Refactor FileIO to the new design

ppapi/shared_impl/ppb_file_io_shared.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PPAPI_SHARED_IMPL_PPB_FILE_IO_SHARED_H_
 #define PPAPI_SHARED_IMPL_PPB_FILE_IO_SHARED_H_
 
-#include <deque>
-
+#include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "ppapi/c/pp_file_info.h"
+#include "ppapi/c/pp_resource.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
-#include "ppapi/shared_impl/resource.h"
-#include "ppapi/shared_impl/tracked_callback.h"
-#include "ppapi/thunk/ppb_file_io_api.h"
 
 namespace ppapi {
 
 namespace thunk {
 class PPB_FileRef_API;
 }
 
-class PPAPI_SHARED_EXPORT PPB_FileIO_Shared : public Resource,
-                                              public thunk::PPB_FileIO_API {
- public:
-  PPB_FileIO_Shared(PP_Instance instance);
-  PPB_FileIO_Shared(const HostResource& host_resource);
+class PPAPI_SHARED_EXPORT PPB_FileIO_Shared {
+ protected:
+  PPB_FileIO_Shared();
   ~PPB_FileIO_Shared();
 
-  // Resource overrides.
-  virtual thunk::PPB_FileIO_API* AsPPB_FileIO_API() OVERRIDE;
-
-  // PPB_FileIO_API implementation.
-  virtual int32_t Open(PP_Resource file_ref,
-                       int32_t open_flags,
-                       scoped_refptr<TrackedCallback> callback) OVERRIDE;
-  virtual int32_t Query(PP_FileInfo* info,
-                        scoped_refptr<TrackedCallback> callback) OVERRIDE;
-  virtual int32_t Touch(PP_Time last_access_time,
-                        PP_Time last_modified_time,
-                        scoped_refptr<TrackedCallback> callback) OVERRIDE;
-  virtual int32_t Read(int64_t offset,
-                       char* buffer,
-                       int32_t bytes_to_read,
-                       scoped_refptr<TrackedCallback> callback) OVERRIDE;
-  virtual int32_t ReadToArray(int64_t offset,
-                              int32_t max_read_length,
-                              PP_ArrayOutput* output_array_buffer,
-                              scoped_refptr<TrackedCallback> callback) OVERRIDE;
-  virtual int32_t Write(int64_t offset,
-                        const char* buffer,
-                        int32_t bytes_to_write,
-                        scoped_refptr<TrackedCallback> callback) OVERRIDE;
-  virtual int32_t SetLength(int64_t length,
-                            scoped_refptr<TrackedCallback> callback) OVERRIDE;
-  virtual int32_t Flush(scoped_refptr<TrackedCallback> callback) OVERRIDE;
-
-  // Callback handler for different types of operations.
-  void ExecuteGeneralCallback(int32_t pp_error);
-  void ExecuteOpenFileCallback(int32_t pp_error);
-  void ExecuteQueryCallback(int32_t pp_error, const PP_FileInfo& info);
-  void ExecuteReadCallback(int32_t pp_error_or_bytes, const char* data);
-
- protected:
-  struct CallbackEntry {
-    CallbackEntry();
-    CallbackEntry(const CallbackEntry& entry);
-    ~CallbackEntry();
-
-    scoped_refptr<TrackedCallback> callback;
-
-    // Output buffer used only by |Read()|.
-    PP_ArrayOutput read_buffer;
-
-    // Pointer back to the caller's PP_FileInfo structure for Query operations.
-    // NULL for non-query operations. Not owned.
-    PP_FileInfo* info;
-  };
-
+  // Only FileIOResource needs this, but leave here as shared code to make the
+  // resource code succinct.
   enum OperationType {
     // There is no pending operation right now.
     OPERATION_NONE,
 
     // If there are pending reads, any other kind of async operation is not
     // allowed.
     OPERATION_READ,
 
     // If there are pending writes, any other kind of async operation is not
     // allowed.
     OPERATION_WRITE,
 
     // If there is a pending operation that is neither read nor write, no
     // further async operation is allowed.
     OPERATION_EXCLUSIVE
   };
 
+  // FileIO operations templates to perform real operation between common
+  // pre/post-condition.
+  int32_t DoOpen(PP_Resource file_ref, int32_t open_flags);
+  int32_t DoQuery();
+  int32_t DoTouch(PP_Time last_access_time, PP_Time last_modified_time);
+  int32_t DoRead(int64_t offset, int32_t bytes_to_read);
+  int32_t DoWrite(int64_t offset, const char* buffer, int32_t bytes_to_write);
+  int32_t DoSetLength(int64_t length);
+  int32_t DoFlush();
+
+  void SetOpenSucceed();
+  bool CheckOpenState(bool should_be_open) const;
+
   // Validated versions of the FileIO API. Subclasses in the proxy and impl
   // implement these so the common error checking stays here.
   virtual int32_t OpenValidated(PP_Resource file_ref_resource,
                                 thunk::PPB_FileRef_API* file_ref_api,
-                                int32_t open_flags,
-                                scoped_refptr<TrackedCallback> callback) = 0;
-  virtual int32_t QueryValidated(PP_FileInfo* info,
-                                 scoped_refptr<TrackedCallback> callback) = 0;
+                                int32_t open_flags) = 0;
+  virtual int32_t QueryValidated() = 0;
   virtual int32_t TouchValidated(PP_Time last_access_time,
-                                 PP_Time last_modified_time,
-                                 scoped_refptr<TrackedCallback> callback) = 0;
+                                 PP_Time last_modified_time) = 0;
   virtual int32_t ReadValidated(int64_t offset,
-                                const PP_ArrayOutput& buffer,
-                                int32_t max_read_length,
-                                scoped_refptr<TrackedCallback> callback) = 0;
+                                int32_t max_read_length) = 0;
   virtual int32_t WriteValidated(int64_t offset,
                                  const char* buffer,
-                                 int32_t bytes_to_write,
-                                 scoped_refptr<TrackedCallback> callback) = 0;
-  virtual int32_t SetLengthValidated(
-      int64_t length,
-      scoped_refptr<TrackedCallback> callback) = 0;
-  virtual int32_t FlushValidated(scoped_refptr<TrackedCallback> callback) = 0;
+                                 int32_t bytes_to_write) = 0;
+  virtual int32_t SetLengthValidated(int64_t length) = 0;
+  virtual int32_t FlushValidated() = 0;
 
-  // Called for every "Validated" function.
+  // Called before every "Validated" function.  It is responsible to make sure
+  // that "state" is correct.  For example, some operations are only valid after
+  // the file is opened, or operations might need to run excludively.  See
+  // subclasses implementation for detail.
   //
-  // This verifies that the callback is valid and that no callback is already
-  // pending, or it is a read(write) request and currently the pending
-  // operations are reads(writes).
-  //
-  // Returns |PP_OK| to indicate that everything is valid or |PP_ERROR_...| if
-  // the call should be aborted and that code returned to the plugin.
-  int32_t CommonCallValidation(bool should_be_open, OperationType new_op);
+  // It returns |PP_OK| on success, or |PP_ERROR_...| for various reasons.
+  virtual int32_t CommonPreCondition(bool should_be_open,
+                                     OperationType new_op) = 0;
 
-  // Sets up a pending callback. This should only be called once it is certain
-  // that |PP_OK_COMPLETIONPENDING| will be returned.
-  //
-  // |read_buffer| is only used by read operations, |info| is used only by
-  // query operations.
-  void RegisterCallback(OperationType op,
-                        scoped_refptr<TrackedCallback> callback,
-                        const PP_ArrayOutput* read_buffer,
-                        PP_FileInfo* info);
-
-  // Pops the oldest callback from the queue and runs it.
-  void RunAndRemoveFirstPendingCallback(int32_t result);
-
-  // The file system type specified in the Open() call. This will be
-  // PP_FILESYSTEMTYPE_INVALID before open was called. This value does not
-  // indicate that the open command actually succeeded.
-  PP_FileSystemType file_system_type_;
+  // Called after every "Validated" function.
+  virtual void CommonPostCondition(OperationType new_op) = 0;
 
   // Set to true when the file has been successfully opened.
   bool file_open_;
 
-  std::deque<CallbackEntry> callbacks_;
-  OperationType pending_op_;
-
   DISALLOW_COPY_AND_ASSIGN(PPB_FileIO_Shared);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_PPB_FILE_IO_SHARED_H_