feat: Add Microservice Pattern, Log aggregation (#2690) (#2719)

* feat: Add Microservice Pattern, Log aggregation. Related: #2690 * docs: Add javaDoc for public methods. Related: #2690 --------- Co-authored-by: Ilkka Seppälä <iluwatar@users.noreply.github.com>
2026-05-15 22:58:59 +00:00 · 2023-12-27 15:06:55 +09:00
parent 5df1fb6f13
commit cd2dbb72d7
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+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2023 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.logaggregation;
+
+/**
+ * The main application class responsible for demonstrating the log aggregation mechanism. Creates
+ * services, generates logs, aggregates, and finally displays the logs.
+ */
+public class App {
+
+  /**
+   * The entry point of the application.
+   *
+   * @param args Command line arguments.
+   * @throws InterruptedException If any thread has interrupted the current thread.
+   */
+  public static void main(String[] args) throws InterruptedException {
+    final CentralLogStore centralLogStore = new CentralLogStore();
+    final LogAggregator aggregator = new LogAggregator(centralLogStore, LogLevel.INFO);
+
+    final LogProducer serviceA = new LogProducer("ServiceA", aggregator);
+    final LogProducer serviceB = new LogProducer("ServiceB", aggregator);
+
+    serviceA.generateLog(LogLevel.INFO, "This is an INFO log from ServiceA");
+    serviceB.generateLog(LogLevel.ERROR, "This is an ERROR log from ServiceB");
+    serviceA.generateLog(LogLevel.DEBUG, "This is a DEBUG log from ServiceA");
+
+    aggregator.stop();
+    centralLogStore.displayLogs();
+  }
+}
@@ -0,0 +1,63 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2023 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.logaggregation;
+
+import java.util.concurrent.ConcurrentLinkedQueue;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * A centralized store for logs. It collects logs from various services and stores them.
+ * This class is thread-safe, ensuring that logs from different services are safely stored
+ * concurrently without data races.
+ */
+@Slf4j
+public class CentralLogStore {
+
+  private final ConcurrentLinkedQueue<LogEntry> logs = new ConcurrentLinkedQueue<>();
+
+  /**
+   * Stores the given log entry into the central log store.
+   *
+   * @param logEntry The log entry to store.
+   */
+  public void storeLog(LogEntry logEntry) {
+    if (logEntry == null) {
+      LOGGER.error("Received null log entry. Skipping.");
+      return;
+    }
+    logs.offer(logEntry);
+  }
+
+  /**
+   * Displays all logs currently stored in the central log store.
+   */
+  public void displayLogs() {
+    LOGGER.info("----- Centralized Logs -----");
+    for (LogEntry logEntry : logs) {
+      LOGGER.info(
+          logEntry.getTimestamp() + " [" + logEntry.getLevel() + "] " + logEntry.getMessage());
+    }
+  }
+}
@@ -0,0 +1,120 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2023 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.logaggregation;
+
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Responsible for collecting and buffering logs from different services.
+ * Once the logs reach a certain threshold or after a certain time interval,
+ * they are flushed to the central log store. This class ensures logs are collected
+ * and processed asynchronously and efficiently, providing both an immediate collection
+ * and periodic flushing.
+ */
+@Slf4j
+public class LogAggregator {
+
+  private static final int BUFFER_THRESHOLD = 3;
+  private final CentralLogStore centralLogStore;
+  private final ConcurrentLinkedQueue<LogEntry> buffer = new ConcurrentLinkedQueue<>();
+  private final LogLevel minLogLevel;
+  private final ExecutorService executorService = Executors.newSingleThreadExecutor();
+  private final AtomicInteger logCount = new AtomicInteger(0);
+
+  /**
+   * constructor of LogAggregator.
+   *
+   * @param centralLogStore central log store implement
+   * @param minLogLevel min log level to store log
+   */
+  public LogAggregator(CentralLogStore centralLogStore, LogLevel minLogLevel) {
+    this.centralLogStore = centralLogStore;
+    this.minLogLevel = minLogLevel;
+    startBufferFlusher();
+  }
+
+  /**
+   * Collects a given log entry, and filters it by the defined log level.
+   *
+   * @param logEntry The log entry to collect.
+   */
+  public void collectLog(LogEntry logEntry) {
+    if (logEntry.getLevel() == null || minLogLevel == null) {
+      LOGGER.warn("Log level or threshold level is null. Skipping.");
+      return;
+    }
+
+    if (logEntry.getLevel().compareTo(minLogLevel) < 0) {
+      LOGGER.debug("Log level below threshold. Skipping.");
+      return;
+    }
+
+    buffer.offer(logEntry);
+
+    if (logCount.incrementAndGet() >= BUFFER_THRESHOLD) {
+      flushBuffer();
+    }
+  }
+
+  /**
+   * Stops the log aggregator service and flushes any remaining logs to
+   * the central log store.
+   *
+   * @throws InterruptedException If any thread has interrupted the current thread.
+   */
+  public void stop() throws InterruptedException {
+    executorService.shutdownNow();
+    if (!executorService.awaitTermination(10, TimeUnit.SECONDS)) {
+      LOGGER.error("Log aggregator did not terminate.");
+    }
+    flushBuffer();
+  }
+
+  private void flushBuffer() {
+    LogEntry logEntry;
+    while ((logEntry = buffer.poll()) != null) {
+      centralLogStore.storeLog(logEntry);
+      logCount.decrementAndGet();
+    }
+  }
+
+  private void startBufferFlusher() {
+    executorService.execute(() -> {
+      while (!Thread.currentThread().isInterrupted()) {
+        try {
+          Thread.sleep(5000); // Flush every 5 seconds.
+          flushBuffer();
+        } catch (InterruptedException e) {
+          Thread.currentThread().interrupt();
+        }
+      }
+    });
+  }
+}
@@ -0,0 +1,42 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2023 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.logaggregation;
+
+import java.time.LocalDateTime;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+/**
+ * Represents a single log entry, capturing essential details like the service name,
+ * log level, message, and the timestamp when the log was generated.
+ */
+@Data
+@AllArgsConstructor
+public class LogEntry {
+  private String serviceName;
+  private LogLevel level;
+  private String message;
+  private LocalDateTime timestamp;
+}
@@ -0,0 +1,38 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2023 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.logaggregation;
+
+/**
+ * Enum representing different log levels.
+ * Defines the severity of a log message, helping in filtering and prioritization.
+ * <ul>
+ *   <li>DEBUG: Detailed information, typically of interest only when diagnosing problems.</li>
+ *   <li>INFO: Confirmation that things are working as expected.</li>
+ *   <li>ERROR: Indicates a problem that needs attention.</li>
+ * </ul>
+ */
+public enum LogLevel {
+  DEBUG, INFO, ERROR
+}
@@ -0,0 +1,54 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2023 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.logaggregation;
+
+import java.time.LocalDateTime;
+import lombok.AllArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Represents a service that produces logs.
+ * The logs are generated based on certain activities or events within the service.
+ * Once a log is generated, it's passed on to the aggregator for further processing.
+ */
+@AllArgsConstructor
+@Slf4j
+public class LogProducer {
+
+  private String serviceName;
+  private LogAggregator aggregator;
+
+  /**
+   * Generates a log entry with the given log level and message.
+   *
+   * @param level The level of the log.
+   * @param message The message of the log.
+   */
+  public void generateLog(LogLevel level, String message) {
+    final LogEntry logEntry = new LogEntry(serviceName, level, message, LocalDateTime.now());
+    LOGGER.info("Producing log: " + logEntry.getMessage());
+    aggregator.collectLog(logEntry);
+  }
+}
@@ -0,0 +1,80 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2023 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.logaggregation;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import java.time.LocalDateTime;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+@ExtendWith(MockitoExtension.class)
+class LogAggregatorTest {
+
+  @Mock
+  private CentralLogStore centralLogStore;
+  private LogAggregator logAggregator;
+
+  @BeforeEach
+  void setUp() {
+    logAggregator = new LogAggregator(centralLogStore, LogLevel.INFO);
+  }
+
+  @Test
+  void whenThreeInfoLogsAreCollected_thenCentralLogStoreShouldStoreAllOfThem() {
+    logAggregator.collectLog(createLogEntry(LogLevel.INFO, "Sample log message 1"));
+    logAggregator.collectLog(createLogEntry(LogLevel.INFO, "Sample log message 2"));
+
+    verifyNoInteractionsWithCentralLogStore();
+
+    logAggregator.collectLog(createLogEntry(LogLevel.INFO, "Sample log message 3"));
+
+    verifyCentralLogStoreInvokedTimes(3);
+  }
+
+  @Test
+  void whenDebugLogIsCollected_thenNoLogsShouldBeStored() {
+    logAggregator.collectLog(createLogEntry(LogLevel.DEBUG, "Sample debug log message"));
+
+    verifyNoInteractionsWithCentralLogStore();
+  }
+
+  private static LogEntry createLogEntry(LogLevel logLevel, String message) {
+    return new LogEntry("ServiceA", logLevel, message, LocalDateTime.now());
+  }
+
+  private void verifyNoInteractionsWithCentralLogStore() {
+    verify(centralLogStore, times(0)).storeLog(any());
+  }
+
+  private void verifyCentralLogStoreInvokedTimes(int times) {
+    verify(centralLogStore, times(times)).storeLog(any());
+  }
+}