pingtimeout commented on code in PR #433: URL: https://github.com/apache/polaris/pull/433#discussion_r2109131986
########## service/common/src/main/java/org/apache/polaris/service/persistence/MetadataCacheManager.java: ########## @@ -0,0 +1,149 @@ +/* + * 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.service.persistence; + +import java.util.Map; +import java.util.function.Supplier; +import org.apache.iceberg.TableMetadata; +import org.apache.iceberg.TableMetadataParser; +import org.apache.iceberg.catalog.TableIdentifier; +import org.apache.polaris.core.PolarisCallContext; +import org.apache.polaris.core.config.FeatureConfiguration; +import org.apache.polaris.core.entity.PolarisEntity; +import org.apache.polaris.core.entity.PolarisEntitySubType; +import org.apache.polaris.core.entity.PolarisEntityType; +import org.apache.polaris.core.entity.table.IcebergTableLikeEntity; +import org.apache.polaris.core.entity.table.TableLikeEntity; +import org.apache.polaris.core.persistence.PolarisMetaStoreManager; +import org.apache.polaris.core.persistence.PolarisResolvedPathWrapper; +import org.apache.polaris.core.persistence.dao.entity.EntityResult; +import org.apache.polaris.core.persistence.resolver.PolarisResolutionManifestCatalogView; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Contains utility methods related to storing TableMetadata in the metastore and retrieving it from + * the metastore + */ +public class MetadataCacheManager { + private static final Logger LOGGER = LoggerFactory.getLogger(MetadataCacheManager.class); + + /** + * Load the cached metadata.json content and location or fall back to `fallback` if one doesn't + * exist. If the metadata is not currently cached, it may be added to the cache. + */ + public static TableMetadata loadTableMetadata( + TableIdentifier tableIdentifier, + int maxBytesToCache, + PolarisCallContext callContext, + PolarisMetaStoreManager metastoreManager, + PolarisResolutionManifestCatalogView resolvedEntityView, + Supplier<TableMetadata> fallback) { + PolarisResolvedPathWrapper resolvedEntities = + resolvedEntityView.getResolvedPath( + tableIdentifier, PolarisEntityType.TABLE_LIKE, PolarisEntitySubType.ICEBERG_TABLE); + // If the table doesn't exist, just fall back fast + if (resolvedEntities == null) { + return fallback.get(); + } + LOGGER.debug(String.format("Loading cached metadata for %s", tableIdentifier)); + IcebergTableLikeEntity tableLikeEntity = + IcebergTableLikeEntity.of(resolvedEntities.getRawLeafEntity()); + Map<String, String> tableEntityProperties = tableLikeEntity.getInternalPropertiesAsMap(); + String entityLocation = tableEntityProperties.get(IcebergTableLikeEntity.METADATA_LOCATION_KEY); + String cacheContent = + tableEntityProperties.get(IcebergTableLikeEntity.METADATA_CACHE_CONTENT_KEY); + String cacheLocation = + tableEntityProperties.get(IcebergTableLikeEntity.METADATA_CACHE_LOCATION_KEY); + if (cacheContent != null && !cacheContent.isEmpty() && entityLocation.equals(cacheLocation)) { + LOGGER.debug(String.format("Using cached metadata for %s", tableIdentifier)); + TableMetadata tableMetadata = TableMetadataParser.fromJson(cacheContent); + return TableMetadata.buildFrom(tableMetadata).withMetadataLocation(cacheLocation).build(); + } else { + TableMetadata fallbackMetadata = fallback.get(); + var cacheResult = + cacheTableMetadata( + tableLikeEntity, + fallbackMetadata, + maxBytesToCache, + callContext, + metastoreManager, + resolvedEntityView); + if (!cacheResult.isSuccess()) { + LOGGER.debug(String.format("Failed to cache metadata for %s", tableIdentifier)); + } + return fallbackMetadata; + } + } + + /** + * Attempt to add table metadata to the cache + * + * @return The result of trying to cache the metadata + */ + private static EntityResult cacheTableMetadata( + IcebergTableLikeEntity tableLikeEntity, + TableMetadata tableMetadata, + int maxBytesToCache, + PolarisCallContext callContext, + PolarisMetaStoreManager metaStoreManager, + PolarisResolutionManifestCatalogView resolvedEntityView) { + String metadataString = TableMetadataParser.toJson(tableMetadata); + if (maxBytesToCache + != FeatureConfiguration.Constants.METADATA_CACHE_MAX_BYTES_INFINITE_CACHING) { + if (metadataString.length() * 2 > maxBytesToCache) { Review Comment: Shouldn't this place use the constant APPROXIMATE_BYTES_PER_CHAR instead of * 2? -- This is an automated message from the Apache Git Service. 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