Mention exception in log message on failures

db-scheduler/src/main/java/com/github/kagkarlsson/scheduler/ExceptionUtils.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) Gustav Karlsson
+ *
+ * <p>Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of the License at
+ *
+ * <p>http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * <p>Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.github.kagkarlsson.scheduler;
+
+final class ExceptionUtils {
+
+  static String describe(Throwable t) {
+    if (t == null) {
+      return null;
+    }
+
+    String typeDescription = t.getClass().getSimpleName();
+    String message = t.getMessage();
+    return typeDescription + (message != null ? ": '" + message + "'" : "");
+  }
+
+  private ExceptionUtils() {}
+}

db-scheduler/src/main/java/com/github/kagkarlsson/scheduler/ExecutePicked.java

@@ -13,6 +13,8 @@
  */
 package com.github.kagkarlsson.scheduler;
 
+import static com.github.kagkarlsson.scheduler.ExceptionUtils.describe;
+
 import com.github.kagkarlsson.scheduler.logging.ConfigurableLogger;
 import com.github.kagkarlsson.scheduler.stats.StatsRegistry;
 import com.github.kagkarlsson.scheduler.task.CompletionHandler;
@@ -129,9 +131,10 @@ private void complete(
       statsRegistry.register(StatsRegistry.SchedulerStatsEvent.COMPLETIONHANDLER_ERROR);
       statsRegistry.register(StatsRegistry.SchedulerStatsEvent.UNEXPECTED_ERROR);
       LOG.error(
-          "Failed while completing execution {}. Execution will likely remain scheduled and locked/picked. "
+          "Failed while completing execution {}, because {}. Execution will likely remain scheduled and locked/picked. "
               + "The execution should be detected as dead after a while, and handled according to the tasks DeadExecutionHandler.",
           execution,
+          describe(e),
           e);
     }
   }
@@ -142,9 +145,8 @@ private void failure(
       Throwable cause,
       Instant executionStarted,
       String errorMessagePrefix) {
-    String logMessage =
-        errorMessagePrefix + " during execution of task with name '{}'. Treating as failure.";
-    failureLogger.log(logMessage, cause, task.getName());
+    String logMessage = "{} {} during execution of task with name '{}'. Treating as failure.";
+    failureLogger.log(logMessage, cause, errorMessagePrefix, describe(cause), task.getName());
 
     ExecutionComplete completeEvent =
         ExecutionComplete.failure(execution, executionStarted, clock.now(), cause);
@@ -158,9 +160,10 @@ private void failure(
       statsRegistry.register(StatsRegistry.SchedulerStatsEvent.FAILUREHANDLER_ERROR);
       statsRegistry.register(StatsRegistry.SchedulerStatsEvent.UNEXPECTED_ERROR);
       LOG.error(
-          "Failed while completing execution {}. Execution will likely remain scheduled and locked/picked. "
+          "Failed while completing execution {}, because {}. Execution will likely remain scheduled and locked/picked. "
               + "The execution should be detected as dead after a while, and handled according to the tasks DeadExecutionHandler.",
           execution,
+          describe(cause),
           e);
     }
   }

db-scheduler/src/test/java/com/github/kagkarlsson/scheduler/ExceptionUtilsTest.java

@@ -0,0 +1,28 @@
+package com.github.kagkarlsson.scheduler;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.nullValue;
+
+import java.io.IOException;
+import org.junit.jupiter.api.Test;
+
+class ExceptionUtilsTest {
+
+  @Test
+  void exceptionWithNoMessageDescribedAsItsClassSimpleName() {
+    assertThat(
+        ExceptionUtils.describe(new IllegalArgumentException()), is("IllegalArgumentException"));
+  }
+
+  @Test
+  void exceptionDescribedAsClassSimpleNameAndMessage() {
+    assertThat(
+        ExceptionUtils.describe(new IOException("timed out")), is("IOException: 'timed out'"));
+  }
+
+  @Test
+  void describingNullIsNull() {
+    assertThat(ExceptionUtils.describe(null), is(nullValue()));
+  }
+}