use default exception handler if custom handler fails

NitorCreations · Feb 6, 2021 · 94ea98e · 94ea98e
1 parent ba97b54
commit 94ea98e
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Showing 4 changed files with 64 additions and 7 deletions.
diff --git a/nflow-engine/src/main/java/io/nflow/engine/exception/DispatcherExceptionAnalyzer.java b/nflow-engine/src/main/java/io/nflow/engine/exception/DispatcherExceptionAnalyzer.java
@@ -1,5 +1,8 @@
 package io.nflow.engine.exception;
 
+import static org.slf4j.LoggerFactory.getLogger;
+
+import org.slf4j.Logger;
 import org.slf4j.event.Level;
 import org.springframework.stereotype.Component;
 
@@ -14,14 +17,36 @@
 @Component
 public class DispatcherExceptionAnalyzer {
 
+  private static final Logger logger = getLogger(DispatcherExceptionAnalyzer.class);
+
   /**
    * Analyze the exception.
    *
    * @param e
    *          The exception to be analyzed.
    * @return How the exception should be handled.
    */
-  public DispatcherExceptionHandling analyze(Exception e) {
+  public final DispatcherExceptionHandling analyzeSafely(Exception e) {
+    try {
+      return analyze(e);
+    } catch (Exception analyzerException) {
+      logger.error("Failed to analyze exception, using default handling.", analyzerException);
+    }
+    return getDefultHandling(e);
+  }
+
+  /**
+   * Override this to provide custom handling.
+   *
+   * @param e
+   *          The exception to be analyzed.
+   * @return How the exception should be handled.
+   */
+  protected DispatcherExceptionHandling analyze(Exception e) {
+    return getDefultHandling(e);
+  }
+
+  private DispatcherExceptionHandling getDefultHandling(Exception e) {
     Builder builder = new DispatcherExceptionHandling.Builder();
     if (e instanceof PollingRaceConditionException) {
       builder.setLogLevel(Level.DEBUG).setLogStackTrace(false).setRandomizeSleep(true);

diff --git a/nflow-engine/src/main/java/io/nflow/engine/internal/executor/WorkflowDispatcher.java b/nflow-engine/src/main/java/io/nflow/engine/internal/executor/WorkflowDispatcher.java
@@ -92,7 +92,7 @@ public void run() {
               dispatch(getNextInstanceIds());
             }
           } catch (Exception e) {
-            DispatcherExceptionHandling handling = exceptionAnalyzer.analyze(e);
+            DispatcherExceptionHandling handling = exceptionAnalyzer.analyzeSafely(e);
             if (handling.log) {
               if (handling.logStackTrace) {
                 StringBuilder sb = new StringBuilder("Exception in executing dispatcher - retrying");

diff --git a/nflow-engine/src/test/java/io/nflow/engine/exception/DispatcherExceptionAnalyzerTest.java b/nflow-engine/src/test/java/io/nflow/engine/exception/DispatcherExceptionAnalyzerTest.java
@@ -16,7 +16,7 @@ public class DispatcherExceptionAnalyzerTest {
 
   @Test
   void analyzeGenericExceptionReturnsDefaults() {
-    DispatcherExceptionHandling handling = analyzer.analyze(new Exception());
+    DispatcherExceptionHandling handling = analyzer.analyzeSafely(new Exception());
 
     assertTrue(handling.log);
     assertEquals(handling.logLevel, Level.ERROR);
@@ -27,7 +27,7 @@ void analyzeGenericExceptionReturnsDefaults() {
 
   @Test
   void analyzePollingRaceConditionException() {
-    DispatcherExceptionHandling handling = analyzer.analyze(new PollingRaceConditionException("error"));
+    DispatcherExceptionHandling handling = analyzer.analyzeSafely(new PollingRaceConditionException("error"));
 
     assertTrue(handling.log);
     assertEquals(handling.logLevel, Level.DEBUG);
@@ -38,7 +38,7 @@ void analyzePollingRaceConditionException() {
 
   @Test
   void analyzePollingBatchException() {
-    DispatcherExceptionHandling handling = analyzer.analyze(new PollingBatchException("error"));
+    DispatcherExceptionHandling handling = analyzer.analyzeSafely(new PollingBatchException("error"));
 
     assertTrue(handling.log);
     assertEquals(handling.logLevel, Level.WARN);
@@ -48,9 +48,41 @@ void analyzePollingBatchException() {
 
   @Test
   void analyzeInterruptedException() {
-    DispatcherExceptionHandling handling = analyzer.analyze(new InterruptedException());
+    DispatcherExceptionHandling handling = analyzer.analyzeSafely(new InterruptedException());
 
     assertFalse(handling.log);
     assertFalse(handling.sleep);
   }
+
+  @Test
+  void customAnalyzerCanBeUsed() {
+    DispatcherExceptionAnalyzer customAnalyzer = new DispatcherExceptionAnalyzer() {
+      @Override
+      protected DispatcherExceptionHandling analyze(Exception e) {
+        return new DispatcherExceptionHandling.Builder().setLogStackTrace(false).build();
+      }
+    };
+
+    DispatcherExceptionHandling handling = customAnalyzer.analyzeSafely(new Exception());
+
+    assertFalse(handling.logStackTrace);
+  }
+
+  @Test
+  void defaultAnalyzerIsUsedWhenCustomerAnalyzerFails() {
+    DispatcherExceptionAnalyzer customAnalyzer = new DispatcherExceptionAnalyzer() {
+      @Override
+      protected DispatcherExceptionHandling analyze(Exception e) {
+        throw new IllegalStateException("fail");
+      }
+    };
+
+    DispatcherExceptionHandling handling = customAnalyzer.analyzeSafely(new Exception());
+
+    assertTrue(handling.log);
+    assertEquals(handling.logLevel, Level.ERROR);
+    assertTrue(handling.logStackTrace);
+    assertTrue(handling.sleep);
+    assertFalse(handling.randomizeSleep);
+  }
 }
diff --git a/nflow-engine/src/test/java/io/nflow/engine/exception/StateSaveExceptionAnalyzerTest.java b/nflow-engine/src/test/java/io/nflow/engine/exception/StateSaveExceptionAnalyzerTest.java
@@ -25,7 +25,7 @@ void defaultAnalyzerReturnsConfiguredDelay() {
   }
 
   @Test
-  void customerAnalyzerCanBeUsed() {
+  void customAnalyzerCanBeUsed() {
     StateSaveExceptionAnalyzer analyzer = new StateSaveExceptionAnalyzer(env) {
       @Override
       protected StateSaveExceptionHandling analyze(Exception e, int saveRetryCount) {