event_iocp.c

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Author : Nick Mathewson
Date : 2010-02-15 19:54:15
Hash : 32c6f1ba
Message : Construct Windows locks using InitializeCriticalSectionAndSpinCount Previously we were using InitializeCriticalSection, which creates a lock that blocks immediately on contention and waits to be rescheduled. This is inefficient; it's better to wait for a little while before telling the US to reschedule us, in case the lock becomes available again really soon (since most locks mostly do). Good pthreads implementations do this automatically. On Windows, though, we need to call this magic function, and we need to pick the spin count ourselves.
event_iocp.c
/*
 * Copyright (c) 2009 Niels Provos, Nick Mathewson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <winsock2.h>
#include <windows.h>
#include <process.h>
#include <stdio.h>
#include <mswsock.h>

#include "event2/util.h"
#include "util-internal.h"
#include "iocp-internal.h"
#include "log-internal.h"
#include "mm-internal.h"
#include "event-internal.h"

#define NOTIFICATION_KEY ((ULONG_PTR)-1)

void
event_overlapped_init(struct event_overlapped *o, iocp_callback cb)
{
	memset(o, 0, sizeof(struct event_overlapped));
	o->cb = cb;
}

static void
handle_entry(OVERLAPPED *o, ULONG_PTR completion_key, DWORD nBytes, int ok)
{
	struct event_overlapped *eo =
	    EVUTIL_UPCAST(o, struct event_overlapped, overlapped);
	eo->cb(eo, completion_key, nBytes, ok);
}

static void
loop(void *_port)
{
	struct event_iocp_port *port = _port;
	long ms = port->ms;
	HANDLE p = port->port;

	if (ms <= 0)
		ms = INFINITE;

	while (1) {
		OVERLAPPED *overlapped=NULL;
		ULONG_PTR key=0;
		DWORD bytes=0;
		int ok = GetQueuedCompletionStatus(p, &bytes, &key,
			&overlapped, ms);
		EnterCriticalSection(&port->lock);
		if (port->shutdown) {
			if (--port->n_live_threads == 0)
				ReleaseSemaphore(port->shutdownSemaphore, 1, NULL);
			LeaveCriticalSection(&port->lock);
			return;
		}
		LeaveCriticalSection(&port->lock);

		if (key != NOTIFICATION_KEY && overlapped)
			handle_entry(overlapped, key, bytes, ok);
		else if (!overlapped)
			break;
	}
	event_warnx("GetQueuedCompletionStatus exited with no event.");
	EnterCriticalSection(&port->lock);
	if (--port->n_live_threads == 0)
		ReleaseSemaphore(port->shutdownSemaphore, 1, NULL);
	LeaveCriticalSection(&port->lock);
}

int
event_iocp_port_associate(struct event_iocp_port *port, evutil_socket_t fd,
    ev_uintptr_t key)
{
	HANDLE h;
	h = CreateIoCompletionPort((HANDLE)fd, port->port, key, port->n_threads);
	if (!h)
		return -1;
	return 0;
}

static void *
get_extension_function(SOCKET s, const GUID *which_fn)
{
	void *ptr = NULL;
	DWORD bytes=0;
	WSAIoctl(s, SIO_GET_EXTENSION_FUNCTION_POINTER,
	    (GUID*)which_fn, sizeof(*which_fn),
	    &ptr, sizeof(ptr),
	    &bytes, NULL, NULL);

	/* No need to detect errors here: if ptr is set, then we have a good
	   function pointer.  Otherwise, we should behave as if we had no
	   function pointer.
	*/
	return ptr;
}

/* Mingw doesn't have these in its mswsock.h.  The values are copied from
   wine.h.   Perhaps if we copy them exactly, the cargo will come again.
*/
#ifndef WSAID_ACCEPTEX
#define WSAID_ACCEPTEX \
	{0xb5367df1,0xcbac,0x11cf,{0x95,0xca,0x00,0x80,0x5f,0x48,0xa1,0x92}}
#endif
#ifndef WSAID_CONNECTEX
#define WSAID_CONNECTEX \
	{0x25a207b9,0xddf3,0x4660,{0x8e,0xe9,0x76,0xe5,0x8c,0x74,0x06,0x3e}}
#endif
#ifndef WSAID_GETACCEPTEXSOCKADDRS
#define WSAID_GETACCEPTEXSOCKADDRS \
	{0xb5367df2,0xcbac,0x11cf,{0x95,0xca,0x00,0x80,0x5f,0x48,0xa1,0x92}}
#endif

static void
init_extension_functions(struct win32_extension_fns *ext)
{
	const GUID acceptex = WSAID_ACCEPTEX;
	const GUID connectex = WSAID_CONNECTEX;
	const GUID getacceptexsockaddrs = WSAID_GETACCEPTEXSOCKADDRS;
	SOCKET s = socket(AF_INET, SOCK_STREAM, 0);
	if (s == INVALID_SOCKET)
		return;
	ext->AcceptEx = get_extension_function(s, &acceptex);
	ext->ConnectEx = get_extension_function(s, &connectex);
	ext->GetAcceptExSockaddrs = get_extension_function(s,
	    &getacceptexsockaddrs);
	closesocket(s);
}

static struct win32_extension_fns the_extension_fns;
static int extension_fns_initialized = 0;

const struct win32_extension_fns *
event_get_win32_extension_fns(void)
{
	return &the_extension_fns;
}

struct event_iocp_port *
event_iocp_port_launch(void)
{
	struct event_iocp_port *port;
	int i;

	if (!extension_fns_initialized)
		init_extension_functions(&the_extension_fns);

	if (!(port = mm_calloc(1, sizeof(struct event_iocp_port))))
		return NULL;
	port->n_threads = 2;
	port->threads = calloc(port->n_threads, sizeof(HANDLE));
	if (!port->threads)
		goto err;

	port->port = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, port->n_threads);
	port->ms = -1;
	if (!port->port)
		goto err;

	port->shutdownSemaphore = CreateSemaphore(NULL, 0, 1, NULL);
	if (!port->shutdownSemaphore)
		goto err;

	for (i=0; i<port->n_threads; ++i) {
		ev_uintptr_t th = _beginthread(loop, 0, port);
		if (th == (ev_uintptr_t)-1)
			goto err;
		port->threads[i] = (HANDLE)th;
		++port->n_live_threads;
	}

	InitializeCriticalSectionAndSpinCount(&port->lock, 1000);

	return port;
err:
	if (port->port)
		CloseHandle(port->port);
	if (port->threads)
		mm_free(port->threads);
	if (port->shutdownSemaphore)
		CloseHandle(port->shutdownSemaphore);
	mm_free(port);
	return NULL;
}

static void
_event_iocp_port_unlock_and_free(struct event_iocp_port *port)
{
	DeleteCriticalSection(&port->lock);
	CloseHandle(port->port);
	CloseHandle(port->shutdownSemaphore);
	mm_free(port->threads);
	mm_free(port);
}

static int
event_iocp_notify_all(struct event_iocp_port *port)
{
	int i, r, ok=1;
	for (i=0; i<port->n_threads; ++i) {
		r = PostQueuedCompletionStatus(port->port, 0, NOTIFICATION_KEY,
		    NULL);
		if (!r)
			ok = 0;
	}
	return ok ? 0 : -1;
}

int
event_iocp_shutdown(struct event_iocp_port *port, long waitMsec)
{
	int n;
	EnterCriticalSection(&port->lock);
	port->shutdown = 1;
	LeaveCriticalSection(&port->lock);
	event_iocp_notify_all(port);

	WaitForSingleObject(port->shutdownSemaphore, waitMsec);
	EnterCriticalSection(&port->lock);
	n = port->n_live_threads;
	LeaveCriticalSection(&port->lock);
	if (n == 0) {
		_event_iocp_port_unlock_and_free(port);
		return 0;
	} else {
		return -1;
	}
}

int
event_iocp_activate_overlapped(
    struct event_iocp_port *port, struct event_overlapped *o,
    ev_uintptr_t key, ev_uint32_t n)
{
	BOOL r;

	r = PostQueuedCompletionStatus(port->port, n, key, &o->overlapped);
	return (r==0) ? -1 : 0;
}

struct event_iocp_port *
event_base_get_iocp(struct event_base *base)
{
#ifdef WIN32
	return base->iocp;
#else
	return NULL;
#endif
}
kc3-lang/libevent/event_iocp.c

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kc3-lang/libevent /event_iocp.c
