зеркало из https://github.com/mozilla/gecko-dev.git
79 строки
2.8 KiB
C
79 строки
2.8 KiB
C
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_FixedBufferOutputStream_h
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#define mozilla_FixedBufferOutputStream_h
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#include <cstddef>
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#include "mozilla/fallible.h"
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#include "mozilla/Mutex.h"
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#include "mozilla/Span.h"
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#include "mozilla/UniquePtr.h"
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#include "nsIOutputStream.h"
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#include "nsStringFwd.h"
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template <class T>
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class RefPtr;
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namespace mozilla {
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class StreamBufferSink;
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// An output stream so you can read your potentially-async input stream into
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// a contiguous buffer using NS_AsyncCopy. Back when streams were more
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// synchronous and people didn't know blocking I/O was bad, if you wanted to
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// read a stream into a flat buffer, you could use NS_ReadInputStreamToString
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// or NS_ReadInputStreamToBuffer. But those don't work with async streams.
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// This can be used to replace hand-rolled Read/AsyncWait() loops. Because you
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// specify the expected size up front, the buffer is pre-allocated so wasteful
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// reallocations can be avoided.
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class FixedBufferOutputStream final : public nsIOutputStream {
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template <typename T, typename... Args>
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friend RefPtr<T> MakeRefPtr(Args&&... aArgs);
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public:
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// Factory method to get a FixedBufferOutputStream by allocating a char buffer
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// with the given length.
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static RefPtr<FixedBufferOutputStream> Create(size_t aLength);
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// Factory method to get a FixedBufferOutputStream by allocating a char buffer
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// with the given length, fallible version.
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static RefPtr<FixedBufferOutputStream> Create(size_t aLength,
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const mozilla::fallible_t&);
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// Factory method to get a FixedBufferOutputStream from a preallocated char
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// buffer. The output stream doesn't take ownership of the char buffer, so the
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// char buffer must outlive the output stream (to avoid a use-after-free).
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static RefPtr<FixedBufferOutputStream> Create(mozilla::Span<char> aBuffer);
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// Factory method to get a FixedBufferOutputStream from an arbitrary
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// StreamBufferSink.
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static RefPtr<FixedBufferOutputStream> Create(
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UniquePtr<StreamBufferSink>&& aSink);
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nsDependentCSubstring WrittenData();
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSIOUTPUTSTREAM
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private:
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explicit FixedBufferOutputStream(UniquePtr<StreamBufferSink>&& aSink);
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~FixedBufferOutputStream() = default;
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const UniquePtr<StreamBufferSink> mSink;
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Mutex mMutex;
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size_t mOffset MOZ_GUARDED_BY(mMutex);
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bool mWriting MOZ_GUARDED_BY(mMutex);
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bool mClosed MOZ_GUARDED_BY(mMutex);
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};
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} // namespace mozilla
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#endif // mozilla_FixedBufferOutputStream_h
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