dom/xhr/XMLHttpRequestString.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_dom_XMLHttpRequestString_h
   8 #define mozilla_dom_XMLHttpRequestString_h
   9
  10 #include "mozilla/Mutex.h"
  11 #include "nsString.h"
  12
  13 namespace mozilla {
  14 namespace dom {
  15
  16 class ArrayBufferBuilder;
  17 class BlobImpl;
  18 class DOMString;
  19 class XMLHttpRequestStringBuffer;
  20 class XMLHttpRequestStringSnapshot;
  21 class XMLHttpRequestStringWriterHelper;
  22 class XMLHttpRequestStringSnapshotReaderHelper;
  23
  24 // We want to avoid the dup of strings when XHR in workers has access to
  25 // responseText for events dispatched during the loading state. For this reason
  26 // we use this class, able to create snapshots of the current size of itself
  27 // without making extra copies.
  28 class XMLHttpRequestString final {
  29   friend class XMLHttpRequestStringWriterHelper;
  30
  31  public:
  32   XMLHttpRequestString();
  33   ~XMLHttpRequestString();
  34
  35   void Truncate();
  36
  37   uint32_t Length() const;
  38
  39   void Append(const nsAString& aString);
  40
  41   // This method should be called only when the string is really needed because
  42   // it can cause the duplication of the strings in case the loading of the XHR
  43   // is not completed yet.
  44   [[nodiscard]] bool GetAsString(nsAString& aString) const;
  45
  46   size_t SizeOfThis(MallocSizeOf aMallocSizeOf) const;
  47
  48   const char16_t* Data() const;
  49
  50   bool IsEmpty() const;
  51
  52   void CreateSnapshot(XMLHttpRequestStringSnapshot& aSnapshot);
  53
  54  private:
  55   XMLHttpRequestString(const XMLHttpRequestString&) = delete;
  56   XMLHttpRequestString& operator=(const XMLHttpRequestString&) = delete;
  57   XMLHttpRequestString& operator=(const XMLHttpRequestString&&) = delete;
  58
  59   RefPtr<XMLHttpRequestStringBuffer> mBuffer;
  60 };
  61
  62 // This class locks the buffer and allows the callee to write data into it.
  63 class MOZ_STACK_CLASS XMLHttpRequestStringWriterHelper final {
  64  public:
  65   explicit XMLHttpRequestStringWriterHelper(XMLHttpRequestString& aString);
  66   ~XMLHttpRequestStringWriterHelper();
  67
  68   /**
  69    * The existing length of the string. Do not call during BulkWrite().
  70    */
  71   uint32_t Length() const;
  72
  73   mozilla::Result<mozilla::BulkWriteHandle<char16_t>, nsresult> BulkWrite(
  74       uint32_t aCapacity);
  75
  76  private:
  77   XMLHttpRequestStringWriterHelper(const XMLHttpRequestStringWriterHelper&) =
  78       delete;
  79   XMLHttpRequestStringWriterHelper& operator=(
  80       const XMLHttpRequestStringWriterHelper&) = delete;
  81   XMLHttpRequestStringWriterHelper& operator=(
  82       const XMLHttpRequestStringWriterHelper&&) = delete;
  83
  84   RefPtr<XMLHttpRequestStringBuffer> mBuffer;
  85   MutexAutoLock mLock;
  86 };
  87
  88 // This class is the internal XMLHttpRequestStringBuffer of the
  89 // XMLHttpRequestString plus the current length. GetAsString will return the
  90 // string with that particular length also if the XMLHttpRequestStringBuffer is
  91 // grown in the meantime.
  92 class XMLHttpRequestStringSnapshot final {
  93   friend class XMLHttpRequestStringBuffer;
  94   friend class XMLHttpRequestStringSnapshotReaderHelper;
  95
  96  public:
  97   XMLHttpRequestStringSnapshot();
  98   ~XMLHttpRequestStringSnapshot();
  99
 100   XMLHttpRequestStringSnapshot& operator=(const XMLHttpRequestStringSnapshot&) =
 101       delete;
 102
 103   void Reset() { ResetInternal(false /* isVoid */); }
 104
 105   void SetVoid() { ResetInternal(true /* isVoid */); }
 106
 107   bool IsVoid() const { return mVoid; }
 108
 109   bool IsEmpty() const { return !mLength; }
 110
 111   [[nodiscard]] bool GetAsString(DOMString& aString) const;
 112
 113  private:
 114   XMLHttpRequestStringSnapshot(const XMLHttpRequestStringSnapshot&) = delete;
 115   XMLHttpRequestStringSnapshot& operator=(
 116       const XMLHttpRequestStringSnapshot&&) = delete;
 117
 118   void Set(XMLHttpRequestStringBuffer* aBuffer, uint32_t aLength);
 119
 120   void ResetInternal(bool aIsVoid);
 121
 122   RefPtr<XMLHttpRequestStringBuffer> mBuffer;
 123   uint32_t mLength;
 124   bool mVoid;
 125 };
 126
 127 // This class locks the buffer and allows the callee to read data from it.
 128 class MOZ_STACK_CLASS XMLHttpRequestStringSnapshotReaderHelper final {
 129  public:
 130   explicit XMLHttpRequestStringSnapshotReaderHelper(
 131       XMLHttpRequestStringSnapshot& aSnapshot);
 132   ~XMLHttpRequestStringSnapshotReaderHelper();
 133
 134   const char16_t* Buffer() const;
 135
 136   uint32_t Length() const;
 137
 138  private:
 139   XMLHttpRequestStringSnapshotReaderHelper(
 140       const XMLHttpRequestStringSnapshotReaderHelper&) = delete;
 141   XMLHttpRequestStringSnapshotReaderHelper& operator=(
 142       const XMLHttpRequestStringSnapshotReaderHelper&) = delete;
 143   XMLHttpRequestStringSnapshotReaderHelper& operator=(
 144       const XMLHttpRequestStringSnapshotReaderHelper&&) = delete;
 145
 146   RefPtr<XMLHttpRequestStringBuffer> mBuffer;
 147   MutexAutoLock mLock;
 148 };
 149
 150 }  // namespace dom
 151 }  // namespace mozilla
 152
 153 #endif  // mozilla_dom_XMLHttpRequestString_h