Add skyfunction to return all registered toolchain labels.

Part of #2219.

Change-Id: I7293fd13bd8e0931f92afd051e18a9e7ce63762d
PiperOrigin-RevId: 161721445

1 files changed, 141 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/RegisteredToolchainsFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/RegisteredToolchainsFunction.java
new file mode 100644
index 0000000000..e77c53d2b9
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/RegisteredToolchainsFunction.java
@@ -0,0 +1,141 @@
+// 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.skyframe;
+
+import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.analysis.ConfiguredTarget;
+import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
+import com.google.devtools.build.lib.analysis.platform.DeclaredToolchainInfo;
+import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.rules.ExternalPackageUtil;
+import com.google.devtools.build.lib.skyframe.ConfiguredTargetFunction.ConfiguredValueCreationException;
+import com.google.devtools.build.skyframe.LegacySkyKey;
+import com.google.devtools.build.skyframe.SkyFunction;
+import com.google.devtools.build.skyframe.SkyFunctionException;
+import com.google.devtools.build.skyframe.SkyFunctionException.Transience;
+import com.google.devtools.build.skyframe.SkyKey;
+import com.google.devtools.build.skyframe.SkyValue;
+import com.google.devtools.build.skyframe.ValueOrException;
+import java.util.List;
+import java.util.Map;
+import javax.annotation.Nullable;
+
+/**
+ * {@link SkyFunction} that returns all registered toolchains available for toolchain resolution.
+ */
+public class RegisteredToolchainsFunction implements SkyFunction {
+
+  @Nullable
+  @Override
+  public SkyValue compute(SkyKey skyKey, Environment env)
+      throws SkyFunctionException, InterruptedException {
+
+    BuildConfiguration configuration = (BuildConfiguration) skyKey.argument();
+
+    // Get the registered toolchains.
+    List<Label> registeredToolchainLabels = ExternalPackageUtil.getRegisteredToolchainLabels(env);
+    if (registeredToolchainLabels == null) {
+      return null;
+    }
+
+    // Load the configured target for each, and get the declared toolchain providers.
+    ImmutableList<DeclaredToolchainInfo> registeredToolchains =
+        configureRegisteredToolchains(env, configuration, registeredToolchainLabels);
+    if (env.valuesMissing()) {
+      return null;
+    }
+
+    return RegisteredToolchainsValue.create(registeredToolchains);
+  }
+
+  private ImmutableList<DeclaredToolchainInfo> configureRegisteredToolchains(
+      Environment env, BuildConfiguration configuration, List<Label> labels)
+      throws InterruptedException, RegisteredToolchainsFunctionException {
+    ImmutableList<SkyKey> keys =
+        labels
+            .stream()
+            .map(
+                label ->
+                    LegacySkyKey.create(
+                        SkyFunctions.CONFIGURED_TARGET,
+                        new ConfiguredTargetKey(label, configuration)))
+            .collect(ImmutableList.toImmutableList());
+
+    Map<SkyKey, ValueOrException<ConfiguredValueCreationException>> values =
+        env.getValuesOrThrow(keys, ConfiguredValueCreationException.class);
+    if (env.valuesMissing()) {
+      return null;
+    }
+    ImmutableList.Builder<DeclaredToolchainInfo> toolchains = new ImmutableList.Builder<>();
+    for (SkyKey key : keys) {
+      ConfiguredTargetKey configuredTargetKey = (ConfiguredTargetKey) key.argument();
+      Label toolchainLabel = configuredTargetKey.getLabel();
+      try {
+        ConfiguredTarget target =
+            ((ConfiguredTargetValue) values.get(key).get()).getConfiguredTarget();
+        DeclaredToolchainInfo toolchainInfo = target.getProvider(DeclaredToolchainInfo.class);
+        if (toolchainInfo == null) {
+          throw new RegisteredToolchainsFunctionException(
+              new InvalidTargetException(toolchainLabel), Transience.PERSISTENT);
+        }
+        toolchains.add(toolchainInfo);
+      } catch (ConfiguredValueCreationException e) {
+        throw new RegisteredToolchainsFunctionException(e, Transience.PERSISTENT);
+      }
+    }
+    return toolchains.build();
+  }
+
+  @Nullable
+  @Override
+  public String extractTag(SkyKey skyKey) {
+    return null;
+  }
+
+  /**
+   * Used to indicate that the given {@link Label} represents a {@link ConfiguredTarget} which is
+   * not a valid {@link DeclaredToolchainInfo} provider.
+   */
+  public static final class InvalidTargetException extends Exception {
+
+    private final Label invalidLabel;
+
+    public InvalidTargetException(Label invalidLabel) {
+      super(String.format("target '%s' does not provide a toolchain", invalidLabel));
+      this.invalidLabel = invalidLabel;
+    }
+
+    public Label getInvalidLabel() {
+      return invalidLabel;
+    }
+  }
+
+  /**
+   * Used to declare all the exception types that can be wrapped in the exception thrown by {@link
+   * #compute}.
+   */
+  public static class RegisteredToolchainsFunctionException extends SkyFunctionException {
+
+    public RegisteredToolchainsFunctionException(
+        InvalidTargetException cause, Transience transience) {
+      super(cause, transience);
+    }
+
+    public RegisteredToolchainsFunctionException(
+        ConfiguredValueCreationException cause, Transience persistent) {
+      super(cause, persistent);
+    }
+  }
+}