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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/dom/FileSystemRequestParent.h"
+#include "mozilla/dom/PFileSystemRequestChild.h"
+#include "nsIGlobalObject.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+class ErrorResult;
+
+namespace dom {
+
+class BlobImpl;
+class FileSystemBase;
+class FileSystemParams;
+
+/*
+ * 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 {
+ friend class PFileSystemRequestChild;
+
+ public:
+ NS_INLINE_DECL_REFCOUNTING(FileSystemTaskChildBase, final)
+
+ /*
+ * 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.
+ */
+ FileSystemTaskChildBase(nsIGlobalObject* aGlobalObject,
+ 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 mozilla::ipc::IPCResult Recv__delete__(
+ const FileSystemResponseValue& value) final;
+
+ nsresult mErrorValue;
+ RefPtr<FileSystemBase> mFileSystem;
+ nsCOMPtr<nsIGlobalObject> mGlobalObject;
+
+ 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:
+ FileSystemTaskParentBase()
+ : Runnable("FileSystemTaskParentBase"),
+ mErrorValue(NS_ERROR_NOT_INITIALIZED) {}
+
+ /*
+ * 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();
+
+ 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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