1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
|
/* -*- 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
|
