SERVER-39763 transactions_target_at_point_in_time.js should disable expiring old chunk history

(cherry picked from commit 688368b4440c18bd048f122d8a729c26e9ad4a6e)

2 files changed, 19 insertions, 5 deletions

diff --git a/jstests/sharding/transactions_target_at_point_in_time.js b/jstests/sharding/transactions_target_at_point_in_time.js
index 3cdfb4b49fe..a09f5491622 100644
--- a/jstests/sharding/transactions_target_at_point_in_time.js
+++ b/jstests/sharding/transactions_target_at_point_in_time.js
@@ -24,7 +24,18 @@ const dbName = "test";
 const collName = "foo";
 const ns = dbName + '.' + collName;
 
-const st = new ShardingTest({shards: 3, mongos: 1, config: 1});
+const st = new ShardingTest({
+    shards: 3,
+    mongos: 1,
+    config: 1,
+    other: {
+        // Disable expiring old chunk history to ensure the transactions are able to read from a
+        // shard that has donated a chunk, even if the migration takes longer than the amount of
+        // time for which a chunk's history is normally stored (see SERVER-39763).
+        configOptions:
+            {setParameter: {"failpoint.skipExpiringOldChunkHistory": "{mode: 'alwaysOn'}"}}
+    }
+});
 
 // Set up one sharded collection with 2 chunks, both on the primary shard.
 
diff --git a/src/mongo/db/s/config/sharding_catalog_manager_chunk_operations.cpp b/src/mongo/db/s/config/sharding_catalog_manager_chunk_operations.cpp
index 86aa76b89dc..a1bd16dc8b8 100644
--- a/src/mongo/db/s/config/sharding_catalog_manager_chunk_operations.cpp
+++ b/src/mongo/db/s/config/sharding_catalog_manager_chunk_operations.cpp
@@ -58,6 +58,7 @@ namespace mongo {
 namespace {
 
 MONGO_FAIL_POINT_DEFINE(migrationCommitVersionError);
+MONGO_FAIL_POINT_DEFINE(skipExpiringOldChunkHistory);
 
 /**
  * Append min, max and version information from chunk to the buffer for logChange purposes.
@@ -684,10 +685,12 @@ StatusWith<BSONObj> ShardingCatalogManager::commitChunkMigration(
     // Update the history of the migrated chunk.
     // Drop the history that is too old (10 seconds of history for now).
     // TODO SERVER-33831 to update the old history removal policy.
-    while (!newHistory.empty() &&
-           newHistory.back().getValidAfter().getSecs() + kHistorySecs <
-               validAfter.get().getSecs()) {
-        newHistory.pop_back();
+    if (!MONGO_FAIL_POINT(skipExpiringOldChunkHistory)) {
+        while (!newHistory.empty() &&
+               newHistory.back().getValidAfter().getSecs() + kHistorySecs <
+                   validAfter.get().getSecs()) {
+            newHistory.pop_back();
+        }
     }
 
     if (!newHistory.empty() && newHistory.front().getValidAfter() >= validAfter.get()) {