SERVER-120912: Support w:n for n>1 for DSC (#52647)

GitOrigin-RevId: b5186a1aeeea6e347c92dd6f6f66b5db03ca7b15

jstests/core/txns/multi_statement_transaction_abort.js

@@ -9,6 +9,7 @@
 
 // TODO (SERVER-39704): Remove the following load after SERVER-39704 is completed
 import {retryOnceOnTransientOnMongos} from "jstests/libs/auto_retry_transaction_in_sharding.js";
+import {PersistenceProviderUtil} from "jstests/libs/server-rss/persistence_provider_util.js";
 
 const dbName = "test";
 const collName = "multi_statement_transaction_abort";
@@ -305,39 +306,43 @@ assert.commandWorked(
     }),
 );
 
-jsTest.log("Aborting transaction attempts to wait for write concern.");
-txnNumber++;
-assert.commandWorked(
-    sessionDb.runCommand({
-        insert: collName,
-        documents: [{a: 1}],
-        txnNumber: NumberLong(txnNumber),
-        startTransaction: true,
-        autocommit: false,
-    }),
-);
-assert.commandFailedWithCode(
-    sessionDb.adminCommand({
-        abortTransaction: 1,
-        txnNumber: NumberLong(txnNumber),
-        writeConcern: {w: 40},
-        autocommit: false,
-    }),
-    ErrorCodes.UnsatisfiableWriteConcern,
-);
+// In disagg, w:N (N>1) is remapped to majority, so the abort below would succeed rather than
+// fail with UnsatisfiableWriteConcern. Skip this block in disagg.
+if (PersistenceProviderUtil.allNodesHavePropertyWithValue(db, "supportsLocalCollections", true)) {
+    jsTest.log("Aborting transaction attempts to wait for write concern.");
+    txnNumber++;
+    assert.commandWorked(
+        sessionDb.runCommand({
+            insert: collName,
+            documents: [{a: 1}],
+            txnNumber: NumberLong(txnNumber),
+            startTransaction: true,
+            autocommit: false,
+        }),
+    );
+    assert.commandFailedWithCode(
+        sessionDb.adminCommand({
+            abortTransaction: 1,
+            txnNumber: NumberLong(txnNumber),
+            writeConcern: {w: 40},
+            autocommit: false,
+        }),
+        ErrorCodes.UnsatisfiableWriteConcern,
+    );
 
-// TODO (SLS-2341): Remove cleanup abort once w:n write concern is supported.
-// On a replica set, the failed abort above leaves the transaction in a dangling state because only
-// the write concern was unsatisfiable, not the abort itself. Abort it properly here to ensure the
-// transaction releases its locks before ending the session. On a sharded cluster, the transaction
-// may already be aborted, so we also accept NoSuchTransaction.
-assert.commandWorkedOrFailedWithCode(
-    sessionDb.adminCommand({
-        abortTransaction: 1,
-        txnNumber: NumberLong(txnNumber),
-        autocommit: false,
-    }),
-    ErrorCodes.NoSuchTransaction,
-);
+    // TODO (SLS-2341): Remove cleanup abort once w:n write concern is supported.
+    // On a replica set, the failed abort above leaves the transaction in a dangling state because only
+    // the write concern was unsatisfiable, not the abort itself. Abort it properly here to ensure the
+    // transaction releases its locks before ending the session. On a sharded cluster, the transaction
+    // may already be aborted, so we also accept NoSuchTransaction.
+    assert.commandWorkedOrFailedWithCode(
+        sessionDb.adminCommand({
+            abortTransaction: 1,
+            txnNumber: NumberLong(txnNumber),
+            autocommit: false,
+        }),
+        ErrorCodes.NoSuchTransaction,
+    );
+}
 
 session.endSession();

src/mongo/db/write_concern.cpp

@@ -73,6 +73,8 @@
 
 namespace mongo {
 
+std::function<void(WriteConcernOptions&)> remapWriteConcernHook;
+
 using repl::OpTime;
 using std::string;
 
@@ -214,6 +216,10 @@ StatusWith<WriteConcernOptions> extractWriteConcern(OperationContext* opCtx,
         }
     }
 
+    if (remapWriteConcernHook) {
+        remapWriteConcernHook(writeConcern);
+    }
+
     Status wcStatus = validateWriteConcern(opCtx, writeConcern);
     if (!wcStatus.isOK()) {
         return wcStatus;

src/mongo/db/write_concern.h

@@ -41,6 +41,7 @@
 #include "mongo/util/modules.h"
 #include "mongo/util/net/hostandport.h"
 
+#include <functional>
 #include <string>
 #include <vector>
 
@@ -59,6 +60,13 @@ class OpTime;
  */
 bool commandSpecifiesWriteConcern(const GenericArguments& requestArgs);
 
+/**
+ * Optional hook to remap write concern options before validation. Modules that restrict supported
+ * write concerns (e.g. DSC) may set this at startup to transparently remap
+ * unsupported values (such as w:N for N>1) to an equivalent supported form.
+ */
+extern std::function<void(WriteConcernOptions&)> remapWriteConcernHook;
+
 /**
  * Attempts to extract a WriteConcernOptions from a command's generic arguments.
  * Verifies that the resulting writeConcern is valid for this particular host.