SERVER-36382 Only snapshot, lineariable and afterClusterTime reads block on prepare conflicts

4 files changed, 12 insertions, 5 deletions

diff --git a/src/mongo/db/read_concern.cpp b/src/mongo/db/read_concern.cpp
index cb8df144d25..53372e23878 100644
--- a/src/mongo/db/read_concern.cpp
+++ b/src/mongo/db/read_concern.cpp
@@ -334,7 +334,12 @@ Status waitForReadConcern(OperationContext* opCtx,
         LOG(debugLevel) << "Using 'committed' snapshot: " << CurOp::get(opCtx)->opDescription();
     }
 
-    if (readConcernArgs.getLevel() == repl::ReadConcernLevel::kAvailableReadConcern) {
+    // Only snapshot, linearizable and afterClusterTime reads should block on prepared transactions.
+    // We don't ignore prepare conflicts if we are in a direct client in case this overrides
+    // behavior set by a higher-level operation.
+    if (readConcernArgs.getLevel() != repl::ReadConcernLevel::kSnapshotReadConcern &&
+        readConcernArgs.getLevel() != repl::ReadConcernLevel::kLinearizableReadConcern &&
+        !afterClusterTime && !atClusterTime && !opCtx->getClient()->isInDirectClient()) {
         opCtx->recoveryUnit()->setIgnorePrepared(true);
     }
 
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp
index d73a1e1faf0..1cc671dcf56 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp
@@ -358,7 +358,8 @@ void WiredTigerRecoveryUnit::_txnOpen() {
             // We reset _majorityCommittedSnapshot to the actual read timestamp used when the
             // transaction was started.
             _majorityCommittedSnapshot =
-                _sessionCache->snapshotManager().beginTransactionOnCommittedSnapshot(session);
+                _sessionCache->snapshotManager().beginTransactionOnCommittedSnapshot(
+                    session, _ignorePrepared);
             break;
         }
         case ReadSource::kLastApplied: {
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.cpp
index 77b6d875a59..011db3e3566 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.cpp
@@ -68,8 +68,8 @@ boost::optional<Timestamp> WiredTigerSnapshotManager::getMinSnapshotForNextCommi
 }
 
 Timestamp WiredTigerSnapshotManager::beginTransactionOnCommittedSnapshot(
-    WT_SESSION* session) const {
-    WiredTigerBeginTxnBlock txnOpen(session);
+    WT_SESSION* session, WiredTigerBeginTxnBlock::IgnorePrepared ignorePrepared) const {
+    WiredTigerBeginTxnBlock txnOpen(session, ignorePrepared);
 
     stdx::lock_guard<stdx::mutex> lock(_committedSnapshotMutex);
     uassert(ErrorCodes::ReadConcernMajorityNotAvailableYet,
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.h b/src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.h
index 493e8dfb1ee..b0592cf9986 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.h
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.h
@@ -62,7 +62,8 @@ public:
      *
      * Throws if there is currently no committed snapshot.
      */
-    Timestamp beginTransactionOnCommittedSnapshot(WT_SESSION* session) const;
+    Timestamp beginTransactionOnCommittedSnapshot(
+        WT_SESSION* session, WiredTigerBeginTxnBlock::IgnorePrepared ignorePrepared) const;
 
     /**
      * Starts a transaction on the last stable local timestamp, set by setLocalSnapshot.