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authorOz Linden <oz@lindenlab.com>2013-11-19 17:59:55 -0500
committerOz Linden <oz@lindenlab.com>2013-11-19 17:59:55 -0500
commit0031e9a97be1bf6e9fe773c23506494d09ce91ae (patch)
tree220f195c82174b7cc8e94dceb2553e59fe5837a5 /indra/llcorehttp/bufferarray.h
parentb7edc965bc77ab21e9a1e3f6b424299a50053529 (diff)
parentebc9bcbf69f7a519677a6522979a6bf6cbb04bb8 (diff)
merge up to 3.6.10-release; some of the storm-68 changes lost
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+/**
+ * @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_