Added UserMetricsAspect

server/src/main/java/ru/dragonestia/picker/LoadBalancerApplication.java

@@ -7,6 +7,8 @@ import io.swagger.v3.oas.annotations.info.License;
 import io.swagger.v3.oas.annotations.servers.Server;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.EnableAspectJAutoProxy;
+import org.springframework.scheduling.annotation.EnableScheduling;
 
 @OpenAPIDefinition(
         info = @Info(
@@ -24,6 +26,8 @@ import org.springframework.boot.autoconfigure.SpringBootApplication;
         }
 )
 @SpringBootApplication
+@EnableAspectJAutoProxy
+@EnableScheduling
 public class LoadBalancerApplication {
 
     public static void main(String[] args) {

server/src/main/java/ru/dragonestia/picker/aspect/UserMetricsAspect.java

@@ -0,0 +1,45 @@
+package ru.dragonestia.picker.aspect;
+
+import io.micrometer.core.instrument.MeterRegistry;
+import jakarta.annotation.PostConstruct;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.log4j.Log4j2;
+import org.aspectj.lang.annotation.After;
+import org.aspectj.lang.annotation.Aspect;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+import ru.dragonestia.picker.repository.UserRepository;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+@Component
+@Aspect
+@RequiredArgsConstructor
+@Log4j2
+public class UserMetricsAspect {
+
+    private final UserRepository userRepository;
+    private final MeterRegistry meterRegistry;
+
+    private final AtomicInteger totalUsers = new AtomicInteger(0);
+
+    @PostConstruct
+    void init() {
+        meterRegistry.gauge("roompicker_total_users", totalUsers);
+    }
+
+    @After("execution(void ru.dragonestia.picker.repository.UserRepository.linkWithRoom(..))")
+    void onLinkUsers() {
+        totalUsers.set(userRepository.countAllUsers());
+    }
+
+    @After("execution(void ru.dragonestia.picker.repository.UserRepository.unlinkWithRoom(..))")
+    void onUnlinkUsers() {
+        totalUsers.set(userRepository.countAllUsers());
+    }
+
+    @Scheduled(fixedDelay = 3_000)
+    void updateUserMetrics() {
+        // TODO: metrics for userRepository.countUsersForNodes()
+    }
+}

server/src/main/java/ru/dragonestia/picker/repository/UserRepository.java

@@ -12,7 +12,7 @@ public interface UserRepository {
 
     Map<User, Boolean> linkWithRoom(Room room, Collection<User> users, boolean force) throws RoomAreFullException;
 
-    int unlinkWithRoom(Room room, Collection<User> users);
+    void unlinkWithRoom(Room room, Collection<User> users);
 
     List<Room> findAllLinkedUserRooms(User user);
 

server/src/main/java/ru/dragonestia/picker/repository/impl/UserRepositoryImpl.java

@@ -66,7 +66,7 @@ public class UserRepositoryImpl implements UserRepository {
     }
 
     @Override
-    public int unlinkWithRoom(Room room, Collection<User> users) {
+    public void unlinkWithRoom(Room room, Collection<User> users) {
         var counter = new AtomicInteger();
 
         lock.writeLock().lock();
@@ -98,7 +98,7 @@ public class UserRepositoryImpl implements UserRepository {
         } finally {
             lock.writeLock().unlock();
         }
-        return counter.get();
+        counter.get();
     }
 
     @Override