Thread-safe implementation of the worker performance counter class

Author: iagaponenko

src/replica/util/Performance.cc

@@ -77,17 +77,9 @@ ostream& operator<<(ostream& os, Performance const& p) {
 WorkerPerformance::WorkerPerformance()
         : receive_time(util::TimeUtils::now()), start_time(0), finish_time(0) {}
 
-uint64_t WorkerPerformance::setUpdateStart() {
-    uint64_t const t = start_time;
-    start_time = util::TimeUtils::now();
-    return t;
-}
+uint64_t WorkerPerformance::setUpdateStart() { return start_time.exchange(util::TimeUtils::now()); }
 
-uint64_t WorkerPerformance::setUpdateFinish() {
-    uint64_t const t = finish_time;
-    finish_time = util::TimeUtils::now();
-    return t;
-}
+uint64_t WorkerPerformance::setUpdateFinish() { return finish_time.exchange(util::TimeUtils::now()); }
 
 unique_ptr<ProtocolPerformance> WorkerPerformance::info() const {
     auto ptr = make_unique<ProtocolPerformance>();
@@ -97,6 +89,12 @@ unique_ptr<ProtocolPerformance> WorkerPerformance::info() const {
     return ptr;
 }
 
+json WorkerPerformance::toJson() const {
+    return json::object({{"receive_time", receive_time.load()},
+                         {"start_time", start_time.load()},
+                         {"finish_time", finish_time.load()}});
+}
+
 ostream& operator<<(ostream& os, WorkerPerformance const& p) {
     os << "WorkerPerformance "
        << " receive:" << p.receive_time << " start:" << p.start_time << " finish:" << p.finish_time

src/replica/util/Performance.h

@@ -28,6 +28,7 @@
  */
 
 // System headers
+#include <atomic>
 #include <cstdint>
 #include <memory>
 #include <ostream>
@@ -116,6 +117,7 @@ std::ostream& operator<<(std::ostream& os, Performance const& p);
  */
 class WorkerPerformance {
 public:
+    /// All (but the request receive time) timestamps will be initialized with 0.
     WorkerPerformance();
     WorkerPerformance(WorkerPerformance const&) = default;
     WorkerPerformance& operator=(WorkerPerformance const&) = default;
@@ -126,9 +128,9 @@ class WorkerPerformance {
 
     std::unique_ptr<ProtocolPerformance> info() const;
 
-    uint64_t receive_time = 0;  /// Received by a worker service
-    uint64_t start_time = 0;    /// Execution started by a worker service
-    uint64_t finish_time = 0;   /// Execution finished by a worker service
+    std::atomic<uint64_t> receive_time;  ///< Received by a worker service
+    std::atomic<uint64_t> start_time;    ///< Execution started by a worker service
+    std::atomic<uint64_t> finish_time;   ///< Execution finished by a worker service
 };
 
 std::ostream& operator<<(std::ostream& os, WorkerPerformance const& p);