Make operations atomic

2 files changed, 43 insertions, 12 deletions

diff --git a/src/core/lib/channel/channelz.cc b/src/core/lib/channel/channelz.cc
index 5c3dc97e69..9e153a3f4f 100644
--- a/src/core/lib/channel/channelz.cc
+++ b/src/core/lib/channel/channelz.cc
@@ -93,8 +93,6 @@ Channel::Channel(grpc_channel* channel, size_t channel_tracer_max_nodes)
   trace_.Init(channel_tracer_max_nodes);
   target_ = grpc_channel_get_target(channel_);
   channel_uuid_ = ChannelzRegistry::Register(this);
-  last_call_started_timestamp_ =
-      grpc_millis_to_timespec(ExecCtx::Get()->Now(), GPR_CLOCK_REALTIME);
 }
 
 Channel::~Channel() {
@@ -103,10 +101,28 @@ Channel::~Channel() {
   ChannelzRegistry::Unregister(channel_uuid_);
 }
 
+Channel::AtomicTimespec::AtomicTimespec() {
+  gpr_atm_no_barrier_store(&tv_sec_, (gpr_atm)0);
+  gpr_atm_no_barrier_store(&tv_nsec_, (gpr_atm)0);
+}
+
+void Channel::AtomicTimespec::Update(gpr_timespec ts) {
+  gpr_atm_no_barrier_store(&tv_sec_, (gpr_atm)ts.tv_sec);
+  gpr_atm_no_barrier_store(&tv_nsec_, (gpr_atm)ts.tv_nsec);
+}
+
+gpr_timespec Channel::AtomicTimespec::Get() {
+  gpr_timespec out;
+  out.clock_type = GPR_CLOCK_REALTIME;
+  out.tv_sec = static_cast<int64_t>(gpr_atm_no_barrier_load(&tv_sec_));
+  out.tv_nsec = static_cast<int32_t>(gpr_atm_no_barrier_load(&tv_nsec_));
+  return out;
+}
+
 void Channel::CallStarted() {
-  calls_started_++;
-  last_call_started_timestamp_ =
-      grpc_millis_to_timespec(ExecCtx::Get()->Now(), GPR_CLOCK_REALTIME);
+  gpr_atm_no_barrier_fetch_add(&calls_started_, (gpr_atm)1);
+  last_call_started_timestamp_.Update(
+      grpc_millis_to_timespec(ExecCtx::Get()->Now(), GPR_CLOCK_REALTIME));
 }
 
 grpc_connectivity_state Channel::GetConnectivityState() {
@@ -181,7 +197,7 @@ char* Channel::RenderJSON() {
                               calls_failed_ ? calls_failed_ : -1);
   json_iterator = grpc_json_create_child(
       json_iterator, json, "lastCallStartedTimestamp",
-      fmt_time(last_call_started_timestamp_), GRPC_JSON_STRING, true);
+      fmt_time(last_call_started_timestamp_.Get()), GRPC_JSON_STRING, true);
 
   // render and return the over json object
   char* json_str = grpc_json_dump_to_string(top_level_json, 0);
diff --git a/src/core/lib/channel/channelz.h b/src/core/lib/channel/channelz.h
index 5cfafc9e14..684402e08f 100644
--- a/src/core/lib/channel/channelz.h
+++ b/src/core/lib/channel/channelz.h
@@ -39,8 +39,12 @@ class Channel : public RefCounted<Channel> {
   ~Channel();
 
   void CallStarted();
-  void CallFailed() { calls_failed_++; }
-  void CallSucceeded() { calls_succeeded_++; }
+  void CallFailed() {
+    gpr_atm_no_barrier_fetch_add(&calls_failed_, (gpr_atm(1)));
+  }
+  void CallSucceeded() {
+    gpr_atm_no_barrier_fetch_add(&calls_succeeded_, (gpr_atm(1)));
+  }
 
   char* RenderJSON();
 
@@ -54,13 +58,24 @@ class Channel : public RefCounted<Channel> {
   intptr_t channel_uuid() { return channel_uuid_; }
 
  private:
+  class AtomicTimespec {
+   public:
+    AtomicTimespec();
+    void Update(gpr_timespec ts);
+    gpr_timespec Get();
+
+   private:
+    gpr_atm tv_sec_;
+    gpr_atm tv_nsec_;
+  };
+
   bool channel_destroyed_ = false;
   grpc_channel* channel_;
   const char* target_;
-  int64_t calls_started_ = 0;
-  int64_t calls_succeeded_ = 0;
-  int64_t calls_failed_ = 0;
-  gpr_timespec last_call_started_timestamp_;
+  gpr_atm calls_started_ = 0;
+  gpr_atm calls_succeeded_ = 0;
+  gpr_atm calls_failed_ = 0;
+  AtomicTimespec last_call_started_timestamp_;
   intptr_t channel_uuid_;
   ManualConstructor<ChannelTrace> trace_;