flink-doris-connector/src/main/java/org/apache/doris/flink/sink/writer/serializer/jsondebezium/JsonDebeziumSchemaChange.java

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package org.apache.doris.flink.sink.writer.serializer.jsondebezium;

import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.CollectionUtil;
import org.apache.flink.util.StringUtils;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.NullNode;
import org.apache.doris.flink.cfg.DorisOptions;
import org.apache.doris.flink.sink.schema.SchemaChangeManager;
import org.apache.doris.flink.sink.writer.ChangeEvent;
import org.apache.doris.flink.tools.cdc.SourceSchema;

import java.util.Map;
import java.util.regex.Pattern;

/**
 * Synchronize the schema change in the upstream data source to the doris database table.
 *
 * <p>There are two schema change modes:<br>
 * 1. {@link JsonDebeziumSchemaChangeImpl} only supports table column name and column type changes,
 * and this mode is used by default. <br>
 * 2. {@link JsonDebeziumSchemaChangeImplV2} supports table column name, column type, default,
 * comment synchronization, supports multi-column changes, and supports column name rename. Need to
 * be enabled by configuring use-new-schema-change.
 */
public abstract class JsonDebeziumSchemaChange implements ChangeEvent {
    protected static String addDropDDLRegex =
            "ALTER\\s+TABLE\\s+[^\\s]+\\s+(ADD|DROP)\\s+(COLUMN\\s+)?([^\\s]+)(\\s+([^\\s]+))?.*";
    protected Pattern addDropDDLPattern;

    // table name of the cdc upstream, format is db.tbl
    protected String sourceTableName;
    protected DorisOptions dorisOptions;
    protected ObjectMapper objectMapper;
    // <cdc db.schema.table, doris db.table>
    protected Map<String, String> tableMapping;
    protected SchemaChangeManager schemaChangeManager;
    protected JsonDebeziumChangeContext changeContext;

    public abstract boolean schemaChange(JsonNode recordRoot);

    public abstract void init(JsonNode recordRoot);

    /** When cdc synchronizes multiple tables, it will capture multiple table schema changes. */
    protected boolean checkTable(JsonNode recordRoot) {
        String db = extractDatabase(recordRoot);
        String tbl = extractTable(recordRoot);
        String dbTbl = db + "." + tbl;
        return sourceTableName.equals(dbTbl);
    }

    protected String extractDatabase(JsonNode record) {
        if (record.get("source").has("schema")) {
            // compatible with schema
            return extractJsonNode(record.get("source"), "schema");
        } else {
            return extractJsonNode(record.get("source"), "db");
        }
    }

    protected String extractTable(JsonNode record) {
        return extractJsonNode(record.get("source"), "table");
    }

    protected String extractJsonNode(JsonNode record, String key) {
        return record != null && record.get(key) != null && !(record.get(key) instanceof NullNode)
                ? record.get(key).asText()
                : null;
    }

    @VisibleForTesting
    public String getDorisTableIdentifier(String cdcTableIdentifier) {
        if (!StringUtils.isNullOrWhitespaceOnly(dorisOptions.getTableIdentifier())) {
            return dorisOptions.getTableIdentifier();
        }
        if (!CollectionUtil.isNullOrEmpty(tableMapping)
                && !StringUtils.isNullOrWhitespaceOnly(cdcTableIdentifier)
                && tableMapping.get(cdcTableIdentifier) != null) {
            return tableMapping.get(cdcTableIdentifier);
        }
        return null;
    }

    protected String getDorisTableIdentifier(JsonNode record) {
        String identifier = getCdcTableIdentifier(record);
        return getDorisTableIdentifier(identifier);
    }

    protected Tuple2<String, String> getDorisTableTuple(JsonNode record) {
        String identifier = getDorisTableIdentifier(record);
        if (StringUtils.isNullOrWhitespaceOnly(identifier)) {
            return null;
        }
        String[] tableInfo = identifier.split("\\.");
        if (tableInfo.length != 2) {
            return null;
        }
        return Tuple2.of(tableInfo[0], tableInfo[1]);
    }

    @VisibleForTesting
    public String getCdcTableIdentifier(JsonNode record) {
        String db = extractJsonNode(record.get("source"), "db");
        String schema = extractJsonNode(record.get("source"), "schema");
        String table = extractJsonNode(record.get("source"), "table");
        return SourceSchema.getString(db, schema, table);
    }

    protected JsonNode extractHistoryRecord(JsonNode record) throws JsonProcessingException {
        if (record != null && record.has("historyRecord")) {
            return objectMapper.readTree(record.get("historyRecord").asText());
        }
        // The ddl passed by some scenes will not be included in the historyRecord,
        // such as DebeziumSourceFunction
        return record;
    }

    @VisibleForTesting
    public void setSchemaChangeManager(SchemaChangeManager schemaChangeManager) {
        this.schemaChangeManager = schemaChangeManager;
    }
}