Prototype for package-specific cache partitions

pkg/analyzer/lib/src/generated/package.dart

Index: pkg/analyzer/lib/src/generated/package.dart
diff --git a/pkg/analyzer/lib/src/generated/package.dart b/pkg/analyzer/lib/src/generated/package.dart
new file mode 100644
index 0000000000000000000000000000000000000000..35132253b474b45e23a9d2259a2c13d2db38321c
--- /dev/null
+++ b/pkg/analyzer/lib/src/generated/package.dart
@@ -0,0 +1,239 @@
+// 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.
+
+library analyzer.src.generated.package;
+
+import 'dart:collection';
+
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/source/package_map_resolver.dart';
+import 'package:analyzer/src/context/builder.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/java_engine.dart';
+import 'package:analyzer/src/generated/sdk.dart';
+import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/generated/utilities_general.dart';
+import 'package:package_config/packages.dart';
+import 'package:yaml/yaml.dart';
+
+/**
+ * Traverses the package structure to determine the transitive dependencies for
+ * a given package.
+ */
+class DependencyFinder {
+  /**
+   * The name of the pubspec.yaml file.
+   */
+  static const String pubspecName = 'pubspec.yaml';
+
+  /**
+   * The resource provider used to access the file system.
+   */
+  final ResourceProvider resourceProvider;
+
+  /**
+   * A table mapping the absolute paths of packages to a list of the names of
+   * the packages on which those packages depend.
+   */
+  final Map<String, List<String>> dependencyMap =
+      new HashMap<String, List<String>>();
+
+  /**
+   * Initialize a newly created dependency finder to use the given
+   * [resourceProvider] to access the file system.
+   */
+  DependencyFinder(this.resourceProvider);
+
+  /**
+   * Return a sorted list of the directories containing all of the packages on
+   * which the package at the given [packageaPath] depends. The [packageMap]

[scheglov, 2016/08/11 18:48:34]

[packagePath]

[Brian Wilkerson, 2016/08/11 20:58:02]

done

+   * maps the names of packages to the directories in which they are contained.
+   *
+   * Throws an [AnalysisException] if any of the packages are missing their
+   * 'pubspec.yaml' file.
+   */
+  List<String> transitiveDependenciesFor(
+      Map<String, List<Folder>> packageMap, String packagePath) {
+    Set<String> processedPackages = new HashSet<String>();
+    Set<String> processedPaths = new HashSet<String>();
+    void process(String packageName) {
+      if (processedPackages.add(packageName)) {
+        List<Folder> folderList = packageMap[packageName];
+        if (folderList == null || folderList.isEmpty) {
+          throw new StateError('No mapping for package "$packageName"');
+        }
+        String packagePath = folderList[0].path;
+        processedPaths.add(packagePath);

[scheglov, 2016/08/11 18:48:35]

Does it handle correctly circular dependencies?

[Brian Wilkerson, 2016/08/11 20:58:02]

Yes. It adds each packageName to processedPackages (line 61) and won't recurse
if the name was already added. But when I added a test I discovered that it
could add the package for which dependencies were being computed, and we don't
want that, so I fixed that bug.

+        List<String> dependencies = _dependenciesFor(packagePath);
+        for (String dependency in dependencies) {
+          process(dependency);
+        }
+      }
+    }
+    List<String> dependencies = _dependenciesFor(packagePath);
+    for (String dependency in dependencies) {

[scheglov, 2016/08/11 18:48:34]

dependencies.forEach(process);

[Brian Wilkerson, 2016/08/11 20:58:02]

done

+      process(dependency);
+    }
+    List<String> transitiveDependencies = new List<String>.from(processedPaths);

[scheglov, 2016/08/11 18:48:35]

processedPaths.toList() would be shorted IMHO.

[Brian Wilkerson, 2016/08/11 20:58:02]

done

+    transitiveDependencies.sort();
+    return transitiveDependencies;
+  }
+
+  /**
+   * Return a list of the names of the packages on which the package at the
+   * [packagePath] depends.
+   */
+  List<String> _dependenciesFor(String packagePath) {
+    return dependencyMap.putIfAbsent(packagePath, () {
+      Set<String> dependencies = new HashSet<String>();
+      YamlNode yamlNode = _readPubspec(packagePath);
+      if (yamlNode is YamlMap) {
+        _gatherDependencies(dependencies, yamlNode['dependencies']);
+      }
+      return new List<String>.from(dependencies);

[scheglov, 2016/08/11 18:48:35]

Same here.
dependencies.toList() lets us to avoid repeating type arguments.

[Brian Wilkerson, 2016/08/11 20:58:02]

done

+    });
+  }
+
+  /**
+   * Add to the given set of [dependecies] all of the package names used as keys
+   * in the given [yamlMap].
+   */
+  void _gatherDependencies(HashSet<String> dependencies, YamlMap yamlMap) {

[scheglov, 2016/08/11 18:48:35]

This function is used only once, probably could be inlined.
Well, unless you want to support also other kinds of dependencies, like
dev_dependencies.

The name looks like it would make more than it does - I expected it to make some
recursive gathering.
Instead it just appends dependencies from a map.

[Brian Wilkerson, 2016/08/11 20:58:02]

It's messy to inline this because of limitations on type promotion and needing
extra local variables. I renames it instead.

+    if (yamlMap is Map) {
+      for (var key in yamlMap.keys) {
+        if (key is String) {
+          dependencies.add(key);
+        }
+      }
+    }
+  }
+
+  /**
+   * Read the content of the pubspec file in the directory at the given
+   * [directoryPath]. Return `null` if the file does not exist, cannot be read,
+   * or has content that is not valid YAML.
+   */
+  YamlNode _readPubspec(String directoryPath) {
+    try {
+      File yamlFile = resourceProvider
+          .getFolder(directoryPath)
+          .getChildAssumingFile(pubspecName);
+      String yamlContent = yamlFile.readAsStringSync();
+      return loadYamlNode(yamlContent);
+    } catch (exception, stackTrace) {
+      throw new AnalysisException('Missing $pubspecName in $directoryPath',
+          new CaughtException(exception, stackTrace));
+    }
+  }
+}
+
+/**
+ * A description of the context in which a package will be analyzed.
+ */
+class PackageDescription {
+  /**
+   * The id of the package being described. The id encodes the actual locations
+   * of the package itself and all of the packages on which it depends.
+   */
+  final String packageId;

[scheglov, 2016/08/11 18:48:35]

Why not just "id"?
We have already told that it's a package :-)

[Brian Wilkerson, 2016/08/11 20:58:02]

Because I like to type :-)

done

+
+  /**
+   * The SDK against which the package will be analyzed.
+   */
+  final DartSdk sdk;
+
+  /**
+   * The analysis options that will be used when analyzing the package.
+   */
+  final AnalysisOptions options;
+
+  /**
+   * Initialize a newly create package description to describe the package with
+   * the given [packageId] that is being analyzed against the given [sdk] using
+   * the given [options].
+   */
+  PackageDescription(this.packageId, this.sdk, this.options);
+
+  @override
+  int get hashCode {
+    int hashCode = options.encodeCrossContextOptions();
+    hashCode = JenkinsSmiHash.combine(hashCode, packageId.hashCode);
+    hashCode = JenkinsSmiHash.combine(hashCode, sdk.hashCode);
+    return JenkinsSmiHash.finish(hashCode);
+  }
+
+  @override
+  bool operator ==(Object other) {
+    return other is PackageDescription &&
+        other.sdk == sdk &&
+        other.options.encodeCrossContextOptions() ==
+            options.encodeCrossContextOptions() &&
+        other.packageId == packageId;
+  }
+}
+
+/**
+ * Manages the contexts in which each package is analyzed.
+ */
+class PackageManager {
+  /**
+   * The resource provider used to access the file system.
+   */
+  final ResourceProvider resourceProvider;
+
+  /**
+   * A table mapping the id's of packages to the context in which the package is
+   * analyzed.
+   */
+  final Map<PackageDescription, AnalysisContext> contextMap =
+      new HashMap<PackageDescription, AnalysisContext>();
+
+  /**
+   * Initialize a newly created package manager.
+   */
+  PackageManager(this.resourceProvider);
+
+  /**
+   * Return the context in which the package at the given [packagePath] should
+   * be analyzed when the given [packages] object is used to resolve package
+   * names, the given [resolver] will be used to resolve 'dart:' URI's, and the
+   * given [options] will control the analysis.
+   */
+  AnalysisContext getContext(String packagePath, Packages packages,
+      DartUriResolver resolver, AnalysisOptions options) {
+    DartSdk sdk = resolver.dartSdk;
+    Map<String, List<Folder>> packageMap =
+        new ContextBuilder(resourceProvider, null, null)
+            .convertPackagesToMap(packages);

[scheglov, 2016/08/11 18:48:35]

It seems that this method should be a function or static.

[Brian Wilkerson, 2016/08/11 20:58:02]

It makes use of both instance fields; how could it be static?

+    PackageDescription description =
+        new PackageDescription(_buildId(packagePath, packageMap), sdk, options);
+    return contextMap.putIfAbsent(description, () {
+      AnalysisContext context = AnalysisEngine.instance.createAnalysisContext();
+      context.sourceFactory = new SourceFactory(<UriResolver>[
+        resolver,
+        new PackageMapUriResolver(resourceProvider, packageMap),
+        new ResourceUriResolver(resourceProvider)
+      ], packages, resourceProvider);
+      context.analysisOptions = options;
+      return context;
+    });
+  }
+
+  /**
+   * Return the id associated with the package at the given [packagePath] when
+   * the given [packageMap] is used to resolve package names.
+   */
+  String _buildId(String packagePath, Map<String, List<Folder>> packageMap) {
+    DependencyFinder finder = new DependencyFinder(resourceProvider);
+    List<String> dependencies =
+        finder.transitiveDependenciesFor(packageMap, packagePath);
+    StringBuffer buffer = new StringBuffer();
+    buffer.write(packagePath);
+    for (String dependency in dependencies) {
+      buffer.write(';');
+      buffer.write(dependency);
+    }
+    return buffer.toString();
+  }
+}