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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "tensorflow/core/lib/io/table.h"
#include "tensorflow/core/lib/core/coding.h"
#include "tensorflow/core/lib/core/errors.h"
#include "tensorflow/core/lib/io/block.h"
#include "tensorflow/core/lib/io/format.h"
#include "tensorflow/core/lib/io/table_options.h"
#include "tensorflow/core/lib/io/two_level_iterator.h"
#include "tensorflow/core/public/env.h"
namespace tensorflow {
namespace table {
struct Table::Rep {
~Rep() { delete index_block; }
Options options;
Status status;
RandomAccessFile* file;
// XXX uint64 cache_id;
BlockHandle metaindex_handle; // Handle to metaindex_block: saved from footer
Block* index_block;
};
Status Table::Open(const Options& options, RandomAccessFile* file,
uint64 size, Table** table) {
*table = NULL;
if (size < Footer::kEncodedLength) {
return errors::DataLoss("file is too short to be an sstable");
}
char footer_space[Footer::kEncodedLength];
StringPiece footer_input;
Status s =
file->Read(size - Footer::kEncodedLength, Footer::kEncodedLength,
&footer_input, footer_space);
if (!s.ok()) return s;
Footer footer;
s = footer.DecodeFrom(&footer_input);
if (!s.ok()) return s;
// Read the index block
BlockContents contents;
Block* index_block = NULL;
if (s.ok()) {
s = ReadBlock(file, footer.index_handle(), &contents);
if (s.ok()) {
index_block = new Block(contents);
}
}
if (s.ok()) {
// We've successfully read the footer and the index block: we're
// ready to serve requests.
Rep* rep = new Table::Rep;
rep->options = options;
rep->file = file;
rep->metaindex_handle = footer.metaindex_handle();
rep->index_block = index_block;
// XXX rep->cache_id = (options.block_cache ?
// options.block_cache->NewId() : 0);
*table = new Table(rep);
} else {
if (index_block) delete index_block;
}
return s;
}
Table::~Table() { delete rep_; }
static void DeleteBlock(void* arg, void* ignored) {
delete reinterpret_cast<Block*>(arg);
}
// Convert an index iterator value (i.e., an encoded BlockHandle)
// into an iterator over the contents of the corresponding block.
Iterator* Table::BlockReader(void* arg, const StringPiece& index_value) {
Table* table = reinterpret_cast<Table*>(arg);
// Cache* block_cache = table->rep_->options.block_cache;
Block* block = NULL;
// Cache::Handle* cache_handle = NULL;
BlockHandle handle;
StringPiece input = index_value;
Status s = handle.DecodeFrom(&input);
// We intentionally allow extra stuff in index_value so that we
// can add more features in the future.
if (s.ok()) {
BlockContents contents;
s = ReadBlock(table->rep_->file, handle, &contents);
if (s.ok()) {
block = new Block(contents);
}
}
Iterator* iter;
if (block != NULL) {
iter = block->NewIterator();
iter->RegisterCleanup(&DeleteBlock, block, NULL);
} else {
iter = NewErrorIterator(s);
}
return iter;
}
Iterator* Table::NewIterator() const {
return NewTwoLevelIterator(rep_->index_block->NewIterator(),
&Table::BlockReader, const_cast<Table*>(this));
}
Status Table::InternalGet(const StringPiece& k, void* arg,
void (*saver)(void*, const StringPiece&,
const StringPiece&)) {
Status s;
Iterator* iiter = rep_->index_block->NewIterator();
iiter->Seek(k);
if (iiter->Valid()) {
BlockHandle handle;
Iterator* block_iter = BlockReader(this, iiter->value());
block_iter->Seek(k);
if (block_iter->Valid()) {
(*saver)(arg, block_iter->key(), block_iter->value());
}
s = block_iter->status();
delete block_iter;
}
if (s.ok()) {
s = iiter->status();
}
delete iiter;
return s;
}
uint64 Table::ApproximateOffsetOf(const StringPiece& key) const {
Iterator* index_iter = rep_->index_block->NewIterator();
index_iter->Seek(key);
uint64 result;
if (index_iter->Valid()) {
BlockHandle handle;
StringPiece input = index_iter->value();
Status s = handle.DecodeFrom(&input);
if (s.ok()) {
result = handle.offset();
} else {
// Strange: we can't decode the block handle in the index block.
// We'll just return the offset of the metaindex block, which is
// close to the whole file size for this case.
result = rep_->metaindex_handle.offset();
}
} else {
// key is past the last key in the file. Approximate the offset
// by returning the offset of the metaindex block (which is
// right near the end of the file).
result = rep_->metaindex_handle.offset();
}
delete index_iter;
return result;
}
} // namespace table
} // namespace tensorflow
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