зеркало из https://github.com/mozilla/gecko-dev.git
243 строки
9.4 KiB
C++
243 строки
9.4 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_dom_FileSystemTaskBase_h
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#define mozilla_dom_FileSystemTaskBase_h
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#include "mozilla/ErrorResult.h"
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#include "mozilla/dom/FileSystemRequestParent.h"
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#include "mozilla/dom/PFileSystemRequestChild.h"
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namespace mozilla {
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namespace dom {
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class BlobImpl;
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class BlobParent;
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class FileSystemBase;
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class FileSystemParams;
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/*
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* The base class to implement a Task class.
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* The task is used to handle the OOP (out of process) operations.
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* The file system operations can only be performed in the parent process. When
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* performing such a parent-process-only operation, a task will delivered the
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* operation to the parent process if needed.
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*
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* The following diagram illustrates the how a API call from the content page
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* starts a task and gets call back results.
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*
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* The left block is the call sequence inside the child process, while the
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* right block is the call sequence inside the parent process.
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*
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* There are two types of API call. One is from the content page of the child
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* process and we mark the steps as (1) to (8). The other is from the content
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* page of the parent process and we mark the steps as (1') to (4').
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*
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* Page Page
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* | |
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* | (1) | (1')
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* ______|________________ | _____________________|_____________
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* | | | | | | |
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* | | Task in | | | Task in | |
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* | | Child Process | | | Parent Process | |
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* | V | IPC | V |
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* [new FileSystemTaskBase()] | | [new FileSystemTaskBase()] |
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* | | | | | | |
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* | | (2) | | | (2') |
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* | V | (3) | | |
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* | [GetRequestParams]------------->[new FileSystemTaskBase(...)] |
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* | | | | | |
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* | | | | | (4) | |
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* | | | | | V |
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* | | | | -----------> [Work] |
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* | | IPC | | |
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* | | | | (5) | (3') |
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* | | | | V |
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* | | | | --------[HandleResult] |
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* | | | | | | |
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* | | | | (6) | |
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* | | (7) | V | |
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* | [SetRequestResult]<-------------[GetRequestResult] | |
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* | | | | | (4') |
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* | | (8) | | | | |
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* | V | | | V |
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* |[HandlerCallback] | IPC | [HandlerCallback] |
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* |_______|_______________| | |_________________________|_________|
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* | | |
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* V V
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* Page Page
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*
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* 1. From child process page
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* Child:
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* (1) Call FileSystem API from content page with JS. Create a task and run.
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* The base constructor [FileSystemTaskBase()] of the task should be called.
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* (2) Forward the task to the parent process through the IPC and call
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* [GetRequestParams] to prepare the parameters of the IPC.
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* Parent:
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* (3) The parent process receives IPC and handle it in
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* FileystemRequestParent.
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* Get the IPC parameters and create a task to run the IPC task. The base
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* constructor [FileSystemTaskBase(aParam, aParent)] of the task should be
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* called to set the task as an IPC task.
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* (4) The task operation will be performed in the member function of [Work].
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* A worker thread will be created to run that function. If error occurs
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* during the operation, call [SetError] to record the error and then abort.
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* (5) After finishing the task operation, call [HandleResult] to send the
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* result back to the child process though the IPC.
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* (6) Call [GetRequestResult] request result to prepare the parameters of the
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* IPC. Because the formats of the error result for different task are the
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* same, FileSystemTaskBase can handle the error message without interfering.
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* Each task only needs to implement its specific success result preparation
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* function -[GetSuccessRequestResult].
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* Child:
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* (7) The child process receives IPC and calls [SetRequestResult] to get the
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* task result. Each task needs to implement its specific success result
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* parsing function [SetSuccessRequestResult] to get the success result.
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* (8) Call [HandlerCallback] to send the task result to the content page.
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* 2. From parent process page
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* We don't need to send the task parameters and result to other process. So
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* there are less steps, but their functions are the same. The correspondence
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* between the two types of steps is:
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* (1') = (1),
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* (2') = (4),
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* (3') = (5),
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* (4') = (8).
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*/
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class FileSystemTaskBase
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: public nsRunnable
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, public PFileSystemRequestChild
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{
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public:
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/*
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* Start the task. If the task is running the child process, it will be
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* forwarded to parent process by IPC, or else, creates a worker thread to
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* do the task work.
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*/
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void
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Start();
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/*
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* The error codes are defined in xpcom/base/ErrorList.h and their
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* corresponding error name and message are defined in dom/base/domerr.msg.
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*/
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void
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SetError(const nsresult& aErrorCode);
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FileSystemBase*
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GetFileSystem() const;
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/*
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* Get the type of permission access required to perform this task.
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*/
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virtual void
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GetPermissionAccessType(nsCString& aAccess) const = 0;
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NS_DECL_NSIRUNNABLE
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protected:
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/*
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* To create a task to handle the page content request.
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*/
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explicit FileSystemTaskBase(FileSystemBase* aFileSystem);
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/*
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* To create a parent process task delivered from the child process through
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* IPC.
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*/
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FileSystemTaskBase(FileSystemBase* aFileSystem,
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const FileSystemParams& aParam,
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FileSystemRequestParent* aParent);
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virtual
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~FileSystemTaskBase();
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/*
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* The function to perform task operation. It will be run on the worker
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* thread of the parent process.
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* Overrides this function to define the task operation for individual task.
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*/
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virtual nsresult
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Work() = 0;
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/*
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* After the task is completed, this function will be called to pass the task
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* result to the content page.
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* Override this function to handle the call back to the content page.
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*/
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virtual void
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HandlerCallback() = 0;
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/*
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* Wrap the task parameter to FileSystemParams for sending it through IPC.
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* It will be called when we need to forward a task from the child process to
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* the prarent process.
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* @param filesystem The string representation of the file system.
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*/
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virtual FileSystemParams
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GetRequestParams(const nsString& aFileSystem) const = 0;
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/*
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* Wrap the task success result to FileSystemResponseValue for sending it
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* through IPC.
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* It will be called when the task is completed successfully and we need to
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* send the task success result back to the child process.
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*/
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virtual FileSystemResponseValue
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GetSuccessRequestResult() const = 0;
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/*
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* Unwrap the IPC message to get the task success result.
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* It will be called when the task is completed successfully and an IPC
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* message is received in the child process and we want to get the task
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* success result.
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*/
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virtual void
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SetSuccessRequestResult(const FileSystemResponseValue& aValue) = 0;
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bool
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HasError() const { return mErrorValue != NS_OK; }
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// Overrides PFileSystemRequestChild
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virtual bool
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Recv__delete__(const FileSystemResponseValue& value) override;
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BlobParent*
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GetBlobParent(BlobImpl* aBlob) const;
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nsresult mErrorValue;
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RefPtr<FileSystemBase> mFileSystem;
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RefPtr<FileSystemRequestParent> mRequestParent;
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private:
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/*
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* After finishing the task operation, handle the task result.
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* If it is an IPC task, send back the IPC result. Or else, send the result
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* to the content page.
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*/
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void
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HandleResult();
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/*
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* Wrap the task result to FileSystemResponseValue for sending it through IPC.
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* It will be called when the task is completed and we need to
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* send the task result back to the child process.
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*/
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FileSystemResponseValue
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GetRequestResult() const;
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/*
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* Unwrap the IPC message to get the task result.
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* It will be called when the task is completed and an IPC message is received
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* in the child process and we want to get the task result.
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*/
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void
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SetRequestResult(const FileSystemResponseValue& aValue);
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};
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} // namespace dom
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} // namespace mozilla
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#endif // mozilla_dom_FileSystemTaskBase_h
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