使用JavaRX将文档插入沙发库时引发DocumentAlreadyExistsException异常时如何继续下一个文档？

Question

我正在处理读取、转换和写入文档到 coucbase 的批处理作业。我正在使用 Java 批量插入文档。我不想使用 upsert，因为我想记录文档是否已经存在于 couchbase 中并调用了 insert。请在下面找到我的代码。当文档已经存在时，将引发 DocumentAlreadyExistsException 并且作业将停止，而不是继续处理下一个文档。如何处理这个问题？

代码：

    public void insertAll(Collection<JsonDocument> documents) {

    Observable.from(documents).flatMap(new Func1<JsonDocument, Observable<JsonDocument>>() {
        @Override
        public Observable<JsonDocument> call(final JsonDocument docToInsert) {
            return couchbaseConfig.catalogBucket().async().insert(docToInsert)
                    .doOnError((Throwable throwable) -> log.error(
                            "Exception {} occured while inerting document {} to cb", throwable.getMessage(),
                            docToInsert));
        }
    }).last().toBlocking().single();

}

例外：

com.couchbase.client.java.error.DocumentAlreadyExistsException: null
at com.couchbase.client.java.bucket.api.Mutate$1$1.call(Mutate.java:154) ~[java-client-2.7.4.jar:na]
at com.couchbase.client.java.bucket.api.Mutate$1$1.call(Mutate.java:132) ~[java-client-2.7.4.jar:na]
at rx.internal.operators.OnSubscribeMap$MapSubscriber.onNext(OnSubscribeMap.java:69) ~[rxjava-1.3.8.jar:1.3.8]
at rx.observers.Subscribers$5.onNext(Subscribers.java:235) ~[rxjava-1.3.8.jar:1.3.8]
at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onNext(OnSubscribeDoOnEach.java:101) ~[rxjava-1.3.8.jar:1.3.8]
at rx.internal.producers.SingleProducer.request(SingleProducer.java:65) ~[rxjava-1.3.8.jar:1.3.8]
at rx.Subscriber.setProducer(Subscriber.java:211) ~[rxjava-1.3.8.jar:1.3.8]
at rx.Subscriber.setProducer(Subscriber.java:205) ~[rxjava-1.3.8.jar:1.3.8]
at rx.Subscriber.setProducer(Subscriber.java:205) ~[rxjava-1.3.8.jar:1.3.8]
at rx.internal.operators.OnSubscribeMap$MapSubscriber.setProducer(OnSubscribeMap.java:102) ~[rxjava-1.3.8.jar:1.3.8]
at rx.Subscriber.setProducer(Subscriber.java:205) ~[rxjava-1.3.8.jar:1.3.8]
at rx.Subscriber.setProducer(Subscriber.java:205) ~[rxjava-1.3.8.jar:1.3.8]
at rx.subjects.AsyncSubject.onCompleted(AsyncSubject.java:103) ~[rxjava-1.3.8.jar:1.3.8]
at com.couchbase.client.core.endpoint.AbstractGenericHandler.completeResponse(AbstractGenericHandler.java:508) ~[core-io-1.7.4.jar:na]
at com.couchbase.client.core.endpoint.AbstractGenericHandler.access$000(AbstractGenericHandler.java:86) ~[core-io-1.7.4.jar:na]
at com.couchbase.client.core.endpoint.AbstractGenericHandler$1.call(AbstractGenericHandler.java:526) ~[core-io-1.7.4.jar:na]
at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55) ~[rxjava-1.3.8.jar:1.3.8]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[na:1.8.0_131]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_131]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) ~[na:1.8.0_131]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) ~[na:1.8.0_131]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) ~[na:1.8.0_131]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) ~[na:1.8.0_131]
at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_131]
Caused by: rx.exceptions.OnErrorThrowable$OnNextValue: OnError while emitting onNext value: com.couchbase.client.core.message.kv.InsertResponse.class
at rx.exceptions.OnErrorThrowable.addValueAsLastCause(OnErrorThrowable.java:118) ~[rxjava-1.3.8.jar:1.3.8]
at rx.internal.operators.OnSubscribeMap$MapSubscriber.onNext(OnSubscribeMap.java:73) ~[rxjava-1.3.8.jar:1.3.8]
... 21 common frames omitted

Answer 1

您可以使用onErrorResumeNext 来抑制错误，如下所示：

Observable.from(docs)
  .flatMap(docToInsert ->
    bucket.insert(docToInsert)
      .doOnError(t -> System.out.println("oops, error inserting " + docToInsert.id() + " : " + t))
      .onErrorResumeNext(t ->
        t instanceof DocumentAlreadyExistsException ? Observable.empty() : Observable.error(t))
  ).toCompletable().await();

请注意，toCompleteable().await() 即使没有发出任何项目也可以工作；如果所有文档都已经存在，single() 会抛出。