279 lines
10 KiB
C++
279 lines
10 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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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#include "nsIIPCBackgroundChildCreateCallback.h"
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#include "nsThreadUtils.h"
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namespace mozilla {
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namespace dom {
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class BlobImpl;
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class FileSystemBase;
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class FileSystemParams;
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class PBlobParent;
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/*
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* The base class to implement a Task class.
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* The file system operations can only be performed in the parent process. In
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* order to avoid duplicated code, we used PBackground for child-parent and
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* parent-parent communications.
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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 any process loading content, while
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* the right block is the call sequence only inside the parent process.
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*
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* Page
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* |
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* | (1)
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* ______|_________________________ | _________________________________
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* | | | | | |
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* | | | | | |
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* | V | IPC | PBackground thread on |
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* | [new FileSystemTaskChildBase()] | | | the parent process |
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* | | | | | |
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* | | (2) | | |
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* | V | (3) | |
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* | [GetRequestParams]------------------->[new FileSystemTaskParentBase()] |
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* | | | | |
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* | | | | | (4) _____________ |
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* | | | | | | | |
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* | | | | | | I/O Thread | |
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* | | | | | | | |
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* | | | | ---------> [IOWork] | |
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* | | IPC | | | | |
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* | | | | | | (5) | |
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* | | | | -------------- | |
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* | | | | | |_____________| |
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* | | | | | |
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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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* | | | | |
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* | | (8) | | | |
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* | V | | | |
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* |[HandlerCallback] | IPC | |
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* |_______|_________________________| | |_________________________________|
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* | |
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* V
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* Page
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*
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* 1. From the process that is handling the request
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* Child/Parent (it can be in any process):
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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 [FileSystemTaskChildBase()] of the task should be
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* 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. Get the IPC parameters and create a task to run the
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* IPC task.
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* (4) The task operation will be performed in the member function of [IOWork].
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* A I/O 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, FileSystemTaskChildBase can handle the error message without
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* 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/Parent:
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* (7) The 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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*/
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class FileSystemTaskChildBase : public PFileSystemRequestChild
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, public nsIIPCBackgroundChildCreateCallback
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{
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public:
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NS_DECL_ISUPPORTS
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NS_DECL_NSIIPCBACKGROUNDCHILDCREATECALLBACK
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/*
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* Start the task. It will dispatch all the information to the parent process,
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* PBackground thread. This method must be called from the owning thread.
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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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* After the task is completed, this function will be called to pass the task
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* result to the content page. This method is called in the owning thread.
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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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bool
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HasError() const { return NS_FAILED(mErrorValue); }
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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 FileSystemTaskChildBase(FileSystemBase* aFileSystem);
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virtual
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~FileSystemTaskChildBase();
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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 parent process. This method runs in the owning thread.
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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& aSerializedDOMPath,
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ErrorResult& aRv) 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. This method runs in the owning thread.
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*/
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virtual void
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SetSuccessRequestResult(const FileSystemResponseValue& aValue,
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ErrorResult& aRv) = 0;
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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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nsresult mErrorValue;
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RefPtr<FileSystemBase> mFileSystem;
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private:
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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 content process and we want to get the task result. This runs on the
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* owning thread.
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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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// This class is the 'alter ego' of FileSystemTaskChildBase in the PBackground
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// world.
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class FileSystemTaskParentBase : public Runnable
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{
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public:
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/*
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* Start the task. This must be called from the PBackground thread only.
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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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/*
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* The function to perform task operation. It will be run on the I/O
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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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IOWork() = 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. This method runs in the PBackground thread.
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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(ErrorResult& aRv) const = 0;
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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. It runs on the PBackground
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* thread.
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*/
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void
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HandleResult();
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// If this task must do something on the main-thread before IOWork(), it must
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// overwrite this method. Otherwise it returns true if the FileSystem must be
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// initialized on the main-thread. It's called from the Background thread.
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virtual bool
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NeedToGoToMainThread() const;
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// This method is called only if NeedToGoToMainThread() returns true.
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// Of course, it runs on the main-thread.
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virtual nsresult
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MainThreadWork();
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bool
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HasError() const { return NS_FAILED(mErrorValue); }
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NS_IMETHOD
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Run() override;
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virtual nsresult
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GetTargetPath(nsAString& aPath) const = 0;
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private:
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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 content. This runs on the PBackground
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* thread.
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*/
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FileSystemResponseValue
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GetRequestResult() const;
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protected:
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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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FileSystemTaskParentBase(FileSystemBase* aFileSystem,
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const FileSystemParams& aParam,
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FileSystemRequestParent* aParent);
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virtual
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~FileSystemTaskParentBase();
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nsresult mErrorValue;
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RefPtr<FileSystemBase> mFileSystem;
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RefPtr<FileSystemRequestParent> mRequestParent;
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nsCOMPtr<nsIEventTarget> mBackgroundEventTarget;
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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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