tracing::trace_state: introduce is_in_state() and set_state() accessors

Use these new methods to manipulate trace_state::_state value.

Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>

tracing/trace_state.cc

@@ -83,7 +83,7 @@ void trace_state::build_parameters_map() {
 }
 
 trace_state::~trace_state() {
-    if (!_primary && _state == state::background) {
+    if (!_primary && is_in_state(state::background)) {
         trace_state_logger.error("Secondary session is in a background state! session_id: {}", session_id());
     }
 
@@ -95,11 +95,11 @@ trace_state::~trace_state() {
 
 void trace_state::stop_foreground_and_write() {
     // Do nothing if state hasn't been initiated
-    if (_state == state::inactive) {
+    if (is_in_state(state::inactive)) {
         return;
     }
 
-    if (_primary && _state == state::foreground) {
+    if (_primary && is_in_state(state::foreground)) {
         // We don't account the session_record event when checking a limit
         // of maximum events per session because there may be only one such
         // event and we don't want to cripple the primary session by
@@ -127,7 +127,7 @@ void trace_state::stop_foreground_and_write() {
         }
     }
 
-    _state = state::background;
+    set_state(state::background);
     trace_state_logger.trace("{}: Current records count is {}",  session_id(), _records->size());
     _local_tracing_ptr->write_session_records(_records, _write_on_close);
 }

tracing/trace_state.hh

@@ -54,15 +54,7 @@ namespace tracing {
 extern logging::logger trace_state_logger;
 
 class trace_state final {
-private:
-    lw_shared_ptr<one_session_records> _records;
-    bool _write_on_close;
-    // Used for calculation of time passed since the beginning of a tracing
-    // session till each tracing event.
-    elapsed_clock::time_point _start;
-    // TRUE for a primary trace_state object
-    bool _primary;
-
+public:
     // A primary session may be in 3 states:
     //   - "inactive": between the creation and a begin() call.
     //   - "foreground": after a begin() call and before a
@@ -83,7 +75,18 @@ private:
         inactive,
         foreground,
         background
-    } _state = state::inactive;
+    };
+
+private:
+    lw_shared_ptr<one_session_records> _records;
+    bool _write_on_close;
+    // Used for calculation of time passed since the beginning of a tracing
+    // session till each tracing event.
+    elapsed_clock::time_point _start;
+    // TRUE for a primary trace_state object
+    bool _primary;
+
+    state _state = state::inactive;
 
     std::chrono::system_clock::rep _started_at;
     gms::inet_address _client;
@@ -151,6 +154,14 @@ public:
         return _records->session_id;
     }
 
+    bool is_in_state(state s) const {
+        return _state == s;
+    }
+
+    void set_state(state s) {
+        _state = s;
+    }
+
     trace_type type() const {
         return _records->session_rec.command;
     }
@@ -177,7 +188,7 @@ private:
         std::atomic_signal_fence(std::memory_order::memory_order_seq_cst);
         _start = elapsed_clock::now();
         std::atomic_signal_fence(std::memory_order::memory_order_seq_cst);
-        _state = state::foreground;
+        set_state(state::foreground);
     }
 
     /**
@@ -339,7 +350,7 @@ private:
 };
 
 inline void trace_state::trace(sstring message) {
-    if (_state == state::inactive) {
+    if (is_in_state(state::inactive)) {
         throw std::logic_error("trying to use a trace() before begin() for \"" + message + "\" tracepoint");
     }
 

tracing/tracing.cc

@@ -47,7 +47,6 @@ namespace tracing {
 logging::logger tracing_logger("tracing");
 const gc_clock::duration tracing::tracing::write_period = std::chrono::seconds(2);
 
-
 std::vector<sstring> trace_type_names = {
     "NONE",
     "QUERY",