storage/browser/fileapi/recursive_operation_delegate.h

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef STORAGE_BROWSER_FILEAPI_RECURSIVE_OPERATION_DELEGATE_H_
   6 #define STORAGE_BROWSER_FILEAPI_RECURSIVE_OPERATION_DELEGATE_H_
   7
   8 #include <queue>
   9 #include <stack>
  10
  11 #include "base/basictypes.h"
  12 #include "base/callback.h"
  13 #include "base/memory/weak_ptr.h"
  14 #include "storage/browser/fileapi/file_system_operation.h"
  15 #include "storage/browser/fileapi/file_system_url.h"
  16
  17 namespace storage {
  18
  19 class FileSystemContext;
  20 class FileSystemOperationRunner;
  21
  22 // A base class for recursive operation delegates.
  23 //
  24 // In short, each subclass should override ProcessFile and ProcessDirectory
  25 // to process a directory or a file. To start the recursive operation it
  26 // should also call StartRecursiveOperation.
  27 class STORAGE_EXPORT RecursiveOperationDelegate
  28     : public base::SupportsWeakPtr<RecursiveOperationDelegate> {
  29  public:
  30   typedef FileSystemOperation::StatusCallback StatusCallback;
  31   typedef FileSystemOperation::FileEntryList FileEntryList;
  32
  33   virtual ~RecursiveOperationDelegate();
  34
  35   // This is called when the consumer of this instance starts a non-recursive
  36   // operation.
  37   virtual void Run() = 0;
  38
  39   // This is called when the consumer of this instance starts a recursive
  40   // operation.
  41   virtual void RunRecursively() = 0;
  42
  43   // This is called each time a file is found while recursively
  44   // performing an operation.
  45   virtual void ProcessFile(const FileSystemURL& url,
  46                            const StatusCallback& callback) = 0;
  47
  48   // This is called each time a directory is found while recursively
  49   // performing an operation.
  50   virtual void ProcessDirectory(const FileSystemURL& url,
  51                                 const StatusCallback& callback) = 0;
  52
  53
  54   // This is called each time after files and subdirectories for a
  55   // directory is processed while recursively performing an operation.
  56   virtual void PostProcessDirectory(const FileSystemURL& url,
  57                                     const StatusCallback& callback) = 0;
  58
  59   // Cancels the currently running operation.
  60   void Cancel();
  61
  62  protected:
  63   explicit RecursiveOperationDelegate(FileSystemContext* file_system_context);
  64
  65   // Starts to process files/directories recursively from the given |root|.
  66   // This will call ProcessFile and ProcessDirectory on each file or directory.
  67   //
  68   // First, this tries to call ProcessFile with |root| regardless whether it is
  69   // actually a file or a directory. If it is a directory, ProcessFile should
  70   // return File::FILE_NOT_A_FILE.
  71   //
  72   // For each directory, the recursive operation works as follows:
  73   // ProcessDirectory is called first for the directory.
  74   // Then the directory contents are read (to obtain its sub directories and
  75   // files in it).
  76   // ProcessFile is called for found files. This may run in parallel.
  77   // The same step is recursively applied to each subdirectory.
  78   // After all files and subdirectories in a directory are processed,
  79   // PostProcessDirectory is called for the directory.
  80   // Here is an example;
  81   // a_dir/ -+- b1_dir/ -+- c1_dir/ -+- d1_file
  82   //         |           |           |
  83   //         |           +- c2_file  +- d2_file
  84   //         |
  85   //         +- b2_dir/ --- e_dir/
  86   //         |
  87   //         +- b3_file
  88   //         |
  89   //         +- b4_file
  90   // Then traverse order is:
  91   // ProcessFile(a_dir) (This should return File::FILE_NOT_A_FILE).
  92   // ProcessDirectory(a_dir).
  93   // ProcessFile(b3_file), ProcessFile(b4_file). (in parallel).
  94   // ProcessDirectory(b1_dir).
  95   // ProcessFile(c2_file)
  96   // ProcessDirectory(c1_dir).
  97   // ProcessFile(d1_file), ProcessFile(d2_file). (in parallel).
  98   // PostProcessDirectory(c1_dir)
  99   // PostProcessDirectory(b1_dir).
 100   // ProcessDirectory(b2_dir)
 101   // ProcessDirectory(e_dir)
 102   // PostProcessDirectory(e_dir)
 103   // PostProcessDirectory(b2_dir)
 104   // PostProcessDirectory(a_dir)
 105   //
 106   // |callback| is fired with base::File::FILE_OK when every file/directory
 107   // under |root| is processed, or fired earlier when any suboperation fails.
 108   void StartRecursiveOperation(const FileSystemURL& root,
 109                                const StatusCallback& callback);
 110
 111   FileSystemContext* file_system_context() { return file_system_context_; }
 112   const FileSystemContext* file_system_context() const {
 113     return file_system_context_;
 114   }
 115
 116   FileSystemOperationRunner* operation_runner();
 117
 118   // Called when Cancel() is called. This is a hook to do something more
 119   // in a derived class. By default, do nothing.
 120   virtual void OnCancel();
 121
 122  private:
 123   void DidTryProcessFile(const FileSystemURL& root,
 124                          base::File::Error error);
 125   void ProcessNextDirectory();
 126   void DidProcessDirectory(base::File::Error error);
 127   void DidReadDirectory(const FileSystemURL& parent,
 128                         base::File::Error error,
 129                         const FileEntryList& entries,
 130                         bool has_more);
 131   void ProcessPendingFiles();
 132   void DidProcessFile(base::File::Error error);
 133   void ProcessSubDirectory();
 134   void DidPostProcessDirectory(base::File::Error error);
 135
 136   // Called when all recursive operation is done (or an error occurs).
 137   void Done(base::File::Error error);
 138
 139   FileSystemContext* file_system_context_;
 140   StatusCallback callback_;
 141   std::stack<FileSystemURL> pending_directories_;
 142   std::stack<std::queue<FileSystemURL> > pending_directory_stack_;
 143   std::queue<FileSystemURL> pending_files_;
 144   int inflight_operations_;
 145   bool canceled_;
 146
 147   DISALLOW_COPY_AND_ASSIGN(RecursiveOperationDelegate);
 148 };
 149
 150 }  // namespace storage
 151
 152 #endif  // STORAGE_BROWSER_FILEAPI_RECURSIVE_OPERATION_DELEGATE_H_