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Diffstat (limited to 'indra/llcorehttp/bufferarray.h')
| -rw-r--r-- | indra/llcorehttp/bufferarray.h | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/indra/llcorehttp/bufferarray.h b/indra/llcorehttp/bufferarray.h new file mode 100644 index 0000000000..1094a435b4 --- /dev/null +++ b/indra/llcorehttp/bufferarray.h @@ -0,0 +1,137 @@ +/** + * @file bufferarray.h + * @brief Public-facing declaration for the BufferArray scatter/gather class + * + * $LicenseInfo:firstyear=2012&license=viewerlgpl$ + * Second Life Viewer Source Code + * Copyright (C) 2012, Linden Research, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; + * version 2.1 of the License only. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + * + * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA + * $/LicenseInfo$ + */ + +#ifndef _LLCORE_BUFFER_ARRAY_H_ +#define _LLCORE_BUFFER_ARRAY_H_ + + +#include <cstdlib> +#include <vector> + +#include "_refcounted.h" + + +namespace LLCore +{ + +class BufferArrayStreamBuf; + +/// A very simple scatter/gather type map for bulk data. The motivation +/// for this class is the writedata callback used by libcurl. Response +/// bodies are delivered to the caller in a sequence of sequential write +/// operations and this class captures them without having to reallocate +/// and move data. +/// +/// The interface looks a little like a unix file descriptor but only +/// just. There is a notion of a current position, starting from 0, +/// which is used as the position in the data when performing read and +/// write operations. The position also moves after various operations: +/// - seek(...) +/// - read(...) +/// - write(...) +/// - append(...) +/// - appendBufferAlloc(...) +/// The object also keeps a total length value which is updated after +/// write and append operations and beyond which the current position +/// cannot be set. +/// +/// Threading: not thread-safe +/// +/// Allocation: Refcounted, heap only. Caller of the constructor +/// is given a single refcount. +/// +class BufferArray : public LLCoreInt::RefCounted +{ +public: + // BufferArrayStreamBuf has intimate knowledge of this + // implementation to implement a buffer-free adapter. + // Changes here will likely need to be reflected there. + friend class BufferArrayStreamBuf; + + BufferArray(); + +protected: + virtual ~BufferArray(); // Use release() + +private: + BufferArray(const BufferArray &); // Not defined + void operator=(const BufferArray &); // Not defined + +public: + // Internal magic number, may be used by unit tests. + static const size_t BLOCK_ALLOC_SIZE = 65540; + + /// Appends the indicated data to the BufferArray + /// modifying current position and total size. New + /// position is one beyond the final byte of the buffer. + /// + /// @return Count of bytes copied to BufferArray + size_t append(const void * src, size_t len); + + /// Similar to @see append(), this call guarantees a + /// contiguous block of memory of requested size placed + /// at the current end of the BufferArray. On return, + /// the data in the memory is considered valid whether + /// the caller writes to it or not. + /// + /// @return Pointer to contiguous region at end + /// of BufferArray of 'len' size. + void * appendBufferAlloc(size_t len); + + /// Current count of bytes in BufferArray instance. + size_t size() const + { + return mLen; + } + + /// Copies data from the given position in the instance + /// to the caller's buffer. Will return a short count of + /// bytes copied if the 'len' extends beyond the data. + size_t read(size_t pos, void * dst, size_t len); + + /// Copies data from the caller's buffer to the instance + /// at the current position. May overwrite existing data, + /// append data when current position is equal to the + /// size of the instance or do a mix of both. + size_t write(size_t pos, const void * src, size_t len); + +protected: + int findBlock(size_t pos, size_t * ret_offset); + + bool getBlockStartEnd(int block, const char ** start, const char ** end); + +protected: + class Block; + typedef std::vector<Block *> container_t; + + container_t mBlocks; + size_t mLen; +}; // end class BufferArray + + +} // end namespace LLCore + +#endif // _LLCORE_BUFFER_ARRAY_H_ |