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ITS#7115: Tighten ldap_pvt_thread_pool_unidle().

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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.
This commit is contained in:
Hallvard Furuseth 2012-01-24 00:47:48 +01:00
parent a8f6deee03
commit 23f3657807
1 changed files with 21 additions and 11 deletions
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32
libraries/libldap_r/tpool.c
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@ -50,6 +50,9 @@ typedef struct ldap_int_tpool_key_s {
/* (Theoretical) max number of pending requests */ /* (Theoretical) max number of pending requests */
#define MAX_PENDING (INT_MAX/2) /* INT_MAX - (room to avoid overflow) */ #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 */ /* Context: thread ID and thread-specific key/data pairs */
typedef struct ldap_int_thread_userctx_s { typedef struct ldap_int_thread_userctx_s {
ldap_pvt_thread_t ltu_id; ldap_pvt_thread_t ltu_id;
@ -462,7 +465,7 @@ ldap_pvt_thread_pool_query(
break; break;
case LDAP_PVT_THREAD_POOL_PARAM_PAUSING: case LDAP_PVT_THREAD_POOL_PARAM_PAUSING:
count = pool->ltp_pause; count = (pool->ltp_pause != 0);
break; break;
case LDAP_PVT_THREAD_POOL_PARAM_PENDING: 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; struct ldap_int_thread_pool_s *pool;
if ( tpool != NULL && (pool = *tpool) != NULL ) { if ( tpool != NULL && (pool = *tpool) != NULL ) {
rc = pool->ltp_pause; rc = (pool->ltp_pause != 0);
} }
return rc; return rc;
@ -716,7 +719,7 @@ ldap_int_thread_pool_wrapper (
*/ */
#define GO_IDLE 8 #define GO_IDLE 8
#define GO_UNIDLE 16 #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 DO_PAUSE 64 /* CHECK_PAUSE; pause the pool */
#define PAUSE_ARG(a) \ #define PAUSE_ARG(a) \
((a) | ((a) & (GO_IDLE|GO_UNIDLE) ? GO_IDLE-1 : CHECK_PAUSE)) ((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 ) handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type )
{ {
struct ldap_int_thread_pool_s *pool; struct ldap_int_thread_pool_s *pool;
int ret = 0, pause; int ret = 0, pause, max_ltp_pause;
if (tpool == NULL) if (tpool == NULL)
return(-1); 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) if (pause_type == CHECK_PAUSE && !pool->ltp_pause)
return(0); 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); 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 */ /* If ltp_pause and not GO_IDLE|GO_UNIDLE: Set GO_IDLE,GO_UNIDLE */
pause_type -= pause; pause_type -= pause;
@ -756,9 +762,11 @@ handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type )
if (pause_type & GO_UNIDLE) { if (pause_type & GO_UNIDLE) {
/* Wait out pause if any, then cancel GO_IDLE */ /* Wait out pause if any, then cancel GO_IDLE */
ret = pause; if (pause > max_ltp_pause) {
for (; pause; pause = pool->ltp_pause) { ret = 1;
ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex); 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_pending_count--;
pool->ltp_active_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 */ /* Tell everyone else to pause or finish, then await that */
ret = 0; ret = 0;
assert(!pool->ltp_pause); 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, /* Let ldap_pvt_thread_pool_submit() through to its ltp_pause test,
* and do not finish threads in ldap_pvt_thread_pool_wrapper() */ * and do not finish threads in ldap_pvt_thread_pool_wrapper() */
pool->ltp_open_count = -pool->ltp_open_count; 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) { while (pool->ltp_active_count > 1) {
ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex); 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); 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)); 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 void
ldap_pvt_thread_pool_unidle( ldap_pvt_thread_pool_t *tpool ) 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); ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
assert(pool->ltp_pause); assert(pool->ltp_pause == PAUSED);
pool->ltp_pause = 0; pool->ltp_pause = 0;
if (pool->ltp_open_count <= 0) /* true when paused, but be paranoid */ if (pool->ltp_open_count <= 0) /* true when paused, but be paranoid */
pool->ltp_open_count = -pool->ltp_open_count; pool->ltp_open_count = -pool->ltp_open_count;