use separate lock for stats

2 files changed, 25 insertions, 6 deletions

diff --git a/storage/src/vespa/storage/persistence/filestorage/filestorhandlerimpl.cpp b/storage/src/vespa/storage/persistence/filestorage/filestorhandlerimpl.cpp
index a6b3a028512..df1c0de36cc 100644
--- a/storage/src/vespa/storage/persistence/filestorage/filestorhandlerimpl.cpp
+++ b/storage/src/vespa/storage/persistence/filestorage/filestorhandlerimpl.cpp
@@ -1183,7 +1183,7 @@ FileStorHandlerImpl::Stripe::release(const document::Bucket & bucket,
     }
     Clock::time_point now_ts = Clock::now();
     double latency = std::chrono::duration<double, std::milli>(now_ts - start_time).count();
-    _active_operations_stats.operation_done(latency);
+    _active_operations_stats.guard().stats().operation_done(latency);
     if (!entry._exclusiveLock && entry._sharedLocks.empty()) {
         _lockedBuckets.erase(iter); // No more locks held
     }
@@ -1221,7 +1221,7 @@ FileStorHandlerImpl::Stripe::lock(const monitor_guard &, const document::Bucket
         (void) inserted;
         assert(inserted.second);
     }
-    _active_operations_stats.operation_started();
+    _active_operations_stats.guard().stats().operation_started();
 }
 
 bool
@@ -1259,10 +1259,10 @@ FileStorHandlerImpl::Stripe::operationIsInhibited(const monitor_guard & guard, c
 ActiveOperationsStats
 FileStorHandlerImpl::Stripe::get_active_operations_stats(bool reset_min_max) const
 {
-    std::lock_guard guard(*_lock);
-    auto result = _active_operations_stats;
+    auto guard = _active_operations_stats.guard();
+    auto result = guard.stats();
     if (reset_min_max) {
-        _active_operations_stats.reset_min_max();
+        guard.stats().reset_min_max();
     }
     return result;
 }
diff --git a/storage/src/vespa/storage/persistence/filestorage/filestorhandlerimpl.h b/storage/src/vespa/storage/persistence/filestorage/filestorhandlerimpl.h
index c4b229418a1..a3667e93fff 100644
--- a/storage/src/vespa/storage/persistence/filestorage/filestorhandlerimpl.h
+++ b/storage/src/vespa/storage/persistence/filestorage/filestorhandlerimpl.h
@@ -98,6 +98,25 @@ public:
             SharedLocks _sharedLocks;
         };
 
+        class SafeActiveOperationsStats {
+        private:
+            std::unique_ptr<std::mutex> _lock;
+            ActiveOperationsStats _stats;
+            struct ctor_tag {};
+        public:
+            class Guard {
+            private:
+                std::lock_guard<std::mutex> _guard;
+                ActiveOperationsStats &_stats;
+            public:
+                Guard(Guard &&) = delete;
+                Guard(std::mutex &lock, ActiveOperationsStats &stats_in, ctor_tag) : _guard(lock), _stats(stats_in) {}
+                ActiveOperationsStats &stats() { return _stats; }
+            };
+            SafeActiveOperationsStats() : _lock(std::make_unique<std::mutex>()), _stats() {}
+            Guard guard() { return Guard(*_lock, _stats, ctor_tag()); }
+        };
+
         Stripe(const FileStorHandlerImpl & owner, MessageSender & messageSender);
         Stripe(Stripe &&) noexcept;
         Stripe(const Stripe &) = delete;
@@ -170,7 +189,7 @@ public:
         atomic_size_t                   _cached_queue_size;
         LockedBuckets                   _lockedBuckets;
         uint32_t                        _active_merges;
-        mutable ActiveOperationsStats   _active_operations_stats;
+        mutable SafeActiveOperationsStats _active_operations_stats;
     };
 
     class BucketLock : public FileStorHandler::BucketLockInterface {