| // Copyright 2017 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.rules.python; |
| |
| import static com.google.common.base.Preconditions.checkArgument; |
| import static com.google.common.base.Preconditions.checkNotNull; |
| |
| import com.google.common.collect.ImmutableSet; |
| import com.google.devtools.build.lib.analysis.config.BuildOptions; |
| import com.google.devtools.build.lib.analysis.config.BuildOptionsCache; |
| import com.google.devtools.build.lib.analysis.config.BuildOptionsView; |
| import com.google.devtools.build.lib.analysis.config.FragmentOptions; |
| import com.google.devtools.build.lib.analysis.config.transitions.PatchTransition; |
| import com.google.devtools.build.lib.events.EventHandler; |
| import com.google.errorprone.annotations.Immutable; |
| |
| /** |
| * An abstract configuration transition that sets the Python version as per its {@link |
| * #determineNewVersion} method, if transitioning is allowed. |
| * |
| * <p>See {@link PythonOptions#canTransitionPythonVersion} for information on when transitioning is |
| * allowed. |
| */ |
| @Immutable |
| public abstract class PythonVersionTransition implements PatchTransition { |
| |
| /** Returns a transition that sets the version to {@code newVersion}. */ |
| public static PythonVersionTransition toConstant(PythonVersion newVersion) { |
| return new ToConstant(newVersion); |
| } |
| |
| /** |
| * Returns a transition that sets the version to {@link PythonOptions#getDefaultPythonVersion}. |
| */ |
| public static PythonVersionTransition toDefault() { |
| return ToDefault.INSTANCE; |
| } |
| |
| private PythonVersionTransition() {} |
| |
| /** |
| * Returns the Python version to transition to, given the configuration. |
| * |
| * <p>Must return a target Python version ({@code PY2} or {@code PY3}). |
| * |
| * <p>Caution: This method must not modify {@code options}. See the class javadoc for {@link |
| * PatchTransition}. |
| */ |
| protected abstract PythonVersion determineNewVersion(BuildOptionsView options); |
| |
| // We added this cache after observing an O(100,000)-node build graph that applied multiple exec |
| // transitions to Python 3 tools on every node. Before this cache, this produced O(100,000) |
| // BuildOptions instances that consumed about a gigabyte of memory. |
| private static final BuildOptionsCache<PythonVersion> cache = |
| new BuildOptionsCache<>(PythonVersionTransition::transitionImpl); |
| |
| @Override |
| public ImmutableSet<Class<? extends FragmentOptions>> requiresOptionFragments() { |
| return ImmutableSet.of(PythonOptions.class); |
| } |
| |
| @Override |
| public BuildOptions patch(BuildOptionsView options, EventHandler eventHandler) { |
| PythonVersion newVersion = determineNewVersion(options); |
| checkArgument(newVersion.isTargetValue(), newVersion); |
| |
| PythonOptions opts = options.get(PythonOptions.class); |
| if (!opts.canTransitionPythonVersion(newVersion)) { |
| return options.underlying(); |
| } |
| return cache.applyTransition(options, newVersion); |
| } |
| |
| private static BuildOptions transitionImpl(BuildOptionsView options, PythonVersion newVersion) { |
| BuildOptionsView newOptions = options.clone(); |
| PythonOptions newOpts = newOptions.get(PythonOptions.class); |
| newOpts.setPythonVersion(newVersion); |
| return newOptions.underlying(); |
| } |
| |
| /** A Python version transition that switches to the value specified in the constructor. */ |
| private static final class ToConstant extends PythonVersionTransition { |
| |
| private final PythonVersion newVersion; |
| |
| ToConstant(PythonVersion newVersion) { |
| this.newVersion = checkNotNull(newVersion); |
| } |
| |
| @Override |
| protected PythonVersion determineNewVersion(BuildOptionsView options) { |
| return newVersion; |
| } |
| |
| @Override |
| public boolean equals(Object other) { |
| if (this == other) { |
| return true; |
| } |
| if (!(other instanceof ToConstant)) { |
| return false; |
| } |
| return newVersion.equals(((ToConstant) other).newVersion); |
| } |
| |
| @Override |
| public int hashCode() { |
| return 37 * ToConstant.class.hashCode() + newVersion.hashCode(); |
| } |
| } |
| |
| /** A Python version transition that switches to the default given in the Python configuration. */ |
| private static final class ToDefault extends PythonVersionTransition { |
| |
| private static final ToDefault INSTANCE = new ToDefault(); |
| |
| // Singleton. |
| private ToDefault() {} |
| |
| @Override |
| protected PythonVersion determineNewVersion(BuildOptionsView options) { |
| return options.get(PythonOptions.class).getDefaultPythonVersion(); |
| } |
| } |
| } |