Copilot commented on code in PR #12834: URL: https://github.com/apache/cloudstack/pull/12834#discussion_r2945859257
########## plugins/network-elements/nsx/src/main/java/org/apache/cloudstack/service/PagedFetcher.java: ########## @@ -0,0 +1,82 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you 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 +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// 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 org.apache.cloudstack.service; + +import java.util.ArrayList; +import java.util.List; +import java.util.Objects; +import java.util.function.BiConsumer; +import java.util.function.Function; + +class PagedFetcher<R, T> { + + private final Function<String, R> fetchPage; + private Function<R, String> cursorExtractor; + private Function<R, List<T>> itemsExtractor; + private BiConsumer<R, List<T>> itemsSetter; + + static <R, T> PagedFetcher<R, T> withPageFetcher(Function<String, R> pageFetcher) { + return new PagedFetcher<>(pageFetcher); + } + + PagedFetcher<R, T> cursorExtractor(Function<R, String> cursorProvider) { + this.cursorExtractor = cursorProvider; + return this; + } + + PagedFetcher<R, T> itemsExtractor(Function<R, List<T>> resultsProvider) { + this.itemsExtractor = resultsProvider; + return this; + } + + PagedFetcher<R, T> itemsSetter(BiConsumer<R, List<T>> resultsSetter) { + this.itemsSetter = resultsSetter; + return this; + } + + private PagedFetcher(Function<String, R> pageFetcher) { + this.fetchPage = pageFetcher; + } + + R fetchAll() { + Objects.requireNonNull(cursorExtractor, "Cursor extractor must be set"); + Objects.requireNonNull(itemsExtractor, "Items extractor must be set"); + Objects.requireNonNull(itemsSetter, "Items setter must be set"); + + R firstPage = fetchPage.apply(null); + String cursor = cursorExtractor.apply(firstPage); + if (cursor == null || cursor.isEmpty()) { + return firstPage; Review Comment: `fetchAll()` currently requires `itemsSetter` to be set even when the first page has no `cursor` (so the setter can never be invoked). Consider deferring the `Objects.requireNonNull(itemsSetter, ...)` check until after the early-return case (or make the setter optional) so single-page callers don’t need to provide a dummy setter. ########## plugins/network-elements/nsx/src/main/java/org/apache/cloudstack/service/PagedFetcher.java: ########## @@ -0,0 +1,82 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you 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 +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// 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 org.apache.cloudstack.service; + +import java.util.ArrayList; +import java.util.List; +import java.util.Objects; +import java.util.function.BiConsumer; +import java.util.function.Function; + +class PagedFetcher<R, T> { + + private final Function<String, R> fetchPage; + private Function<R, String> cursorExtractor; + private Function<R, List<T>> itemsExtractor; + private BiConsumer<R, List<T>> itemsSetter; + + static <R, T> PagedFetcher<R, T> withPageFetcher(Function<String, R> pageFetcher) { + return new PagedFetcher<>(pageFetcher); + } + + PagedFetcher<R, T> cursorExtractor(Function<R, String> cursorProvider) { + this.cursorExtractor = cursorProvider; + return this; + } + + PagedFetcher<R, T> itemsExtractor(Function<R, List<T>> resultsProvider) { + this.itemsExtractor = resultsProvider; + return this; + } + + PagedFetcher<R, T> itemsSetter(BiConsumer<R, List<T>> resultsSetter) { + this.itemsSetter = resultsSetter; + return this; + } + + private PagedFetcher(Function<String, R> pageFetcher) { + this.fetchPage = pageFetcher; + } + + R fetchAll() { + Objects.requireNonNull(cursorExtractor, "Cursor extractor must be set"); + Objects.requireNonNull(itemsExtractor, "Items extractor must be set"); + Objects.requireNonNull(itemsSetter, "Items setter must be set"); + + R firstPage = fetchPage.apply(null); + String cursor = cursorExtractor.apply(firstPage); + if (cursor == null || cursor.isEmpty()) { + return firstPage; + } + + List<T> firstResults = itemsExtractor.apply(firstPage); + List<T> allItems = firstResults != null + ? new ArrayList<>(firstResults) + : new ArrayList<>(); + while (cursor != null && !cursor.isEmpty()) { + R nextPage = fetchPage.apply(cursor); + List<T> nextItems = itemsExtractor.apply(nextPage); + if (nextItems != null && !nextItems.isEmpty()) { + allItems.addAll(nextItems); + } + cursor = cursorExtractor.apply(nextPage); Review Comment: `fetchAll()` assumes `fetchPage.apply(...)` never returns null; if it does, the subsequent extractor calls will throw an NPE without a clear message. Consider adding `Objects.requireNonNull` (or equivalent) for `firstPage` and each `nextPage` to fail fast with a descriptive error when the page fetcher unexpectedly returns null. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
