dimas-b commented on code in PR #1528: URL: https://github.com/apache/polaris/pull/1528#discussion_r2078288730
########## polaris-core/src/main/java/org/apache/polaris/core/persistence/pagination/ReadEverythingPageToken.java: ########## @@ -0,0 +1,95 @@ +/* + * 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.polaris.core.persistence.pagination; + +import java.util.List; + +/** + * A {@link PageToken} implementation for readers who want to read everything. The behavior when + * using this token should be the same as when reading without a token. + */ +public class ReadEverythingPageToken extends PageToken { + + private ReadEverythingPageToken() { + this.pageSize = Integer.MAX_VALUE; + validate(); + } + + /** Get a {@link ReadEverythingPageToken} */ + public static ReadEverythingPageToken get() { + return new ReadEverythingPageToken(); + } + + public static PageTokenBuilder<ReadEverythingPageToken> builder() { + return new ReadEverythingPageTokenBuilder(); + } + + @Override + protected PageTokenBuilder<?> getBuilder() { + return builder(); + } + + /** A {@link PageTokenBuilder} implementation for {@link ReadEverythingPageToken} */ + public static class ReadEverythingPageTokenBuilder Review Comment: Why not leverage generated builders by using `@PolarisImmutable`? ########## polaris-core/src/main/java/org/apache/polaris/core/persistence/pagination/PageToken.java: ########## @@ -0,0 +1,179 @@ +/* + * 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.polaris.core.persistence.pagination; + +import java.nio.charset.StandardCharsets; +import java.util.Arrays; +import java.util.Base64; +import java.util.List; +import java.util.stream.Collectors; +import java.util.stream.Stream; + +/** + * Represents a page token that can be used by operations like `listTables`. Clients that specify a + * `pageSize` (or a `pageToken`) may receive a `next-page-token` in the response, the content of + * which is a serialized PageToken. + * + * <p>By providing that in the next query's `pageToken`, the client can resume listing where they + * left off. If the client provides a `pageToken` or `pageSize` but `next-page-token` is null in the + * response, that means there is no more data to read. + */ +public abstract class PageToken { + + public int pageSize; + + public static final PageToken END = null; + public static final int DEFAULT_PAGE_SIZE = 1000; + + protected void validate() { + if (pageSize <= 0) { + throw new IllegalArgumentException("Page size must be greater than zero"); + } + } + + /** + * Get a new PageTokenBuilder from a PageToken. The PageTokenBuilder type should match the + * PageToken type. Implementations may also provide a static `builder` method to obtain the same + * PageTokenBuilder. + */ + protected abstract PageTokenBuilder<?> getBuilder(); + + /** Allows `PageToken` implementations to implement methods like `fromLimit` */ + public abstract static class PageTokenBuilder<T extends PageToken> { + + /** + * A prefix that tokens are expected to start with, ideally unique across `PageTokenBuilder` + * implementations. + */ + public abstract String tokenPrefix(); + + /** + * The number of expected components in a token. This should match the number of components + * returned by getComponents and shouldn't account for the prefix or the checksum. + */ + public abstract int expectedComponents(); + + /** Deserialize a string into a {@link PageToken} */ + public final PageToken fromString(String tokenString) { + if (tokenString == null) { + throw new IllegalArgumentException("Cannot build page token from null string"); + } else if (tokenString.isEmpty()) { + if (this instanceof ReadEverythingPageToken.ReadEverythingPageTokenBuilder) { + return ReadEverythingPageToken.get(); Review Comment: Is `null` that much different from an empty string? Since the intention is to convey both the "page pointer" and the "page size" in `PageToken`, why have have a `from(@Nullable String token, int pageSize)` method? ########## polaris-core/src/main/java/org/apache/polaris/core/persistence/BasePersistence.java: ########## @@ -408,4 +414,7 @@ boolean hasChildren( default BasePersistence detach() { return this; } + + @Nonnull + PageToken.PageTokenBuilder<?> pageTokenBuilder(); Review Comment: minor: Builders are usually quite simple collectors of programmatically collected arguments. Here it looks like this is more of a "parser". I'd personally prefer builders to be generated (immutables), and have custom parser factory interface. ########## polaris-core/src/main/java/org/apache/polaris/core/persistence/pagination/ReadEverythingPageToken.java: ########## @@ -0,0 +1,95 @@ +/* + * 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.polaris.core.persistence.pagination; + +import java.util.List; + +/** + * A {@link PageToken} implementation for readers who want to read everything. The behavior when + * using this token should be the same as when reading without a token. + */ +public class ReadEverythingPageToken extends PageToken { + + private ReadEverythingPageToken() { + this.pageSize = Integer.MAX_VALUE; + validate(); + } + + /** Get a {@link ReadEverythingPageToken} */ + public static ReadEverythingPageToken get() { + return new ReadEverythingPageToken(); + } + + public static PageTokenBuilder<ReadEverythingPageToken> builder() { + return new ReadEverythingPageTokenBuilder(); + } + + @Override + protected PageTokenBuilder<?> getBuilder() { + return builder(); + } + + /** A {@link PageTokenBuilder} implementation for {@link ReadEverythingPageToken} */ + public static class ReadEverythingPageTokenBuilder + extends PageTokenBuilder<ReadEverythingPageToken> { + + private ReadEverythingPageTokenBuilder() {} + + @Override + public String tokenPrefix() { + return "polaris-read-everything"; + } + + @Override + public int expectedComponents() { + return 0; + } + + @Override + protected ReadEverythingPageToken fromStringComponents(List<String> components) { + return ReadEverythingPageToken.get(); Review Comment: IMHO this is a skew in builder API and another point to my comment about "parser interface". The method signature reads as if components always matter, but they are ignored here. ########## polaris-core/src/main/java/org/apache/polaris/core/persistence/pagination/PageToken.java: ########## @@ -0,0 +1,179 @@ +/* + * 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.polaris.core.persistence.pagination; + +import java.nio.charset.StandardCharsets; +import java.util.Arrays; +import java.util.Base64; +import java.util.List; +import java.util.stream.Collectors; +import java.util.stream.Stream; + +/** + * Represents a page token that can be used by operations like `listTables`. Clients that specify a + * `pageSize` (or a `pageToken`) may receive a `next-page-token` in the response, the content of + * which is a serialized PageToken. + * + * <p>By providing that in the next query's `pageToken`, the client can resume listing where they + * left off. If the client provides a `pageToken` or `pageSize` but `next-page-token` is null in the + * response, that means there is no more data to read. + */ +public abstract class PageToken { + + public int pageSize; + + public static final PageToken END = null; + public static final int DEFAULT_PAGE_SIZE = 1000; + + protected void validate() { + if (pageSize <= 0) { + throw new IllegalArgumentException("Page size must be greater than zero"); + } + } + + /** + * Get a new PageTokenBuilder from a PageToken. The PageTokenBuilder type should match the + * PageToken type. Implementations may also provide a static `builder` method to obtain the same + * PageTokenBuilder. + */ + protected abstract PageTokenBuilder<?> getBuilder(); + + /** Allows `PageToken` implementations to implement methods like `fromLimit` */ + public abstract static class PageTokenBuilder<T extends PageToken> { + + /** + * A prefix that tokens are expected to start with, ideally unique across `PageTokenBuilder` + * implementations. + */ + public abstract String tokenPrefix(); + + /** + * The number of expected components in a token. This should match the number of components + * returned by getComponents and shouldn't account for the prefix or the checksum. + */ + public abstract int expectedComponents(); + + /** Deserialize a string into a {@link PageToken} */ + public final PageToken fromString(String tokenString) { + if (tokenString == null) { + throw new IllegalArgumentException("Cannot build page token from null string"); + } else if (tokenString.isEmpty()) { + if (this instanceof ReadEverythingPageToken.ReadEverythingPageTokenBuilder) { + return ReadEverythingPageToken.get(); + } else { + return fromLimit(DEFAULT_PAGE_SIZE); + } + } else { + try { + String decoded = + new String(Base64.getDecoder().decode(tokenString), StandardCharsets.UTF_8); + String[] parts = decoded.split(":"); + + // +2 to account for the prefix and checksum. + if (parts.length != expectedComponents() + 2 || !parts[0].equals(tokenPrefix())) { + throw new IllegalArgumentException("Invalid token format in token: " + tokenString); + } + + // Cut off prefix and checksum + T result = fromStringComponents(Arrays.asList(parts).subList(1, parts.length - 1)); + result.validate(); + return result; + } catch (Exception e) { + throw new IllegalArgumentException("Failed to decode page token: " + tokenString, e); Review Comment: nit: `Invalid page token: ...` (It's the client's fault, not server's) -- This is an automated message from the Apache Git Service. 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