Initial LibraryBundleCache implementation.

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

+// 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' show UTF8;
+import 'dart:core' hide Resource;
+
+import 'package:analyzer/dart/element/element.dart';
+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/summary/format.dart';
+import 'package:analyzer/src/summary/idl.dart';
+import 'package:analyzer/src/summary/summarize_elements.dart';
+import 'package:crypto/crypto.dart';
+
+/**
+ * The cache of per-library [PackageBundle]s.
+ *
+ * Note that currently this class is not intended for interactive use.
+ */
+class LibraryBundleCache {
+  /**
+   * To ensure that operations of writing files are atomic we create a temporary
+   * file with this name in the [cacheFolder] and then rename it once we are
+   * done writing.
+   */
+  final String tempFileName;
+
+  /**
+   * The folder to read and write files.
+   */
+  final Folder cacheFolder;
+
+  /**
+   * The context in which this cache is used.
+   */
+  final AnalysisContext context;
+
+  /**
+   * Opaque data that reflects the current configuration, such as the [context]
+   * options, and is mixed into the hashes.
+   */
+  final List<int> configSalt;
+
+  final Map<Source, CacheLibraryUris> _libraryUrisMap =
+      <Source, CacheLibraryUris>{};
+  final Map<Source, List<Source>> _libraryClosureMap = <Source, List<Source>>{};
+  final Map<Source, List<int>> _sourceContentHashMap = <Source, List<int>>{};
+
+  LibraryBundleCache(
+      this.tempFileName, this.cacheFolder, this.context, this.configSalt);
+
+  /**
+   * Clear internal caches so that we read from file system again.
+   */
+  void clearInternalCaches() {
+    _libraryUrisMap.clear();
+    _libraryClosureMap.clear();
+    _sourceContentHashMap.clear();
+  }
+
+  /**
+   * Write information about the [library] into the cache.
+   */
+  void putLibrary(LibraryElement library) {
+    try {
+      _writeUris(library);
+      List<int> hash = _getLibraryClosureHash(library.source);
+      String hashStr = CryptoUtils.bytesToHex(hash);
+      PackageBundleAssembler assembler = new PackageBundleAssembler();
+      assembler.serializeLibraryElement(library);
+      List<int> bytes = assembler.assemble().toBuffer();
+      _safeWriteBytes('$hashStr.sum', bytes);
+    } catch (e) {}
+  }
+
+  /**
+   * Read the [PackageBundle] for the library with the given [source] from
+   * the cache. The returned bundle will correspond to the state when the set
+   * of direct and indirect dependencies is resolved in the [context]. Return
+   * `null` if such bundle does not exist.
+   */
+  PackageBundle readBundle(Source source) {
+    try {
+      List<int> hash = _getLibraryClosureHash(source);
+      String hashStr = CryptoUtils.bytesToHex(hash);
+      List<int> bytes = _safeReadBytes('$hashStr.sum');
+      if (bytes == null) {
+        return null;
+      }
+      return new PackageBundle.fromBuffer(bytes);
+    } catch (e) {
+      return null;
+    }
+  }
+
+  /**
+   * Fill the whole source closure of the library with the given
+   * [librarySource]. It includes defining units and parts of the library and
+   * all its directly or indirectly imported or exported libraries.
+   */
+  void _appendLibraryClosure(Set<Source> closure, Source librarySource) {
+    if (closure.add(librarySource)) {
+      CacheLibraryUris libraryUris = _getUris(librarySource);
+      if (libraryUris == null) {
+        throw new StateError('No URIs for $librarySource');
+      }
+      // Append parts.
+      for (String partUri in libraryUris.partUris) {
+        Source partSource =
+            context.sourceFactory.resolveUri(librarySource, partUri);
+        if (partSource == null) {
+          throw new StateError('Unable to resolve $partUri in $librarySource');
+        }
+        closure.add(partSource);
+      }
+      // Append imports and exports.
+      void appendLibrarySources(String refUri) {
+        Source refSource =
+            context.sourceFactory.resolveUri(librarySource, refUri);
+        if (refSource == null) {
+          throw new StateError('Unable to resolve $refUri in $librarySource');
+        }
+        _appendLibraryClosure(closure, refSource);
+      }
+      libraryUris.importedUris.forEach(appendLibrarySources);
+      libraryUris.exportedUris.forEach(appendLibrarySources);
+    }
+  }
+
+  /**
+   * Return the whole source closure of the library with the given
+   * [librarySource]. It includes defining units and parts of the library and
+   * of all its directly or indirectly imported or exported libraries.
+   */
+  List<Source> _getLibraryClosure(Source librarySource) {
+    return _libraryClosureMap.putIfAbsent(librarySource, () {
+      Set<Source> closure = new Set<Source>();
+      _appendLibraryClosure(closure, librarySource);
+      return closure.toList();
+    });
+  }
+
+  /**
+   * Return the [context]-specific hash of the closure of the library with
+   * the given [librarySource].
+   */
+  List<int> _getLibraryClosureHash(Source librarySource) {
+    List<Source> closure = _getLibraryClosure(librarySource);
+    MD5 md5 = new MD5();
+    for (Source source in closure) {
+      List<int> sourceHash = _getSourceContentHash(source);
+      md5.add(sourceHash);
+    }
+    md5.add(configSalt);
+    return md5.close();
+  }
+
+  /**
+   * Compute a hash of the given [source] contents.
+   */
+  List<int> _getSourceContentHash(Source source) {
+    return _sourceContentHashMap.putIfAbsent(source, () {
+      String sourceText = source.contents.data;
+      List<int> sourceBytes = UTF8.encode(sourceText);
+      return (new MD5()..add(sourceBytes)).close();
+    });
+  }
+
+  /**
+   * Get the URIs information of the library with the given [librarySource],
+   * maybe `null` if the information is not in the cache.
+   */
+  CacheLibraryUris _getUris(Source librarySource) {
+    CacheLibraryUris uris = _libraryUrisMap[librarySource];
+    if (uris == null) {
+      String fileName = _getUrisFileName(librarySource);
+      List<int> bytes = _safeReadBytes(fileName);
+      if (bytes == null) {
+        return null;
+      }
+      uris = new CacheLibraryUris.fromBuffer(bytes);
+      _libraryUrisMap[librarySource] = uris;
+    }
+    return uris;
+  }
+
+  /**
+   * Return the name of the file with the [librarySource] URIs information.
+   */
+  String _getUrisFileName(Source librarySource) {
+    List<int> hash = _getSourceContentHash(librarySource);
+    String hashStr = CryptoUtils.bytesToHex(hash);
+    return '$hashStr.uris';
+  }
+
+  /**
+   * Return bytes of the file with the given [relPath] in the cache, or `null`
+   * if the file does not exist.
+   */
+  List<int> _safeReadBytes(String relPath) {
+    Resource urisFile = cacheFolder.getChild(relPath);
+    if (urisFile is File) {
+      try {
+        return urisFile.readAsBytesSync();
+      } on FileSystemException {}
+    }
+    return null;
+  }
+
+  /**
+   * Atomically write the given [bytes] into the file with the given [relPath].
+   * Silently ignores any errors.
+   */
+  void _safeWriteBytes(String relPath, List<int> bytes) {
+    try {
+      String absPath = cacheFolder.getChild(relPath).path;
+      File tempFile = cacheFolder.getChild(tempFileName);
+      tempFile.writeAsBytesSync(bytes);
+      tempFile.renameSync(absPath);
+    } catch (e) {}
+  }
+
+  /**
+   * Write URIs information for the given [library] and its direct and
+   * indirect imports/exports.
+   */
+  void _writeUris(LibraryElement library,
+      [Set<LibraryElement> writtenLibraries]) {
+    Source librarySource = library.source;
+    // Do nothing if already cached.
+    if (_libraryUrisMap.containsKey(librarySource)) {
+      return;
+    }
+    // Stop recursion cycle.
+    writtenLibraries ??= new Set<LibraryElement>();
+    if (!writtenLibraries.add(library)) {
+      return;
+    }
+    // Prepare import/export URIs.
+    List<String> importUris = <String>[];
+    List<String> exportUris = <String>[];
+    for (ImportElement element in library.imports) {
+      String uri = element.uri;
+      if (uri != null) {
+        importUris.add(uri);
+        _writeUris(element.importedLibrary, writtenLibraries);
+      }
+    }
+    for (ExportElement element in library.exports) {
+      String uri = element.uri;
+      if (uri != null) {
+        exportUris.add(uri);
+        _writeUris(element.exportedLibrary, writtenLibraries);
+      }
+    }
+    // Write the URIs.
+    CacheLibraryUrisBuilder b = new CacheLibraryUrisBuilder(
+        importedUris: importUris,
+        exportedUris: exportUris,
+        partUris: library.parts.map((e) => e.uri).toList());
+    List<int> bytes = b.toBuffer();
+    String fileName = _getUrisFileName(librarySource);
+    _safeWriteBytes(fileName, bytes);
+    // Put into the cache to avoid reading it later.
+    _libraryUrisMap[librarySource] = new CacheLibraryUris.fromBuffer(bytes);
+  }
+}