SERVER-39154 Create a fail point to make it so if a LockManager lock cannot be acquired immediately, then the operation fails

2 files changed, 42 insertions, 0 deletions

diff --git a/src/mongo/db/concurrency/lock_state.cpp b/src/mongo/db/concurrency/lock_state.cpp
index 0ce20b0aa3b..fc5457d3172 100644
--- a/src/mongo/db/concurrency/lock_state.cpp
+++ b/src/mongo/db/concurrency/lock_state.cpp
@@ -42,11 +42,15 @@
 #include "mongo/util/background.h"
 #include "mongo/util/concurrency/ticketholder.h"
 #include "mongo/util/debug_util.h"
+#include "mongo/util/fail_point_service.h"
 #include "mongo/util/log.h"
 #include "mongo/util/mongoutils/str.h"
 #include "mongo/util/scopeguard.h"
 
 namespace mongo {
+
+MONGO_FAIL_POINT_DEFINE(failNonIntentLocksIfWaitNeeded);
+
 namespace {
 
 /**
@@ -474,6 +478,15 @@ void LockerImpl::lock(OperationContext* opCtx, ResourceId resId, LockMode mode,
 
     invariant(result == LOCK_WAITING);
 
+    // This failpoint is used to time out non-intent locks if they cannot be granted immediately.
+    // Testing-only.
+    if (MONGO_FAIL_POINT(failNonIntentLocksIfWaitNeeded)) {
+        uassert(ErrorCodes::LockTimeout,
+                str::stream() << "Cannot immediately acquire lock '" << resId.toString()
+                              << "'. Timing out due to failpoint.",
+                (mode == MODE_IS || mode == MODE_IX));
+    }
+
     lockComplete(opCtx, resId, mode, deadline);
 }
 
diff --git a/src/mongo/db/concurrency/lock_state_test.cpp b/src/mongo/db/concurrency/lock_state_test.cpp
index 115d1b5c42b..e6bc546b11f 100644
--- a/src/mongo/db/concurrency/lock_state_test.cpp
+++ b/src/mongo/db/concurrency/lock_state_test.cpp
@@ -39,6 +39,7 @@
 #include "mongo/db/concurrency/lock_manager_test_help.h"
 #include "mongo/db/concurrency/locker.h"
 #include "mongo/unittest/unittest.h"
+#include "mongo/util/fail_point_service.h"
 #include "mongo/util/log.h"
 #include "mongo/util/timer.h"
 
@@ -120,6 +121,34 @@ TEST(LockerImpl, ConflictUpgradeWithTimeout) {
     locker2.unlockGlobal();
 }
 
+TEST(LockerImpl, FailPointInLockFailsNonIntentLocksIfTheyCannotBeImmediatelyGranted) {
+    // Granted MODE_X lock, fail incoming MODE_S and MODE_X.
+    const ResourceId resId(RESOURCE_COLLECTION, "TestDB.collection"_sd);
+
+    LockerImpl locker1;
+    locker1.lockGlobal(MODE_IX);
+    locker1.lock(resId, MODE_X);
+
+    {
+        FailPointEnableBlock failWaitingNonPartitionedLocks("failNonIntentLocksIfWaitNeeded");
+
+        // MODE_S attempt.
+        LockerImpl locker2;
+        locker2.lockGlobal(MODE_IS);
+        ASSERT_THROWS_CODE(
+            locker2.lock(resId, MODE_S, Date_t::max()), DBException, ErrorCodes::LockTimeout);
+        locker2.unlockGlobal();
+
+        // MODE_X attempt.
+        LockerImpl locker3;
+        locker3.lockGlobal(MODE_IX);
+        ASSERT_THROWS_CODE(
+            locker3.lock(resId, MODE_X, Date_t::max()), DBException, ErrorCodes::LockTimeout);
+        locker3.unlockGlobal();
+    }
+
+    locker1.unlockGlobal();
+}
 
 TEST(LockerImpl, ReadTransaction) {
     LockerImpl locker;