health_check_using_rpc: refine comment

src/brpc/controller.h

@@ -325,7 +325,9 @@ public:
     bool is_done_allowed_to_run_in_place() const
     { return has_flag(FLAGS_ALLOW_DONE_TO_RUN_IN_PLACE); }
 
-    // TODO(zhujiahsun): comment
+    // Tell RPC that this particular call is used to do health check. These two
+    // functions is used by the developers of brpc and should not be touched or
+    // called by users.
     void set_health_check_call(bool f) { set_flag(FLAGS_HEALTH_CHECK_CALL, f); }
     bool has_health_check_call() const { return has_flag(FLAGS_HEALTH_CHECK_CALL); }
 

src/brpc/socket.cpp

@@ -94,9 +94,12 @@ DEFINE_int32(connect_timeout_as_unreachable, 3,
              "times *continuously*, the error is changed to ENETUNREACH which "
              "fails the main socket as well when this socket is pooled.");
 
-DEFINE_bool(health_check_using_rpc, false, "todo");
-DEFINE_string(health_check_path, "/health", "todo");
-DEFINE_int32(health_check_timeout_ms, 300, "todo");
+DEFINE_bool(health_check_using_rpc, false, "By default health check succeeds if server"
+        "can be connected. If this flag is set, health check is completed not only"
+        "when server can be connected but also an additional http call succeeds"
+        "indicated by FLAGS_health_check_path and FLAGS_health_check_timeout_ms");
+DEFINE_string(health_check_path, "/health", "Http path of health check call");
+DEFINE_int32(health_check_timeout_ms, 300, "Timeout of health check call");
 
 static bool validate_connect_timeout_as_unreachable(const char*, int32_t v) {
     return v >= 2 && v < 1000/*large enough*/;
@@ -1045,7 +1048,7 @@ bool HealthCheckTask::OnTriggeringTask(timespec* next_abstime) {
             options.timeout_ms = FLAGS_health_check_timeout_ms;
             brpc::Channel channel;
             if (channel.Init(_id, &options) != 0) {
-                // SetFailed() again to trigger next round of health checking
+                // SetFailed to trigger next round of health checking
                 ptr->SetFailed();
                 return false;
             }

src/brpc/socket.h

@@ -349,8 +349,12 @@ public:
     void SetLogOff();
     bool IsLogOff() const;
 
-    // TODO(zhujiashun)
+    // Check Whether the state is in health check using rpc state or
+    // not, which means this socket would not be selected in further
+    // user request until rpc succeed and can only be used by health
+    // check rpc call.
     bool IsHealthCheckingUsingRPC() const;
+    // Reset health check state to the initial state(which is false)
     void ResetHealthCheckingUsingRPC();
 
     // Start to process edge-triggered events from the fd.
@@ -795,8 +799,8 @@ private:
     butil::Mutex _stream_mutex;
     std::set<StreamId> *_stream_set;
 
-    // If this flag is set, then the current socket is used to health check
-    // and should not health check again
+    // If this flag is set, socket is now in health check state using
+    // application-level rpc.
     butil::atomic<bool> _health_checking_using_rpc;
 };