SERVER-38094 Add write concern that waits for majority commit point but not committed snapshot

4 files changed, 25 insertions, 4 deletions

diff --git a/src/mongo/db/repl/repl_set_config.cpp b/src/mongo/db/repl/repl_set_config.cpp
index 0ae3ca2635d..e79ffa8fe89 100644
--- a/src/mongo/db/repl/repl_set_config.cpp
+++ b/src/mongo/db/repl/repl_set_config.cpp
@@ -609,7 +609,8 @@ Status ReplSetConfig::validate() const {
 
 Status ReplSetConfig::checkIfWriteConcernCanBeSatisfied(
     const WriteConcernOptions& writeConcern) const {
-    if (!writeConcern.wMode.empty() && writeConcern.wMode != WriteConcernOptions::kMajority) {
+    if (!writeConcern.wMode.empty() && writeConcern.wMode != WriteConcernOptions::kMajority &&
+        writeConcern.wMode != WriteConcernOptions::kInternalMajorityNoSnapshot) {
         StatusWith<ReplSetTagPattern> tagPatternStatus = findCustomWriteMode(writeConcern.wMode);
         if (!tagPatternStatus.isOK()) {
             return tagPatternStatus.getStatus();
diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index 48304b9234c..824db78c888 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -1478,9 +1478,24 @@ bool ReplicationCoordinatorImpl::_doneWaitingForReplication_inlock(
             opTime, writeConcern.wNumNodes, useDurableOpTime);
     }
 
+    const bool modeIsMajorityNoSnapshot =
+        writeConcern.wMode == WriteConcernOptions::kInternalMajorityNoSnapshot;
+
     StringData patternName;
-    if (writeConcern.wMode == WriteConcernOptions::kMajority) {
-        if (_externalState->snapshotsEnabled() && !testingSnapshotBehaviorInIsolation) {
+    if (writeConcern.wMode == WriteConcernOptions::kMajority || modeIsMajorityNoSnapshot) {
+        if (modeIsMajorityNoSnapshot) {
+            // The internal majority no snapshot write concern waits for an opTime to be majority
+            // committed, but not necessarily in the committed snapshot.
+            const auto lastCommittedOpTime = _topCoord->getLastCommittedOpTime();
+            if (lastCommittedOpTime < opTime) {
+                LOG(1) << "Required optime: " << opTime
+                       << " is not yet majority committed, last committed optime: "
+                       << lastCommittedOpTime;
+                return false;
+            }
+
+            // Fall through to wait for "majority" write concern.
+        } else if (_externalState->snapshotsEnabled() && !testingSnapshotBehaviorInIsolation) {
             // Make sure we have a valid "committed" snapshot up to the needed optime.
             if (!_currentCommittedSnapshot) {
                 return false;
diff --git a/src/mongo/db/write_concern_options.cpp b/src/mongo/db/write_concern_options.cpp
index 37103194a60..59fb840ec9a 100644
--- a/src/mongo/db/write_concern_options.cpp
+++ b/src/mongo/db/write_concern_options.cpp
@@ -67,10 +67,13 @@ const int WriteConcernOptions::kNoWaiting(-1);
 
 const StringData WriteConcernOptions::kWriteConcernField = "writeConcern"_sd;
 const char WriteConcernOptions::kMajority[] = "majority";
+const char WriteConcernOptions::kInternalMajorityNoSnapshot[] = "internalMajorityNoSnapshot";
 
 const BSONObj WriteConcernOptions::Default = BSONObj();
 const BSONObj WriteConcernOptions::Acknowledged(BSON("w" << W_NORMAL));
 const BSONObj WriteConcernOptions::Unacknowledged(BSON("w" << W_NONE));
+const BSONObj WriteConcernOptions::InternalMajorityNoSnapshot(
+    BSON("w" << WriteConcernOptions::kInternalMajorityNoSnapshot));
 const BSONObj WriteConcernOptions::Majority(BSON("w" << WriteConcernOptions::kMajority));
 const Seconds WriteConcernOptions::kWriteConcernTimeoutSystem{15};
 const Seconds WriteConcernOptions::kWriteConcernTimeoutMigration{30};
diff --git a/src/mongo/db/write_concern_options.h b/src/mongo/db/write_concern_options.h
index 80d85d305dc..8a68a39bf8e 100644
--- a/src/mongo/db/write_concern_options.h
+++ b/src/mongo/db/write_concern_options.h
@@ -49,9 +49,11 @@ public:
     static const BSONObj Acknowledged;
     static const BSONObj Unacknowledged;
     static const BSONObj Majority;
+    static const BSONObj InternalMajorityNoSnapshot;
 
     static const StringData kWriteConcernField;
-    static const char kMajority[];  // = "majority"
+    static const char kMajority[];                    // = "majority"
+    static const char kInternalMajorityNoSnapshot[];  // = "internalMajorityNoSnapshot"
 
     static const Seconds kWriteConcernTimeoutSystem;
     static const Seconds kWriteConcernTimeoutMigration;