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WriteAvroSchemaAttributeStrategy.java
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WriteAvroSchemaAttributeStrategy.java
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/*
* 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.nifi.schema.access;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Collections;
import java.util.EnumSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import org.apache.avro.Schema;
import org.apache.nifi.avro.AvroTypeUtil;
import org.apache.nifi.serialization.record.RecordSchema;
public class WriteAvroSchemaAttributeStrategy implements SchemaAccessWriter {
private final Map<RecordSchema, String> avroSchemaTextCache = new LinkedHashMap<RecordSchema, String>() {
@Override
protected boolean removeEldestEntry(Map.Entry<RecordSchema, String> eldest) {
return size() > 10;
}
};
@Override
public void writeHeader(final RecordSchema schema, final OutputStream out) throws IOException {
}
@Override
public Map<String, String> getAttributes(final RecordSchema schema) {
// First, check if schema has the Avro Text available already.
final Optional<String> schemaFormat = schema.getSchemaFormat();
if (schemaFormat.isPresent() && AvroTypeUtil.AVRO_SCHEMA_FORMAT.equals(schemaFormat.get())) {
final Optional<String> schemaText = schema.getSchemaText();
if (schemaText.isPresent()) {
return Collections.singletonMap("avro.schema", schemaText.get());
}
}
String schemaText = avroSchemaTextCache.get(schema);
if (schemaText == null) {
final Schema avroSchema = AvroTypeUtil.extractAvroSchema(schema);
schemaText = avroSchema.toString();
avroSchemaTextCache.put(schema, schemaText);
}
return Collections.singletonMap("avro.schema", schemaText);
}
@Override
public void validateSchema(final RecordSchema schema) throws SchemaNotFoundException {
}
@Override
public Set<SchemaField> getRequiredSchemaFields() {
return EnumSet.noneOf(SchemaField.class);
}
}