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Code Issues Releases Wiki Activity

Use callback to avoid blocking in omapi_listener_shutdown.

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This commit is contained in:
David Lawrence
2000-03-14 03:53:20 +00:00
parent 66290e9bfb
commit 6bdf7cb13e
1 changed files with 127 additions and 110 deletions
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237
lib/omapi/listener.c
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@@ -33,14 +33,33 @@ typedef struct omapi_listener_object {
isc_mutex_t mutex;
isc_task_t *task;
isc_socket_t *socket; /* Listening socket. */
dns_acl_t *acl;
void (*callback)(void *);
void *callback_arg;
/*
* Locked by mutex.
*/
isc_boolean_t accepting;
isc_condition_t waiter;
isc_boolean_t listening;
ISC_LIST(omapi_connection_t) connections;
} omapi_listener_t;
static void
free_listener(omapi_listener_t *listener) {
/*
* Break the link between the listener object and its parent
* (usually a generic object); this is done so the server's
* reference to its managing object does not prevent the
* listener object from being destroyed.
*/
OBJECT_DEREF(&listener->inner->outer);
OBJECT_DEREF(&listener->inner);
/*
* The listener object can now be freed.
*/
OBJECT_DEREF(&listener);
}
/*
* Reader callback for a listener object. Accept an incoming connection.
*/
@@ -51,9 +70,12 @@ listener_accept(isc_task_t *task, isc_event_t *event) {
isc_buffer_t *obuffer = NULL;
isc_task_t *connection_task = NULL;
isc_socket_t *socket;
isc_sockaddr_t sockaddr;
isc_netaddr_t netaddr;
omapi_connection_t *connection = NULL;
omapi_object_t *protocol = NULL;
omapi_listener_t *listener;
int match;
/*
* XXXDCL audit error handling
@@ -71,14 +93,40 @@ listener_accept(isc_task_t *task, isc_event_t *event) {
if (result == ISC_R_CANCELED) {
/*
* omapi_listener_shutdown was called. Stop accepting incoming
* connection by not queuing another accept.
* omapi_listener_shutdown was called.
*/
LOCK(&listener->mutex);
listener->accepting = ISC_FALSE;
SIGNAL(&listener->waiter);
UNLOCK(&listener->mutex);
listener->listening = ISC_FALSE;
if (ISC_LIST_HEAD(listener->connections) == NULL) {
UNLOCK(&listener->mutex);
free_listener(listener);
} else {
/*
* All connections this listener was responsible for
* must be removed.
*
* XXXDCL
* Since it is possible that this shutdown was
* triggered by one of the clients, it would be nice
* to give it a little time to exit, as well as allow
* any other connections to finish up cleanly.
* Unfortunately, since this could be called in the
* task/event thread of a program (as it is in named),
* no other events can be delivered while this routine
* blocks, so a loop to use isc_condition_waituntil
* until all of the connections are gone is pointless.
*/
for (connection = ISC_LIST_HEAD(listener->connections);
connection != NULL;
connection = ISC_LIST_NEXT(connection, link))
omapi_connection_disconnect((omapi_object_t *)
connection,
OMAPI_FORCE_DISCONNECT);
UNLOCK(&listener->mutex);
}
return;
}
@@ -90,13 +138,33 @@ listener_accept(isc_task_t *task, isc_event_t *event) {
/*
* Check for the validity of new connection event.
* If the result is not ISC_R_SUCCESS, what can really
* be done about it other than just flunking out of here?
*/
if (result != ISC_R_SUCCESS)
/*
* The result is probably ISC_R_UNEXPECTED. What can really
* be done about it other than just * flunking out of here?
*/
return;
/*
* Is the connection from a valid host?
*/
result = isc_socket_getpeername(socket, &sockaddr);
if (result == ISC_R_SUCCESS) {
isc_netaddr_fromsockaddr(&netaddr, &sockaddr);
result = dns_acl_match(&netaddr, NULL, listener->acl,
NULL, &match, NULL);
}
if (result != ISC_R_SUCCESS || match <= 0) {
/*
* Permission denied. Close the connection.
* XXXDCL isc_log_write an error.
*/
isc_socket_detach(&socket);
return;
}
/*
* The new connection is good to go. Allocate the buffers for it and
@@ -166,7 +234,9 @@ listener_accept(isc_task_t *task, isc_event_t *event) {
* object, but since there's no easy way to use omapi_object_reference
* with the ISC_LIST macros, that reference is just not counted.
*/
LOCK(&listener->mutex);
ISC_LIST_APPEND(listener->connections, connection, link);
UNLOCK(&listener->mutex);
/*
* Remember the listener that accepted the connection, so it
@@ -202,7 +272,10 @@ free_task:
}
isc_result_t
omapi_listener_listen(omapi_object_t *caller, isc_sockaddr_t *addr, int max) {
omapi_listener_listen(omapi_object_t *caller, isc_sockaddr_t *addr,
dns_acl_t *acl, int max, void (*callback)(void *),
void *callback_arg)
{
isc_result_t result;
isc_task_t *task;
omapi_listener_t *listener;
@@ -229,9 +302,8 @@ omapi_listener_listen(omapi_object_t *caller, isc_sockaddr_t *addr, int max) {
listener->task = task;
ISC_LIST_INIT(listener->connections);
RUNTIME_CHECK(isc_mutex_init(&listener->mutex) == ISC_R_SUCCESS);
RUNTIME_CHECK(isc_condition_init(&listener->waiter) == ISC_R_SUCCESS);
ISC_LIST_INIT(listener->connections);
/*
* Create a socket on which to listen.
@@ -254,7 +326,8 @@ omapi_listener_listen(omapi_object_t *caller, isc_sockaddr_t *addr, int max) {
* Queue up the first accept event. The listener object
* will be passed to listener_accept() when it is called.
*/
listener->accepting = ISC_TRUE;
dns_acl_attach(acl, &listener->acl);
listener->listening = ISC_TRUE;
result = isc_socket_accept(listener->socket, task,
listener_accept, listener);
}
@@ -266,11 +339,21 @@ omapi_listener_listen(omapi_object_t *caller, isc_sockaddr_t *addr, int max) {
OBJECT_REF(&caller->outer, listener);
OBJECT_REF(&listener->inner, caller);
} else
/*
* The callback is not set until here because it should
* only be called if the listener was successfully set up.
*/
listener->callback = callback;
listener->callback_arg = callback_arg;
} else {
/*
* Failed to set up the listener.
*/
listener->listening = ISC_FALSE;
OBJECT_DEREF(&listener);
}
return (result);
}
@@ -278,10 +361,6 @@ omapi_listener_listen(omapi_object_t *caller, isc_sockaddr_t *addr, int max) {
void
omapi_listener_shutdown(omapi_object_t *listener) {
omapi_listener_t *l;
omapi_connection_t *c;
isc_time_t timeout;
isc_interval_t interval;
isc_result_t result = ISC_R_SUCCESS;
REQUIRE((listener != NULL && listener->type == omapi_type_listener) ||
(listener->outer != NULL &&
@@ -302,82 +381,6 @@ omapi_listener_shutdown(omapi_object_t *listener) {
* Stop accepting connections.
*/
isc_socket_cancel(l->socket, NULL, ISC_SOCKCANCEL_ACCEPT);
/*
* All connections this listener was responsible for must be gone.
* Since it is possible that this shutdown was triggered by one
* of the clients, give it a little time to exit, as well as
* allowing other connections to finish up cleanly. The
* cancelled accept event also needs to be received before
* the listener task, socket and object can be destroyed.
*
* isc_time_nowplusinterval returns an isc_result_t; anything other
* than ISC_R_SUCCESS is wildly unexpected because the Unix
* implementation uses gettimeofday(), which is documented to only
* return an error if its argument is an invalid memory address, and
* the Win32 implementation always returns ISC_R_SUCCESS. In any
* event, if it fails, there is nothing to do but soldier on.
* The waituntil would immediately timeout, and the connections
* would be forcibly blown away.
*
* 5 seconds is an arbitrary constant.
*/
isc_interval_set(&interval, 5, 0);
isc_time_nowplusinterval(&timeout, &interval);
LOCK(&l->mutex);
while (! ISC_LIST_EMPTY(l->connections) && result == ISC_R_SUCCESS) {
ISC_UTIL_TRACE(fprintf(stderr, "WAIT %p LOCK %p %s %d\n",
&l->waiter, &l->mutex,
__FILE__, __LINE__));
result = isc_condition_waituntil(&l->waiter, &l->mutex,
&timeout);
ISC_UTIL_TRACE(fprintf(stderr, "WAITED %p LOCKED %p %s %d\n",
&l->waiter, &l->mutex,
__FILE__, __LINE__));
}
/*
* If there are still some connections hanging about,
* they won't be for long.
*/
for (c = ISC_LIST_HEAD(l->connections); c != NULL;
c = ISC_LIST_NEXT(c, link))
omapi_connection_disconnect((omapi_object_t *)c,
OMAPI_FORCE_DISCONNECT);
/*
* Again wait for any remaining connections to be destroyed, and
* ensure the listen socket has received the cancelled accept event.
* This will happen rapidly now because they were all cancelled.
*/
while (! ISC_LIST_EMPTY(l->connections) || l->accepting)
WAIT(&l->waiter, &l->mutex);
/*
* The accept cancel event should now have been posted,
* and the connections should be gone.
*/
INSIST(! l->accepting && ISC_LIST_EMPTY(l->connections));
UNLOCK(&l->mutex);
/*
* Break the link between the listener object and its parent
* (usually a generic object); this is done so the server's
* reference to its managing object does not prevent the listener
* object from being destroyed.
*/
OBJECT_DEREF(&l->inner->outer);
OBJECT_DEREF(&l->inner);
/*
* The listener object can now be freed.
*/
OBJECT_DEREF(&l);
}
static isc_result_t
@@ -414,20 +417,27 @@ listener_destroy(omapi_object_t *listener) {
l = (omapi_listener_t *)listener;
LOCK(&l->mutex);
INSIST(ISC_LIST_EMPTY(l->connections));
if (l->task != NULL) {
isc_task_destroy(&l->task);
l->task = NULL;
}
if (l->socket != NULL) {
isc_socket_detach(&l->socket);
l->socket = NULL;
}
UNLOCK(&l->mutex);
RUNTIME_CHECK(isc_mutex_destroy(&l->mutex) == ISC_R_SUCCESS);
RUNTIME_CHECK(isc_condition_destroy(&l->waiter) == ISC_R_SUCCESS);
if (l->task != NULL)
isc_task_destroy(&l->task);
if (l->socket != NULL)
isc_socket_detach(&l->socket);
if (l->acl != NULL)
dns_acl_detach(&l->acl);
/*
* XXDCL Technically, all the memory is not yet freed. Hmm.
* Somehow this callback stuff (or its "event" equivalent) needs to
* go into object_dereference.
*/
(*l->callback)(l->callback_arg);
}
static isc_result_t
@@ -449,11 +459,18 @@ listener_signalhandler(omapi_object_t *listener, const char *name, va_list ap)
c = va_arg(ap, omapi_connection_t *);
LOCK(&l->mutex);
ISC_LIST_UNLINK(l->connections, c, link);
SIGNAL(&l->waiter);
UNLOCK(&l->mutex);
if (! l->listening && ISC_LIST_HEAD(l->connections) == NULL) {
/*
* The listener has been shutdown and the last
* connection was received.
*/
UNLOCK(&l->mutex);
free_listener(l);
} else
UNLOCK(&l->mutex);
result = ISC_R_SUCCESS;
} else