Stop optimizing uses of "pub list".

pkg/analysis_server/lib/src/source/optimizing_pub_package_map_provider.dart

-// Copyright (c) 2015, 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 source.optimizing_pub_package_map_provider;
-
-import 'dart:core' hide Resource;
-
-import 'package:analyzer/file_system/file_system.dart';
-import 'package:analyzer/source/package_map_provider.dart';
-import 'package:analyzer/source/pub_package_map_provider.dart';
-import 'package:analyzer/src/generated/sdk_io.dart';
-
-/**
- * Extension of [PackageMapInfo] that tracks the modification timestamps of
- * pub dependencies.  This allows the analysis server to avoid making redundant
- * calls to "pub list" when nothing has changed.
- */
-class OptimizingPubPackageMapInfo extends PackageMapInfo {
-  /**
-   * Map from file path to the file's modification timestamp prior to running
-   * "pub list".  Since the set of dependencies is not always known prior to
-   * running "pub list", some or all of the dependencies may be missing from
-   * this map.
-   */
-  final Map<String, int> modificationTimes;
-
-  OptimizingPubPackageMapInfo(Map<String, List<Folder>> packageMap,
-      Set<String> dependencies, this.modificationTimes)
-      : super(packageMap, dependencies);
-
-  /**
-   * Return `true` if the given [path] is listed as a dependency, and we cannot
-   * prove using modification timestamps that it is unchanged.
-   * [resourceProvider] is used (if necessary) to read the [path]'s
-   * modification time.
-   */
-  bool isChangedDependency(String path, ResourceProvider resourceProvider) {
-    if (!dependencies.contains(path)) {
-      // Path is not a dependency.
-      return false;
-    }
-    int lastModificationTime = modificationTimes[path];
-    if (lastModificationTime != null) {
-      Resource resource = resourceProvider.getResource(path);
-      if (resource is File) {
-        try {
-          if (resource.modificationStamp == lastModificationTime) {
-            // Path is a dependency, but it hasn't changed since the last run
-            // of "pub list".
-            return false;
-          }
-        } on FileSystemException {
-          // Path is a dependency, but we can't read its timestamp.  Assume
-          // it's changed to be safe.
-        }
-      }
-    }
-    // Path is a dependency, and we couldn't prove that it hadn't changed.
-    // Assume it's changed to be safe.
-    return true;
-  }
-}
-
-/**
- * Extension of [PubPackageMapProvider] that outputs additional information to
- * allow the analysis server to avoid making redundant calls to "pub list" when
- * nothing has changed.
- */
-class OptimizingPubPackageMapProvider extends PubPackageMapProvider {
-  OptimizingPubPackageMapProvider(
-      ResourceProvider resourceProvider, DirectoryBasedDartSdk sdk, [RunPubList runPubList])
-      : super(resourceProvider, sdk, runPubList);
-
-  /**
-   * Compute a package map for the given folder by executing "pub list".  If
-   * [previousInfo] is provided, it is used as a guess of which files the
-   * package map is likely to depend on; the modification times of those files
-   * are captured prior to executing "pub list" so that they can be used to
-   * avoid making redundant calls to "pub list" in the future.
-   *
-   * Also, in the case where dependencies can't be determined because of an
-   * error, the dependencies from [previousInfo] will be preserved.
-   */
-  OptimizingPubPackageMapInfo computePackageMap(Folder folder,
-      [OptimizingPubPackageMapInfo previousInfo]) {
-    // Prior to running "pub list", read the modification timestamps of all of
-    // the old dependencies (if known).
-    Map<String, int> modificationTimes = <String, int>{};
-    if (previousInfo != null) {
-      for (String path in previousInfo.dependencies) {
-        Resource resource = resourceProvider.getResource(path);
-        if (resource is File) {
-          try {
-            modificationTimes[path] = resource.modificationStamp;
-          } on FileSystemException {
-            // File no longer exists.  Don't record a timestamp for it; this
-            // will ensure that if the file reappears, we will re-run "pub
-            // list" regardless of the timestamp it reappears with.
-          }
-        }
-      }
-    }
-
-    // Try running "pub list".
-    PackageMapInfo info = super.computePackageMap(folder);
-    if (info == null) {
-      // Computing the package map resulted in an error.  Merge the old
-      // dependencies with the new ones, if possible.
-      info = super.computePackageMapError(folder);
-      if (previousInfo != null) {
-        info.dependencies.addAll(previousInfo.dependencies);
-      }
-    }
-
-    // Discard any elements of modificationTimes that are no longer
-    // dependencies.
-    if (previousInfo != null) {
-      for (String dependency
-          in previousInfo.dependencies.difference(info.dependencies)) {
-        modificationTimes.remove(dependency);
-      }
-    }
-
-    // Bundle the modificationTimes with the other info.
-    return new OptimizingPubPackageMapInfo(
-        info.packageMap, info.dependencies, modificationTimes);
-  }
-
-  @override
-  PackageMapInfo computePackageMapError(Folder folder) {
-    // Return null to indicate to our override of computePackageMap that there
-    // was an error, so it can compute dependencies correctly.
-    return null;
-  }
-}