src/main/java/com/google/devtools/build/lib/runtime/ServerBuilder.java

// Copyright 2016 The Bazel Authors. All rights reserved.
//
// Licensed 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 com.google.devtools.build.lib.runtime;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.packages.AttributeContainer;
import com.google.devtools.build.lib.packages.RuleClass;
import com.google.devtools.build.lib.query2.AbstractBlazeQueryEnvironment;
import com.google.devtools.build.lib.query2.QueryEnvironmentFactory;
import com.google.devtools.build.lib.runtime.proto.InvocationPolicyOuterClass.InvocationPolicy;
import com.google.devtools.build.lib.util.Preconditions;

/**
 * Builder class to create a {@link BlazeRuntime} instance. This class is part of the module API,
 * which allows modules to affect how the server is initialized.
 */
public final class ServerBuilder {
  private QueryEnvironmentFactory queryEnvironmentFactory;
  private final InvocationPolicy.Builder invocationPolicyBuilder = InvocationPolicy.newBuilder();
  private Function<RuleClass, AttributeContainer> attributeContainerFactory;
  private final ImmutableList.Builder<BlazeCommand> commands = ImmutableList.builder();

  @VisibleForTesting
  public ServerBuilder() {}

  QueryEnvironmentFactory getQueryEnvironmentFactory() {
    return queryEnvironmentFactory == null
        ? new QueryEnvironmentFactory()
        : queryEnvironmentFactory;
  }

  InvocationPolicy getInvocationPolicy() {
    return invocationPolicyBuilder.build();
  }

  Function<RuleClass, AttributeContainer> getAttributeContainerFactory() {
    return attributeContainerFactory == null
        ? AttributeContainer.ATTRIBUTE_CONTAINER_FACTORY
        : attributeContainerFactory;
  }

  @VisibleForTesting
  public ImmutableList<BlazeCommand> getCommands() {
    return commands.build();
  }

  /**
   * Merges the given invocation policy into the per-server invocation policy. While this can accept
   * any number of policies, the end result is order-dependent if multiple policies attempt to
   * police the same options, so it's probably a good idea to not have too many modules that call
   * this.
   */
  public ServerBuilder addInvocationPolicy(InvocationPolicy policy) {
    invocationPolicyBuilder.mergeFrom(Preconditions.checkNotNull(policy));
    return this;
  }

  /**
   * Sets a factory for creating {@link AbstractBlazeQueryEnvironment} instances. Note that only one
   * factory per server is allowed. If none is set, the server uses the default implementation.
   */
  public ServerBuilder setQueryEnvironmentFactory(QueryEnvironmentFactory queryEnvironmentFactory) {
    Preconditions.checkState(
        this.queryEnvironmentFactory == null,
        "At most one query environment factory supported. But found two: %s and %s",
        this.queryEnvironmentFactory,
        queryEnvironmentFactory);
    this.queryEnvironmentFactory = Preconditions.checkNotNull(queryEnvironmentFactory);
    return this;
  }

  /**
   * Sets a factory for creating {@link AttributeContainer} instances. Only one factory per server
   * is allowed. If none is set, the server uses the default implementation.
   */
  public ServerBuilder setAttributeContainerFactory(
      Function<RuleClass, AttributeContainer> attributeContainerFactory) {
    Preconditions.checkState(
        this.attributeContainerFactory == null,
        "At most one attribute container factory supported. But found two: %s and %s",
        this.attributeContainerFactory,
        attributeContainerFactory);
    this.attributeContainerFactory = Preconditions.checkNotNull(attributeContainerFactory);
    return this;
  }

  /**
   * Adds the given command to the server. This overload only exists to avoid array object creation
   * in the common case.
   */
  public ServerBuilder addCommands(BlazeCommand command) {
    this.commands.add(Preconditions.checkNotNull(command));
    return this;
  }

  /** Adds the given commands to the server. */
  public ServerBuilder addCommands(BlazeCommand... commands) {
    this.commands.add(commands);
    return this;
  }
}