From 655df0d9c0714a408fb85cd822cbfff48375f49b Mon Sep 17 00:00:00 2001
From: Jonathan Cobb <jonathan@kyuss.org>
Date: Wed, 8 Jan 2020 04:52:01 -0500
Subject: [PATCH] improve exception handling in threads

---
 .../util/daemon/ExceptionHandler.java         | 25 +++++++++++++++
 .../cobbzilla/util/daemon/ZillaRuntime.java   | 23 ++------------
 .../org/cobbzilla/util/main/BaseMain.java     | 31 ++++++++++++-------
 3 files changed, 47 insertions(+), 32 deletions(-)
 create mode 100644 src/main/java/org/cobbzilla/util/daemon/ExceptionHandler.java

diff --git a/src/main/java/org/cobbzilla/util/daemon/ExceptionHandler.java b/src/main/java/org/cobbzilla/util/daemon/ExceptionHandler.java
new file mode 100644
index 0000000..90fe188
--- /dev/null
+++ b/src/main/java/org/cobbzilla/util/daemon/ExceptionHandler.java
@@ -0,0 +1,25 @@
+package org.cobbzilla.util.daemon;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public interface ExceptionHandler {
+
+    void handle(Exception e);
+
+    Logger log = LoggerFactory.getLogger(ExceptionHandler.class);
+
+    ExceptionHandler DEFAULT_EX_RUNNABLE = e -> log.error("Error: " + e);
+
+    static ExceptionHandler exceptionRunnable(Class<? extends Throwable>[] fatalExceptionClasses) {
+        return e -> {
+            for (Class<? extends Throwable> c : fatalExceptionClasses) {
+                if (c.isAssignableFrom(e.getClass())) {
+                    if (e instanceof RuntimeException) throw (RuntimeException) e;
+                    ZillaRuntime.die("fatal exception: "+e);
+                }
+            }
+            DEFAULT_EX_RUNNABLE.handle(e);
+        };
+    }
+}
diff --git a/src/main/java/org/cobbzilla/util/daemon/ZillaRuntime.java b/src/main/java/org/cobbzilla/util/daemon/ZillaRuntime.java
index 252a9ea..5d9f7e6 100644
--- a/src/main/java/org/cobbzilla/util/daemon/ZillaRuntime.java
+++ b/src/main/java/org/cobbzilla/util/daemon/ZillaRuntime.java
@@ -31,6 +31,7 @@ import static java.util.concurrent.TimeUnit.SECONDS;
 import static java.util.stream.LongStream.range;
 import static org.apache.commons.collections.CollectionUtils.collect;
 import static org.apache.commons.lang3.exception.ExceptionUtils.getStackTrace;
+import static org.cobbzilla.util.daemon.ExceptionHandler.DEFAULT_EX_RUNNABLE;
 import static org.cobbzilla.util.io.FileUtil.abs;
 import static org.cobbzilla.util.io.FileUtil.list;
 import static org.cobbzilla.util.reflect.ReflectionUtil.instantiate;
@@ -66,27 +67,9 @@ public class ZillaRuntime {
     public static boolean bool(Boolean b) { return b != null && b; }
     public static boolean bool(Boolean b, boolean val) { return b != null ? b : val; }
 
-    public interface ExceptionRunnable { void handle(Exception e); }
-
-    public static final ExceptionRunnable DEFAULT_EX_RUNNABLE = e -> {
-        log.error("Error: " + e);
-    };
-
-    public static ExceptionRunnable exceptionRunnable (Class<? extends Throwable>[] fatalExceptionClasses) {
-        return e -> {
-            for (Class<? extends Throwable> c : fatalExceptionClasses) {
-                if (c.isAssignableFrom(e.getClass())) {
-                    if (e instanceof RuntimeException) throw (RuntimeException) e;
-                    die("fatal exception: "+e);
-                }
-            }
-            DEFAULT_EX_RUNNABLE.handle(e);
-        };
-    }
-
     public static Thread background (Runnable r) { return background(r, DEFAULT_EX_RUNNABLE); }
 
-    public static Thread background (Runnable r, ExceptionRunnable ex) {
+    public static Thread background (Runnable r, ExceptionHandler ex) {
         final Thread t = new Thread(() -> {
             try {
                 r.run();
@@ -124,7 +107,7 @@ public class ZillaRuntime {
     public static <T> T retry (Callable<T> func,
                                int tries,
                                Function<Integer, Long> backoff,
-                               ExceptionRunnable ex) {
+                               ExceptionHandler ex) {
         Exception lastEx = null;
         try {
             for (int i = 0; i < tries; i++) {
diff --git a/src/main/java/org/cobbzilla/util/main/BaseMain.java b/src/main/java/org/cobbzilla/util/main/BaseMain.java
index 3a160d8..a354382 100644
--- a/src/main/java/org/cobbzilla/util/main/BaseMain.java
+++ b/src/main/java/org/cobbzilla/util/main/BaseMain.java
@@ -1,8 +1,10 @@
 package org.cobbzilla.util.main;
 
 import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
+import org.cobbzilla.util.daemon.ExceptionHandler;
 import org.cobbzilla.util.daemon.ZillaRuntime;
 import org.kohsuke.args4j.CmdLineException;
 import org.kohsuke.args4j.CmdLineParser;
@@ -22,18 +24,6 @@ public abstract class BaseMain<OPT extends BaseMainOptions> {
 
     protected abstract void run() throws Exception;
 
-    public void runOrDie () { try { run(); } catch (Exception e) { die("runOrDie: "+e, e); } }
-
-    public void runOrDie (ZillaRuntime.ExceptionRunnable errorHandler) {
-        try { run(); } catch (Exception e) { errorHandler.handle(e); }
-    }
-
-    public Thread runInBackground () { return background(this::runOrDie); }
-
-    public Thread runInBackground (ZillaRuntime.ExceptionRunnable errorHandler) {
-        return background(() -> runOrDie(errorHandler));
-    }
-
     @Getter private String[] args;
     public void setArgs(String[] args) throws CmdLineException {
         this.args = args;
@@ -116,4 +106,21 @@ public abstract class BaseMain<OPT extends BaseMainOptions> {
         System.exit(1);
         return null;
     }
+
+    public Thread runInBackground (ExceptionHandler errorHandler) {
+        return background(new RunWithHandler(this, errorHandler), errorHandler);
+    }
+
+    @AllArgsConstructor
+    private static class RunWithHandler implements Runnable {
+        private final BaseMain runnable;
+        private final ExceptionHandler errorHandler;
+        @Override public void run() {
+            try {
+                runnable.run();
+            } catch (Exception e) {
+                errorHandler.handle(e);
+            }
+        }
+    }
 }