Нативная реализация слежения за окончанием работы процесса

src/main/java/com/github/_1c_syntax/bsl/languageserver/ParentProcessWatcher.java

@@ -26,9 +26,11 @@
 import lombok.extern.slf4j.Slf4j;
 import org.eclipse.lsp4j.services.LanguageServer;
 import org.springframework.context.event.EventListener;
-import org.springframework.scheduling.annotation.Scheduled;
 import org.springframework.stereotype.Component;
 
+import javax.annotation.CheckForNull;
+import java.util.Optional;
+
 /**
  * Наблюдатель за жизнью родительского процесса, запустившего Language Server.
  */
@@ -38,7 +40,6 @@
 public class ParentProcessWatcher {
 
   private final LanguageServer languageServer;
-  private long parentProcessId;
 
   /**
    * Обработчик события {@link LanguageServerInitializeRequestReceivedEvent}.
@@ -49,29 +50,23 @@ public class ParentProcessWatcher {
    */
   @EventListener
   public void handleEvent(LanguageServerInitializeRequestReceivedEvent event) {
-    var processId = event.getParams().getProcessId();
+    @CheckForNull Integer processId = event.getParams().getProcessId();
     if (processId == null) {
       return;
     }
-    parentProcessId = processId;
-  }
 
-  /**
-   * Фоновая процедура, отслеживающая родительский процесс.
-   */
-  @Scheduled(fixedDelay = 30000L)
-  public void watch() {
-    if (parentProcessId == 0) {
+    // Can't register onExit callback on current process.
+    if (ProcessHandle.current().pid() == processId) {
       return;
     }
 
-    boolean processIsAlive = ProcessHandle.of(parentProcessId)
-      .map(ProcessHandle::isAlive)
-      .orElse(false);
-
-    if (!processIsAlive) {
-      LOGGER.error("Parent process with pid {} is not found. Closing application...", parentProcessId);
-      languageServer.exit();
-    }
+    Optional.of(processId)
+      .flatMap(ProcessHandle::of)
+      .map(ProcessHandle::onExit)
+      .ifPresent(onExitCallback -> onExitCallback.thenRun(() -> {
+        LOGGER.warn("Parent process with pid {} is not found. Closing application...", processId);
+        languageServer.exit();
+      }));
   }
+
 }

src/test/java/com/github/_1c_syntax/bsl/languageserver/ParentProcessWatcherTest.java

@@ -25,53 +25,63 @@
 import org.eclipse.lsp4j.InitializeParams;
 import org.eclipse.lsp4j.services.LanguageServer;
 import org.junit.jupiter.api.Test;
-import org.mockito.InjectMocks;
-import org.mockito.Mock;
-import org.springframework.boot.test.context.SpringBootTest;
 
+import java.io.IOException;
+import java.time.Duration;
+
+import static org.awaitility.Awaitility.await;
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 
-@SpringBootTest
 class ParentProcessWatcherTest {
 
-  @InjectMocks
-  private ParentProcessWatcher parentProcessWatcher;
-
-  @Mock
-  private LanguageServer languageServer;
-
   @Test
-  void testParentProcessIsDead() {
+  void testParentProcessIsDead() throws IOException, InterruptedException {
     // given
+    var languageServer = mock(LanguageServer.class);
+    var parentProcessWatcher = new ParentProcessWatcher(languageServer);
+
     var params = new InitializeParams();
-    params.setProcessId(-1);
+    var process = new ProcessBuilder("timeout", "2").start();
+    var pid = process.pid();
+    params.setProcessId((int) pid);
 
     var event = new LanguageServerInitializeRequestReceivedEvent(languageServer, params);
     parentProcessWatcher.handleEvent(event);
 
     // when
-    parentProcessWatcher.watch();
+    process.waitFor();
 
     // then
-    verify(languageServer, times(1)).exit();
+    await()
+      .atMost(Duration.ofSeconds(1))
+      .untilAsserted(
+        () -> verify(languageServer, times(1)).exit()
+      );
   }
 
   @Test
   void testParentProcessIsAlive() {
     // given
+    var languageServer = mock(LanguageServer.class);
+    var parentProcessWatcher = new ParentProcessWatcher(languageServer);
+
     var params = new InitializeParams();
     params.setProcessId((int) ProcessHandle.current().pid());
 
     var event = new LanguageServerInitializeRequestReceivedEvent(languageServer, params);
-    parentProcessWatcher.handleEvent(event);
 
     // when
-    parentProcessWatcher.watch();
+    parentProcessWatcher.handleEvent(event);
 
     // then
-    verify(languageServer, never()).exit();
+    await()
+      .during(Duration.ofSeconds(1))
+      .untilAsserted(
+        () -> verify(languageServer, never()).exit()
+      );
   }
 
 }