| /* |
| * 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.cassandra.db.guardrails; |
| |
| import javax.annotation.Nullable; |
| |
| import org.apache.cassandra.config.DatabaseDescriptor; |
| import org.apache.cassandra.service.ClientState; |
| import org.apache.cassandra.utils.FBUtilities; |
| |
| /** |
| * Provider of {@link GuardrailsConfig}s for a {@link ClientState}. |
| * <p> |
| * The {@link Default} implementation always retuns the {@link GuardrailsConfig} parsed from {@code cassandra.yaml}, |
| * but different implementations can return different configurations based on the specified {@link ClientState}. |
| * <p> |
| * Custom implementations can be specified at runtime with the system property {@link #CUSTOM_IMPLEMENTATION_PROPERTY}. |
| * These configurations can be used to read the guardrails configuration from some other source, and provide different |
| * configurations depending on the {@link ClientState} or some other factors. However, this mechanism for pluggability |
| * and the related {@link GuardrailsConfig} interface are not officially supported and may change in a minor release. |
| */ |
| public interface GuardrailsConfigProvider |
| { |
| public static final String CUSTOM_IMPLEMENTATION_PROPERTY = "cassandra.custom_guardrails_config_provider_class"; |
| |
| static final GuardrailsConfigProvider instance = System.getProperty(CUSTOM_IMPLEMENTATION_PROPERTY) == null |
| ? new Default() |
| : build(System.getProperty(CUSTOM_IMPLEMENTATION_PROPERTY)); |
| |
| /** |
| * Returns the {@link GuardrailsConfig} to be used for the specified {@link ClientState}. |
| * |
| * @param state a client state, maybe {@code null} if the guardrails check for which we are getting the config is |
| * for a background process that is not associated to a user query. |
| * @return the configuration to be used for {@code state} |
| */ |
| GuardrailsConfig getOrCreate(@Nullable ClientState state); |
| |
| /** |
| * Creates an instance of the custom guardrails config provider of the given class. |
| * |
| * @param customImpl the fully qualified classname of the guardrails config provider to be instantiated |
| * @return a new instance of the specified custom guardrails config provider of the given class. |
| */ |
| static GuardrailsConfigProvider build(String customImpl) |
| { |
| return FBUtilities.construct(customImpl, "custom guardrails config provider"); |
| } |
| |
| /** |
| * Default implementation of {@link GuardrailsConfigProvider} that always returns the {@link GuardrailsConfig} |
| * parsed from {@code cassandra.yaml}, independently of the {@link ClientState}. |
| */ |
| class Default implements GuardrailsConfigProvider |
| { |
| @Override |
| public GuardrailsConfig getOrCreate(@Nullable ClientState state) |
| { |
| return DatabaseDescriptor.getGuardrailsConfig(); |
| } |
| } |
| } |