rebase events to tevent and align to upstream

1 files changed, 567 insertions, 0 deletions

diff --git a/tevent/tevent_aio.c b/tevent/tevent_aio.c
new file mode 100644
index 00000000..7c3473b9
--- /dev/null
+++ b/tevent/tevent_aio.c
@@ -0,0 +1,567 @@
+/* 
+   Unix SMB/CIFS implementation.
+
+   main select loop and event handling - aio/epoll hybrid implementation
+
+   Copyright (C) Andrew Tridgell	2006
+
+   based on events_standard.c
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/*
+  this is a very strange beast. The Linux AIO implementation doesn't
+  yet integrate properly with epoll, but there is a kernel patch that
+  allows the aio wait primitives to be used to wait for epoll events,
+  and this can be used to give us a unified event system incorporating
+  both aio events and epoll events
+
+  this is _very_ experimental code
+*/
+
+#include "system/filesys.h"
+#include "replace.h"
+#include "tevent.h"
+#include "tevent_internal.h"
+#include "tevent_util.h"
+#include <sys/epoll.h>
+#include <libaio.h>
+
+#define MAX_AIO_QUEUE_DEPTH	100
+#ifndef IOCB_CMD_EPOLL_WAIT
+#define IOCB_CMD_EPOLL_WAIT	9
+#endif
+
+struct aio_event_context {
+	/* a pointer back to the generic event_context */
+	struct event_context *ev;
+
+	/* list of filedescriptor events */
+	struct fd_event *fd_events;
+
+	/* number of registered fd event handlers */
+	int num_fd_events;
+
+	uint32_t destruction_count;
+
+	io_context_t ioctx;
+
+	struct epoll_event epevent[MAX_AIO_QUEUE_DEPTH];
+
+	struct iocb *epoll_iocb;
+
+	int epoll_fd;
+	int is_epoll_set;
+	pid_t pid;
+};
+
+struct aio_event {
+	struct event_context *event_ctx;
+	struct iocb iocb;
+	void *private_data;
+	event_aio_handler_t handler;
+};
+
+/*
+  map from EVENT_FD_* to EPOLLIN/EPOLLOUT
+*/
+static uint32_t epoll_map_flags(uint16_t flags)
+{
+	uint32_t ret = 0;
+	if (flags & EVENT_FD_READ) ret |= (EPOLLIN | EPOLLERR | EPOLLHUP);
+	if (flags & EVENT_FD_WRITE) ret |= (EPOLLOUT | EPOLLERR | EPOLLHUP);
+	return ret;
+}
+
+/*
+ free the epoll fd
+*/
+static int aio_ctx_destructor(struct aio_event_context *aio_ev)
+{
+	io_queue_release(aio_ev->ioctx);
+	close(aio_ev->epoll_fd);
+	aio_ev->epoll_fd = -1;
+	return 0;
+}
+
+static void epoll_add_event(struct aio_event_context *aio_ev, struct fd_event *fde);
+
+/*
+  reopen the epoll handle when our pid changes
+  see http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for an 
+  demonstration of why this is needed
+ */
+static void epoll_check_reopen(struct aio_event_context *aio_ev)
+{
+	struct fd_event *fde;
+
+	if (aio_ev->pid == getpid()) {
+		return;
+	}
+
+	close(aio_ev->epoll_fd);
+	aio_ev->epoll_fd = epoll_create(MAX_AIO_QUEUE_DEPTH);
+	if (aio_ev->epoll_fd == -1) {
+		ev_debug(aio_ev->ev, EV_DEBUG_FATAL, "Failed to recreate epoll handle after fork\n");
+		return;
+	}
+	aio_ev->pid = getpid();
+	for (fde=aio_ev->fd_events;fde;fde=fde->next) {
+		epoll_add_event(aio_ev, fde);
+	}
+}
+
+#define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT	(1<<0)
+#define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR	(1<<1)
+#define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR	(1<<2)
+
+/*
+ add the epoll event to the given fd_event
+*/
+static void epoll_add_event(struct aio_event_context *aio_ev, struct fd_event *fde)
+{
+	struct epoll_event event;
+	if (aio_ev->epoll_fd == -1) return;
+
+	fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
+	/* if we don't want events yet, don't add an aio_event */
+	if (fde->flags == 0) return;
+
+	memset(&event, 0, sizeof(event));
+	event.events = epoll_map_flags(fde->flags);
+	event.data.ptr = fde;
+	epoll_ctl(aio_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event);
+	fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+
+	/* only if we want to read we want to tell the event handler about errors */
+	if (fde->flags & EVENT_FD_READ) {
+		fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+	}
+}
+
+/*
+ delete the epoll event for given fd_event
+*/
+static void epoll_del_event(struct aio_event_context *aio_ev, struct fd_event *fde)
+{
+	struct epoll_event event;
+
+	DLIST_REMOVE(aio_ev->fd_events, fde);
+
+	if (aio_ev->epoll_fd == -1) return;
+
+	fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
+	/* if there's no aio_event, we don't need to delete it */
+	if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) return;
+
+	ZERO_STRUCT(event);
+	event.events = epoll_map_flags(fde->flags);
+	event.data.ptr = fde;
+	epoll_ctl(aio_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event);
+
+	fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+}
+
+/*
+ change the epoll event to the given fd_event
+*/
+static void epoll_mod_event(struct aio_event_context *aio_ev, struct fd_event *fde)
+{
+	struct epoll_event event;
+	if (aio_ev->epoll_fd == -1) return;
+
+	fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
+	ZERO_STRUCT(event);
+	event.events = epoll_map_flags(fde->flags);
+	event.data.ptr = fde;
+	epoll_ctl(aio_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event);
+
+	/* only if we want to read we want to tell the event handler about errors */
+	if (fde->flags & EVENT_FD_READ) {
+		fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+	}
+}
+
+static void epoll_change_event(struct aio_event_context *aio_ev, struct fd_event *fde)
+{
+	bool got_error = (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR);
+	bool want_read = (fde->flags & EVENT_FD_READ);
+	bool want_write= (fde->flags & EVENT_FD_WRITE);
+
+	if (aio_ev->epoll_fd == -1) return;
+
+	fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
+	/* there's already an event */
+	if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT) {
+		if (want_read || (want_write && !got_error)) {
+			epoll_mod_event(aio_ev, fde);
+			return;
+		}
+		epoll_del_event(aio_ev, fde);
+		return;
+	}
+
+	/* there's no aio_event attached to the fde */
+	if (want_read || (want_write && !got_error)) {
+		DLIST_ADD(aio_ev->fd_events, fde);
+		epoll_add_event(aio_ev, fde);
+		return;
+	}
+}
+
+static int setup_epoll_wait(struct aio_event_context *aio_ev)
+{
+	if (aio_ev->is_epoll_set) {
+		return 0;
+	}
+	memset(aio_ev->epoll_iocb, 0, sizeof(*aio_ev->epoll_iocb));
+	aio_ev->epoll_iocb->aio_fildes = aio_ev->epoll_fd;
+	aio_ev->epoll_iocb->aio_lio_opcode = IOCB_CMD_EPOLL_WAIT;
+	aio_ev->epoll_iocb->aio_reqprio = 0;
+
+	aio_ev->epoll_iocb->u.c.nbytes = MAX_AIO_QUEUE_DEPTH;
+	aio_ev->epoll_iocb->u.c.offset = -1;
+	aio_ev->epoll_iocb->u.c.buf = aio_ev->epevent;
+
+	if (io_submit(aio_ev->ioctx, 1, &aio_ev->epoll_iocb) != 1) {
+		return -1;
+	}
+	aio_ev->is_epoll_set = 1;
+
+	return 0;
+}
+
+
+/*
+  event loop handling using aio/epoll hybrid
+*/
+static int aio_event_loop(struct aio_event_context *aio_ev, struct timeval *tvalp)
+{
+	int ret, i;
+	uint32_t destruction_count = ++aio_ev->destruction_count;
+	struct timespec timeout;
+	struct io_event events[8];
+
+	if (aio_ev->epoll_fd == -1) return -1;
+
+	if (aio_ev->ev->num_signal_handlers && 
+	    common_event_check_signal(aio_ev->ev)) {
+		return 0;
+	}
+
+	if (tvalp) {
+		timeout.tv_sec = tvalp->tv_sec;
+		timeout.tv_nsec = tvalp->tv_usec;
+		timeout.tv_nsec *= 1000;
+	}
+
+	if (setup_epoll_wait(aio_ev) < 0) 
+		return -1;
+
+	ret = io_getevents(aio_ev->ioctx, 1, 8,
+			   events, tvalp?&timeout:NULL);
+
+	if (ret == -EINTR) {
+		if (aio_ev->ev->num_signal_handlers) {
+			common_event_check_signal(aio_ev->ev);
+		}
+		return 0;
+	}
+
+	if (ret == 0 && tvalp) {
+		/* we don't care about a possible delay here */
+		common_event_loop_timer_delay(aio_ev->ev);
+		return 0;
+	}
+
+	for (i=0;i<ret;i++) {
+		struct io_event *event = &events[i];
+		struct iocb *finished = event->obj;
+
+		switch (finished->aio_lio_opcode) {
+		case IO_CMD_PWRITE:
+		case IO_CMD_PREAD: {
+			struct aio_event *ae = talloc_get_type(finished->data, 
+							       struct aio_event);
+			if (ae) {
+				talloc_set_destructor(ae, NULL);
+				ae->handler(ae->event_ctx, ae, 
+					    event->res, ae->private_data);
+				talloc_free(ae);
+			}
+			break;
+		}
+		case IOCB_CMD_EPOLL_WAIT: {
+			struct epoll_event *ep = (struct epoll_event *)finished->u.c.buf;
+			struct fd_event *fde;
+			uint16_t flags = 0;
+			int j;
+
+			aio_ev->is_epoll_set = 0;
+
+			for (j=0; j<event->res; j++, ep++) {
+				fde = talloc_get_type(ep->data.ptr, 
+						      struct fd_event);
+				if (fde == NULL) {
+					return -1;
+				}
+				if (ep->events & (EPOLLHUP|EPOLLERR)) {
+					fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
+					if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) {
+						epoll_del_event(aio_ev, fde);
+						continue;
+					}
+					flags |= EVENT_FD_READ;
+				}
+				if (ep->events & EPOLLIN) flags |= EVENT_FD_READ;
+				if (ep->events & EPOLLOUT) flags |= EVENT_FD_WRITE;
+				if (flags) {
+					fde->handler(aio_ev->ev, fde, flags, fde->private_data);
+				}
+			}
+			break;
+		}
+		}
+		if (destruction_count != aio_ev->destruction_count) {
+			return 0;
+		}
+	}
+
+	return 0;
+}
+
+/*
+  create a aio_event_context structure.
+*/
+static int aio_event_context_init(struct event_context *ev)
+{
+	struct aio_event_context *aio_ev;
+	
+	aio_ev = talloc_zero(ev, struct aio_event_context);
+	if (!aio_ev) return -1;
+
+	aio_ev->ev = ev;
+	aio_ev->epoll_iocb = talloc(aio_ev, struct iocb);
+
+	if (io_queue_init(MAX_AIO_QUEUE_DEPTH, &aio_ev->ioctx) != 0) {
+		talloc_free(aio_ev);
+		return -1;
+	}
+
+	aio_ev->epoll_fd = epoll_create(MAX_AIO_QUEUE_DEPTH);
+	if (aio_ev->epoll_fd == -1) {
+		talloc_free(aio_ev);
+		return -1;
+	}
+	aio_ev->pid = getpid();
+
+	talloc_set_destructor(aio_ev, aio_ctx_destructor);
+
+	ev->additional_data = aio_ev;
+
+	if (setup_epoll_wait(aio_ev) < 0) {
+		talloc_free(aio_ev);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+  destroy an fd_event
+*/
+static int aio_event_fd_destructor(struct fd_event *fde)
+{
+	struct event_context *ev = fde->event_ctx;
+	struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data,
+							   struct aio_event_context);
+
+	epoll_check_reopen(aio_ev);
+
+	aio_ev->num_fd_events--;
+	aio_ev->destruction_count++;
+
+	epoll_del_event(aio_ev, fde);
+
+	if (fde->flags & EVENT_FD_AUTOCLOSE) {
+		close(fde->fd);
+		fde->fd = -1;
+	}
+
+	return 0;
+}
+
+/*
+  add a fd based event
+  return NULL on failure (memory allocation error)
+*/
+static struct fd_event *aio_event_add_fd(struct event_context *ev, TALLOC_CTX *mem_ctx,
+					 int fd, uint16_t flags,
+					 event_fd_handler_t handler,
+					 void *private_data)
+{
+	struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data,
+							   struct aio_event_context);
+	struct fd_event *fde;
+
+	epoll_check_reopen(aio_ev);
+
+	fde = talloc(mem_ctx?mem_ctx:ev, struct fd_event);
+	if (!fde) return NULL;
+
+	fde->event_ctx		= ev;
+	fde->fd			= fd;
+	fde->flags		= flags;
+	fde->handler		= handler;
+	fde->private_data	= private_data;
+	fde->additional_flags	= 0;
+	fde->additional_data	= NULL;
+
+	aio_ev->num_fd_events++;
+	talloc_set_destructor(fde, aio_event_fd_destructor);
+
+	DLIST_ADD(aio_ev->fd_events, fde);
+	epoll_add_event(aio_ev, fde);
+
+	return fde;
+}
+
+
+/*
+  return the fd event flags
+*/
+static uint16_t aio_event_get_fd_flags(struct fd_event *fde)
+{
+	return fde->flags;
+}
+
+/*
+  set the fd event flags
+*/
+static void aio_event_set_fd_flags(struct fd_event *fde, uint16_t flags)
+{
+	struct event_context *ev;
+	struct aio_event_context *aio_ev;
+
+	if (fde->flags == flags) return;
+
+	ev = fde->event_ctx;
+	aio_ev = talloc_get_type(ev->additional_data, struct aio_event_context);
+
+	fde->flags = flags;
+
+	epoll_check_reopen(aio_ev);
+
+	epoll_change_event(aio_ev, fde);
+}
+
+/*
+  do a single event loop using the events defined in ev 
+*/
+static int aio_event_loop_once(struct event_context *ev)
+{
+	struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data,
+		 					   struct aio_event_context);
+	struct timeval tval;
+
+	tval = common_event_loop_timer_delay(ev);
+	if (ev_timeval_is_zero(&tval)) {
+		return 0;
+	}
+
+	epoll_check_reopen(aio_ev);
+
+	return aio_event_loop(aio_ev, &tval);
+}
+
+/*
+  return on failure or (with 0) if all fd events are removed
+*/
+static int aio_event_loop_wait(struct event_context *ev)
+{
+	struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data,
+							   struct aio_event_context);
+	while (aio_ev->num_fd_events) {
+		if (aio_event_loop_once(ev) != 0) {
+			break;
+		}
+	}
+
+	return 0;
+}
+
+/*
+  called when a disk IO event needs to be cancelled
+*/
+static int aio_destructor(struct aio_event *ae)
+{
+	struct event_context *ev = ae->event_ctx;
+	struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data,
+							   struct aio_event_context);
+	struct io_event result;
+	io_cancel(aio_ev->ioctx, &ae->iocb, &result);
+	/* TODO: handle errors from io_cancel()! */
+	return 0;
+}
+
+/* submit an aio disk IO event */
+static struct aio_event *aio_event_add_aio(struct event_context *ev, 
+					   TALLOC_CTX *mem_ctx,
+					   struct iocb *iocb,
+					   event_aio_handler_t handler,
+					   void *private_data)
+{
+	struct aio_event_context *aio_ev = talloc_get_type(ev->additional_data,
+							   struct aio_event_context);
+	struct iocb *iocbp;
+	struct aio_event *ae = talloc(mem_ctx?mem_ctx:ev, struct aio_event);
+	if (ae == NULL) return NULL;
+
+	ae->event_ctx    = ev;
+	ae->iocb         = *iocb;
+	ae->handler      = handler;
+	ae->private_data = private_data;
+	iocbp = &ae->iocb;
+
+	if (io_submit(aio_ev->ioctx, 1, &iocbp) != 1) {
+		talloc_free(ae);
+		return NULL;
+	}
+	ae->iocb.data = ae;
+	talloc_set_destructor(ae, aio_destructor);
+
+	return ae;
+}
+
+static const struct event_ops aio_event_ops = {
+	.context_init	= aio_event_context_init,
+	.add_fd		= aio_event_add_fd,
+	.add_aio        = aio_event_add_aio,
+	.get_fd_flags	= aio_event_get_fd_flags,
+	.set_fd_flags	= aio_event_set_fd_flags,
+	.add_timed	= common_event_add_timed,
+	.add_signal	= common_event_add_signal,
+	.loop_once	= aio_event_loop_once,
+	.loop_wait	= aio_event_loop_wait,
+};
+
+bool events_aio_init(void)
+{
+	return event_register_backend("aio", &aio_event_ops);
+}
+