refactor(profiling): simplify CPU timer internals

Author: taegyunkim

ddtrace/internal/datadog/profiling/dd_wrapper/include/profiler_stats.hpp

@@ -114,10 +114,7 @@ class ProfilerStats
     size_t get_sample_capture_cpu_time_us() const;
 
     void add_wall_sample_capture_cpu_time_us(size_t cpu_time_us);
-    size_t get_wall_sample_capture_cpu_time_us() const;
-
     void add_cpu_timer_drain_cpu_time_us(size_t cpu_time_us);
-    size_t get_cpu_timer_drain_cpu_time_us() const;
 
     // Returns a JSON string containing relevant Profiler Stats to be included
     // in the libdatadog payload.

ddtrace/internal/datadog/profiling/dd_wrapper/src/profiler_stats.cpp

@@ -240,24 +240,12 @@ Datadog::ProfilerStats::add_wall_sample_capture_cpu_time_us(size_t cpu_time_us)
     wall_sample_capture_cpu_time_us += cpu_time_us;
 }
 
-size_t
-Datadog::ProfilerStats::get_wall_sample_capture_cpu_time_us() const
-{
-    return wall_sample_capture_cpu_time_us;
-}
-
 void
 Datadog::ProfilerStats::add_cpu_timer_drain_cpu_time_us(size_t cpu_time_us)
 {
     cpu_timer_drain_cpu_time_us += cpu_time_us;
 }
 
-size_t
-Datadog::ProfilerStats::get_cpu_timer_drain_cpu_time_us() const
-{
-    return cpu_timer_drain_cpu_time_us;
-}
-
 std::string
 Datadog::ProfilerStats::get_internal_metadata_json()
 {

ddtrace/internal/datadog/profiling/stack/include/cpu_sample_ring.hpp

@@ -105,12 +105,6 @@ class CpuSampleRing
         tail_.store(advance(tail), std::memory_order_release);
         return true;
     }
-
-    // This is a best-effort snapshot. It must not be used to coordinate work.
-    [[nodiscard]] bool empty() const noexcept
-    {
-        return tail_.load(std::memory_order_acquire) == head_.load(std::memory_order_acquire);
-    }
 };
 
 } // namespace CpuTimer

ddtrace/internal/datadog/profiling/stack/src/cpu_timer.cpp

@@ -1180,14 +1180,7 @@ void
 Engine::disable_for_fault_handler_swap()
 {
 #if DD_CPU_TIMER_SUPPORTED
-    std::lock_guard<std::mutex> lock(g_state.registry_lock);
-    if (!g_state.active.load(std::memory_order_acquire)) {
-        return;
-    }
-    g_state.handler_hijack_disable_count.fetch_add(1, std::memory_order_relaxed);
-    g_state.active.store(false, std::memory_order_release);
-    g_state.permanently_disabled.store(true, std::memory_order_release);
-    disable_all_timers_locked();
+    disable_all_timers_for_hijack();
 #endif
 }
 

ddtrace/internal/datadog/profiling/stack/test/test_cpu_sample_ring.cpp

@@ -66,7 +66,6 @@ TEST(CpuSampleRing, StartsEmpty)
     RawSample out{};
 
     EXPECT_EQ(ring.capacity(), 64u);
-    EXPECT_TRUE(ring.empty());
     EXPECT_FALSE(ring.pop_for_consumer(out));
 }
 
@@ -80,15 +79,13 @@ TEST(CpuSampleRing, ProducerReserveDoesNotPublish)
     ASSERT_NE(reserved, nullptr);
     *reserved = sample;
 
-    EXPECT_TRUE(ring.empty());
     EXPECT_FALSE(ring.pop_for_consumer(out));
 
     ring.publish_for_producer();
 
-    EXPECT_FALSE(ring.empty());
     ASSERT_TRUE(ring.pop_for_consumer(out));
     expect_sample_eq(out, sample);
-    EXPECT_TRUE(ring.empty());
+    EXPECT_FALSE(ring.pop_for_consumer(out));
 }
 
 TEST(CpuSampleRing, CapacityKeepsOneSlotOpenToDistinguishFullFromEmpty)
@@ -111,7 +108,6 @@ TEST(CpuSampleRing, CapacityKeepsOneSlotOpenToDistinguishFullFromEmpty)
     }
 
     RawSample out{};
-    EXPECT_TRUE(ring.empty());
     EXPECT_FALSE(ring.pop_for_consumer(out));
 }
 
@@ -147,7 +143,7 @@ TEST(CpuSampleRing, WraparoundPreservesFifoOrder)
         ASSERT_TRUE(ring.pop_for_consumer(out));
         expect_sample_eq(out, make_sample(expected_id));
     }
-    EXPECT_TRUE(ring.empty());
+    EXPECT_FALSE(ring.pop_for_consumer(out));
 }
 
 TEST(CpuSampleRing, ConcurrentProducerAndConsumerPreserveWholeFifoSamples)
@@ -175,5 +171,6 @@ TEST(CpuSampleRing, ConcurrentProducerAndConsumerPreserveWholeFifoSamples)
     }
 
     producer.join();
-    EXPECT_TRUE(ring.empty());
+    RawSample out{};
+    EXPECT_FALSE(ring.pop_for_consumer(out));
 }