SERVER-36494 Test that active txn entries aren't truncated

Add tests for initial sync, recovery, and the inMemory storage engine.

Also, avoid taking a global X lock in replSetReconfig, we only need IX.

1 files changed, 76 insertions, 0 deletions

diff --git a/jstests/replsets/initial_sync_preserves_active_txns.js b/jstests/replsets/initial_sync_preserves_active_txns.js
new file mode 100644
index 00000000000..4e9f1ad1dcb
--- /dev/null
+++ b/jstests/replsets/initial_sync_preserves_active_txns.js
@@ -0,0 +1,76 @@
+/**
+ * When the oplog size grows during initial sync to exceed the configured maximum, the node must
+ * truncate the oplog only up to the oldest active transaction timestamp at the time of the last
+ * stable checkpoint. The first oplog entry that belongs to an active transaction is preserved, and
+ * all entries after it.
+ *
+ * This tests the oldestActiveTransactionTimestamp, which is calculated from the "startOpTime"
+ * field of documents in the config.transactions collection.
+ *
+ * @tags: [uses_transactions, uses_prepare_transaction]
+ */
+
+(function() {
+    "use strict";
+    load("jstests/core/txns/libs/prepare_helpers.js");
+
+    const replSet = new ReplSetTest({
+        // Oplog can be truncated each "sync" cycle. Increase its frequency to once per second.
+        nodeOptions: {syncdelay: 1, setParameter: {logComponentVerbosity: tojson({storage: 1})}},
+        nodes: 1
+    });
+
+    replSet.startSet(PrepareHelpers.replSetStartSetOptions);
+    replSet.initiate();
+    const primary = replSet.getPrimary();
+    const primaryOplog = primary.getDB("local").oplog.rs;
+    assert.lte(primaryOplog.dataSize(), PrepareHelpers.oplogSizeBytes);
+
+    const coll = primary.getDB("test").test;
+    assert.commandWorked(coll.insert({}, {writeConcern: {w: "majority"}}));
+
+    jsTestLog("Prepare a transaction");
+
+    const session = primary.startSession();
+    session.startTransaction();
+    assert.commandWorked(session.getDatabase("test").test.insert({myTransaction: 1}));
+    const prepareTimestamp = PrepareHelpers.prepareTransaction(session);
+    const txnEntry = primary.getDB("config").transactions.findOne();
+    assert.eq(txnEntry.startOpTime.ts, prepareTimestamp, tojson(txnEntry));
+
+    jsTestLog("Insert documents until oplog exceeds oplogSize");
+
+    // Oplog with prepared txn grows indefinitely - let it reach twice its supposed max size.
+    PrepareHelpers.growOplogPastMaxSize(replSet);
+
+    jsTestLog("Find prepare oplog entry");
+
+    const oplogEntry = primaryOplog.findOne({prepare: true});
+    assert.eq(oplogEntry.ts, prepareTimestamp, tojson(oplogEntry));
+
+    jsTestLog("Add a secondary node");
+
+    const secondary = replSet.add({rsConfig: {votes: 0, priority: 0}});
+    replSet.reInitiate();
+
+    jsTestLog("Reinitiated, awaiting secondary node");
+
+    replSet.awaitSecondaryNodes();
+
+    jsTestLog("Checking secondary oplog and config.transactions");
+
+    // Oplog grew past maxSize, and it includes the oldest active transaction's entry.
+    const secondaryOplog = secondary.getDB("local").oplog.rs;
+    assert.gt(secondaryOplog.dataSize(), PrepareHelpers.oplogSizeBytes);
+    const secondaryOplogEntry = secondaryOplog.findOne({prepare: true});
+    assert.eq(secondaryOplogEntry.ts, prepareTimestamp, tojson(secondaryOplogEntry));
+
+    const secondaryTxnEntry = secondary.getDB("config").transactions.findOne();
+    assert.eq(secondaryTxnEntry, txnEntry, tojson(secondaryTxnEntry));
+
+    // TODO(SERVER-36492): commit or abort, await oplog truncation
+    // See recovery_preserves_active_txns.js for example.
+    // Until then, skip validation, the stashed transaction's lock prevents validation.
+    TestData.skipCheckDBHashes = true;
+    replSet.stopSet(undefined, undefined, {skipValidation: true});
+})();