szetszwo commented on code in PR #733:
URL: https://github.com/apache/ratis/pull/733#discussion_r963468832
##########
ratis-common/src/main/java/org/apache/ratis/util/Daemon.java:
##########
@@ -17,24 +17,76 @@
*/
package org.apache.ratis.util;
+import javax.annotation.Nullable;
+import java.util.concurrent.atomic.AtomicReference;
+
public class Daemon extends Thread {
{
setDaemon(true);
}
- /** Construct a daemon thread. */
+ /** If the thread meets an uncaught exception, this field will be set. */
+ private final AtomicReference<Throwable> throwable = new
AtomicReference<>(null);
+ private ErrorRecorded statedServer;
+
+ /** Construct a daemon thread with no arguments, left only for extension. */
public Daemon() {
super();
+ setUncaughtExceptionHandler((thread, t) -> {
+ onError(t);
+ });
+ }
+
+ /** Construct a daemon thread with flexible arguments. */
+ public Daemon(Builder builder) {
+ super(builder.runnable);
+ setName(builder.name);
+ this.statedServer = builder.statedServer;
+ setUncaughtExceptionHandler((thread, t) -> {
+ onError(t);
+ });
+ }
+
+ /**
+ * This will be invoked on uncaught exceptions.
+ * Necessary bookkeeping or graceful exit logics should be put here.
+ *
+ * @param t the crashing error
+ */
+ public void onError(Throwable t) {
+ throwable.set(t);
+ if (statedServer != null) {
+ // Rely on the server to log
+ statedServer.setError(t);
+ }
}
- /** Construct a daemon thread with the given runnable. */
- public Daemon(Runnable runnable) {
- this(runnable, runnable.toString());
+ @Nullable
+ public Throwable getError() {
+ return throwable.get();
}
- /** Construct a daemon thread with the given runnable. */
- public Daemon(Runnable runnable, String name) {
- super(runnable);
- this.setName(name);
+ public static class Builder {
+ private final String name;
+ private Runnable runnable;
+ private ErrorRecorded statedServer;
+
+ public Builder(String name) {
Review Comment:
We may enforce it in the `build()` method as below:
```java
Objects.requireNonNull(name, "name == null");
```
A Builder should not have parameters in its constructor.
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