SERVER-70055 Make TTL monitor pick up config changes immediately

3 files changed, 53 insertions, 10 deletions

diff --git a/src/mongo/db/ttl.cpp b/src/mongo/db/ttl.cpp
index c2720153e7d..34e1bc23cc9 100644
--- a/src/mongo/db/ttl.cpp
+++ b/src/mongo/db/ttl.cpp
@@ -308,6 +308,10 @@ CounterMetric ttlCollSubpassesIncreasedPriority("ttl.collSubpassesIncreasedPrior
 
 using MtabType = TenantMigrationAccessBlocker::BlockerType;
 
+TTLMonitor::TTLMonitor()
+    : BackgroundJob(false /* selfDelete */),
+      _ttlMonitorSleepSecs(Seconds{ttlMonitorSleepSecs.load()}) {}
+
 TTLMonitor* TTLMonitor::get(ServiceContext* serviceCtx) {
     return getTTLMonitor(serviceCtx).get();
 }
@@ -323,19 +327,48 @@ void TTLMonitor::set(ServiceContext* serviceCtx, std::unique_ptr<TTLMonitor> mon
     ttlMonitor = std::move(monitor);
 }
 
+Status TTLMonitor::onUpdateTTLMonitorSleepSeconds(int newSleepSeconds) {
+    if (auto client = Client::getCurrent()) {
+        if (auto ttlMonitor = TTLMonitor::get(client->getServiceContext())) {
+            ttlMonitor->updateSleepSeconds(Seconds{newSleepSeconds});
+        }
+    }
+    return Status::OK();
+}
+
+void TTLMonitor::updateSleepSeconds(Seconds newSeconds) {
+    {
+        stdx::lock_guard lk(_stateMutex);
+        _ttlMonitorSleepSecs = newSeconds;
+    }
+    _notificationCV.notify_all();
+}
+
 void TTLMonitor::run() {
     ThreadClient tc(name(), getGlobalServiceContext());
     AuthorizationSession::get(cc())->grantInternalAuthorization(&cc());
 
     while (true) {
         {
-            // Wait until either ttlMonitorSleepSecs passes or a shutdown is requested.
-            auto deadline = Date_t::now() + Seconds(ttlMonitorSleepSecs.load());
+            auto startTime = Date_t::now();
+            // Wait until either ttlMonitorSleepSecs passes, a shutdown is requested, or the
+            // sleeping time has changed.
             stdx::unique_lock<Latch> lk(_stateMutex);
+            auto deadline = startTime + _ttlMonitorSleepSecs;
 
             MONGO_IDLE_THREAD_BLOCK;
-            _shuttingDownCV.wait_until(
-                lk, deadline.toSystemTimePoint(), [&] { return _shuttingDown; });
+            while (Date_t::now() <= deadline && !_shuttingDown) {
+                _notificationCV.wait_until(lk, deadline.toSystemTimePoint());
+                // Recompute the deadline in case the sleep time has changed since we started.
+                auto newDeadline = startTime + _ttlMonitorSleepSecs;
+                if (deadline != newDeadline) {
+                    LOGV2_INFO(7005501,
+                               "TTL sleep deadline has changed",
+                               "oldDeadline"_attr = deadline,
+                               "newDeadline"_attr = newDeadline);
+                    deadline = newDeadline;
+                }
+            }
 
             if (_shuttingDown) {
                 return;
@@ -374,7 +407,7 @@ void TTLMonitor::shutdown() {
     {
         stdx::lock_guard<Latch> lk(_stateMutex);
         _shuttingDown = true;
-        _shuttingDownCV.notify_one();
+        _notificationCV.notify_all();
     }
     wait();
     LOGV2(3684101, "Finished shutting down TTL collection monitor thread");
diff --git a/src/mongo/db/ttl.h b/src/mongo/db/ttl.h
index be0cc3145ab..6aa0f137ea3 100644
--- a/src/mongo/db/ttl.h
+++ b/src/mongo/db/ttl.h
@@ -49,12 +49,14 @@ void shutdownTTLMonitor(ServiceContext* serviceContext);
 
 class TTLMonitor : public BackgroundJob {
 public:
-    explicit TTLMonitor() : BackgroundJob(false /* selfDelete */) {}
+    TTLMonitor();
 
     static TTLMonitor* get(ServiceContext* serviceCtx);
 
     static void set(ServiceContext* serviceCtx, std::unique_ptr<TTLMonitor> monitor);
 
+    static Status onUpdateTTLMonitorSleepSeconds(int newSleepSeconds);
+
     std::string name() const {
         return "TTLMonitor";
     }
@@ -71,6 +73,8 @@ public:
      */
     void onStepUp(OperationContext* opCtx);
 
+    void updateSleepSeconds(Seconds newSeconds);
+
     long long getTTLPasses_forTest();
     long long getTTLSubPasses_forTest();
 
@@ -154,11 +158,15 @@ private:
     // Protects the state below.
     mutable Mutex _stateMutex = MONGO_MAKE_LATCH("TTLMonitorStateMutex");
 
-    // Signaled to wake up the thread, if the thread is waiting. The thread will check whether
-    // _shuttingDown is set and stop accordingly.
-    mutable stdx::condition_variable _shuttingDownCV;
+    // Signaled to wake up the thread, if the thread is waiting. This condition variable is used to
+    // notify the thread of either:
+    // * The server is shutting down.
+    // * The ttlMonitorSleepSecs variable has changed.
+    // If the server is shutting down the monitor will stop.
+    mutable stdx::condition_variable _notificationCV;
 
     bool _shuttingDown = false;
+    Seconds _ttlMonitorSleepSecs;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/ttl.idl b/src/mongo/db/ttl.idl
index bfc96c06909..7c399b18127 100644
--- a/src/mongo/db/ttl.idl
+++ b/src/mongo/db/ttl.idl
@@ -27,7 +27,8 @@
 
 global:
     cpp_namespace: mongo
-
+    cpp_includes:
+        - "mongo/db/ttl.h"
 server_parameters:
     ttlMonitorEnabled:
         description: "Enable the TTL monitor."
@@ -41,6 +42,7 @@ server_parameters:
         set_at: [ startup, runtime ]
         cpp_vartype: AtomicWord<int>
         cpp_varname: ttlMonitorSleepSecs
+        on_update: "TTLMonitor::onUpdateTTLMonitorSleepSeconds"
         default: 60
         validator:
             gt: 0