Import wiredtiger: 1055c64267ae9ee9a1ef11a9826dd409259b13d2 from branch mongodb-4.4

ref: 836466fade..1055c64267
for: 4.3.1

WT-4909       Fix potential code caching/re-ordering issue in __search_insert_append
WT-4965       Disable problematic eviction during checkpoints

3 files changed, 21 insertions, 3 deletions

diff --git a/src/third_party/wiredtiger/import.data b/src/third_party/wiredtiger/import.data
index fbc03b4e86a..49e3237bd7b 100644
--- a/src/third_party/wiredtiger/import.data
+++ b/src/third_party/wiredtiger/import.data
@@ -1,6 +1,6 @@
 {
-    "commit": "836466fade7ff00065bff23eea86c8c21b52b3da", 
+    "commit": "1055c64267ae9ee9a1ef11a9826dd409259b13d2", 
     "github": "wiredtiger/wiredtiger.git", 
     "vendor": "wiredtiger", 
-    "branch": "mongodb-4.2"
+    "branch": "mongodb-4.4"
 }
diff --git a/src/third_party/wiredtiger/src/btree/bt_sync.c b/src/third_party/wiredtiger/src/btree/bt_sync.c
index 4334b29c7e8..a7d34d49f84 100644
--- a/src/third_party/wiredtiger/src/btree/bt_sync.c
+++ b/src/third_party/wiredtiger/src/btree/bt_sync.c
@@ -321,10 +321,19 @@ __wt_sync_file(WT_SESSION_IMPL *session, WT_CACHE_OP syncop)
 			 * cache clean but with history that cannot be
 			 * discarded), that is not wasted effort because
 			 * checkpoint doesn't need to write the page again.
+			 *
+			 * XXX Only attempt this eviction when there are no
+			 * readers older than the checkpoint.  Otherwise, a bug
+			 * in eviction can mark the page clean and discard
+			 * history, causing those reads to incorrectly see
+			 * newer versions of data than they should.
 			 */
 			if (!WT_PAGE_IS_INTERNAL(page) &&
 			    page->read_gen == WT_READGEN_WONT_NEED &&
-			    !tried_eviction) {
+			    !tried_eviction &&
+			    (!F_ISSET(txn, WT_TXN_HAS_TS_READ) ||
+			    txn->read_timestamp ==
+			    conn->txn_global.pinned_timestamp)) {
 				WT_ERR_BUSY_OK(
 				    __wt_page_release_evict(session, walk, 0));
 				walk = prev;
diff --git a/src/third_party/wiredtiger/src/btree/row_srch.c b/src/third_party/wiredtiger/src/btree/row_srch.c
index 8603d329c15..a01ef5a49a7 100644
--- a/src/third_party/wiredtiger/src/btree/row_srch.c
+++ b/src/third_party/wiredtiger/src/btree/row_srch.c
@@ -30,6 +30,15 @@ __search_insert_append(WT_SESSION_IMPL *session, WT_CURSOR_BTREE *cbt,
 
 	if ((ins = WT_SKIP_LAST(ins_head)) == NULL)
 		return (0);
+	/*
+	 * Since the head of the skip list doesn't get mutated within this
+	 * function, the compiler may move this assignment above within the
+	 * loop below if it needs to (and may read a different value on each
+	 * loop due to other threads mutating the skip list).
+	 *
+	 * Place a read barrier here to avoid this issue.
+	 */
+	WT_READ_BARRIER();
 	key.data = WT_INSERT_KEY(ins);
 	key.size = WT_INSERT_KEY_SIZE(ins);