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Diffstat (limited to 'src/leveldb/table/block_builder.cc')
-rw-r--r-- | src/leveldb/table/block_builder.cc | 109 |
1 files changed, 0 insertions, 109 deletions
diff --git a/src/leveldb/table/block_builder.cc b/src/leveldb/table/block_builder.cc deleted file mode 100644 index db660cd07..000000000 --- a/src/leveldb/table/block_builder.cc +++ /dev/null @@ -1,109 +0,0 @@ -// 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. -// -// BlockBuilder generates blocks where keys are prefix-compressed: -// -// When we store a key, we drop the prefix shared with the previous -// string. This helps reduce the space requirement significantly. -// Furthermore, once every K keys, we do not apply the prefix -// compression and store the entire key. We call this a "restart -// point". The tail end of the block stores the offsets of all of the -// restart points, and can be used to do a binary search when looking -// for a particular key. Values are stored as-is (without compression) -// immediately following the corresponding key. -// -// An entry for a particular key-value pair has the form: -// shared_bytes: varint32 -// unshared_bytes: varint32 -// value_length: varint32 -// key_delta: char[unshared_bytes] -// value: char[value_length] -// shared_bytes == 0 for restart points. -// -// The trailer of the block has the form: -// restarts: uint32[num_restarts] -// num_restarts: uint32 -// restarts[i] contains the offset within the block of the ith restart point. - -#include "table/block_builder.h" - -#include <algorithm> -#include <assert.h> -#include "leveldb/comparator.h" -#include "leveldb/table_builder.h" -#include "util/coding.h" - -namespace leveldb { - -BlockBuilder::BlockBuilder(const Options* options) - : options_(options), - restarts_(), - counter_(0), - finished_(false) { - assert(options->block_restart_interval >= 1); - restarts_.push_back(0); // First restart point is at offset 0 -} - -void BlockBuilder::Reset() { - buffer_.clear(); - restarts_.clear(); - restarts_.push_back(0); // First restart point is at offset 0 - counter_ = 0; - finished_ = false; - last_key_.clear(); -} - -size_t BlockBuilder::CurrentSizeEstimate() const { - return (buffer_.size() + // Raw data buffer - restarts_.size() * sizeof(uint32_t) + // Restart array - sizeof(uint32_t)); // Restart array length -} - -Slice BlockBuilder::Finish() { - // Append restart array - for (size_t i = 0; i < restarts_.size(); i++) { - PutFixed32(&buffer_, restarts_[i]); - } - PutFixed32(&buffer_, restarts_.size()); - finished_ = true; - return Slice(buffer_); -} - -void BlockBuilder::Add(const Slice& key, const Slice& value) { - Slice last_key_piece(last_key_); - assert(!finished_); - assert(counter_ <= options_->block_restart_interval); - assert(buffer_.empty() // No values yet? - || options_->comparator->Compare(key, last_key_piece) > 0); - size_t shared = 0; - if (counter_ < options_->block_restart_interval) { - // See how much sharing to do with previous string - const size_t min_length = std::min(last_key_piece.size(), key.size()); - while ((shared < min_length) && (last_key_piece[shared] == key[shared])) { - shared++; - } - } else { - // Restart compression - restarts_.push_back(buffer_.size()); - counter_ = 0; - } - const size_t non_shared = key.size() - shared; - - // Add "<shared><non_shared><value_size>" to buffer_ - PutVarint32(&buffer_, shared); - PutVarint32(&buffer_, non_shared); - PutVarint32(&buffer_, value.size()); - - // Add string delta to buffer_ followed by value - buffer_.append(key.data() + shared, non_shared); - buffer_.append(value.data(), value.size()); - - // Update state - last_key_.resize(shared); - last_key_.append(key.data() + shared, non_shared); - assert(Slice(last_key_) == key); - counter_++; -} - -} // namespace leveldb |