diff options
Diffstat (limited to 'src/third_party/wiredtiger/src/txn/txn.c')
| -rw-r--r-- | src/third_party/wiredtiger/src/txn/txn.c | 84 |
1 files changed, 51 insertions, 33 deletions
diff --git a/src/third_party/wiredtiger/src/txn/txn.c b/src/third_party/wiredtiger/src/txn/txn.c index f835fea8f67..e8fd8c0c119 100644 --- a/src/third_party/wiredtiger/src/txn/txn.c +++ b/src/third_party/wiredtiger/src/txn/txn.c @@ -1,5 +1,5 @@ /*- - * Copyright (c) 2014-2015 MongoDB, Inc. + * Copyright (c) 2014-2016 MongoDB, Inc. * Copyright (c) 2008-2014 WiredTiger, Inc. * All rights reserved. * @@ -216,6 +216,7 @@ __wt_txn_update_oldest(WT_SESSION_IMPL *session, bool force) conn = S2C(session); txn_global = &conn->txn_global; +retry: current_id = last_running = txn_global->current; oldest_session = NULL; prev_oldest_id = txn_global->oldest_id; @@ -287,43 +288,60 @@ __wt_txn_update_oldest(WT_SESSION_IMPL *session, bool force) WT_TXNID_LT(txn_global->last_running, last_running); /* Update the oldest ID. */ - if ((WT_TXNID_LT(prev_oldest_id, oldest_id) || last_running_moved) && - __wt_atomic_casiv32(&txn_global->scan_count, 1, -1)) { - WT_ORDERED_READ(session_cnt, conn->session_cnt); - for (i = 0, s = txn_global->states; i < session_cnt; i++, s++) { - if ((id = s->id) != WT_TXN_NONE && - WT_TXNID_LT(id, last_running)) - last_running = id; - if ((id = s->snap_min) != WT_TXN_NONE && - WT_TXNID_LT(id, oldest_id)) - oldest_id = id; - } - - if (WT_TXNID_LT(last_running, oldest_id)) - oldest_id = last_running; - -#ifdef HAVE_DIAGNOSTIC + if (WT_TXNID_LT(prev_oldest_id, oldest_id) || last_running_moved) { /* - * Make sure the ID doesn't move past any named snapshots. - * - * Don't include the read/assignment in the assert statement. - * Coverity complains if there are assignments only done in - * diagnostic builds, and when the read is from a volatile. + * We know we want to update. Check if we're racing. */ - id = txn_global->nsnap_oldest_id; - WT_ASSERT(session, - id == WT_TXN_NONE || !WT_TXNID_LT(id, oldest_id)); + if (__wt_atomic_casiv32(&txn_global->scan_count, 1, -1)) { + WT_ORDERED_READ(session_cnt, conn->session_cnt); + for (i = 0, s = txn_global->states; + i < session_cnt; i++, s++) { + if ((id = s->id) != WT_TXN_NONE && + WT_TXNID_LT(id, last_running)) + last_running = id; + if ((id = s->snap_min) != WT_TXN_NONE && + WT_TXNID_LT(id, oldest_id)) + oldest_id = id; + } + + if (WT_TXNID_LT(last_running, oldest_id)) + oldest_id = last_running; + +#ifdef HAVE_DIAGNOSTIC + /* + * Make sure the ID doesn't move past any named + * snapshots. + * + * Don't include the read/assignment in the assert + * statement. Coverity complains if there are + * assignments only done in diagnostic builds, and + * when the read is from a volatile. + */ + id = txn_global->nsnap_oldest_id; + WT_ASSERT(session, + id == WT_TXN_NONE || !WT_TXNID_LT(id, oldest_id)); #endif - if (WT_TXNID_LT(txn_global->last_running, last_running)) - txn_global->last_running = last_running; - if (WT_TXNID_LT(txn_global->oldest_id, oldest_id)) - txn_global->oldest_id = oldest_id; - WT_ASSERT(session, txn_global->scan_count == -1); - txn_global->scan_count = 0; + if (WT_TXNID_LT(txn_global->last_running, last_running)) + txn_global->last_running = last_running; + if (WT_TXNID_LT(txn_global->oldest_id, oldest_id)) + txn_global->oldest_id = oldest_id; + WT_ASSERT(session, txn_global->scan_count == -1); + txn_global->scan_count = 0; + } else { + /* + * We wanted to update the oldest ID but we're racing + * another thread. Retry if this is a forced update. + */ + WT_ASSERT(session, txn_global->scan_count > 0); + (void)__wt_atomic_subiv32(&txn_global->scan_count, 1); + if (force) { + __wt_yield(); + goto retry; + } + } } else { if (WT_VERBOSE_ISSET(session, WT_VERB_TRANSACTION) && - current_id - oldest_id > 10000 && last_running_moved && - oldest_session != NULL) { + current_id - oldest_id > 10000 && oldest_session != NULL) { (void)__wt_verbose(session, WT_VERB_TRANSACTION, "old snapshot %" PRIu64 " pinned in session %d [%s]" |