((MonoObject *)ar)->vtable->domain;
+                       mono_thread_push_appdomain_ref (domain);
+                       if (mono_domain_set (domain, FALSE)) {
+                               ASyncCall *ac;
+
+                               mono_async_invoke (ar);
+                               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);
+               }
+
+               data = dequeue_job (&io_queue_lock, &async_io_queue);
+       
+               if (!data) {
+                       guint32 wr;
+                       int timeout = 10000;
+                       guint32 start_time = GetTickCount ();
+                       
+                       do {
+                               wr = WaitForSingleObjectEx (io_job_added, (guint32)timeout, TRUE);
+                               if (THREAD_WANTS_A_BREAK (thread))
+                                       mono_thread_interruption_checkpoint ();
+                       
+                               timeout -= GetTickCount () - start_time;
+                       
+                               if (wr != WAIT_TIMEOUT)
+                                       data = dequeue_job (&io_queue_lock, &async_io_queue);
+                       }
+                       while (!data && timeout > 0);
+               }
+
+               if (!data) {
+                       if (InterlockedDecrement (&io_worker_threads) < 2) {
+                               /* If we have pending items, keep the thread alive */
+                               if (InterlockedCompareExchange (&pending_io_items, 0, 0) != 0) {
+                                       InterlockedIncrement (&io_worker_threads);
+                                       continue;
+                               }
+                       }
+                       return;
+               }
+               
+               InterlockedIncrement (&busy_io_worker_threads);
+       }
+
+       g_assert_not_reached ();
+}
+
+static void
+start_io_thread_or_queue (MonoSocketAsyncResult *ares)
+{
+       int busy, worker;
+       MonoDomain *domain;
+
+       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);
+               domain = ((ares) ? ((MonoObject *) ares)->vtable->domain : mono_domain_get ());
+               mono_thread_create (mono_get_root_domain (), async_invoke_io_thread, ares);
+       } else {
+               append_job (&io_queue_lock, &async_io_queue, ares);
+               ReleaseSemaphore (io_job_added, 1, NULL);
+       }
+}
+
 static GSList *
 process_io_event (GSList *list, int event)
 {
@@ -169,13 +329,18 @@ process_io_event (GSList *list, int event)
                state = (MonoSocketAsyncResult *) list->data;
                if (get_event_from_state (state) == event)
                        break;
+               
                list = list->next;
        }
 
        if (list != NULL) {
                oldlist = g_slist_remove_link (oldlist, list);
                g_slist_free_1 (list);
-               start_thread_or_queue (state->ares);
+#ifdef EPOLL_DEBUG
+               g_print ("Dispatching event %d on socket %d\n", event, state->handle);
+#endif
+               InterlockedIncrement (&pending_io_items);
+               start_io_thread_or_queue (state);
        }
 
        return oldlist;
@@ -193,7 +358,7 @@ mark_bad_fds (mono_pollfd *pfds, int nfds)
                if (pfd->fd == -1)
                        continue;
 
-               ret = mono_poll (pfds, 1, 0);
+               ret = mono_poll (pfd, 1, 0);
                if (ret == -1 && errno == EBADF) {
                        pfd->revents |= MONO_POLLNVAL;
                        count++;
@@ -206,7 +371,7 @@ mark_bad_fds (mono_pollfd *pfds, int nfds)
 }
 
 static void
-socket_io_main (gpointer p)
+socket_io_poll_main (gpointer p)
 {
 #define INITIAL_POLLFD_SIZE    1024
 #define POLL_ERRORS (MONO_POLLERR | MONO_POLLHUP | MONO_POLLNVAL)
@@ -217,10 +382,9 @@ socket_io_main (gpointer p)
        gint i;
        MonoThread *thread;
 
        thread = mono_thread_current ();
        thread->threadpool_thread = TRUE;
-       thread->state |= ThreadState_Background;
+       ves_icall_System_Threading_Thread_SetState (thread, ThreadState_Background);
 
        allocated = INITIAL_POLLFD_SIZE;
        pfds = g_new0 (mono_pollfd, allocated);
@@ -236,7 +400,7 @@ socket_io_main (gpointer p)
 
                do {
                        if (nsock == -1) {
-                               if ((thread->state & ThreadState_StopRequested) != 0)
+                               if (THREAD_WANTS_A_BREAK (thread))
                                        mono_thread_interruption_checkpoint ();
                        }
 
@@ -271,6 +435,8 @@ socket_io_main (gpointer p)
 
                /* 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 || pfd->fd == data->newpfd->fd)
@@ -288,8 +454,16 @@ socket_io_main (gpointer p)
                                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 */
+                       }
 
-                       read (data->pipe [0], one, 1);
                        INIT_POLLFD (&pfds [i], data->newpfd->fd, data->newpfd->events);
                        ReleaseSemaphore (data->new_sem, 1, NULL);
                        if (i >= maxfd)
@@ -335,38 +509,273 @@ socket_io_main (gpointer p)
        }
 }
 
+#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 ();
+       thread->threadpool_thread = TRUE;
+       ves_icall_System_Threading_Thread_SetState (thread, ThreadState_Background);
+       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;
+                       GSList *list;
+
+                       evt = &events [i];
+                       fd = evt->data.fd;
+                       list = 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, g_slist_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) {
+                               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 {
+                               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)
+{
+#ifdef HAVE_EPOLL
+       GSList *list, *next;
+       MonoSocketAsyncResult *state;
+
+       if (socket_io_data.epoll_disabled == TRUE || socket_io_data.inited == FALSE)
+               return;
+
+       EnterCriticalSection (&socket_io_data.io_lock);
+       list = g_hash_table_lookup (socket_io_data.sock_to_state, GINT_TO_POINTER (sock));
+       if (list) {
+               g_hash_table_remove (socket_io_data.sock_to_state, GINT_TO_POINTER (sock));
+       }
+       LeaveCriticalSection (&socket_io_data.io_lock);
+       
+       while (list) {
+               state = (MonoSocketAsyncResult *) list->data;
+               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 = g_slist_remove_link (list, list);
+               list = process_io_event (list, MONO_POLLIN);
+               if (list)
+                       process_io_event (list, MONO_POLLOUT);
+
+               list = next;
+       }
+#endif
+}
+
+#ifdef PLATFORM_WIN32
+static void
+connect_hack (gpointer 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)
 {
-       if (pipe (data->pipe) != 0) {
-               int err = errno;
-               perror ("mono");
-               g_assert (err);
+#ifdef PLATFORM_WIN32
+       struct sockaddr_in server;
+       struct sockaddr_in client;
+       SOCKET srv;
+       int len;
+#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);
+       mono_thread_create (mono_get_root_domain (), connect_hack, &server);
+       len = sizeof (server);
+       data->pipe [0] = accept (srv, (SOCKADDR *) &client, &len);
+       g_assert (data->pipe [0] != INVALID_SOCKET);
+       closesocket (srv);
+#endif
+       mono_io_max_worker_threads = mono_max_worker_threads / 2;
+       if (mono_io_max_worker_threads < 10)
+               mono_io_max_worker_threads = 10;
 
        data->sock_to_state = g_hash_table_new (g_direct_hash, g_direct_equal);
-       data->new_sem = CreateSemaphore (NULL, 1, 1, NULL);
-       mono_thread_create (mono_get_root_domain (), socket_io_main, data);
+
+       if (data->epoll_disabled)
+               data->new_sem = CreateSemaphore (NULL, 1, 1, NULL);
+       io_job_added = CreateSemaphore (NULL, 0, 0x7fffffff, NULL);
+       InitializeCriticalSection (&io_queue_lock);
+       if (data->epoll_disabled) {
+               mono_thread_create (mono_get_root_domain (), socket_io_poll_main, data);
+       }
+#ifdef HAVE_EPOLL
+       else {
+               mono_thread_create (mono_get_root_domain (), socket_io_epoll_main, data);
+       }
+#endif
+       InterlockedCompareExchange (&data->inited, 1, 0);
+       LeaveCriticalSection (&data->io_lock);
 }
 
 static void
-socket_io_add (MonoAsyncResult *ares, MonoSocketAsyncResult *state)
+socket_io_add_poll (MonoSocketAsyncResult *state)
 {
        int events;
        char msg [1];
        GSList *list;
        SocketIOData *data = &socket_io_data;
 
-       state->ares = ares;
-       if (InterlockedCompareExchange (&data->inited, -1, -1) == 0) {
-               EnterCriticalSection (&data->io_lock);
-               if (0 == data->inited) {
-                       socket_io_init (data);
-                       data->inited = 1;
-               }
-               LeaveCriticalSection (&data->io_lock);
+#if defined(PLATFORM_MACOSX) || defined(PLATFORM_BSD6)
+       /* select() for connect() does not work well on the Mac. Bug #75436. */
+       /* Bug #77637 for the BSD 6 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);
@@ -385,7 +794,74 @@ socket_io_add (MonoAsyncResult *ares, MonoSocketAsyncResult *state)
        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
        write (data->pipe [1], msg, 1);
+#else
+       send ((SOCKET) data->pipe [1], msg, 1, 0);
+#endif
+}
+
+#ifdef HAVE_EPOLL
+static gboolean
+socket_io_add_epoll (MonoSocketAsyncResult *state)
+{
+       GSList *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 = g_hash_table_lookup (data->sock_to_state, GINT_TO_POINTER (fd));
+       if (list == NULL) {
+               list = g_slist_alloc ();
+               list->data = state;
+               epoll_op = EPOLL_CTL_ADD;
+       } else {
+               list = g_slist_append (list, 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;
+
+       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
@@ -398,28 +874,25 @@ socket_io_filter (MonoObject *target, MonoObject *state)
        if (target == NULL || state == NULL)
                return FALSE;
 
-       klass = InterlockedCompareExchangePointer ((gpointer *) &socket_async_call_klass, NULL, NULL);
-       if (klass == NULL) {
-               MonoImage *system_assembly = mono_image_loaded ("System");
-
-               if (system_assembly == NULL)
-                       return FALSE;
-
-               klass = mono_class_from_name (system_assembly, "System.Net.Sockets", "Socket/SocketAsyncCall");
-               if (klass == NULL) {
-                       /* Should never happen... */
-                       g_print ("socket_io_filter: SocketAsyncCall class not found.\n");
-                       return FALSE;
-               }
-
-               InterlockedCompareExchangePointer ((gpointer *) &socket_async_call_klass, klass, NULL);
+       if (socket_async_call_klass == NULL) {
+               klass = target->vtable->klass;
+               /* Check if it's SocketAsyncCall in System
+                * 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 (target->vtable->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)
                return FALSE;
 
        op = sock_res->operation;
-       if (op < AIO_FIRST || op >= AIO_LAST)
+       if (op < AIO_OP_FIRST || op >= AIO_OP_LAST)
                return FALSE;
 
        return TRUE;
@@ -428,7 +901,17 @@ socket_io_filter (MonoObject *target, MonoObject *state)
 static void
 mono_async_invoke (MonoAsyncResult *ares)
 {
-       ASyncCall *ac = (ASyncCall *)ares->data;
+       ASyncCall *ac = (ASyncCall *)ares->object_data;
+       MonoThread *thread = NULL;
+
+       if (ares->execution_context) {
+               /* use captured ExecutionContext (if available) */
+               thread = mono_thread_current ();
+               MONO_OBJECT_SETREF (ares, original_context, thread->execution_context);
+               MONO_OBJECT_SETREF (thread, execution_context, ares->execution_context);
+       } else {
+               ares->original_context = NULL;
+       }
 
        ac->msg->exc = NULL;
        ac->res = mono_message_invoke (ares->async_delegate, ac->msg, 
@@ -441,8 +924,16 @@ mono_async_invoke (MonoAsyncResult *ares)
                MonoObject *exc = NULL;
                void *pa = &ares;
                mono_runtime_invoke (ac->cb_method, ac->cb_target, pa, &exc);
-               if (!ac->msg->exc)
-                       ac->msg->exc = 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_OBJECT_SETREF (thread, execution_context, ares->original_context);
+               ares->original_context = NULL;
        }
 
        /* notify listeners */
@@ -470,16 +961,19 @@ mono_thread_pool_init ()
        MONO_GC_REGISTER_ROOT (ares_htable);
        InitializeCriticalSection (&socket_io_data.io_lock);
        InitializeCriticalSection (&ares_lock);
-       ares_htable = mono_g_hash_table_new (NULL, NULL);
+       ares_htable = mono_g_hash_table_new_type (NULL, NULL, MONO_HASH_KEY_VALUE_GC);
        job_added = CreateSemaphore (NULL, 0, 0x7fffffff, NULL);
        GetSystemInfo (&info);
-       if (getenv ("MONO_THREADS_PER_CPU") != NULL) {
-               threads_per_cpu = atoi (getenv ("MONO_THREADS_PER_CPU"));
+       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;
        }
 
-       mono_max_worker_threads = threads_per_cpu * info.dwNumberOfProcessors;
+       mono_max_worker_threads = 20 + threads_per_cpu * info.dwNumberOfProcessors;
+
+       async_call_klass = mono_class_from_name (mono_defaults.corlib, "System", "MonoAsyncCall");
+       g_assert (async_call_klass);
 }
 
 MonoAsyncResult *
@@ -492,21 +986,23 @@ mono_thread_pool_add (MonoObject *target, MonoMethodMessage *msg, MonoDelegate *
 
 #ifdef HAVE_BOEHM_GC
        ac = GC_MALLOC (sizeof (ASyncCall));
+#elif defined(HAVE_SGEN_GC)
+       ac = mono_object_new (mono_domain_get (), async_call_klass);
 #else
        /* We'll leak the event if creaated... */
        ac = g_new0 (ASyncCall, 1);
 #endif
        ac->wait_event = NULL;
-       ac->msg = msg;
-       ac->state = state;
+       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);
                ac->cb_target = async_callback;
        }
 
-       ares = mono_async_result_new (domain, NULL, ac->state, ac);
-       ares->async_delegate = target;
+       ares = mono_async_result_new (domain, NULL, ac->state, NULL, ac);
+       MONO_OBJECT_SETREF (ares, async_delegate, target);
 
        EnterCriticalSection (&ares_lock);
        mono_g_hash_table_insert (ares_htable, ares, ares);
@@ -534,9 +1030,9 @@ start_thread_or_queue (MonoAsyncResult *ares)
                InterlockedIncrement (&mono_worker_threads);
                InterlockedIncrement (&busy_worker_threads);
                domain = ((MonoObject *) ares)->vtable->domain;
-               mono_thread_create (domain, async_invoke_thread, ares);
+               mono_thread_create (mono_get_root_domain (), async_invoke_thread, ares);
        } else {
-               append_job (ares);
+               append_job (&mono_delegate_section, &async_call_queue, ares);
                ReleaseSemaphore (job_added, 1, NULL);
        }
 }
@@ -560,7 +1056,7 @@ mono_thread_pool_finish (MonoAsyncResult *ares, MonoArray **out_args, MonoObject
        }
 
        ares->endinvoke_called = 1;
-       ac = (ASyncCall *)ares->data;
+       ac = (ASyncCall *)ares->object_data;
 
        g_assert (ac != NULL);
 
@@ -568,7 +1064,7 @@ mono_thread_pool_finish (MonoAsyncResult *ares, MonoArray **out_args, MonoObject
        if (!ares->completed) {
                if (ares->handle == NULL) {
                        ac->wait_event = CreateEvent (NULL, TRUE, FALSE, NULL);
-                       ares->handle = (MonoObject *) mono_wait_handle_new (mono_object_domain (ares), ac->wait_event);
+                       MONO_OBJECT_SETREF (ares, handle, (MonoObject *) mono_wait_handle_new (mono_object_domain (ares), ac->wait_event));
                }
                mono_monitor_exit ((MonoObject *) ares);
                WaitForSingleObjectEx (ac->wait_event, INFINITE, TRUE);
@@ -576,7 +1072,7 @@ mono_thread_pool_finish (MonoAsyncResult *ares, MonoArray **out_args, MonoObject
                mono_monitor_exit ((MonoObject *) ares);
        }
 
-       *exc = ac->msg->exc;
+       *exc = ac->msg->exc; /* FIXME: GC add write barrier */
        *out_args = ac->out_args;
 
        return ac->res;
@@ -590,7 +1086,7 @@ mono_thread_pool_cleanup (void)
        EnterCriticalSection (&mono_delegate_section);
        g_list_free (async_call_queue);
        async_call_queue = NULL;
-       release = (gint) InterlockedCompareExchange (&busy_worker_threads, 0, -1);
+       release = (gint) InterlockedCompareExchange (&mono_worker_threads, 0, -1);
        LeaveCriticalSection (&mono_delegate_section);
        if (job_added)
                ReleaseSemaphore (job_added, release, NULL);
@@ -599,45 +1095,49 @@ mono_thread_pool_cleanup (void)
 }
 
 static void
-append_job (MonoAsyncResult *ar)
+append_job (CRITICAL_SECTION *cs, GList **plist, gpointer ar)
 {
-       GList *tmp;
+       GList *tmp, *list;
 
-       EnterCriticalSection (&mono_delegate_section);
-       if (async_call_queue == NULL) {
-               async_call_queue = g_list_append (async_call_queue, ar); 
+       EnterCriticalSection (cs);
+       list = *plist;
+       if (list == NULL) {
+               list = g_list_append (list, ar); 
        } else {
-               for (tmp = async_call_queue; tmp && tmp->data != NULL; tmp = tmp->next);
+               for (tmp = list; tmp && tmp->data != NULL; tmp = tmp->next);
                if (tmp == NULL) {
-                       async_call_queue = g_list_append (async_call_queue, ar); 
+                       list = g_list_append (list, ar); 
                } else {
                        tmp->data = ar;
                }
        }
-       LeaveCriticalSection (&mono_delegate_section);
+       *plist = list;
+       LeaveCriticalSection (cs);
 }
 
-static MonoAsyncResult *
-dequeue_job (void)
+static gpointer
+dequeue_job (CRITICAL_SECTION *cs, GList **plist)
 {
-       MonoAsyncResult *ar = NULL;
-       GList *tmp, *tmp2;
+       gpointer ar = NULL;
+       GList *tmp, *tmp2, *list;
 
-       EnterCriticalSection (&mono_delegate_section);
-       tmp = async_call_queue;
+       EnterCriticalSection (cs);
+       list = *plist;
+       tmp = list;
        if (tmp) {
-               ar = (MonoAsyncResult *) tmp->data;
+               ar = tmp->data;
                tmp->data = NULL;
                tmp2 = tmp;
                for (tmp2 = tmp; tmp2->next != NULL; tmp2 = tmp2->next);
                if (tmp2 != tmp) {
-                       async_call_queue = tmp->next;
+                       list = tmp->next;
                        tmp->next = NULL;
                        tmp2->next = tmp;
                        tmp->prev = tmp2;
                }
        }
-       LeaveCriticalSection (&mono_delegate_section);
+       *plist = list;
+       LeaveCriticalSection (cs);
 
        return ar;
 }
@@ -651,7 +1151,7 @@ async_invoke_thread (gpointer data)
  
        thread = mono_thread_current ();
        thread->threadpool_thread = TRUE;
-       thread->state |= ThreadState_Background;
+       ves_icall_System_Threading_Thread_SetState (thread, ThreadState_Background);
 
        for (;;) {
                MonoAsyncResult *ar;
@@ -661,16 +1161,24 @@ async_invoke_thread (gpointer data)
                        /* worker threads invokes methods in different domains,
                         * so we need to set the right domain here */
                        domain = ((MonoObject *)ar)->vtable->domain;
+                       mono_thread_push_appdomain_ref (domain);
                        if (mono_domain_set (domain, FALSE)) {
-                               mono_thread_push_appdomain_ref (domain);
+                               ASyncCall *ac;
+
                                mono_async_invoke (ar);
-                               mono_thread_pop_appdomain_ref ();
+                               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);
                }
 
-               data = dequeue_job ();
-       
+               data = dequeue_job (&mono_delegate_section, &async_call_queue);
+
                if (!data) {
                        guint32 wr;
                        int timeout = 10000;
@@ -678,13 +1186,13 @@ async_invoke_thread (gpointer data)
                        
                        do {
                                wr = WaitForSingleObjectEx (job_added, (guint32)timeout, TRUE);
-                               if ((thread->state & ThreadState_StopRequested)!=0)
+                               if (THREAD_WANTS_A_BREAK (thread))
                                        mono_thread_interruption_checkpoint ();
                        
                                timeout -= GetTickCount () - start_time;
                        
                                if (wr != WAIT_TIMEOUT)
-                                       data = dequeue_job ();
+                                       data = dequeue_job (&mono_delegate_section, &async_call_queue);
                        }
                        while (!data && timeout > 0);
                }
@@ -695,10 +1203,10 @@ async_invoke_thread (gpointer data)
        
                        while (!data && workers <= min) {
                                WaitForSingleObjectEx (job_added, INFINITE, TRUE);
-                               if ((thread->state & ThreadState_StopRequested)!=0)
+                               if (THREAD_WANTS_A_BREAK (thread))
                                        mono_thread_interruption_checkpoint ();
                        
-                               data = dequeue_job ();
+                               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); 
                        }
@@ -760,61 +1268,3 @@ ves_icall_System_Threading_ThreadPool_SetMinThreads (gint workerThreads, gint co
        return TRUE;
 }
 
-static void
-overlapped_callback (guint32 error, guint32 numbytes, WapiOverlapped *overlapped)
-{
-       MonoFSAsyncResult *ares;
-       MonoThread *thread;
-       MONO_ARCH_SAVE_REGS;
-
-       ares = (MonoFSAsyncResult *) overlapped->handle1;
-       ares->completed = TRUE;
-       if (ares->bytes_read != -1)
-               ares->bytes_read = numbytes;
-       else
-               ares->count = numbytes;
-
-       thread = mono_thread_attach (mono_object_domain (ares));
-       if (ares->async_callback != NULL) {
-               gpointer p [1];
-
-               *p = ares;
-               mono_runtime_invoke (ares->async_callback->method_info->method, NULL, p, NULL);
-       }
-
-       SetEvent (ares->wait_handle->handle);
-       mono_thread_detach (thread);
-       g_free (overlapped);
-}
-
-MonoBoolean
-ves_icall_System_Threading_ThreadPool_BindHandle (gpointer handle)
-{
-       MONO_ARCH_SAVE_REGS;
-
-#ifdef PLATFORM_WIN32
-       return FALSE;
-#else
-       if (!BindIoCompletionCallback (handle, overlapped_callback, 0)) {
-               gint error = GetLastError ();
-               MonoException *exc;
-               gchar *msg;
-
-               if (error == ERROR_INVALID_PARAMETER) {
-                       exc = mono_get_exception_argument (NULL, "Invalid parameter.");
-               } else {
-                       msg = g_strdup_printf ("Win32 error %d.", error);
-                       exc = mono_exception_from_name_msg (mono_defaults.corlib,
-                                                           "System",
-                                                           "ApplicationException", msg);
-                       g_free (msg);
-               }
-
-               mono_raise_exception (exc);
-       }
-
-       return TRUE;
-#endif
-}
-