1 files changed, 180 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
new file mode 100644
index 0000000000..ae4ee55bff
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+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
@@ -0,0 +1,180 @@
+// 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.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.cmdline.LabelValidator;
+import com.google.devtools.build.lib.packages.BuildFileContainsErrorsException;
+import com.google.devtools.build.lib.packages.BuildFileNotFoundException;
+import com.google.devtools.build.lib.packages.NoSuchPackageException;
+import com.google.devtools.build.lib.packages.PackageIdentifier;
+import com.google.devtools.build.lib.pkgcache.PathPackageLocator;
+import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.vfs.Path;
+import com.google.devtools.build.lib.vfs.PathFragment;
+import com.google.devtools.build.lib.vfs.RootedPath;
+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 java.io.IOException;
+import java.util.concurrent.atomic.AtomicReference;
+
+import javax.annotation.Nullable;
+
+/**
+ * SkyFunction for {@link PackageLookupValue}s.
+ */
+class PackageLookupFunction implements SkyFunction {
+
+  private final AtomicReference<ImmutableSet<String>> deletedPackages;
+
+  PackageLookupFunction(AtomicReference<ImmutableSet<String>> deletedPackages) {
+    this.deletedPackages = deletedPackages;
+  }
+
+  @Override
+  public SkyValue compute(SkyKey skyKey, Environment env) throws PackageLookupFunctionException {
+    PathPackageLocator pkgLocator = PrecomputedValue.PATH_PACKAGE_LOCATOR.get(env);
+    PackageIdentifier packageKey = (PackageIdentifier) skyKey.argument();
+    if (!packageKey.getRepository().isDefault()) {
+      return computeExternalPackageLookupValue(skyKey, env);
+    }
+    PathFragment pkg = packageKey.getPackageFragment();
+
+    // This represents a package lookup at the package root.
+    if (pkg.equals(PathFragment.EMPTY_FRAGMENT)) {
+      return PackageLookupValue.invalidPackageName("The empty package name is invalid");
+    }
+
+    String pkgName = pkg.getPathString();
+    String packageNameErrorMsg = LabelValidator.validatePackageName(pkgName);
+    if (packageNameErrorMsg != null) {
+      return PackageLookupValue.invalidPackageName("Invalid package name '" + pkgName + "': "
+          + packageNameErrorMsg);
+    }
+
+    if (deletedPackages.get().contains(pkg.getPathString())) {
+      return PackageLookupValue.deletedPackage();
+    }
+
+    // TODO(bazel-team): The following is O(n^2) on the number of elements on the package path due
+    // to having restart the SkyFunction after every new dependency. However, if we try to batch
+    // the missing value keys, more dependencies than necessary will be declared. This wart can be
+    // fixed once we have nicer continuation support [skyframe-loading]
+    for (Path packagePathEntry : pkgLocator.getPathEntries()) {
+      PackageLookupValue value = getPackageLookupValue(env, packagePathEntry, pkg);
+      if (value == null || value.packageExists()) {
+        return value;
+      }
+    }
+    return PackageLookupValue.noBuildFile();
+  }
+
+  @Nullable
+  @Override
+  public String extractTag(SkyKey skyKey) {
+    return null;
+  }
+
+  private PackageLookupValue getPackageLookupValue(Environment env, Path packagePathEntry,
+      PathFragment pkgFragment) throws PackageLookupFunctionException {
+    PathFragment buildFileFragment;
+    if (pkgFragment.getPathString().equals(PackageFunction.EXTERNAL_PACKAGE_NAME)) {
+      buildFileFragment = new PathFragment("WORKSPACE");
+    } else {
+      buildFileFragment = pkgFragment.getChild("BUILD");
+    }
+    RootedPath buildFileRootedPath = RootedPath.toRootedPath(packagePathEntry,
+        buildFileFragment);
+    String basename = buildFileRootedPath.asPath().getBaseName();
+    SkyKey fileSkyKey = FileValue.key(buildFileRootedPath);
+    FileValue fileValue = null;
+    try {
+      fileValue = (FileValue) env.getValueOrThrow(fileSkyKey, IOException.class,
+          FileSymlinkCycleException.class, InconsistentFilesystemException.class);
+    } catch (IOException e) {
+      String pkgName = pkgFragment.getPathString();
+      // TODO(bazel-team): throw an IOException here and let PackageFunction wrap that into a
+      // BuildFileNotFoundException.
+      throw new PackageLookupFunctionException(new BuildFileNotFoundException(pkgName,
+          "IO errors while looking for " + basename + " file reading "
+              + buildFileRootedPath.asPath() + ": " + e.getMessage(), e),
+           Transience.PERSISTENT);
+    } catch (FileSymlinkCycleException e) {
+      String pkgName = buildFileRootedPath.asPath().getPathString();
+      throw new PackageLookupFunctionException(new BuildFileNotFoundException(pkgName,
+          "Symlink cycle detected while trying to find " + basename + " file "
+              + buildFileRootedPath.asPath()),
+          Transience.PERSISTENT);
+    } catch (InconsistentFilesystemException e) {
+      // This error is not transient from the perspective of the PackageLookupFunction.
+      throw new PackageLookupFunctionException(e, Transience.PERSISTENT);
+    }
+    if (fileValue == null) {
+      return null;
+    }
+    if (fileValue.isFile()) {
+      return PackageLookupValue.success(buildFileRootedPath.getRoot());
+    }
+    return PackageLookupValue.noBuildFile();
+  }
+
+  /**
+   * Gets a PackageLookupValue from a different Bazel repository.
+   *
+   * To do this, it looks up the "external" package and finds a path mapping for the repository
+   * name.
+   */
+  private PackageLookupValue computeExternalPackageLookupValue(
+      SkyKey skyKey, Environment env) throws PackageLookupFunctionException {
+    PackageIdentifier id = (PackageIdentifier) skyKey.argument();
+    SkyKey repositoryKey = RepositoryValue.key(id.getRepository());
+    RepositoryValue repositoryValue = null;
+    try {
+      repositoryValue = (RepositoryValue) env.getValueOrThrow(
+          repositoryKey, NoSuchPackageException.class, IOException.class, EvalException.class);
+      if (repositoryValue == null) {
+        return null;
+      }
+    } catch (NoSuchPackageException e) {
+      throw new PackageLookupFunctionException(e, Transience.PERSISTENT);
+    } catch (IOException e) {
+      throw new PackageLookupFunctionException(new BuildFileContainsErrorsException(
+          PackageFunction.EXTERNAL_PACKAGE_NAME, e.getMessage()), Transience.PERSISTENT);
+    } catch (EvalException e) {
+      throw new PackageLookupFunctionException(new BuildFileContainsErrorsException(
+          PackageFunction.EXTERNAL_PACKAGE_NAME, e.getMessage()), Transience.PERSISTENT);
+    }
+
+    return getPackageLookupValue(env, repositoryValue.getPath(), id.getPackageFragment());
+  }
+
+  /**
+   * Used to declare all the exception types that can be wrapped in the exception thrown by
+   * {@link PackageLookupFunction#compute}.
+   */
+  private static final class PackageLookupFunctionException extends SkyFunctionException {
+    public PackageLookupFunctionException(NoSuchPackageException e, Transience transience) {
+      super(e, transience);
+    }
+
+    public PackageLookupFunctionException(InconsistentFilesystemException e,
+        Transience transience) {
+      super(e, transience);
+    }
+  }
+}