Github user mattyb149 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/2735#discussion_r191038313
--- Diff:
nifi-nar-bundles/nifi-standard-services/nifi-dbcp-service-bundle/nifi-dbcp-service/src/main/java/org/apache/nifi/dbcp/DBCPConnectionPoolLookup.java
---
@@ -0,0 +1,140 @@
+/*
+ * 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.dbcp;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.nifi.annotation.behavior.DynamicProperty;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnDisabled;
+import org.apache.nifi.annotation.lifecycle.OnEnabled;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.controller.AbstractControllerService;
+import org.apache.nifi.controller.ConfigurationContext;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+
+import java.sql.Connection;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@Tags({ "dbcp", "jdbc", "database", "connection", "pooling", "store" })
+@CapabilityDescription("Provides a DBCPService that can be used to
dynamically select another DBCPService. This service " +
+ "requires an attribute named 'database.name' to be passed in when
asking for a connection, and will throw an exception " +
+ "if the attribute is missing. The value of 'database.name' will be
used to select the DBCPService that has been " +
+ "registered with that name. This will allow multiple DBCPServices
to be defined and registered, and then selected " +
+ "dynamically at runtime by tagging flow files with the appropriate
'database.name' attribute.")
+@DynamicProperty(name = "The ", value = "JDBC property value",
expressionLanguageScope = ExpressionLanguageScope.NONE,
+ description = "")
+public class DBCPConnectionPoolLookup extends AbstractControllerService
implements DBCPService {
+
+ public static final String DATABASE_NAME_ATTRIBUTE = "database.name";
+
+ private volatile Map<String,DBCPService> dbcpServiceMap;
+
+ @Override
+ protected PropertyDescriptor
getSupportedDynamicPropertyDescriptor(final String propertyDescriptorName) {
+ return new PropertyDescriptor.Builder()
+ .name(propertyDescriptorName)
+ .description("The DBCPService to return when database.name
= '" + propertyDescriptorName + "'")
+ .identifiesControllerService(DBCPService.class)
+ .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+ .build();
+ }
+
+ @Override
+ protected Collection<ValidationResult>
customValidate(ValidationContext context) {
+ final List<ValidationResult> results = new ArrayList<>();
+
+ int numDefinedServices = 0;
+ for (final PropertyDescriptor descriptor :
context.getProperties().keySet()) {
+ if (descriptor.isDynamic()) {
+ numDefinedServices++;
+ }
+
+ final String referencedId =
context.getProperty(descriptor).getValue();
+ if (this.getIdentifier().equals(referencedId)) {
+ results.add(new ValidationResult.Builder()
+ .subject(descriptor.getDisplayName())
+ .explanation("the current service cannot be
registered as a DBCPService to lookup")
+ .valid(false)
+ .build());
+ }
+ }
+
+ if (numDefinedServices == 0) {
+ results.add(new ValidationResult.Builder()
+ .subject(this.getClass().getSimpleName())
+ .explanation("at least one DBCPService must be defined
via dynamic properties")
+ .valid(false)
+ .build());
+ }
+
+ return results;
+ }
+
+ @OnEnabled
+ public void onEnabled(final ConfigurationContext context) {
+ final Map<String,DBCPService> serviceMap = new HashMap<>();
+
+ for (final PropertyDescriptor descriptor :
context.getProperties().keySet()) {
+ if (descriptor.isDynamic()) {
+ final DBCPService dbcpService =
context.getProperty(descriptor).asControllerService(DBCPService.class);
+ serviceMap.put(descriptor.getName(), dbcpService);
+ }
+ }
+
+ dbcpServiceMap = Collections.unmodifiableMap(serviceMap);
+ }
+
+ @OnDisabled
+ public void onDisabled() {
+ dbcpServiceMap = null;
+ }
+
+ @Override
+ public Connection getConnection() throws ProcessException {
+ throw new UnsupportedOperationException("Cannot lookup
DBCPConnectionPool without attributes");
--- End diff --
Should there be a property or something for a default connection pool?
---
