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/*
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* Chunk.cpp
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* Ottoman
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*
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* Created by Jens Alfke on 8/27/09.
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* Copyright 2009 Jens Alfke. All rights reserved.
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* BSD-Licensed: See the file "LICENSE.txt" for details.
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*/
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#include "Chunk.h"
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#include <assert.h>
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#include <errno.h>
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#include <stddef.h>
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namespace Mooseyard {
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uint16_t Chunk::type() const {
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return _keyLength == 0xFFFF ?(uint16_t)_type :KeyValueChunk::kChunkType;
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}
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const KeyValueChunk* Chunk::asKeyValue() const {
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return _keyLength == 0xFFFF ?NULL :(const KeyValueChunk*)this;
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}
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size_t Chunk::writeMultiple (File *file, uint16_t type,
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Blob blobs[], int count) throw(File::Error) {
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assert(type != KeyValueChunk::kChunkType);
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Blob nuBlobs[count+1];
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uint32_t size = sizeof(Chunk);
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for (int i=0; i<count; i++) {
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nuBlobs[i+1] = blobs[i];
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size += blobs[i].length;
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}
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Chunk chunk(size, type);
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nuBlobs[0] = Blob(&chunk, sizeof(chunk));
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return file->writeMultiple(nuBlobs, count+1);
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}
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size_t Chunk::writePadding (File *file) {
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off_t padding = file->position() & 0x03;
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if (padding == 0)
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return 0;
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else {
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padding = 4 - padding;
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uint32_t zero = 0;
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Blob pad(&zero, (size_t)padding);
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return writeMultiple(file, kChunkTypePadding, &pad, 1);
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}
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}
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void KeyValueChunk::validate() const throw(File::Error) {
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if (_keyLength >= 0xFFFFU)
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throw File::Error(ERANGE, "Invalid key length (0xFFFF)");
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if (valuePtr() > end())
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throw File::Error(ERANGE, "Bad KeyValueChunk (key-length too large to fit)");
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}
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Blob KeyValueChunk::key() const {
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return Blob(&_keyLength +1, _keyLength); // KeyValueChunk doesn't have _type
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}
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const char* KeyValueChunk::valuePtr() const {
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size_t vptr = (size_t) key().end();
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vptr = (vptr+3) & ~3; // 4-byte align
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return (const char*)vptr;
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}
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Blob KeyValueChunk::value() const {
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const char *vp = valuePtr();
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return Blob(vp, (const char*)end()-vp);
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}
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bool KeyValueChunk::hasKey (Blob key) const {
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return key.length==_keyLength
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&& memcmp(key.bytes, &_keyLength +1, key.length)==0;
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}
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size_t KeyValueChunk::write (File* file, FilePosition pos, Blob key, Blob value) throw(File::Error) {
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if (key.length >= 0xFFFFU)
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throw File::Error(ERANGE, "Key too long (>=64k)");
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uint16_t keyLength = key.length;
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uint32_t size = sizeof(uint32_t) + sizeof(uint16_t) + keyLength;
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size_t pad = (pos + size) & 0x3;
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if (pad)
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pad = 4-pad;
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uint32_t zeros = 0;
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size += pad + value.length;
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Chunk chunk(size, KeyValueChunk::kChunkType);
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chunk._keyLength = keyLength;
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Blob b[4] = {
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Blob(&chunk, sizeof(chunk._size)+sizeof(chunk._keyLength)),
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key,
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Blob(&zeros, pad),
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value};
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return file->writeMultiple(b,4);
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}
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ChunkIterator::ChunkIterator (File* file, FilePosition start)
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:_file(file),
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_pos(start),
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_length((FilePosition)_file->length()),
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_chunk(NULL)
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{
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_loadChunk();
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}
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void ChunkIterator::_loadChunk() {
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if (_pos < _length) {
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_chunk = (const Chunk*) _file->mappedPosition(_pos);
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if (_chunk->size() < sizeof(Chunk) || _pos+_chunk->size() > _length)
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_chunk = NULL;
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} else {
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_chunk = NULL;
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}
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}
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bool ChunkIterator::atEOF() const {
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return _pos == _length;
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}
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bool ChunkIterator::next() {
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if (_chunk) {
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_pos += _chunk->size();
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_loadChunk();
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}
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return _chunk != NULL;
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}
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}
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