1 files changed, 276 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationCollection.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationCollection.java
new file mode 100644
index 0000000000..e36a6817bc
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationCollection.java
@@ -0,0 +1,276 @@
+// Copyright 2014 Google Inc. 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.analysis.config;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ListMultimap;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
+import com.google.devtools.build.lib.packages.Attribute;
+import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
+import com.google.devtools.build.lib.packages.Attribute.Transition;
+import com.google.devtools.build.lib.packages.InputFile;
+import com.google.devtools.build.lib.packages.PackageGroup;
+import com.google.devtools.build.lib.packages.Rule;
+import com.google.devtools.build.lib.packages.Target;
+
+import java.io.PrintStream;
+import java.io.Serializable;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * The primary container for all main {@link BuildConfiguration} instances,
+ * currently "target", "data", and "host".
+ *
+ * <p>The target configuration is used for all targets specified on the command
+ * line. Data dependencies of targets in the target configuration use the data
+ * configuration instead.
+ *
+ * <p>The host configuration is used for tools that are executed during the
+ * build, e. g, compilers.
+ *
+ * <p>The "related" configurations are also contained in this class.
+ */
+@ThreadSafe
+public final class BuildConfigurationCollection implements Serializable {
+  private final ImmutableList<BuildConfiguration> targetConfigurations;
+
+  public BuildConfigurationCollection(List<BuildConfiguration> targetConfigurations)
+      throws InvalidConfigurationException {
+    this.targetConfigurations = ImmutableList.copyOf(targetConfigurations);
+
+    // Except for the host configuration (which may be identical across target configs), the other
+    // configurations must all have different cache keys or we will end up with problems.
+    HashMap<String, BuildConfiguration> cacheKeyConflictDetector = new HashMap<>();
+    for (BuildConfiguration config : getAllConfigurations()) {
+      if (cacheKeyConflictDetector.containsKey(config.cacheKey())) {
+        throw new InvalidConfigurationException("Conflicting configurations: " + config + " & "
+            + cacheKeyConflictDetector.get(config.cacheKey()));
+      }
+      cacheKeyConflictDetector.put(config.cacheKey(), config);
+    }
+  }
+
+  /**
+   * Creates an empty configuration collection which will return null for everything.
+   */
+  public BuildConfigurationCollection() {
+    this.targetConfigurations = ImmutableList.of();
+  }
+
+  public static BuildConfiguration configureTopLevelTarget(BuildConfiguration topLevelConfiguration,
+      Target toTarget) {
+    if (toTarget instanceof InputFile || toTarget instanceof PackageGroup) {
+      return null;
+    }
+    return topLevelConfiguration.getTransitions().toplevelConfigurationHook(toTarget);
+  }
+
+  public ImmutableList<BuildConfiguration> getTargetConfigurations() {
+    return targetConfigurations;
+  }
+
+  /**
+   * Returns all configurations that can be reached from the target configuration through any kind
+   * of configuration transition.
+   */
+  public Collection<BuildConfiguration> getAllConfigurations() {
+    Set<BuildConfiguration> result = new LinkedHashSet<>();
+    for (BuildConfiguration config : targetConfigurations) {
+      result.addAll(config.getAllReachableConfigurations());
+    }
+    return result;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (!(obj instanceof BuildConfigurationCollection)) {
+      return false;
+    }
+    BuildConfigurationCollection that = (BuildConfigurationCollection) obj;
+    return this.targetConfigurations.equals(that.targetConfigurations);
+  }
+
+  @Override
+  public int hashCode() {
+    return targetConfigurations.hashCode();
+  }
+
+  /**
+   * Prints the configuration graph in dot format to the given print stream. This is only intended
+   * for debugging.
+   */
+  public void dumpAsDotGraph(PrintStream out) {
+    out.println("digraph g {");
+    out.println("  ratio = 0.3;");
+    for (BuildConfiguration config : getAllConfigurations()) {
+      String from = config.shortCacheKey();
+      for (Map.Entry<? extends Transition, ConfigurationHolder> entry :
+          config.getTransitions().getTransitionTable().entrySet()) {
+        BuildConfiguration toConfig = entry.getValue().getConfiguration();
+        if (toConfig == config) {
+          continue;
+        }
+        String to = toConfig == null ? "ERROR" : toConfig.shortCacheKey();
+        out.println("  \"" + from + "\" -> \"" + to + "\" [label=\"" + entry.getKey() + "\"]");
+      }
+    }
+    out.println("}");
+  }
+
+  /**
+   * The outgoing transitions for a build configuration.
+   */
+  public static class Transitions implements Serializable {
+    protected final BuildConfiguration configuration;
+
+    /**
+     * Look up table for the configuration transitions, i.e., HOST, DATA, etc.
+     */
+    private final Map<? extends Transition, ConfigurationHolder> transitionTable;
+
+    // TODO(bazel-team): Consider merging transitionTable into this.
+    private final ListMultimap<? super SplitTransition<?>, BuildConfiguration> splitTransitionTable;
+
+    public Transitions(BuildConfiguration configuration,
+        Map<? extends Transition, ConfigurationHolder> transitionTable,
+        ListMultimap<? extends SplitTransition<?>, BuildConfiguration> splitTransitionTable) {
+      this.configuration = configuration;
+      this.transitionTable = ImmutableMap.copyOf(transitionTable);
+      this.splitTransitionTable = ImmutableListMultimap.copyOf(splitTransitionTable);
+    }
+
+    public Transitions(BuildConfiguration configuration,
+        Map<? extends Transition, ConfigurationHolder> transitionTable) {
+      this(configuration, transitionTable,
+          ImmutableListMultimap.<SplitTransition<?>, BuildConfiguration>of());
+    }
+
+    public Map<? extends Transition, ConfigurationHolder> getTransitionTable() {
+      return transitionTable;
+    }
+
+    public ListMultimap<? super SplitTransition<?>, BuildConfiguration> getSplitTransitionTable() {
+      return splitTransitionTable;
+    }
+
+    public List<BuildConfiguration> getSplitConfigurations(SplitTransition<?> transition) {
+      if (splitTransitionTable.containsKey(transition)) {
+        return splitTransitionTable.get(transition);
+      } else {
+        Preconditions.checkState(transition.defaultsToSelf());
+        return ImmutableList.of(configuration);
+      }
+    }
+
+    /**
+     * Adds all configurations that are directly reachable from this configuration through
+     * any kind of configuration transition.
+     */
+    public void addDirectlyReachableConfigurations(Collection<BuildConfiguration> queue) {
+      for (ConfigurationHolder holder : transitionTable.values()) {
+        if (holder.configuration != null) {
+          queue.add(holder.configuration);
+        }
+      }
+      queue.addAll(splitTransitionTable.values());
+    }
+
+    /**
+     * Artifacts need an owner in Skyframe. By default it's the same configuration as what
+     * the configured target has, but it can be overridden if necessary.
+     *
+     * @return the artifact owner configuration
+     */
+    public BuildConfiguration getArtifactOwnerConfiguration() {
+      return configuration;
+    }
+
+    /**
+     * Returns the new configuration after traversing a dependency edge with a
+     * given configuration transition.
+     *
+     * @param configurationTransition the configuration transition
+     * @return the new configuration
+     */
+    public BuildConfiguration getConfiguration(Transition configurationTransition) {
+      ConfigurationHolder holder = transitionTable.get(configurationTransition);
+      if (holder == null && configurationTransition.defaultsToSelf()) {
+        return configuration;
+      }
+      return holder.configuration;
+    }
+
+    /**
+     * Arbitrary configuration transitions can be implemented by overriding this hook.
+     */
+    @SuppressWarnings("unused")
+    public BuildConfiguration configurationHook(Rule fromTarget,
+        Attribute attribute, Target toTarget, BuildConfiguration toConfiguration) {
+      return toConfiguration;
+    }
+
+    /**
+     * Associating configurations to top-level targets can be implemented by overriding this hook.
+     */
+    @SuppressWarnings("unused")
+    public BuildConfiguration toplevelConfigurationHook(Target toTarget) {
+      return configuration;
+    }
+  }
+
+  /**
+   * A holder class for {@link BuildConfiguration} instances that allows {@code null} values,
+   * because none of the Table implementations allow them.
+   */
+  public static final class ConfigurationHolder implements Serializable {
+    private final BuildConfiguration configuration;
+
+    public ConfigurationHolder(BuildConfiguration configuration) {
+      this.configuration = configuration;
+    }
+
+    public BuildConfiguration getConfiguration() {
+      return configuration;
+    }
+
+    @Override
+    public int hashCode() {
+      return configuration == null ? 0 : configuration.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (o == this) {
+        return true;
+      }
+      if (!(o instanceof ConfigurationHolder)) {
+        return false;
+      }
+      return Objects.equals(configuration, ((ConfigurationHolder) o).configuration);
+    }
+  }
+}