SERVER-28624 Further reduce dependency on ReplicationExecutor type.

* Replace getDiagnosticString() with appendDiagnosticBSON() in TaskExecutors.
* Introduce appendDiagnostics to ReplicationCoordinator, to hide the implementation
  detail that ReplicationCoordinatorImpl has a TaskExecutor.

23 files changed, 71 insertions, 166 deletions

diff --git a/src/mongo/db/repl/base_cloner.h b/src/mongo/db/repl/base_cloner.h
index 23218b09785..d73def7e5dc 100644
--- a/src/mongo/db/repl/base_cloner.h
+++ b/src/mongo/db/repl/base_cloner.h
@@ -49,11 +49,6 @@ public:
     virtual ~BaseCloner() {}
 
     /**
-     * Returns diagnostic information.
-     */
-    virtual std::string getDiagnosticString() const = 0;
-
-    /**
      * Returns true if the cloner has been started (but has not completed).
      */
     virtual bool isActive() const = 0;
diff --git a/src/mongo/db/repl/base_cloner_test_fixture.cpp b/src/mongo/db/repl/base_cloner_test_fixture.cpp
index 58eca351ca7..ebaa135090f 100644
--- a/src/mongo/db/repl/base_cloner_test_fixture.cpp
+++ b/src/mongo/db/repl/base_cloner_test_fixture.cpp
@@ -157,8 +157,10 @@ void BaseClonerTest::scheduleNetworkResponse(NetworkOperationIterator noi,
 
 void BaseClonerTest::scheduleNetworkResponse(const BSONObj& obj) {
     if (!getNet()->hasReadyRequests()) {
+        BSONObjBuilder b;
+        getExecutor().appendDiagnosticBSON(&b);
         log() << "Expected network request for resp: " << obj;
-        log() << "      replExec: " << getExecutor().getDiagnosticString();
+        log() << "      replExec: " << b.done();
         log() << "      net:" << getNet()->getDiagnosticString();
     }
     if (getStatus() != getDetectableErrorStatus()) {
@@ -190,9 +192,6 @@ void BaseClonerTest::finishProcessingNetworkResponse() {
 }
 
 void BaseClonerTest::testLifeCycle() {
-    // GetDiagnosticString
-    ASSERT_FALSE(getCloner()->getDiagnosticString().empty());
-
     // IsActiveAfterStart
     ASSERT_FALSE(getCloner()->isActive());
     ASSERT_OK(getCloner()->startup());
diff --git a/src/mongo/db/repl/collection_cloner.cpp b/src/mongo/db/repl/collection_cloner.cpp
index c89709f2fe8..72fc777ff08 100644
--- a/src/mongo/db/repl/collection_cloner.cpp
+++ b/src/mongo/db/repl/collection_cloner.cpp
@@ -154,21 +154,6 @@ const NamespaceString& CollectionCloner::getSourceNamespace() const {
     return _sourceNss;
 }
 
-std::string CollectionCloner::getDiagnosticString() const {
-    LockGuard lk(_mutex);
-    str::stream output;
-    output << "CollectionCloner";
-    output << " executor: " << _executor->getDiagnosticString();
-    output << " source: " << _source.toString();
-    output << " source namespace: " << _sourceNss.toString();
-    output << " destination namespace: " << _destNss.toString();
-    output << " collection options: " << _options.toBSON();
-    output << " active: " << _isActive_inlock();
-    output << " listIndexes fetcher: " << _listIndexesFetcher.getDiagnosticString();
-    output << " find fetcher: " << (_findFetcher ? _findFetcher->getDiagnosticString() : "");
-    return output;
-}
-
 bool CollectionCloner::isActive() const {
     LockGuard lk(_mutex);
     return _isActive_inlock();
diff --git a/src/mongo/db/repl/collection_cloner.h b/src/mongo/db/repl/collection_cloner.h
index 1c65161fd97..9f08215a078 100644
--- a/src/mongo/db/repl/collection_cloner.h
+++ b/src/mongo/db/repl/collection_cloner.h
@@ -114,8 +114,6 @@ public:
 
     const NamespaceString& getSourceNamespace() const;
 
-    std::string getDiagnosticString() const override;
-
     bool isActive() const override;
 
     Status startup() noexcept override;
diff --git a/src/mongo/db/repl/database_cloner.cpp b/src/mongo/db/repl/database_cloner.cpp
index fe892ba157f..649d6d8efa3 100644
--- a/src/mongo/db/repl/database_cloner.cpp
+++ b/src/mongo/db/repl/database_cloner.cpp
@@ -142,24 +142,6 @@ const std::vector<BSONObj>& DatabaseCloner::getCollectionInfos_forTest() const {
     return _collectionInfos;
 }
 
-std::string DatabaseCloner::getDiagnosticString() const {
-    LockGuard lk(_mutex);
-    return _getDiagnosticString_inlock();
-}
-
-std::string DatabaseCloner::_getDiagnosticString_inlock() const {
-    str::stream output;
-    output << "DatabaseCloner";
-    output << " executor: " << _executor->getDiagnosticString();
-    output << " source: " << _source.toString();
-    output << " database: " << _dbname;
-    output << " listCollections filter" << _listCollectionsFilter;
-    output << " active: " << _isActive_inlock();
-    output << " collection info objects (empty if listCollections is in progress): "
-           << _collectionInfos.size();
-    return output;
-}
-
 bool DatabaseCloner::isActive() const {
     LockGuard lk(_mutex);
     return _isActive_inlock();
diff --git a/src/mongo/db/repl/database_cloner.h b/src/mongo/db/repl/database_cloner.h
index 97a4c0cbc4c..73006606586 100644
--- a/src/mongo/db/repl/database_cloner.h
+++ b/src/mongo/db/repl/database_cloner.h
@@ -130,8 +130,6 @@ public:
      */
     const std::vector<BSONObj>& getCollectionInfos_forTest() const;
 
-    std::string getDiagnosticString() const override;
-
     bool isActive() const override;
 
     Status startup() noexcept override;
@@ -203,8 +201,6 @@ private:
      */
     void _finishCallback_inlock(UniqueLock& lk, const Status& status);
 
-    std::string _getDiagnosticString_inlock() const;
-
     //
     // All member variables are labeled with one of the following codes indicating the
     // synchronization rules for accessing them.
diff --git a/src/mongo/db/repl/multiapplier.cpp b/src/mongo/db/repl/multiapplier.cpp
index ac78a4f2c8c..32efe2c68a7 100644
--- a/src/mongo/db/repl/multiapplier.cpp
+++ b/src/mongo/db/repl/multiapplier.cpp
@@ -67,21 +67,6 @@ MultiApplier::~MultiApplier() {
     DESTRUCTOR_GUARD(shutdown(); join(););
 }
 
-std::string MultiApplier::toString() const {
-    return getDiagnosticString();
-}
-
-std::string MultiApplier::getDiagnosticString() const {
-    stdx::lock_guard<stdx::mutex> lk(_mutex);
-    str::stream output;
-    output << "MultiApplier";
-    output << " active: " << _isActive_inlock();
-    output << ", ops: " << _operations.front().ts.timestamp().toString();
-    output << " - " << _operations.back().ts.timestamp().toString();
-    output << ", executor: " << _executor->getDiagnosticString();
-    return output;
-}
-
 bool MultiApplier::isActive() const {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
     return _isActive_inlock();
diff --git a/src/mongo/db/repl/multiapplier.h b/src/mongo/db/repl/multiapplier.h
index 37f094b0324..97567fde6cc 100644
--- a/src/mongo/db/repl/multiapplier.h
+++ b/src/mongo/db/repl/multiapplier.h
@@ -101,16 +101,6 @@ public:
     virtual ~MultiApplier();
 
     /**
-     * Returns diagnostic information.
-     */
-    std::string getDiagnosticString() const;
-
-    /**
-     * Returns an informational string.
-     */
-    std::string toString() const;
-
-    /**
      * Returns true if the applier has been started (but has not completed).
      */
     bool isActive() const;
diff --git a/src/mongo/db/repl/repl_set_commands.cpp b/src/mongo/db/repl/repl_set_commands.cpp
index 2f3b46bcfc0..2429351c364 100644
--- a/src/mongo/db/repl/repl_set_commands.cpp
+++ b/src/mongo/db/repl/repl_set_commands.cpp
@@ -76,8 +76,7 @@ class ReplExecutorSSM : public ServerStatusMetric {
 public:
     ReplExecutorSSM() : ServerStatusMetric("repl.executor") {}
     virtual void appendAtLeaf(BSONObjBuilder& b) const {
-        ReplicationExecutor* exec = getGlobalReplicationCoordinator()->getExecutor();
-        b.append("executor", exec->getDiagnosticBSON());
+        getGlobalReplicationCoordinator()->appendDiagnosticBSON(&b);
     }
 } replExecutorSSM;
 
diff --git a/src/mongo/db/repl/replication_coordinator.h b/src/mongo/db/repl/replication_coordinator.h
index d5557213bb4..8446e718d30 100644
--- a/src/mongo/db/repl/replication_coordinator.h
+++ b/src/mongo/db/repl/replication_coordinator.h
@@ -73,7 +73,6 @@ class OplogReader;
 class OpTime;
 class ReadConcernArgs;
 class ReplSetConfig;
-class ReplicationExecutor;
 class ReplSetHeartbeatArgs;
 class ReplSetHeartbeatArgsV1;
 class ReplSetHeartbeatResponse;
@@ -133,11 +132,6 @@ public:
     virtual void shutdown(OperationContext* opCtx) = 0;
 
     /**
-     * Returns a pointer to the ReplicationExecutor.
-     */
-    virtual ReplicationExecutor* getExecutor() = 0;
-
-    /**
      * Returns a reference to the parsed command line arguments that are related to replication.
      */
     virtual const ReplSettings& getSettings() const = 0;
@@ -857,6 +851,11 @@ public:
     virtual OpTime getCurrentCommittedSnapshotOpTime() const = 0;
 
     /**
+     * Appends diagnostics about the replication subsystem.
+     */
+    virtual void appendDiagnosticBSON(BSONObjBuilder* bob) = 0;
+
+    /**
      * Appends connection information to the provided BSONObjBuilder.
      */
     virtual void appendConnectionStats(executor::ConnectionPoolStats* stats) const = 0;
diff --git a/src/mongo/db/repl/replication_coordinator_external_state.h b/src/mongo/db/repl/replication_coordinator_external_state.h
index 4ef66c3dc15..2724cde6e66 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state.h
+++ b/src/mongo/db/repl/replication_coordinator_external_state.h
@@ -58,7 +58,6 @@ namespace repl {
 class LastVote;
 class ReplSettings;
 class ReplicationCoordinator;
-class ReplicationExecutor;
 
 /**
  * This class represents the interface the ReplicationCoordinator uses to interact with the
diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index 20a4f921310..abc0844d4fb 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -410,6 +410,11 @@ LogicalTime ReplicationCoordinatorImpl::_getCurrentCommittedLogicalTime_inlock()
     return LogicalTime(_getCurrentCommittedSnapshotOpTime_inlock().getTimestamp());
 }
 
+void ReplicationCoordinatorImpl::appendDiagnosticBSON(mongo::BSONObjBuilder* bob) {
+    BSONObjBuilder eBuilder(bob->subobjStart("executor"));
+    _replExecutor.appendDiagnosticBSON(&eBuilder);
+}
+
 void ReplicationCoordinatorImpl::appendConnectionStats(executor::ConnectionPoolStats* stats) const {
     _replExecutor.appendConnectionStats(stats);
 }
diff --git a/src/mongo/db/repl/replication_coordinator_impl.h b/src/mongo/db/repl/replication_coordinator_impl.h
index 1fdff0ca777..84b1fce4a6b 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.h
+++ b/src/mongo/db/repl/replication_coordinator_impl.h
@@ -105,10 +105,12 @@ public:
 
     virtual void shutdown(OperationContext* opCtx) override;
 
-    virtual ReplicationExecutor* getExecutor() override {
+    ReplicationExecutor* getExecutor() {
         return &_replExecutor;
     }
 
+    virtual void appendDiagnosticBSON(BSONObjBuilder* bob) override;
+
     virtual const ReplSettings& getSettings() const override;
 
     virtual Mode getReplicationMode() const override;
diff --git a/src/mongo/db/repl/replication_coordinator_mock.h b/src/mongo/db/repl/replication_coordinator_mock.h
index 0e9109b1665..fdfa491f0ad 100644
--- a/src/mongo/db/repl/replication_coordinator_mock.h
+++ b/src/mongo/db/repl/replication_coordinator_mock.h
@@ -57,9 +57,7 @@ public:
 
     virtual void shutdown(OperationContext* opCtx);
 
-    virtual ReplicationExecutor* getExecutor() override {
-        return nullptr;
-    };
+    virtual void appendDiagnosticBSON(BSONObjBuilder* bob) override {}
 
     virtual const ReplSettings& getSettings() const;
 
diff --git a/src/mongo/db/repl/replication_executor.cpp b/src/mongo/db/repl/replication_executor.cpp
index 3f9f0c5836b..8dc65f6d7e3 100644
--- a/src/mongo/db/repl/replication_executor.cpp
+++ b/src/mongo/db/repl/replication_executor.cpp
@@ -71,59 +71,45 @@ ReplicationExecutor::~ReplicationExecutor() {
 }
 
 BSONObj ReplicationExecutor::getDiagnosticBSON() const {
+    BSONObjBuilder b;
+    appendDiagnosticBSON(&b);
+    return b.obj();
+}
+
+void ReplicationExecutor::appendDiagnosticBSON(BSONObjBuilder* builder) const {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
-    BSONObjBuilder builder;
 
     // Counters
-    BSONObjBuilder counters(builder.subobjStart("counters"));
-    counters.appendIntOrLL("eventCreated", _counterCreatedEvents);
-    counters.appendIntOrLL("eventWait", _counterCreatedEvents);
-    counters.appendIntOrLL("cancels", _counterCancels);
-    counters.appendIntOrLL("waits", _counterWaits);
-    counters.appendIntOrLL("scheduledNetCmd", _counterScheduledCommands);
-    counters.appendIntOrLL("scheduledDBWork", _counterScheduledDBWorks);
-    counters.appendIntOrLL("scheduledXclWork", _counterScheduledExclusiveWorks);
-    counters.appendIntOrLL("scheduledWorkAt", _counterScheduledWorkAts);
-    counters.appendIntOrLL("scheduledWork", _counterScheduledWorks);
-    counters.appendIntOrLL("schedulingFailures", _counterSchedulingFailures);
-    counters.done();
+    {
+        BSONObjBuilder counters(builder->subobjStart("counters"));
+        counters.appendIntOrLL("eventCreated", _counterCreatedEvents);
+        counters.appendIntOrLL("eventWait", _counterCreatedEvents);
+        counters.appendIntOrLL("cancels", _counterCancels);
+        counters.appendIntOrLL("waits", _counterWaits);
+        counters.appendIntOrLL("scheduledNetCmd", _counterScheduledCommands);
+        counters.appendIntOrLL("scheduledDBWork", _counterScheduledDBWorks);
+        counters.appendIntOrLL("scheduledXclWork", _counterScheduledExclusiveWorks);
+        counters.appendIntOrLL("scheduledWorkAt", _counterScheduledWorkAts);
+        counters.appendIntOrLL("scheduledWork", _counterScheduledWorks);
+        counters.appendIntOrLL("schedulingFailures", _counterSchedulingFailures);
+    }
 
     // Queues
-    BSONObjBuilder queues(builder.subobjStart("queues"));
-    queues.appendIntOrLL("networkInProgress", _networkInProgressQueue.size());
-    queues.appendIntOrLL("dbWorkInProgress", _dbWorkInProgressQueue.size());
-    queues.appendIntOrLL("exclusiveInProgress", _exclusiveLockInProgressQueue.size());
-    queues.appendIntOrLL("sleepers", _sleepersQueue.size());
-    queues.appendIntOrLL("ready", _readyQueue.size());
-    queues.appendIntOrLL("free", _freeQueue.size());
-    queues.done();
-
-    builder.appendIntOrLL("unsignaledEvents", _unsignaledEvents.size());
-    builder.appendIntOrLL("eventWaiters", _totalEventWaiters);
-    builder.append("shuttingDown", _inShutdown);
-    builder.append("networkInterface", _networkInterface->getDiagnosticString());
-    return builder.obj();
-}
-
-std::string ReplicationExecutor::getDiagnosticString() const {
-    stdx::lock_guard<stdx::mutex> lk(_mutex);
-    return _getDiagnosticString_inlock();
-}
-
-std::string ReplicationExecutor::_getDiagnosticString_inlock() const {
-    str::stream output;
-    output << "ReplicationExecutor";
-    output << " networkInProgress:" << _networkInProgressQueue.size();
-    output << " dbWorkInProgress:" << _dbWorkInProgressQueue.size();
-    output << " exclusiveInProgress:" << _exclusiveLockInProgressQueue.size();
-    output << " sleeperQueue:" << _sleepersQueue.size();
-    output << " ready:" << _readyQueue.size();
-    output << " free:" << _freeQueue.size();
-    output << " unsignaledEvents:" << _unsignaledEvents.size();
-    output << " eventWaiters:" << _totalEventWaiters;
-    output << " shuttingDown:" << _inShutdown;
-    output << " networkInterface:" << _networkInterface->getDiagnosticString();
-    return output;
+    {
+        BSONObjBuilder queues(builder->subobjStart("queues"));
+        queues.appendIntOrLL("networkInProgress", _networkInProgressQueue.size());
+        queues.appendIntOrLL("dbWorkInProgress", _dbWorkInProgressQueue.size());
+        queues.appendIntOrLL("exclusiveInProgress", _exclusiveLockInProgressQueue.size());
+        queues.appendIntOrLL("sleepers", _sleepersQueue.size());
+        queues.appendIntOrLL("ready", _readyQueue.size());
+        queues.appendIntOrLL("free", _freeQueue.size());
+        queues.done();
+    }
+
+    builder->appendIntOrLL("unsignaledEvents", _unsignaledEvents.size());
+    builder->appendIntOrLL("eventWaiters", _totalEventWaiters);
+    builder->append("shuttingDown", _inShutdown);
+    builder->append("networkInterface", _networkInterface->getDiagnosticString());
 }
 
 Date_t ReplicationExecutor::now() {
diff --git a/src/mongo/db/repl/replication_executor.h b/src/mongo/db/repl/replication_executor.h
index c5e20a8ac68..3205b816776 100644
--- a/src/mongo/db/repl/replication_executor.h
+++ b/src/mongo/db/repl/replication_executor.h
@@ -105,8 +105,8 @@ public:
      */
     virtual ~ReplicationExecutor();
 
-    std::string getDiagnosticString() const override;
     BSONObj getDiagnosticBSON() const;
+    void appendDiagnosticBSON(BSONObjBuilder* b) const override;
     Date_t now() override;
     void startup() override;
     void shutdown() override;
@@ -226,11 +226,6 @@ private:
     typedef stdx::list<EventHandle> EventList;
 
     /**
-     * Returns diagnostic info
-     */
-    std::string _getDiagnosticString_inlock() const;
-
-    /**
      * Implementation of makeEvent() for use when _mutex is already held.
      */
     StatusWith<EventHandle> makeEvent_inlock();
diff --git a/src/mongo/db/s/sharding_task_executor.cpp b/src/mongo/db/s/sharding_task_executor.cpp
index 83cfc8cb833..17f5b5fd861 100644
--- a/src/mongo/db/s/sharding_task_executor.cpp
+++ b/src/mongo/db/s/sharding_task_executor.cpp
@@ -64,8 +64,8 @@ void ShardingTaskExecutor::join() {
     _executor->join();
 }
 
-std::string ShardingTaskExecutor::getDiagnosticString() const {
-    return _executor->getDiagnosticString();
+void ShardingTaskExecutor::appendDiagnosticBSON(mongo::BSONObjBuilder* builder) const {
+    _executor->appendDiagnosticBSON(builder);
 }
 
 Date_t ShardingTaskExecutor::now() {
diff --git a/src/mongo/db/s/sharding_task_executor.h b/src/mongo/db/s/sharding_task_executor.h
index 7828b56dd94..efd4bff1de2 100644
--- a/src/mongo/db/s/sharding_task_executor.h
+++ b/src/mongo/db/s/sharding_task_executor.h
@@ -56,7 +56,7 @@ public:
     void startup() override;
     void shutdown() override;
     void join() override;
-    std::string getDiagnosticString() const override;
+    void appendDiagnosticBSON(BSONObjBuilder* builder) const override;
     Date_t now() override;
     StatusWith<EventHandle> makeEvent() override;
     void signalEvent(const EventHandle& event) override;
diff --git a/src/mongo/executor/task_executor.h b/src/mongo/executor/task_executor.h
index a17b6482451..04f911da5dc 100644
--- a/src/mongo/executor/task_executor.h
+++ b/src/mongo/executor/task_executor.h
@@ -134,9 +134,9 @@ public:
     virtual void join() = 0;
 
     /**
-     * Returns diagnostic information.
+     * Writes diagnostic information into "b".
      */
-    virtual std::string getDiagnosticString() const = 0;
+    virtual void appendDiagnosticBSON(BSONObjBuilder* b) const = 0;
 
     /**
      * Gets the current time.  Callbacks should use this method to read the system clock.
diff --git a/src/mongo/executor/thread_pool_task_executor.cpp b/src/mongo/executor/thread_pool_task_executor.cpp
index fcb27cd5c29..7d111ae6f95 100644
--- a/src/mongo/executor/thread_pool_task_executor.cpp
+++ b/src/mongo/executor/thread_pool_task_executor.cpp
@@ -188,30 +188,24 @@ void ThreadPoolTaskExecutor::join() {
     invariant(_unsignaledEvents.empty());
 }
 
-BSONObj ThreadPoolTaskExecutor::_getDiagnosticBSON() const {
+void ThreadPoolTaskExecutor::appendDiagnosticBSON(BSONObjBuilder* b) const {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
-    BSONObjBuilder builder;
 
     // ThreadPool details
     // TODO: fill in
-    BSONObjBuilder poolCounters(builder.subobjStart("pool"));
+    BSONObjBuilder poolCounters(b->subobjStart("pool"));
     poolCounters.appendIntOrLL("inProgressCount", _poolInProgressQueue.size());
     poolCounters.done();
 
     // Queues
-    BSONObjBuilder queues(builder.subobjStart("queues"));
+    BSONObjBuilder queues(b->subobjStart("queues"));
     queues.appendIntOrLL("networkInProgress", _networkInProgressQueue.size());
     queues.appendIntOrLL("sleepers", _sleepersQueue.size());
     queues.done();
 
-    builder.appendIntOrLL("unsignaledEvents", _unsignaledEvents.size());
-    builder.append("shuttingDown", _inShutdown);
-    builder.append("networkInterface", _net->getDiagnosticString());
-    return builder.obj();
-}
-
-std::string ThreadPoolTaskExecutor::getDiagnosticString() const {
-    return _getDiagnosticBSON().toString();
+    b->appendIntOrLL("unsignaledEvents", _unsignaledEvents.size());
+    b->append("shuttingDown", _inShutdown);
+    b->append("networkInterface", _net->getDiagnosticString());
 }
 
 Date_t ThreadPoolTaskExecutor::now() {
@@ -376,6 +370,9 @@ void ThreadPoolTaskExecutor::cancel(const CallbackHandle& cbHandle) {
     invariant(cbHandle.isValid());
     auto cbState = checked_cast<CallbackState*>(getCallbackFromHandle(cbHandle));
     stdx::unique_lock<stdx::mutex> lk(_mutex);
+    if (_inShutdown) {
+        return;
+    }
     cbState->canceled.store(1);
     if (cbState->isNetworkOperation) {
         lk.unlock();
diff --git a/src/mongo/executor/thread_pool_task_executor.h b/src/mongo/executor/thread_pool_task_executor.h
index 98298624b80..9d6a6d940b9 100644
--- a/src/mongo/executor/thread_pool_task_executor.h
+++ b/src/mongo/executor/thread_pool_task_executor.h
@@ -68,7 +68,7 @@ public:
     void startup() override;
     void shutdown() override;
     void join() override;
-    std::string getDiagnosticString() const override;
+    void appendDiagnosticBSON(BSONObjBuilder* b) const;
     Date_t now() override;
     StatusWith<EventHandle> makeEvent() override;
     void signalEvent(const EventHandle& event) override;
@@ -147,11 +147,6 @@ private:
      */
     void runCallback(std::shared_ptr<CallbackState> cbState);
 
-    /**
-     * Returns bson for diagnostics
-     */
-    BSONObj _getDiagnosticBSON() const;
-
     // The network interface used for remote command execution and waiting.
     std::unique_ptr<NetworkInterface> _net;
 
diff --git a/src/mongo/unittest/task_executor_proxy.cpp b/src/mongo/unittest/task_executor_proxy.cpp
index ffaf7b049c9..ccd8e9e6b02 100644
--- a/src/mongo/unittest/task_executor_proxy.cpp
+++ b/src/mongo/unittest/task_executor_proxy.cpp
@@ -57,8 +57,8 @@ void TaskExecutorProxy::join() {
     _executor->join();
 }
 
-std::string TaskExecutorProxy::getDiagnosticString() const {
-    return _executor->getDiagnosticString();
+void TaskExecutorProxy::appendDiagnosticBSON(mongo::BSONObjBuilder* builder) const {
+    _executor->appendDiagnosticBSON(builder);
 }
 
 Date_t TaskExecutorProxy::now() {
diff --git a/src/mongo/unittest/task_executor_proxy.h b/src/mongo/unittest/task_executor_proxy.h
index 4f2076f4991..738a53d9322 100644
--- a/src/mongo/unittest/task_executor_proxy.h
+++ b/src/mongo/unittest/task_executor_proxy.h
@@ -53,7 +53,7 @@ public:
     virtual void startup() override;
     virtual void shutdown() override;
     virtual void join() override;
-    virtual std::string getDiagnosticString() const override;
+    virtual void appendDiagnosticBSON(BSONObjBuilder* builder) const override;
     virtual Date_t now() override;
     virtual StatusWith<EventHandle> makeEvent() override;
     virtual void signalEvent(const EventHandle& event) override;