1 files changed, 134 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/TargetMarkerFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/TargetMarkerFunction.java
new file mode 100644
index 0000000000..3f9f22f61c
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/TargetMarkerFunction.java
@@ -0,0 +1,134 @@
+// 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.skyframe;
+
+import com.google.devtools.build.lib.packages.BuildFileNotFoundException;
+import com.google.devtools.build.lib.packages.NoSuchPackageException;
+import com.google.devtools.build.lib.packages.NoSuchTargetException;
+import com.google.devtools.build.lib.packages.Package;
+import com.google.devtools.build.lib.packages.PackageIdentifier;
+import com.google.devtools.build.lib.packages.Target;
+import com.google.devtools.build.lib.syntax.Label;
+import com.google.devtools.build.lib.vfs.PathFragment;
+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;
+
+/**
+ * A SkyFunction for {@link TargetMarkerValue}s.
+ */
+public final class TargetMarkerFunction implements SkyFunction {
+
+  public TargetMarkerFunction() {
+  }
+
+  @Override
+  public SkyValue compute(SkyKey key, Environment env) throws TargetMarkerFunctionException {
+    Label label = (Label) key.argument();
+    PathFragment pkgForLabel = label.getPackageFragment();
+
+    if (label.getName().contains("/")) {
+      // This target is in a subdirectory, therefore it could potentially be invalidated by
+      // a new BUILD file appearing in the hierarchy.
+      PathFragment containingDirectory = label.toPathFragment().getParentDirectory();
+      ContainingPackageLookupValue containingPackageLookupValue = null;
+      try {
+        PackageIdentifier newPkgId = new PackageIdentifier(
+            label.getPackageIdentifier().getRepository(), containingDirectory);
+        containingPackageLookupValue = (ContainingPackageLookupValue) env.getValueOrThrow(
+            ContainingPackageLookupValue.key(newPkgId),
+            BuildFileNotFoundException.class, InconsistentFilesystemException.class);
+      } catch (BuildFileNotFoundException e) {
+        // Thrown when there are IO errors looking for BUILD files.
+        throw new TargetMarkerFunctionException(e);
+      } catch (InconsistentFilesystemException e) {
+        throw new TargetMarkerFunctionException(new NoSuchTargetException(label,
+            e.getMessage()));
+      }
+      if (containingPackageLookupValue == null) {
+        return null;
+      }
+      if (!containingPackageLookupValue.hasContainingPackage()) {
+        // This means the label's package doesn't exist. E.g. there is no package 'a' and we are
+        // trying to build the target for label 'a:b/foo'.
+        throw new TargetMarkerFunctionException(new BuildFileNotFoundException(
+            pkgForLabel.getPathString(), "BUILD file not found on package path for '"
+                + pkgForLabel.getPathString() + "'"));
+      }
+      if (!containingPackageLookupValue.getContainingPackageName().equals(
+              label.getPackageIdentifier())) {
+        throw new TargetMarkerFunctionException(new NoSuchTargetException(label,
+            String.format("Label '%s' crosses boundary of subpackage '%s'", label,
+                containingPackageLookupValue.getContainingPackageName())));
+      }
+    }
+
+    SkyKey pkgSkyKey = PackageValue.key(label.getPackageIdentifier());
+    NoSuchPackageException nspe = null;
+    Package pkg;
+    try {
+      PackageValue value = (PackageValue)
+          env.getValueOrThrow(pkgSkyKey, NoSuchPackageException.class);
+      if (value == null) {
+        return null;
+      }
+      pkg = value.getPackage();
+    } catch (NoSuchPackageException e) {
+      // For consistency with pre-Skyframe Blaze, we can return a valid Target from a Package
+      // containing errors.
+      pkg = e.getPackage();
+      if (pkg == null) {
+        // Re-throw this exception with our key because root causes should be targets, not packages.
+        throw new TargetMarkerFunctionException(e);
+      }
+      nspe = e;
+    }
+
+    Target target;
+    try {
+      target = pkg.getTarget(label.getName());
+    } catch (NoSuchTargetException e) {
+      throw new TargetMarkerFunctionException(e);
+    }
+
+    if (nspe != null) {
+      // There is a target, but its package is in error. We rethrow so that the root cause is the
+      // target, not the package. Note that targets are only in error when their package is
+      // "in error" (because a package is in error if there was an error evaluating the package, or
+      // if one of its targets was in error).
+      throw new TargetMarkerFunctionException(new NoSuchTargetException(target, nspe));
+    }
+    return TargetMarkerValue.TARGET_MARKER_INSTANCE;
+  }
+
+  @Override
+  public String extractTag(SkyKey skyKey) {
+    return Label.print((Label) skyKey.argument());
+  }
+
+  /**
+   * Used to declare all the exception types that can be wrapped in the exception thrown by
+   * {@link TargetMarkerFunction#compute}.
+   */
+  private static final class TargetMarkerFunctionException extends SkyFunctionException {
+    public TargetMarkerFunctionException(NoSuchTargetException e) {
+      super(e, Transience.PERSISTENT);
+    }
+
+    public TargetMarkerFunctionException(NoSuchPackageException e) {
+      super(e, Transience.PERSISTENT);
+    }
+  }
+}