Add a SkyFunction to perform toolchain resolution.

Part of #2219.

Change-Id: I339009c13639144ca756eb07c520df7d430a64e3
PiperOrigin-RevId: 161826487

1 files changed, 125 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ToolchainResolutionFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ToolchainResolutionFunction.java
new file mode 100644
index 0000000000..7a61c67271
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ToolchainResolutionFunction.java
@@ -0,0 +1,125 @@
+// 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.platform.DeclaredToolchainInfo;
+import com.google.devtools.build.lib.analysis.platform.PlatformInfo;
+import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.packages.NoSuchThingException;
+import com.google.devtools.build.lib.skyframe.ConfiguredTargetFunction.ConfiguredValueCreationException;
+import com.google.devtools.build.lib.skyframe.RegisteredToolchainsFunction.InvalidTargetException;
+import com.google.devtools.build.lib.skyframe.ToolchainResolutionValue.ToolchainResolutionKey;
+import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.skyframe.SkyFunction;
+import com.google.devtools.build.skyframe.SkyFunctionException;
+import com.google.devtools.build.skyframe.SkyKey;
+import com.google.devtools.build.skyframe.SkyValue;
+import javax.annotation.Nullable;
+
+/** {@link SkyFunction} which performs toolchain resolution for a class of rules. */
+public class ToolchainResolutionFunction implements SkyFunction {
+
+  @Nullable
+  @Override
+  public SkyValue compute(SkyKey skyKey, Environment env)
+      throws SkyFunctionException, InterruptedException {
+    ToolchainResolutionKey key = (ToolchainResolutionKey) skyKey.argument();
+
+    // Get all toolchains.
+    RegisteredToolchainsValue toolchains;
+    try {
+      toolchains =
+          (RegisteredToolchainsValue)
+              env.getValueOrThrow(
+                  RegisteredToolchainsValue.key(key.configuration()),
+                  ConfiguredValueCreationException.class,
+                  InvalidTargetException.class,
+                  EvalException.class);
+      if (toolchains == null) {
+        return null;
+      }
+    } catch (ConfiguredValueCreationException e) {
+      throw new ToolchainResolutionFunctionException(e);
+    } catch (InvalidTargetException e) {
+      throw new ToolchainResolutionFunctionException(e);
+    } catch (EvalException e) {
+      throw new ToolchainResolutionFunctionException(e);
+    }
+
+    // Find the right one.
+    DeclaredToolchainInfo toolchain =
+        resolveConstraints(
+            key.toolchainType(),
+            key.targetPlatform(),
+            key.execPlatform(),
+            toolchains.registeredToolchains());
+    return ToolchainResolutionValue.create(toolchain.toolchainLabel());
+  }
+
+  // TODO(katre): Implement real resolution.
+  private DeclaredToolchainInfo resolveConstraints(
+      Label toolchainType,
+      PlatformInfo targetPlatform,
+      PlatformInfo execPlatform,
+      ImmutableList<DeclaredToolchainInfo> toolchains)
+      throws ToolchainResolutionFunctionException {
+    for (DeclaredToolchainInfo toolchain : toolchains) {
+      if (toolchain.toolchainType().equals(toolchainType)) {
+        return toolchain;
+      }
+    }
+    throw new ToolchainResolutionFunctionException(new NoToolchainFoundException(toolchainType));
+  }
+
+  @Nullable
+  @Override
+  public String extractTag(SkyKey skyKey) {
+    return null;
+  }
+
+  /** Used to indicate that a toolchain was not found for the current request. */
+  public static final class NoToolchainFoundException extends NoSuchThingException {
+    private final Label missingToolchainType;
+
+    public NoToolchainFoundException(Label missingToolchainType) {
+      super(String.format("no matching toolchain found for %s", missingToolchainType));
+      this.missingToolchainType = missingToolchainType;
+    }
+
+    public Label missingToolchainType() {
+      return missingToolchainType;
+    }
+  }
+
+  /** Used to indicate errors during the computation of an {@link ToolchainResolutionValue}. */
+  private static final class ToolchainResolutionFunctionException extends SkyFunctionException {
+    public ToolchainResolutionFunctionException(NoToolchainFoundException e) {
+      super(e, Transience.PERSISTENT);
+    }
+
+    public ToolchainResolutionFunctionException(ConfiguredValueCreationException e) {
+      super(e, Transience.PERSISTENT);
+    }
+
+    public ToolchainResolutionFunctionException(InvalidTargetException e) {
+      super(e, Transience.PERSISTENT);
+    }
+
+    public ToolchainResolutionFunctionException(EvalException e) {
+      super(e, Transience.PERSISTENT);
+    }
+  }
+}