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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_dom_FileSystemTaskBase_h
#define mozilla_dom_FileSystemTaskBase_h
#include "mozilla/ErrorResult.h"
#include "mozilla/dom/FileSystemRequestParent.h"
#include "mozilla/dom/PFileSystemRequestChild.h"
#include "nsIIPCBackgroundChildCreateCallback.h"
#include "nsThreadUtils.h"
namespace mozilla {
namespace dom {
class BlobImpl;
class FileSystemBase;
class FileSystemParams;
class PBlobParent;
/*
* The base class to implement a Task class.
* The file system operations can only be performed in the parent process. In
* order to avoid duplicated code, we used PBackground for child-parent and
* parent-parent communications.
*
* The following diagram illustrates the how a API call from the content page
* starts a task and gets call back results.
*
* The left block is the call sequence inside any process loading content, while
* the right block is the call sequence only inside the parent process.
*
* Page
* |
* | (1)
* ______|_________________________ | _________________________________
* | | | | | |
* | | | | | |
* | V | IPC | PBackground thread on |
* | [new FileSystemTaskChildBase()] | | | the parent process |
* | | | | | |
* | | (2) | | |
* | V | (3) | |
* | [GetRequestParams]------------------->[new FileSystemTaskParentBase()] |
* | | | | |
* | | | | | (4) _____________ |
* | | | | | | | |
* | | | | | | I/O Thread | |
* | | | | | | | |
* | | | | ---------> [IOWork] | |
* | | IPC | | | | |
* | | | | | | (5) | |
* | | | | -------------- | |
* | | | | | |_____________| |
* | | | | | |
* | | | | V |
* | | | | [HandleResult] |
* | | | | | |
* | | | | (6) |
* | | (7) | V |
* | [SetRequestResult]<---------------------[GetRequestResult] |
* | | | | |
* | | (8) | | | |
* | V | | | |
* |[HandlerCallback] | IPC | |
* |_______|_________________________| | |_________________________________|
* | |
* V
* Page
*
* 1. From the process that is handling the request
* Child/Parent (it can be in any process):
* (1) Call FileSystem API from content page with JS. Create a task and run.
* The base constructor [FileSystemTaskChildBase()] of the task should be
* called.
* (2) Forward the task to the parent process through the IPC and call
* [GetRequestParams] to prepare the parameters of the IPC.
* Parent:
* (3) The parent process receives IPC and handle it in
* FileystemRequestParent. Get the IPC parameters and create a task to run the
* IPC task.
* (4) The task operation will be performed in the member function of [IOWork].
* A I/O thread will be created to run that function. If error occurs
* during the operation, call [SetError] to record the error and then abort.
* (5) After finishing the task operation, call [HandleResult] to send the
* result back to the child process though the IPC.
* (6) Call [GetRequestResult] request result to prepare the parameters of the
* IPC. Because the formats of the error result for different task are the
* same, FileSystemTaskChildBase can handle the error message without
* interfering.
* Each task only needs to implement its specific success result preparation
* function -[GetSuccessRequestResult].
* Child/Parent:
* (7) The process receives IPC and calls [SetRequestResult] to get the
* task result. Each task needs to implement its specific success result
* parsing function [SetSuccessRequestResult] to get the success result.
* (8) Call [HandlerCallback] to send the task result to the content page.
*/
class FileSystemTaskChildBase : public PFileSystemRequestChild
, public nsIIPCBackgroundChildCreateCallback
{
public:
NS_DECL_ISUPPORTS
NS_DECL_NSIIPCBACKGROUNDCHILDCREATECALLBACK
/*
* Start the task. It will dispatch all the information to the parent process,
* PBackground thread. This method must be called from the owning thread.
*/
void
Start();
/*
* The error codes are defined in xpcom/base/ErrorList.h and their
* corresponding error name and message are defined in dom/base/domerr.msg.
*/
void
SetError(const nsresult& aErrorCode);
FileSystemBase*
GetFileSystem() const;
/*
* After the task is completed, this function will be called to pass the task
* result to the content page. This method is called in the owning thread.
* Override this function to handle the call back to the content page.
*/
virtual void
HandlerCallback() = 0;
bool
HasError() const { return NS_FAILED(mErrorValue); }
protected:
/*
* To create a task to handle the page content request.
*/
explicit FileSystemTaskChildBase(FileSystemBase* aFileSystem);
virtual
~FileSystemTaskChildBase();
/*
* Wrap the task parameter to FileSystemParams for sending it through IPC.
* It will be called when we need to forward a task from the child process to
* the parent process. This method runs in the owning thread.
* @param filesystem The string representation of the file system.
*/
virtual FileSystemParams
GetRequestParams(const nsString& aSerializedDOMPath,
ErrorResult& aRv) const = 0;
/*
* Unwrap the IPC message to get the task success result.
* It will be called when the task is completed successfully and an IPC
* message is received in the child process and we want to get the task
* success result. This method runs in the owning thread.
*/
virtual void
SetSuccessRequestResult(const FileSystemResponseValue& aValue,
ErrorResult& aRv) = 0;
// Overrides PFileSystemRequestChild
virtual bool
Recv__delete__(const FileSystemResponseValue& value) override;
nsresult mErrorValue;
RefPtr<FileSystemBase> mFileSystem;
private:
/*
* Unwrap the IPC message to get the task result.
* It will be called when the task is completed and an IPC message is received
* in the content process and we want to get the task result. This runs on the
* owning thread.
*/
void
SetRequestResult(const FileSystemResponseValue& aValue);
};
// This class is the 'alter ego' of FileSystemTaskChildBase in the PBackground
// world.
class FileSystemTaskParentBase : public Runnable
{
public:
/*
* Start the task. This must be called from the PBackground thread only.
*/
void
Start();
/*
* The error codes are defined in xpcom/base/ErrorList.h and their
* corresponding error name and message are defined in dom/base/domerr.msg.
*/
void
SetError(const nsresult& aErrorCode);
/*
* The function to perform task operation. It will be run on the I/O
* thread of the parent process.
* Overrides this function to define the task operation for individual task.
*/
virtual nsresult
IOWork() = 0;
/*
* Wrap the task success result to FileSystemResponseValue for sending it
* through IPC. This method runs in the PBackground thread.
* It will be called when the task is completed successfully and we need to
* send the task success result back to the child process.
*/
virtual FileSystemResponseValue
GetSuccessRequestResult(ErrorResult& aRv) const = 0;
/*
* After finishing the task operation, handle the task result.
* If it is an IPC task, send back the IPC result. It runs on the PBackground
* thread.
*/
void
HandleResult();
// If this task must do something on the main-thread before IOWork(), it must
// overwrite this method. Otherwise it returns true if the FileSystem must be
// initialized on the main-thread. It's called from the Background thread.
virtual bool
NeedToGoToMainThread() const;
// This method is called only if NeedToGoToMainThread() returns true.
// Of course, it runs on the main-thread.
virtual nsresult
MainThreadWork();
bool
HasError() const { return NS_FAILED(mErrorValue); }
NS_IMETHOD
Run() override;
virtual nsresult
GetTargetPath(nsAString& aPath) const = 0;
private:
/*
* Wrap the task result to FileSystemResponseValue for sending it through IPC.
* It will be called when the task is completed and we need to
* send the task result back to the content. This runs on the PBackground
* thread.
*/
FileSystemResponseValue
GetRequestResult() const;
protected:
/*
* To create a parent process task delivered from the child process through
* IPC.
*/
FileSystemTaskParentBase(FileSystemBase* aFileSystem,
const FileSystemParams& aParam,
FileSystemRequestParent* aParent);
virtual
~FileSystemTaskParentBase();
nsresult mErrorValue;
RefPtr<FileSystemBase> mFileSystem;
RefPtr<FileSystemRequestParent> mRequestParent;
nsCOMPtr<nsIEventTarget> mBackgroundEventTarget;
};
} // namespace dom
} // namespace mozilla
#endif // mozilla_dom_FileSystemTaskBase_h
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