Internal cleanup

gloop/base/tracer.h

@@ -917,6 +917,24 @@ class Tracer {
     cpu_profile_ticks_.fetch_add(ticks, std::memory_order_relaxed);
   }
 
+  // Returns the total lock contention delay accumulated in this Tracer, if
+  // supported by the concrete tracer type.
+  // Note that this only works when the --dapper_lock_contention_reporting flag
+  // is set.
+  uint64_t lock_contention_delay_us() const {
+    return lock_contention_delay_us_.load(std::memory_order_relaxed);
+  }
+
+  // Increments the lock contention delay by the specified duration, if
+  // supported by the concrete tracer type.
+  // Note that this only works when the --dapper_lock_contention_reporting flag
+  // is set.
+  void add_lock_contention_delay_safe(absl::Duration duration) {
+    lock_contention_delay_us_.fetch_add(
+        static_cast<uint64_t>(absl::ToInt64Microseconds(duration)),
+        std::memory_order_relaxed);
+  }
+
   // Registers a notification to be called just before this Tracer's final
   // ref is released by the application.
   //
@@ -1370,6 +1388,9 @@ class Tracer {
   // meant to be used by Dapper/Census internal libraries only.
   std::atomic<int32_t> cpu_profile_ticks_ = 0;
 
+  // Stores the lock contention delay in microseconds.
+  std::atomic<uint64_t> lock_contention_delay_us_{0};
+
   // An optional callback to invoked the first time the Tracer's reference count
   // drops to zero. This allows an application to capture the Tracer without
   // disrupting its natural lifetime as recorded in start_time/stop_time.

gloop/base/tracer_test.cc

@@ -313,7 +313,7 @@ class TestTracer : public Tracer {
 
 TEST(Tracer, Size) {
 #ifdef NDEBUG
-  EXPECT_EQ(sizeof(Tracer), 112);
+  EXPECT_EQ(sizeof(Tracer), 120);
 #endif
 }