diff options
Diffstat (limited to 'src/support/hazard.c')
| -rw-r--r-- | src/support/hazard.c | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/src/support/hazard.c b/src/support/hazard.c index 7e88ad183fe..6a1b7149a91 100644 --- a/src/support/hazard.c +++ b/src/support/hazard.c @@ -1,5 +1,5 @@ /*- - * Copyright (c) 2014-2016 MongoDB, Inc. + * Copyright (c) 2014-2017 MongoDB, Inc. * Copyright (c) 2008-2014 WiredTiger, Inc. * All rights reserved. * @@ -22,6 +22,7 @@ hazard_grow(WT_SESSION_IMPL *session) WT_HAZARD *nhazard; size_t size; void *ohazard; + uint64_t hazard_gen; /* * Allocate a new, larger hazard pointer array and copy the contents of @@ -40,10 +41,6 @@ hazard_grow(WT_SESSION_IMPL *session) ohazard = session->hazard; WT_PUBLISH(session->hazard, nhazard); - __wt_spin_lock(session, &S2C(session)->api_lock); - __wt_conn_foc_add(session, ohazard); - __wt_spin_unlock(session, &S2C(session)->api_lock); - /* * Increase the size of the session's pointer array after swapping it * into place (the session's reference must be updated before eviction @@ -51,6 +48,15 @@ hazard_grow(WT_SESSION_IMPL *session) */ WT_PUBLISH(session->hazard_size, (uint32_t)(size * 2)); + /* + * Threads using the hazard pointer array from now on will use the new + * one. Increment the hazard pointer generation number, and schedule a + * future free of the old memory. Ignore any failure, leak the memory. + */ + hazard_gen = __wt_gen_next(session, WT_GEN_HAZARD); + WT_IGNORE_RET( + __wt_stash_add(session, WT_GEN_HAZARD, hazard_gen, ohazard, 0)); + return (0); } @@ -325,6 +331,13 @@ __wt_hazard_check(WT_SESSION_IMPL *session, WT_REF *ref) WT_STAT_CONN_INCR(session, cache_hazard_checks); /* + * Hazard pointer arrays might grow and be freed underneath us; enter + * the current hazard resource generation for the duration of the walk + * to ensure that doesn't happen. + */ + __wt_session_gen_enter(session, WT_GEN_HAZARD); + + /* * No lock is required because the session array is fixed size, but it * may contain inactive entries. We must review any active session * that might contain a hazard pointer, so insert a read barrier after @@ -350,12 +363,17 @@ __wt_hazard_check(WT_SESSION_IMPL *session, WT_REF *ref) if (hp->ref == ref) { WT_STAT_CONN_INCRV(session, cache_hazard_walks, walk_cnt); - return (hp); + goto done; } } } WT_STAT_CONN_INCRV(session, cache_hazard_walks, walk_cnt); - return (NULL); + hp = NULL; + +done: /* Leave the current resource generation. */ + __wt_session_gen_leave(session, WT_GEN_HAZARD); + + return (hp); } /* |