Introduce AsyncFileUtil and deprecate FileSystemFileUtilProxy

In LocalFileSystemOperation we used to use a synchronous implementation
(implemented as FileSystemFileUtil) to perform subtasks (e.g. file_util::Copy
type operation), but it's not always natural to have synchronous
implementation depending on filesystem types. For example async interface
works much better if we need to talk to a remote server or a device.

This patch introduces an async version of FileUtil, AsyncFileUtil,
and replaces FileSystemFileUtil+Proxy implementation with it.

After this patch, each filesystem can choose either:
- implement synchronous FileSystemFileUtil and use it with AsyncFileUtilAdapter, or
- directly implement asynchronous AsyncFileUtil

BUG=154835
TEST=existing tests

Review URL: https://codereview.chromium.org/12035049

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@179299 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 21 insertions, 77 deletions

diff --git a/webkit/fileapi/file_system_file_util.h b/webkit/fileapi/file_system_file_util.h
index 8c05c1d7..5d4b72c 100644
--- a/webkit/fileapi/file_system_file_util.h
+++ b/webkit/fileapi/file_system_file_util.h
@@ -8,20 +8,17 @@
 #include "base/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/platform_file.h"
-#include "webkit/fileapi/file_system_url.h"
+#include "webkit/fileapi/file_snapshot_policy.h"
 #include "webkit/storage/webkit_storage_export.h"
 
 namespace base {
 class Time;
 }
 
-namespace webkit_blob {
-class ShareableFileReference;
-}
-
 namespace fileapi {
 
 class FileSystemOperationContext;
+class FileSystemURL;
 
 // A file utility interface that provides basic file utility methods for
 // FileSystem API.
@@ -47,20 +44,6 @@ class WEBKIT_STORAGE_EXPORT FileSystemFileUtil {
     virtual bool IsDirectory() = 0;
   };
 
-  // A policy flag for CreateSnapshotFile.
-  enum SnapshotFilePolicy {
-    kSnapshotFileUnknown,
-
-    // The implementation just uses the local file as the snapshot file.
-    // The FileAPI backend does nothing on the returned file.
-    kSnapshotFileLocal,
-
-    // The implementation returns a temporary file as the snapshot file.
-    // The FileAPI backend takes care of the lifetime of the returned file
-    // and will delete when the last reference of the file is dropped.
-    kSnapshotFileTemporary,
-  };
-
   class WEBKIT_STORAGE_EXPORT EmptyFileEnumerator
       : public AbstractFileEnumerator {
     virtual FilePath Next() OVERRIDE;
@@ -72,11 +55,8 @@ class WEBKIT_STORAGE_EXPORT FileSystemFileUtil {
   virtual ~FileSystemFileUtil() {}
 
   // Creates or opens a file with the given flags.
-  // If PLATFORM_FILE_CREATE is set in |file_flags| it always tries to create
-  // a new file at the given |url| and calls back with
-  // PLATFORM_FILE_ERROR_FILE_EXISTS if the |url| already exists.
-  //
-  // This is used only for Pepper/NaCL File API.
+  // See header comments for AsyncFileUtil::CreateOrOpen() for more details.
+  // This is used only by Pepper/NaCL File API.
   virtual base::PlatformFileError CreateOrOpen(
       FileSystemOperationContext* context,
       const FileSystemURL& url,
@@ -85,7 +65,6 @@ class WEBKIT_STORAGE_EXPORT FileSystemFileUtil {
       bool* created) = 0;
 
   // Closes the given file handle.
-  //
   // This is used only for Pepper/NaCL File API.
   virtual base::PlatformFileError Close(
       FileSystemOperationContext* context,
@@ -93,19 +72,13 @@ class WEBKIT_STORAGE_EXPORT FileSystemFileUtil {
 
   // Ensures that the given |url| exist.  This creates a empty new file
   // at |url| if the |url| does not exist.
-  // If a new file han not existed and is created at the |url|,
-  // |created| is set true and |error code|
-  // is set PLATFORM_FILE_OK.
-  // If the file already exists, |created| is set false and |error code|
-  // is set PLATFORM_FILE_OK.
-  // If the file hasn't existed but it couldn't be created for some other
-  // reasons, |created| is set false and |error code| indicates the error.
+  // See header comments for AsyncFileUtil::EnsureFileExists() for more details.
   virtual base::PlatformFileError EnsureFileExists(
       FileSystemOperationContext* context,
       const FileSystemURL& url, bool* created) = 0;
 
-  // Creates directory at given url. It's an error to create
-  // if |exclusive| is true and dir already exists.
+  // Creates directory at given url.
+  // See header comments for AsyncFileUtil::CreateDirectory() for more details.
   virtual base::PlatformFileError CreateDirectory(
       FileSystemOperationContext* context,
       const FileSystemURL& url,
@@ -113,6 +86,7 @@ class WEBKIT_STORAGE_EXPORT FileSystemFileUtil {
       bool recursive) = 0;
 
   // Retrieves the information about a file.
+  // See header comments for AsyncFileUtil::GetFileInfo() for more details.
   virtual base::PlatformFileError GetFileInfo(
       FileSystemOperationContext* context,
       const FileSystemURL& url,
@@ -126,6 +100,9 @@ class WEBKIT_STORAGE_EXPORT FileSystemFileUtil {
   //
   // The supplied context must remain valid at least lifetime of the enumerator
   // instance.
+  //
+  // TODO(kinuko): Drop recursive flag so that each FileUtil no longer
+  // needs to implement recursive logic.
   virtual scoped_ptr<AbstractFileEnumerator> CreateFileEnumerator(
       FileSystemOperationContext* context,
       const FileSystemURL& root_url,
@@ -139,17 +116,16 @@ class WEBKIT_STORAGE_EXPORT FileSystemFileUtil {
       const FileSystemURL& file_system_url,
       FilePath* local_file_path) = 0;
 
-  // Updates the file metadata information.  Unlike posix's touch, it does
-  // not create a file even if |url| does not exist, but instead fails
-  // with PLATFORM_FILE_ERROR_NOT_FOUND.
+  // Updates the file metadata information.
+  // See header comments for AsyncFileUtil::Touch() for more details.
   virtual base::PlatformFileError Touch(
       FileSystemOperationContext* context,
       const FileSystemURL& url,
       const base::Time& last_access_time,
       const base::Time& last_modified_time) = 0;
 
-  // Truncates a file to the given length.  If |length| is greater than the
-  // current length of the file, the file will be extended with zeroes.
+  // Truncates a file to the given length.
+  // See header comments for AsyncFileUtil::Truncate() for more details.
   virtual base::PlatformFileError Truncate(
       FileSystemOperationContext* context,
       const FileSystemURL& url,
@@ -174,62 +150,30 @@ class WEBKIT_STORAGE_EXPORT FileSystemFileUtil {
       bool copy) = 0;
 
   // Copies in a single file from a different filesystem.
-  //
-  // This returns:
-  // - PLATFORM_FILE_ERROR_NOT_FOUND if |src_file_path|
-  //   or the parent directory of |dest_url| does not exist.
-  // - PLATFORM_FILE_ERROR_INVALID_OPERATION if |dest_url| exists and
-  //   is not a file.
-  // - PLATFORM_FILE_ERROR_FAILED if |dest_url| does not exist and
-  //   its parent path is a file.
-  //
+  // See header comments for AsyncFileUtil::CopyInForeignFile() for
+  // more details.
   virtual base::PlatformFileError CopyInForeignFile(
         FileSystemOperationContext* context,
         const FilePath& src_file_path,
         const FileSystemURL& dest_url) = 0;
 
   // Deletes a single file.
-  //
-  // This returns:
-  // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
-  // - PLATFORM_FILE_ERROR_NOT_A_FILE if |url| is not a file.
-  //
+  // See header comments for AsyncFileUtil::DeleteFile() for more details.
   virtual base::PlatformFileError DeleteFile(
       FileSystemOperationContext* context,
       const FileSystemURL& url) = 0;
 
   // Deletes a single empty directory.
-  //
-  // This returns:
-  // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
-  // - PLATFORM_FILE_ERROR_NOT_A_DIRECTORY if |url| is not a directory.
-  // - PLATFORM_FILE_ERROR_NOT_EMPTY if |url| is not empty.
-  //
+  // See header comments for AsyncFileUtil::DeleteDirectory() for more details.
   virtual base::PlatformFileError DeleteDirectory(
       FileSystemOperationContext* context,
       const FileSystemURL& url) = 0;
 
   // Creates a local snapshot file for a given |url| and returns the
   // metadata and platform path of the snapshot file via |callback|.
-  // In regular filesystem cases the implementation may simply return
-  // the metadata of the file itself (as well as GetMetadata does),
-  // while in non-regular filesystem case the backend may create a
-  // temporary snapshot file which holds the file data and return
-  // the metadata of the temporary file.
-  //
-  // |file_info| is the metadata of the snapshot file created.
-  // |platform_path| is the path to the snapshot file created.
-  // |policy| should indicate the policy how the fileapi backend
-  // should handle the returned file.
-  //
-  // This returns:
-  // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
-  // - PLATFORM_FILE_ERROR_NOT_A_FILE if |url| is not a file.
-  //
-  // The field values of |file_info| are undefined (implementation
-  // dependent) in error cases, and the caller should always
-  // check the return code.
   //
+  // See header comments for AsyncFileUtil::CreateSnapshotFile() for
+  // more details.
   virtual base::PlatformFileError CreateSnapshotFile(
       FileSystemOperationContext* context,
       const FileSystemURL& url,