Implement File.lastModified.

runtime/bin/file_impl.dart

Index: runtime/bin/file_impl.dart
diff --git a/runtime/bin/file_impl.dart b/runtime/bin/file_impl.dart
index 4df9e7a4748e5c254fbb04ce8e35e6984af59426..452c9a7479b2d6af2ccff12fc81dd7b87e49443d 100644
--- a/runtime/bin/file_impl.dart
+++ b/runtime/bin/file_impl.dart
@@ -2,6 +2,8 @@
 // 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.
 
+final int _MS_PER_SECOND = 1000;

[Anders Johnsen, 2012/05/24 12:05:42]

Could this be renamed to _kMsPerSecond? Also, would it be possible to put it
into one of the objects, e.g. FileBase::_kMsPerSecond?

[Mads Ager (google), 2012/05/24 12:09:21]

No, that is not the style we have for constants in Dart code. It is our style
for constants in C++.

[Anders Johnsen, 2012/05/24 12:12:59]

I stand corrected. We do have a ton of k... constants in this file though.

[Mads Ager (google), 2012/05/24 12:18:43]

That is true. We should update those. I do prefer kName for constants myself so
this will be painful. ;-)

+
 class _FileInputStream extends _BaseDataInputStream implements InputStream {
   _FileInputStream(String name) {
     var file = new File(name);
@@ -225,12 +227,13 @@ class _FileUtils {
   static final kTruncateRequest = 9;
   static final kLengthRequest = 10;
   static final kLengthFromNameRequest = 11;
-  static final kFlushRequest = 12;
-  static final kReadByteRequest = 13;
-  static final kWriteByteRequest = 14;
-  static final kReadListRequest = 15;
-  static final kWriteListRequest = 16;
-  static final kWriteStringRequest = 17;
+  static final kLastModifiedRequest = 12;
+  static final kFlushRequest = 13;
+  static final kReadByteRequest = 14;
+  static final kWriteByteRequest = 15;
+  static final kReadListRequest = 16;
+  static final kWriteListRequest = 17;
+  static final kWriteStringRequest = 18;
 
   static final kSuccessResponse = 0;
   static final kIllegalArgumentResponse = 1;
@@ -274,6 +277,7 @@ class _FileUtils {
   static fullPath(String name) native "File_FullPath";
   static directory(String name) native "File_Directory";
   static lengthFromName(String name) native "File_LengthFromName";
+  static lastModified(String name) native "File_LastModified";
   static int close(int id) native "File_Close";
   static readByte(int id) native "File_ReadByte";
   static readList(int id, List<int> buffer, int offset, int bytes)
@@ -298,83 +302,58 @@ class _FileUtils {
   static SendPort newServicePort() native "File_NewServicePort";
 
   static bool checkedExists(String name) {
-    if (name is !String) {
-      throw new IllegalArgumentException();
-    }
+    if (name is !String) throw new IllegalArgumentException();
     var result = exists(name);
-    if (result is OSError) {
-      throw new FileIOException("Cannot check existence of file '$name'",
-                                result);
-    }
+    throwIfError(result, "Cannot check existence of file '$name'");
     return result;
   }
 
   static int checkedOpen(String name, int mode) {
-    if (name is !String || mode is !int) {
-      throw new IllegalArgumentException();
-    };
+    if (name is !String || mode is !int) throw new IllegalArgumentException();
     var result = open(name, mode);
-    if (result is OSError) {
-      throw new FileIOException("Cannot open file '$name'", result);
-    }
+    throwIfError(result, "Cannot open file '$name'");
     return result;
   }
 
   static bool checkedCreate(String name) {
-    if (name is !String) {
-      throw new IllegalArgumentException();
-    };
+    if (name is !String) throw new IllegalArgumentException();
     var result = create(name);
-    if (result is OSError) {
-      throw new FileIOException("Cannot create file '$name'", result);
-    }
+    throwIfError(result, "Cannot create file '$name'");
     return true;
   }
 
   static bool checkedDelete(String name) {
-    if (name is !String) {
-      throw new IllegalArgumentException();
-    };
+    if (name is !String) throw new IllegalArgumentException();
     var result = delete(name);
-    if (result is OSError) {
-      throw new FileIOException("Cannot delete file '$name'", result);
-    }
+    throwIfError(result, "Cannot delete file '$name'");
     return true;
   }
 
   static String checkedFullPath(String name) {
-    if (name is !String) {
-      throw new IllegalArgumentException();
-    };
+    if (name is !String) throw new IllegalArgumentException();
     var result = fullPath(name);
-    if (result is OSError) {
-      throw new FileIOException(
-          "Cannot retrieve full path for file '$name'", result);
-    }
+    throwIfError(result, "Cannot retrieve full path for file '$name'");
     return result;
   }
 
   static String checkedDirectory(String name) {
-    if (name is !String) {
-      throw new IllegalArgumentException();
-    }
+    if (name is !String) throw new IllegalArgumentException();
     var result = directory(name);
-    if (result is OSError) {
-      throw new FileIOException(
-          "Cannot retrieve directory for file '$name'", result);
-    }
+    throwIfError(result, "Cannot retrieve directory for file '$name'");
     return result;
   }
 
   static int checkedLengthFromName(String name) {
-    if (name is !String) {
-      throw new IllegalArgumentException();
-    }
+    if (name is !String) throw new IllegalArgumentException();
     var result = lengthFromName(name);
-    if (result is OSError) {
-      throw new FileIOException(
-          "Cannot retrieve length of file '$name'", result);
-    }
+    throwIfError(result, "Cannot retrieve length of file '$name'");
+    return result;
+  }
+
+  static int checkedLastModified(String name) {
+    if (name is !String) throw new IllegalArgumentException();
+    var result = lastModified(name);
+    throwIfError(result, "Cannot retrieve modification time for file '$name'");
     return result;
   }
 
@@ -386,10 +365,15 @@ class _FileUtils {
   }
 
   static int checkedWriteString(int id, String string) {
-    if (string is !String) return -1;
+    if (string is !String) throw new IllegalArgumentException();
     return writeString(id, string);
   }
 
+  static throwIfError(Object result, String msg) {
+    if (result is OSError) {
+      throw new FileIOException(msg, result);
+    }
+  }
 }
 
 // Base class for _File and _RandomAccessFile with shared functions.
@@ -533,12 +517,27 @@ class _File extends _FileBase implements File {
   }
 
   int lengthSync() {
-    var result = _FileUtils.checkedLengthFromName(_name);
-    if (result is OSError) {
-      throw new FileIOException("Cannot retrieve length of file '$_name'",
-                                result);
-    }
-    return result;
+    return _FileUtils.checkedLengthFromName(_name);
+  }
+
+  Future<Date> lastModified() {
+    _ensureFileService();
+    List request = new List(2);
+    request[0] = _FileUtils.kLastModifiedRequest;
+    request[1] = _name;
+    return _fileService.call(request).transform((response) {
+      if (_isErrorResponse(response)) {
+        throw _exceptionFromResponse(response,
+                                     "Cannot retrieve modification time "
+                                     "for file '$_name'");
+      }
+      return new Date.fromEpoch(response * _MS_PER_SECOND);

[Søren Gjesse, 2012/05/24 12:43:45]

How about having the result be in ms so we don't have the * _MS_PER_SECOND here
but in the OS files instead. Then we could change to use a more precise system
call (if it exists) with less changes to the code.

[Mads Ager (google), 2012/05/24 13:09:41]

Good call. That makes sense. Will do.

+    });
+  }
+
+  Date lastModifiedSync() {
+    var result = _FileUtils.checkedLastModified(_name);
+    return new Date.fromEpoch(result * _MS_PER_SECOND);

[Søren Gjesse, 2012/05/24 12:43:45]

Ditto.

   }
 
   RandomAccessFile openSync([FileMode mode = FileMode.READ]) {
@@ -916,7 +915,7 @@ class _RandomAccessFile extends _FileBase implements RandomAccessFile {
     _checkNotClosed();
     var result = _FileUtils.checkedWriteString(_id, string);
     if (result is OSError) {
-      throw new FileIOException("writeString failed for file '$_name'", result);
+      throw new FileIOException("writeString failed for file '$_name'");
     }
     return result;
   }