summaryrefslogtreecommitdiffstats
path: root/dom/xhr/XMLHttpRequestString.h
blob: b02040b7ea46a725cc5d443de0b132a00b4c8761 (plain)
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
255
/* -*- 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_XMLHttpRequestString_h
#define mozilla_dom_XMLHttpRequestString_h

#include "mozilla/Mutex.h"
#include "mozilla/RefPtr.h"
#include "mozilla/dom/DOMString.h"
#include "nsString.h"

namespace mozilla {

class Mutex;

namespace dom {

class DOMString;
class XMLHttpRequestStringBuffer;
class XMLHttpRequestStringSnapshot;
class XMLHttpRequestStringWriterHelper;
class XMLHttpRequestStringSnapshotReaderHelper;

// We want to avoid the dup of strings when XHR in workers has access to
// responseText for events dispatched during the loading state. For this reason
// we use this class, able to create snapshots of the current size of itself
// without making extra copies.
class XMLHttpRequestString final
{
  friend class XMLHttpRequestStringWriterHelper;

public:
  XMLHttpRequestString();
  ~XMLHttpRequestString();

  void Truncate();

  uint32_t Length() const;

  void Append(const nsAString& aString);

  // This method should be called only when the string is really needed because
  // it can cause the duplication of the strings in case the loading of the XHR
  // is not completed yet.
  MOZ_MUST_USE bool GetAsString(nsAString& aString) const;

  size_t SizeOfThis(MallocSizeOf aMallocSizeOf) const;

  const char16_t* Data() const;

  bool IsEmpty() const;

  void CreateSnapshot(XMLHttpRequestStringSnapshot& aSnapshot);

private:
  XMLHttpRequestString(const XMLHttpRequestString&) = delete;
  XMLHttpRequestString& operator=(const XMLHttpRequestString&) = delete;
  XMLHttpRequestString& operator=(const XMLHttpRequestString&&) = delete;

  RefPtr<XMLHttpRequestStringBuffer> mBuffer;
};

// This class locks the buffer and allows the callee to write data into it.
class MOZ_STACK_CLASS XMLHttpRequestStringWriterHelper final
{
public:
  explicit XMLHttpRequestStringWriterHelper(XMLHttpRequestString& aString);

  bool
  AddCapacity(int32_t aCapacity);

  char16_t*
  EndOfExistingData();

  void
  AddLength(int32_t aLength);

private:
  XMLHttpRequestStringWriterHelper(const XMLHttpRequestStringWriterHelper&) = delete;
  XMLHttpRequestStringWriterHelper& operator=(const XMLHttpRequestStringWriterHelper&) = delete;
  XMLHttpRequestStringWriterHelper& operator=(const XMLHttpRequestStringWriterHelper&&) = delete;

  RefPtr<XMLHttpRequestStringBuffer> mBuffer;
  MutexAutoLock mLock;
};

// This class is the internal XMLHttpRequestStringBuffer of the
// XMLHttpRequestString plus the current length. GetAsString will return the
// string with that particular length also if the XMLHttpRequestStringBuffer is
// grown in the meantime.
class XMLHttpRequestStringSnapshot final
{
  friend class XMLHttpRequestStringBuffer;
  friend class XMLHttpRequestStringSnapshotReaderHelper;

public:
  XMLHttpRequestStringSnapshot();
  ~XMLHttpRequestStringSnapshot();

  XMLHttpRequestStringSnapshot& operator=(const XMLHttpRequestStringSnapshot&);

  void Reset()
  {
    ResetInternal(false /* isVoid */);
  }

  void SetVoid()
  {
    ResetInternal(true /* isVoid */);
  }

  bool IsVoid() const
  {
    return mVoid;
  }

  bool IsEmpty() const
  {
    return !mLength;
  }

  MOZ_MUST_USE bool GetAsString(DOMString& aString) const;

private:
  XMLHttpRequestStringSnapshot(const XMLHttpRequestStringSnapshot&) = delete;
  XMLHttpRequestStringSnapshot& operator=(const XMLHttpRequestStringSnapshot&&) = delete;

  void Set(XMLHttpRequestStringBuffer* aBuffer, uint32_t aLength);

  void ResetInternal(bool aIsVoid);

  RefPtr<XMLHttpRequestStringBuffer> mBuffer;
  uint32_t mLength;
  bool mVoid;
};

// This class locks the buffer and allows the callee to read data from it.
class MOZ_STACK_CLASS XMLHttpRequestStringSnapshotReaderHelper final
{
public:
  explicit XMLHttpRequestStringSnapshotReaderHelper(XMLHttpRequestStringSnapshot& aSnapshot);

  const char16_t*
  Buffer() const;

  uint32_t
  Length() const;

private:
  XMLHttpRequestStringSnapshotReaderHelper(const XMLHttpRequestStringSnapshotReaderHelper&) = delete;
  XMLHttpRequestStringSnapshotReaderHelper& operator=(const XMLHttpRequestStringSnapshotReaderHelper&) = delete;
  XMLHttpRequestStringSnapshotReaderHelper& operator=(const XMLHttpRequestStringSnapshotReaderHelper&&) = delete;

  RefPtr<XMLHttpRequestStringBuffer> mBuffer;
  MutexAutoLock mLock;
};

class XMLHttpRequestStringBuffer final
{
  friend class XMLHttpRequestStringWriterHelper;
  friend class XMLHttpRequestStringSnapshotReaderHelper;

public:
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(XMLHttpRequestStringBuffer)
  NS_DECL_OWNINGTHREAD

  XMLHttpRequestStringBuffer()
    : mMutex("XMLHttpRequestStringBuffer::mMutex")
  {
  }

  uint32_t
  Length()
  {
    MutexAutoLock lock(mMutex);
    return mData.Length();
  }

  uint32_t
  UnsafeLength() const
  {
    return mData.Length();
  }

  void
  Append(const nsAString& aString)
  {
    NS_ASSERT_OWNINGTHREAD(XMLHttpRequestStringBuffer);

    MutexAutoLock lock(mMutex);
    mData.Append(aString);
  }

  MOZ_MUST_USE bool
  GetAsString(nsAString& aString)
  {
    MutexAutoLock lock(mMutex);
    return aString.Assign(mData, mozilla::fallible);
  }

  size_t
  SizeOfThis(MallocSizeOf aMallocSizeOf) const
  {
    return mData.SizeOfExcludingThisIfUnshared(aMallocSizeOf);
  }

  MOZ_MUST_USE bool
  GetAsString(DOMString& aString, uint32_t aLength)
  {
    MutexAutoLock lock(mMutex);
    MOZ_ASSERT(aLength <= mData.Length());
    nsStringBuffer* buf = nsStringBuffer::FromString(mData);
    if (buf) {
      // We have to use SetEphemeralStringBuffer, because once we release our
      // mutex mData can get mutated from some other thread while the DOMString
      // is still alive.
      aString.SetEphemeralStringBuffer(buf, aLength);
      return true;
    }

    // We can get here if mData is empty.  In that case it won't have an
    // nsStringBuffer....
    MOZ_ASSERT(mData.IsEmpty());
    return aString.AsAString().Assign(mData.BeginReading(), aLength,
                                      mozilla::fallible);
  }

  void
  CreateSnapshot(XMLHttpRequestStringSnapshot& aSnapshot)
  {
    MutexAutoLock lock(mMutex);
    aSnapshot.Set(this, mData.Length());
  }

private:
  ~XMLHttpRequestStringBuffer()
  {}

  nsString& UnsafeData()
  {
    return mData;
  }

  Mutex mMutex;

  // The following member variable is protected by mutex.
  nsString mData;
};

} // dom namespace
} // mozilla namespace

#endif // mozilla_dom_XMLHttpRequestString_h