private bool IsFileContentsUpToDate(FileSystemEntities entities, FullPathChanges fullPathChanges, FileWithContents existingFileWithContents)
{
Debug.Assert(existingFileWithContents.Contents != null);
var fullPath = existingFileWithContents.FileName.FullPath;
if (fullPathChanges != null)
{
// We don't get file change events for file in symlinks, so we can't
// rely on fullPathChanges contents for our heuristic of avoiding file
// system access.
if (!FileDatabaseSnapshot.IsContainedInSymLinkHelper(entities.Directories, existingFileWithContents.FileName))
{
return(fullPathChanges.ShouldSkipLoadFileContents(fullPath));
}
}
// Do the "expensive" check by going to the file system.
var fi = _fileSystem.GetFileInfoSnapshot(fullPath);
return
((fi.Exists) &&
(fi.IsFile) &&
(fi.LastWriteTimeUtc == existingFileWithContents.Contents.UtcLastModified));
}
/// <summary>
/// Note: Concurrency: There are potentially many readers (search threads), but
/// only one writer (us). Updating the hash table with the line below assumes
/// that 1) the entry exists and 2) the hash table implementation does not
/// mutate any of its internal state when updating an existing entry.
/// <para>
/// 1) is verified because we the "filesToRead" collections only contains
/// file names contained in this table.</para>
/// <para>
/// 2) is verified because the two possible implementations, <see cref="Dictionary{TKey,TValue}"/>
/// and <see cref="SlimHashTable{TKey,TValue}"/> behave that way.</para>
/// </summary>
private static void DangerousUpdateFileTableEntry(FileDatabaseSnapshot fileDatabase,
FileName fileName,
FileContents newContents)
{
fileDatabase.Files[fileName] = new FileWithContents(fileName, newContents);
}
