Initial version of Bazel SummaryProvider.

pkg/analyzer/lib/src/summary/bazel_summary.dart

Index: pkg/analyzer/lib/src/summary/bazel_summary.dart
diff --git a/pkg/analyzer/lib/src/summary/bazel_summary.dart b/pkg/analyzer/lib/src/summary/bazel_summary.dart
new file mode 100644
index 0000000000000000000000000000000000000000..f3073953d7326137cc0c6449d520d1522707a6ff
--- /dev/null
+++ b/pkg/analyzer/lib/src/summary/bazel_summary.dart
@@ -0,0 +1,191 @@
+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:convert';
+
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/generated/utilities_collection.dart';
+import 'package:analyzer/src/summary/idl.dart';
+import 'package:convert/convert.dart';
+import 'package:crypto/crypto.dart';
+import 'package:meta/meta.dart';
+
+/**
+ * Return the path of the directory where bundles for the given [uri] should be
+ * looked for.  This directory should contain corresponding pairs of `*.api.ds`
+ * and `*.full.ds` files, possibly more than one pair.  Return `null` if the
+ * given [uri] does not have the expected structure, so the output path cannot
+ * be computed.
+ */
+typedef String GetOutputPath(ResourceProvider provider, Uri uri);
+
+/**
+ * Information about a Dart package in Bazel.
+ */
+class Package {
+  final String bundlePath;
+  final PackageBundle bundle;
+  final Set<String> _unitUris = new Set<String>();
+
+  Package(this.bundlePath, this.bundle) {
+    _unitUris.addAll(bundle.unlinkedUnitUris);
+  }
+}
+
+/**
+ * Class that reads summaries of Bazel packages.
+ *
+ * When the client needs to produce a resolution result for a new [Source], it
+ * should call [getPackages] to checked whether there is the set of packages

[Brian Wilkerson, 2016/09/27 21:04:47]

"checked" --> "check"

+ * to resynthesize resolution results.
+ */
+class SummaryProvider {
+  final ResourceProvider provider;
+  final GetOutputPath getOutputPath;
+  final AnalysisContext context;
+
+  /**
+   * Mapping from bundle paths to corresponding [Package]s.  The packages in
+   * the map were consistent with their constituent sources at the moment when
+   * they were put into the map.
+   */
+  final Map<String, Package> bundlePathToPackageMap = <String, Package>{};
+
+  /**
+   * When we detected than some bundle is not consistent with its constituent
+   * sources (i.e. even its unlinked state is not consistent), we remember
+   * this fact to avoid loading and checking consistency next time.
+   */
+  final Set<String> knownInconsistentBundlePaths = new Set<String>();
+
+  SummaryProvider(this.provider, this.getOutputPath, this.context);
+
+  /**
+   * Return the [Package] that contains information about the source with
+   * the given [uri], or `null` if such package does not exist.
+   */
+  @visibleForTesting
+  Package getPackageForUri(Uri uri) {
+    String outputPath = getOutputPath(provider, uri);
+    if (outputPath != null) {
+      List<Package> packages = _getPackages(outputPath);
+      for (Package package in packages) {
+        String uriStr = uri.toString();
+        if (package._unitUris.contains(uriStr)) {
+          return package;
+        }
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Return the complete list of [Package]s that are required to provide all
+   * resolution results for the given [source].
+   *
+   * The same list of packages is returned for the same [Source], i.e. always
+   * the full list, not a difference with a previous request.  It is up to the
+   * client to decide whether some of the returned packages should be excluded
+   * as already mixed into a resynthesizer.
+   *
+   * If the full set of packages cannot be produced, for example because some
+   * bundles are not built, or out of date, etc, then `null` is returned.
+   */
+  List<PackageBundle> getPackages(Source source) {
+    // TODO(scheglov) implement
+    return null;
+  }
+
+  /**
+   * Return the hexadecimal string for the given [source] contents.
+   */
+  String _computeSourceHashHex(Source source) {
+    String text = context.getContents(source).data;
+    List<int> bytes = UTF8.encode(text);
+    List<int> hashBytes = md5.convert(bytes).bytes;
+    return hex.encode(hashBytes);
+  }
+
+  /**
+   * Return the [Package] from the file with the given [path], or `null` if the
+   * file does not exist, or it cannot be read, or is not consistent with the
+   * sources it contains, etc.
+   */
+  Package _getPackage(String path) {
+    // Check if the bundle know to be inconsistent, missing, etc.

[Brian Wilkerson, 2016/09/27 21:04:47]

"know" -> "is known"

+    if (knownInconsistentBundlePaths.contains(path)) {
+      return null;
+    }
+    // Attempt to get from the cache or read from the file system.
+    try {
+      Package package = bundlePathToPackageMap[path];
+      if (package == null) {
+        File file = provider.getFile(path);
+        List<int> bytes = file.readAsBytesSync();
+        PackageBundle bundle = new PackageBundle.fromBuffer(bytes);
+        // Check for consistency, and fail if it's not.
+        if (!_isUnlinkedBundleConsistent(bundle)) {
+          knownInconsistentBundlePaths.add(path);
+          return null;
+        }
+        // OK, put the package into the cache.
+        package = new Package(path, bundle);
+        bundlePathToPackageMap[path] = package;
+      }
+      return package;
+    } catch (_) {

[Paul Berry, 2016/09/28 12:38:20]

Could we log the exception somewhere?  It might be useful to help with debugging
if Bazel summary support mysteriously doesn't work on someone's machine.

+      return null;
+    }
+  }
+
+  /**
+   * Return all consistent [Package]s in the given [folderPath].
+   */
+  List<Package> _getPackages(String folderPath) {
+    List<Package> packages = <Package>[];
+    try {
+      Folder folder = provider.getFolder(folderPath);
+      List<Resource> children = folder.getChildren();
+      for (Resource child in children) {
+        if (child is File) {
+          String packagePath = child.path;
+          if (packagePath.toLowerCase().endsWith('.full.ds')) {
+            Package package = _getPackage(packagePath);
+            if (package != null) {
+              packages.add(package);
+            }
+          }
+        }
+      }
+    } on FileSystemException {}
+    return packages;
+  }
+
+  /**
+   * Return `true` if the unlinked information of the [bundle] is consistent
+   * with its constituent sources.
+   */
+  bool _isUnlinkedBundleConsistent(PackageBundle bundle) {
+    try {
+      // Compute hashes of the constituent sources.
+      List<String> actualHashes = <String>[];
+      for (String uri in bundle.unlinkedUnitUris) {
+        Source source = context.sourceFactory.resolveUri(null, uri);
+        if (source == null) {
+          return false;
+        }
+        String hash = _computeSourceHashHex(source);
+        actualHashes.add(hash);
+      }
+      // Compare sorted actual and bundle unit hashes.
+      List<String> bundleHashes = bundle.unlinkedUnitHashes.toList()..sort();
+      actualHashes.sort();
+      return listsEqual(actualHashes, bundleHashes);
+    } catch (_) {

[Paul Berry, 2016/09/28 12:38:20]

Similar comment here.

+      return false;
+    }
+  }
+}