Import wiredtiger: 45fd19bcb1007fd4e473d77ddd09d3157ff15c7e from branch mongodb-4.2

ref: 63b8cf2e0b..45fd19bcb1
for: 4.1.3

WT-3879       Disallow checkpoint from evicting metadata pages
WT-4090       Low priority reads
WT-4119       Avoid restarts updating / removing during a column store scan
WT-4131       Rename lookaside to cache overflow
WT-4154       Surface the oldest read timestamp
WT-4156       Add new wiredtiger_salvage top level API
WT-4177       Backup cursor open should force a log file switch
WT-4218       Change eviction to evict prepared updates
WT-4231       Fix ctags index of functions with attributes
WT-4246       Change transaction update list to support indirect references
WT-4259       Restore ref to the previous state rather than MEM when eviction fails
WT-4261       Test salvage of out-of-sync metadata/turtle files
WT-4267       fixed-length column store operations can corrupt data
WT-4268       Random abort should wait until record files exist before starting timer
WT-4270       Add an operation field to know where threads hang
WT-4272       Increase startup timeout to 30 seconds for slow I/O systems
WT-4274       Fix memory leak in wt4156_metadata_salvage test
WT-4277       Make truncate in column stores more efficient
WT-4281       Shorten runtime of Python test suite
WT-4282       Don't transition pages from limbo to mem unless required
WT-4283       Restore WT_ERROR and use a corrupt flag
WT-4284       Print a verbose message in recovery on error too
WT-4285       Fix wt4156_metadata_salvage Coverity/lint complaints
WT-4286       Column store should skip end-of-table checks if there's an exact match
WT-4288       Don't let return value of closing conn overwrite WT_TRY_SALVAGE
WT-4289       Update WT_DATA_CORRUPTION to WT_TRY_SALVAGE in test_txn19.py
WT-4291       Fix test_txn19.py error detection
WT-4292       Add call to testutil_cleanup to avoid memory leak
WT-4300       Setting the update timestamp can overwrite the WT_REF.addr field
WT-4301       WT_CURSOR.reserve operations can leak memory when committed
WT-4305       Add a gating variable for long running prepare support
WT-4306       Fix mode if metadata pages need eviction

1 files changed, 14 insertions, 10 deletions

diff --git a/src/third_party/wiredtiger/src/btree/bt_random.c b/src/third_party/wiredtiger/src/btree/bt_random.c
index 4f310b27237..ed68513b245 100644
--- a/src/third_party/wiredtiger/src/btree/bt_random.c
+++ b/src/third_party/wiredtiger/src/btree/bt_random.c
@@ -169,27 +169,27 @@ __wt_row_random_leaf(WT_SESSION_IMPL *session, WT_CURSOR_BTREE *cbt)
  *	Find a random page in a tree for either sampling or eviction.
  */
 int
-__wt_random_descent(WT_SESSION_IMPL *session, WT_REF **refp, bool eviction)
+__wt_random_descent(WT_SESSION_IMPL *session, WT_REF **refp, uint32_t flags)
 {
 	WT_BTREE *btree;
 	WT_DECL_RET;
 	WT_PAGE *page;
 	WT_PAGE_INDEX *pindex;
 	WT_REF *current, *descent;
-	uint32_t flags, i, entries, retry;
+	uint32_t i, entries, retry;
+	bool eviction;
 
 	*refp = NULL;
 
 	btree = S2BT(session);
 	current = NULL;
 	retry = 100;
-
-	/* Eviction should not be tapped to do eviction. */
-	if (eviction)
-		flags = WT_READ_CACHE | WT_READ_NO_EVICT | WT_READ_NO_GEN |
-		    WT_READ_NO_WAIT | WT_READ_NOTFOUND_OK | WT_READ_RESTART_OK;
-	else
-		flags = WT_READ_RESTART_OK;
+	/*
+	 * This function is called by eviction to find a random page in the
+	 * cache. That case is indicated by the WT_READ_CACHE flag. Ordinary
+	 * lookups in a tree will read pages into cache as needed.
+	 */
+	eviction = LF_ISSET(WT_READ_CACHE);
 
 	if (0) {
 restart:	/*
@@ -302,11 +302,15 @@ __wt_btcur_next_random(WT_CURSOR_BTREE *cbt)
 	WT_UPDATE *upd;
 	wt_off_t size;
 	uint64_t n, skip;
+	uint32_t read_flags;
 	bool valid;
 
 	btree = cbt->btree;
 	cursor = &cbt->iface;
 	session = (WT_SESSION_IMPL *)cbt->iface.session;
+	read_flags = WT_READ_RESTART_OK;
+	if (F_ISSET(cbt, WT_CBT_READ_ONCE))
+		FLD_SET(read_flags, WT_READ_WONT_NEED);
 
 	/*
 	 * Only supports row-store: applications can trivially select a random
@@ -337,7 +341,7 @@ __wt_btcur_next_random(WT_CURSOR_BTREE *cbt)
 	if (cbt->ref == NULL || cbt->next_random_sample_size == 0) {
 		WT_ERR(__cursor_func_init(cbt, true));
 		WT_WITH_PAGE_INDEX(session,
-		    ret = __wt_random_descent(session, &cbt->ref, false));
+		    ret = __wt_random_descent(session, &cbt->ref, read_flags));
 		if (ret == 0)
 			goto random_page_entry;