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Posted to cvs@httpd.apache.org by sf...@apache.org on 2012/02/27 23:04:55 UTC
svn commit: r1294356 - in /httpd/httpd/trunk: CHANGES include/httpd.h
server/mpm/event/event.c
Author: sf
Date: Mon Feb 27 22:04:54 2012
New Revision: 1294356
URL: http://svn.apache.org/viewvc?rev=1294356&view=rev
Log:
Take care not to call ap_start_lingering_close from the listener thread,
because it may block when flushing data to the client.
>From the listener thread, do a lingering close without flushing. This is
OK because we only do this if there has been an error during write
completion or if our send buffers are empty because we are in keep-alive.
PR: 52229
Modified:
httpd/httpd/trunk/CHANGES
httpd/httpd/trunk/include/httpd.h
httpd/httpd/trunk/server/mpm/event/event.c
Modified: httpd/httpd/trunk/CHANGES
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/CHANGES?rev=1294356&r1=1294355&r2=1294356&view=diff
==============================================================================
--- httpd/httpd/trunk/CHANGES [utf-8] (original)
+++ httpd/httpd/trunk/CHANGES [utf-8] Mon Feb 27 22:04:54 2012
@@ -1,9 +1,12 @@
-*- coding: utf-8 -*-
Changes with Apache 2.5.0
+ *) mpm_event: Don't do a blocking write when starting a lingering close
+ from the listener thread. PR 52229. [Stefan Fritsch]
+
*) core: In maintainer mode, replace apr_palloc with a version that
initializes the allocated memory with non-zero values, except if
- AP_DEBUG_NO_ALLOC_POISON is defined.
+ AP_DEBUG_NO_ALLOC_POISON is defined. [Stefan Fritsch]
*) mod_log_config: Check during config test that directories for access logs
exist. PR 29941. [Stefan Fritsch]
Modified: httpd/httpd/trunk/include/httpd.h
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/include/httpd.h?rev=1294356&r1=1294355&r2=1294356&view=diff
==============================================================================
--- httpd/httpd/trunk/include/httpd.h (original)
+++ httpd/httpd/trunk/include/httpd.h Mon Feb 27 22:04:54 2012
@@ -1147,6 +1147,8 @@ struct conn_rec {
/**
* Enumeration of connection states
+ * The two states CONN_STATE_LINGER_NORMAL and CONN_STATE_LINGER_SHORT may
+ * only be set by the MPM. Use CONN_STATE_LINGER outside of the MPM.
*/
typedef enum {
CONN_STATE_CHECK_REQUEST_LINE_READABLE,
@@ -1154,9 +1156,9 @@ typedef enum {
CONN_STATE_HANDLER,
CONN_STATE_WRITE_COMPLETION,
CONN_STATE_SUSPENDED,
- CONN_STATE_LINGER,
- CONN_STATE_LINGER_NORMAL,
- CONN_STATE_LINGER_SHORT
+ CONN_STATE_LINGER, /* connection may be closed with lingering */
+ CONN_STATE_LINGER_NORMAL, /* MPM has started lingering close with normal timeout */
+ CONN_STATE_LINGER_SHORT /* MPM has started lingering close with short timeout */
} conn_state_e;
/**
Modified: httpd/httpd/trunk/server/mpm/event/event.c
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/server/mpm/event/event.c?rev=1294356&r1=1294355&r2=1294356&view=diff
==============================================================================
--- httpd/httpd/trunk/server/mpm/event/event.c (original)
+++ httpd/httpd/trunk/server/mpm/event/event.c Mon Feb 27 22:04:54 2012
@@ -755,70 +755,96 @@ static void set_signals(void)
#endif
}
+static int start_lingering_close_common(event_conn_state_t *cs)
+{
+ apr_status_t rv;
+ struct timeout_queue *q;
+ apr_socket_t *csd = cs->pfd.desc.s;
+#ifdef AP_DEBUG
+ {
+ rv = apr_socket_timeout_set(csd, 0);
+ AP_DEBUG_ASSERT(rv == APR_SUCCESS);
+ }
+#else
+ apr_socket_timeout_set(csd, 0);
+#endif
+ /*
+ * If some module requested a shortened waiting period, only wait for
+ * 2s (SECONDS_TO_LINGER). This is useful for mitigating certain
+ * DoS attacks.
+ */
+ if (apr_table_get(cs->c->notes, "short-lingering-close")) {
+ cs->expiration_time =
+ apr_time_now() + apr_time_from_sec(SECONDS_TO_LINGER);
+ q = &short_linger_q;
+ cs->pub.state = CONN_STATE_LINGER_SHORT;
+ }
+ else {
+ cs->expiration_time =
+ apr_time_now() + apr_time_from_sec(MAX_SECS_TO_LINGER);
+ q = &linger_q;
+ cs->pub.state = CONN_STATE_LINGER_NORMAL;
+ }
+ apr_thread_mutex_lock(timeout_mutex);
+ TO_QUEUE_APPEND(*q, cs);
+ cs->pfd.reqevents = APR_POLLIN | APR_POLLHUP | APR_POLLERR;
+ rv = apr_pollset_add(event_pollset, &cs->pfd);
+ apr_thread_mutex_unlock(timeout_mutex);
+ if (rv != APR_SUCCESS && !APR_STATUS_IS_EEXIST(rv)) {
+ ap_log_error(APLOG_MARK, APLOG_ERR, rv, ap_server_conf,
+ "start_lingering_close: apr_pollset_add failure");
+ apr_thread_mutex_lock(timeout_mutex);
+ TO_QUEUE_REMOVE(*q, cs);
+ apr_thread_mutex_unlock(timeout_mutex);
+ apr_socket_close(cs->pfd.desc.s);
+ apr_pool_clear(cs->p);
+ ap_push_pool(worker_queue_info, cs->p);
+ return 0;
+ }
+ return 1;
+}
+
/*
- * close our side of the connection
+ * Close our side of the connection, flushing data to the client first.
* Pre-condition: cs is not in any timeout queue and not in the pollset,
* timeout_mutex is not locked
* return: 0 if connection is fully closed,
* 1 if connection is lingering
- * may be called by listener or by worker thread
+ * May only be called by worker thread.
*/
-static int start_lingering_close(event_conn_state_t *cs)
+static int start_lingering_close_blocking(event_conn_state_t *cs)
{
- apr_status_t rv;
-
if (ap_start_lingering_close(cs->c)) {
apr_pool_clear(cs->p);
ap_push_pool(worker_queue_info, cs->p);
return 0;
}
- else {
- apr_socket_t *csd = ap_get_conn_socket(cs->c);
- struct timeout_queue *q;
+ return start_lingering_close_common(cs);
+}
-#ifdef AP_DEBUG
- {
- rv = apr_socket_timeout_set(csd, 0);
- AP_DEBUG_ASSERT(rv == APR_SUCCESS);
- }
-#else
- apr_socket_timeout_set(csd, 0);
-#endif
- /*
- * If some module requested a shortened waiting period, only wait for
- * 2s (SECONDS_TO_LINGER). This is useful for mitigating certain
- * DoS attacks.
- */
- if (apr_table_get(cs->c->notes, "short-lingering-close")) {
- cs->expiration_time =
- apr_time_now() + apr_time_from_sec(SECONDS_TO_LINGER);
- q = &short_linger_q;
- cs->pub.state = CONN_STATE_LINGER_SHORT;
- }
- else {
- cs->expiration_time =
- apr_time_now() + apr_time_from_sec(MAX_SECS_TO_LINGER);
- q = &linger_q;
- cs->pub.state = CONN_STATE_LINGER_NORMAL;
- }
- apr_thread_mutex_lock(timeout_mutex);
- TO_QUEUE_APPEND(*q, cs);
- cs->pfd.reqevents = APR_POLLIN | APR_POLLHUP | APR_POLLERR;
- rv = apr_pollset_add(event_pollset, &cs->pfd);
- apr_thread_mutex_unlock(timeout_mutex);
- if (rv != APR_SUCCESS && !APR_STATUS_IS_EEXIST(rv)) {
- ap_log_error(APLOG_MARK, APLOG_ERR, rv, ap_server_conf,
- "start_lingering_close: apr_pollset_add failure");
- apr_thread_mutex_lock(timeout_mutex);
- TO_QUEUE_REMOVE(*q, cs);
- apr_thread_mutex_unlock(timeout_mutex);
- apr_socket_close(cs->pfd.desc.s);
- apr_pool_clear(cs->p);
- ap_push_pool(worker_queue_info, cs->p);
- return 0;
- }
+/*
+ * Close our side of the connection, NOT flushing data to the client.
+ * This should only be called if there has been an error or if we know
+ * that our send buffers are empty.
+ * Pre-condition: cs is not in any timeout queue and not in the pollset,
+ * timeout_mutex is not locked
+ * return: 0 if connection is fully closed,
+ * 1 if connection is lingering
+ * may be called by listener thread
+ */
+static int start_lingering_close_nonblocking(event_conn_state_t *cs)
+{
+ conn_rec *c = cs->c;
+ apr_socket_t *csd = cs->pfd.desc.s;
+
+ if (c->aborted
+ || apr_socket_shutdown(csd, APR_SHUTDOWN_WRITE) != APR_SUCCESS) {
+ apr_socket_close(csd);
+ apr_pool_clear(cs->p);
+ ap_push_pool(worker_queue_info, cs->p);
+ return 0;
}
- return 1;
+ return start_lingering_close_common(cs);
}
/*
@@ -983,7 +1009,7 @@ read_request:
}
if (cs->pub.state == CONN_STATE_LINGER) {
- if (!start_lingering_close(cs))
+ if (!start_lingering_close_blocking(cs))
return 0;
}
else if (cs->pub.state == CONN_STATE_CHECK_REQUEST_LINE_READABLE) {
@@ -1530,7 +1556,7 @@ static void * APR_THREAD_FUNC listener_t
ap_log_error(APLOG_MARK, APLOG_ERR, rc, ap_server_conf,
"pollset remove failed");
apr_thread_mutex_unlock(timeout_mutex);
- start_lingering_close(cs);
+ start_lingering_close_nonblocking(cs);
break;
}
@@ -1541,7 +1567,7 @@ static void * APR_THREAD_FUNC listener_t
* re-connect to a different process.
*/
if (!have_idle_worker) {
- start_lingering_close(cs);
+ start_lingering_close_nonblocking(cs);
break;
}
rc = push2worker(out_pfd, event_pollset);
@@ -1688,14 +1714,15 @@ static void * APR_THREAD_FUNC listener_t
keepalive_q.count);
process_timeout_queue(&keepalive_q,
timeout_time + ap_server_conf->keep_alive_timeout,
- start_lingering_close);
+ start_lingering_close_nonblocking);
}
else {
process_timeout_queue(&keepalive_q, timeout_time,
- start_lingering_close);
+ start_lingering_close_nonblocking);
}
/* Step 2: write completion timeouts */
- process_timeout_queue(&write_completion_q, timeout_time, start_lingering_close);
+ process_timeout_queue(&write_completion_q, timeout_time,
+ start_lingering_close_nonblocking);
/* Step 3: (normal) lingering close completion timeouts */
process_timeout_queue(&linger_q, timeout_time, stop_lingering_close);
/* Step 4: (short) lingering close completion timeouts */