From 37dbfa3684f6ed562a8adffae8dfcf83c60574fa Mon Sep 17 00:00:00 2001
From: Hallvard Furuseth <hallvard@openldap.org>
Date: Tue, 24 Jan 2012 00:47:48 +0100
Subject: [PATCH] ITS#7115: Tighten ldap_pvt_thread_pool_unidle().
Only wait out already-started pauses, not pause reqests.
ltp_pause now says whether a pause is requested or has started.
This reduces the chance that slapd:send_ldap_ber() will start
a pause in the middle of an operation.
---
libraries/libldap_r/tpool.c | 32 +++++++++++++++++++++-----------
1 file changed, 21 insertions(+), 11 deletions(-)
diff --git a/libraries/libldap_r/tpool.c b/libraries/libldap_r/tpool.c
index 6780307756..140e1af55a 100644
--- a/libraries/libldap_r/tpool.c
+++ b/libraries/libldap_r/tpool.c
@@ -50,6 +50,9 @@ typedef struct ldap_int_tpool_key_s {
/* (Theoretical) max number of pending requests */
#define MAX_PENDING (INT_MAX/2) /* INT_MAX - (room to avoid overflow) */
+/* pool->ltp_pause values */
+enum { NOT_PAUSED = 0, WANT_PAUSE = 1, PAUSED = 2 };
+
/* Context: thread ID and thread-specific key/data pairs */
typedef struct ldap_int_thread_userctx_s {
ldap_pvt_thread_t ltu_id;
@@ -462,7 +465,7 @@ ldap_pvt_thread_pool_query(
break;
case LDAP_PVT_THREAD_POOL_PARAM_PAUSING:
- count = pool->ltp_pause;
+ count = (pool->ltp_pause != 0);
break;
case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
@@ -512,7 +515,7 @@ ldap_pvt_thread_pool_pausing( ldap_pvt_thread_pool_t *tpool )
struct ldap_int_thread_pool_s *pool;
if ( tpool != NULL && (pool = *tpool) != NULL ) {
- rc = pool->ltp_pause;
+ rc = (pool->ltp_pause != 0);
}
return rc;
@@ -716,7 +719,7 @@ ldap_int_thread_pool_wrapper (
*/
#define GO_IDLE 8
#define GO_UNIDLE 16
-#define CHECK_PAUSE 32 /* if (ltp_pause) { GO_IDLE; GO_UNIDLE; } */
+#define CHECK_PAUSE 32 /* if ltp_pause: GO_IDLE; wait; GO_UNIDLE */
#define DO_PAUSE 64 /* CHECK_PAUSE; pause the pool */
#define PAUSE_ARG(a) \
((a) | ((a) & (GO_IDLE|GO_UNIDLE) ? GO_IDLE-1 : CHECK_PAUSE))
@@ -725,7 +728,7 @@ static int
handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type )
{
struct ldap_int_thread_pool_s *pool;
- int ret = 0, pause;
+ int ret = 0, pause, max_ltp_pause;
if (tpool == NULL)
return(-1);
@@ -738,9 +741,12 @@ handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type )
if (pause_type == CHECK_PAUSE && !pool->ltp_pause)
return(0);
+ /* Let pool_unidle() ignore requests for new pauses */
+ max_ltp_pause = pause_type==PAUSE_ARG(GO_UNIDLE) ? WANT_PAUSE : NOT_PAUSED;
+
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
- pause = pool->ltp_pause; /* 0 or 1 */
+ pause = pool->ltp_pause; /* NOT_PAUSED, WANT_PAUSE or PAUSED */
/* If ltp_pause and not GO_IDLE|GO_UNIDLE: Set GO_IDLE,GO_UNIDLE */
pause_type -= pause;
@@ -756,9 +762,11 @@ handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type )
if (pause_type & GO_UNIDLE) {
/* Wait out pause if any, then cancel GO_IDLE */
- ret = pause;
- for (; pause; pause = pool->ltp_pause) {
- ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
+ if (pause > max_ltp_pause) {
+ ret = 1;
+ do {
+ ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
+ } while (pool->ltp_pause > max_ltp_pause);
}
pool->ltp_pending_count--;
pool->ltp_active_count++;
@@ -768,7 +776,7 @@ handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type )
/* Tell everyone else to pause or finish, then await that */
ret = 0;
assert(!pool->ltp_pause);
- pool->ltp_pause = 1;
+ pool->ltp_pause = WANT_PAUSE;
/* Let ldap_pvt_thread_pool_submit() through to its ltp_pause test,
* and do not finish threads in ldap_pvt_thread_pool_wrapper() */
pool->ltp_open_count = -pool->ltp_open_count;
@@ -779,6 +787,8 @@ handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type )
while (pool->ltp_active_count > 1) {
ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
}
+ assert(pool->ltp_pause == WANT_PAUSE);
+ pool->ltp_pause = PAUSED;
}
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
@@ -792,7 +802,7 @@ ldap_pvt_thread_pool_idle( ldap_pvt_thread_pool_t *tpool )
handle_pause(tpool, PAUSE_ARG(GO_IDLE));
}
-/* Cancel pool_idle(). If a pause was requested, wait for it first. */
+/* Cancel pool_idle(). If the pool is paused, wait it out first. */
void
ldap_pvt_thread_pool_unidle( ldap_pvt_thread_pool_t *tpool )
{
@@ -838,7 +848,7 @@ ldap_pvt_thread_pool_resume (
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
- assert(pool->ltp_pause);
+ assert(pool->ltp_pause == PAUSED);
pool->ltp_pause = 0;
if (pool->ltp_open_count <= 0) /* true when paused, but be paranoid */
pool->ltp_open_count = -pool->ltp_open_count;
--
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