Summary: Add hash index support to data blocks, which helps to reduce the CPU utilization of point-lookup operations. This feature is backward compatible with the data block created without the hash index. It is disabled by default unless `BlockBasedTableOptions::data_block_index_type` is set to `data_block_index_type = kDataBlockBinaryAndHash.` The DB size would be bigger with the hash index option as a hash table is added at the end of each data block. If the hash utilization ratio is 1:1, the space overhead is one byte per key. The hash table utilization ratio is adjustable using `BlockBasedTableOptions::data_block_hash_table_util_ratio`. A lower utilization ratio will improve more on the point-lookup efficiency, but take more space too. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4174 Differential Revision: D8965914 Pulled By: fgwu fbshipit-source-id: 1c6bae5d1fc39c80282d8890a72e9e67bc247198
899 lines
30 KiB
C++
899 lines
30 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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//
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// Decodes the blocks generated by block_builder.cc.
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#include "table/block.h"
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#include <algorithm>
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#include <string>
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#include <unordered_map>
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#include <vector>
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#include "monitoring/perf_context_imp.h"
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#include "port/port.h"
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#include "port/stack_trace.h"
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#include "rocksdb/comparator.h"
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#include "table/block_prefix_index.h"
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#include "table/data_block_footer.h"
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#include "table/format.h"
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#include "util/coding.h"
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#include "util/logging.h"
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namespace rocksdb {
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// Helper routine: decode the next block entry starting at "p",
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// storing the number of shared key bytes, non_shared key bytes,
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// and the length of the value in "*shared", "*non_shared", and
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// "*value_length", respectively. Will not derefence past "limit".
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//
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// If any errors are detected, returns nullptr. Otherwise, returns a
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// pointer to the key delta (just past the three decoded values).
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struct DecodeEntry {
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inline const char* operator()(const char* p, const char* limit,
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uint32_t* shared, uint32_t* non_shared,
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uint32_t* value_length) {
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// We need 2 bytes for shared and non_shared size. We also need one more
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// byte either for value size or the actual value in case of value delta
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// encoding.
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assert(limit - p >= 3);
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*shared = reinterpret_cast<const unsigned char*>(p)[0];
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*non_shared = reinterpret_cast<const unsigned char*>(p)[1];
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*value_length = reinterpret_cast<const unsigned char*>(p)[2];
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if ((*shared | *non_shared | *value_length) < 128) {
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// Fast path: all three values are encoded in one byte each
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p += 3;
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} else {
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if ((p = GetVarint32Ptr(p, limit, shared)) == nullptr) return nullptr;
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if ((p = GetVarint32Ptr(p, limit, non_shared)) == nullptr) return nullptr;
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if ((p = GetVarint32Ptr(p, limit, value_length)) == nullptr) {
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return nullptr;
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}
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}
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// Using an assert in place of "return null" since we should not pay the
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// cost of checking for corruption on every single key decoding
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assert(!(static_cast<uint32_t>(limit - p) < (*non_shared + *value_length)));
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return p;
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}
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};
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struct DecodeKey {
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inline const char* operator()(const char* p, const char* limit,
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uint32_t* shared, uint32_t* non_shared) {
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uint32_t value_length;
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return DecodeEntry()(p, limit, shared, non_shared, &value_length);
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}
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};
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// In format_version 4, which is used by index blocks, the value size is not
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// encoded before the entry, as the value is known to be the handle with the
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// known size.
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struct DecodeKeyV4 {
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inline const char* operator()(const char* p, const char* limit,
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uint32_t* shared, uint32_t* non_shared) {
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// We need 2 bytes for shared and non_shared size. We also need one more
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// byte either for value size or the actual value in case of value delta
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// encoding.
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if (limit - p < 3) return nullptr;
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*shared = reinterpret_cast<const unsigned char*>(p)[0];
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*non_shared = reinterpret_cast<const unsigned char*>(p)[1];
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if ((*shared | *non_shared) < 128) {
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// Fast path: all three values are encoded in one byte each
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p += 2;
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} else {
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if ((p = GetVarint32Ptr(p, limit, shared)) == nullptr) return nullptr;
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if ((p = GetVarint32Ptr(p, limit, non_shared)) == nullptr) return nullptr;
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}
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return p;
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}
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};
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void DataBlockIter::Next() {
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assert(Valid());
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ParseNextDataKey();
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}
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void IndexBlockIter::Next() {
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assert(Valid());
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ParseNextIndexKey();
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}
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void IndexBlockIter::Prev() {
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assert(Valid());
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// Scan backwards to a restart point before current_
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const uint32_t original = current_;
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while (GetRestartPoint(restart_index_) >= original) {
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if (restart_index_ == 0) {
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// No more entries
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current_ = restarts_;
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restart_index_ = num_restarts_;
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return;
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}
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restart_index_--;
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}
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SeekToRestartPoint(restart_index_);
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do {
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if (!ParseNextIndexKey()) {
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break;
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}
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// Loop until end of current entry hits the start of original entry
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} while (NextEntryOffset() < original);
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}
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// Similar to IndexBlockIter::Prev but also caches the prev entries
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void DataBlockIter::Prev() {
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assert(Valid());
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assert(prev_entries_idx_ == -1 ||
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static_cast<size_t>(prev_entries_idx_) < prev_entries_.size());
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// Check if we can use cached prev_entries_
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if (prev_entries_idx_ > 0 &&
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prev_entries_[prev_entries_idx_].offset == current_) {
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// Read cached CachedPrevEntry
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prev_entries_idx_--;
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const CachedPrevEntry& current_prev_entry =
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prev_entries_[prev_entries_idx_];
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const char* key_ptr = nullptr;
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if (current_prev_entry.key_ptr != nullptr) {
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// The key is not delta encoded and stored in the data block
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key_ptr = current_prev_entry.key_ptr;
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key_pinned_ = true;
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} else {
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// The key is delta encoded and stored in prev_entries_keys_buff_
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key_ptr = prev_entries_keys_buff_.data() + current_prev_entry.key_offset;
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key_pinned_ = false;
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}
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const Slice current_key(key_ptr, current_prev_entry.key_size);
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current_ = current_prev_entry.offset;
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key_.SetKey(current_key, false /* copy */);
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value_ = current_prev_entry.value;
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return;
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}
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// Clear prev entries cache
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prev_entries_idx_ = -1;
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prev_entries_.clear();
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prev_entries_keys_buff_.clear();
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// Scan backwards to a restart point before current_
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const uint32_t original = current_;
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while (GetRestartPoint(restart_index_) >= original) {
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if (restart_index_ == 0) {
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// No more entries
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current_ = restarts_;
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restart_index_ = num_restarts_;
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return;
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}
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restart_index_--;
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}
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SeekToRestartPoint(restart_index_);
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do {
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if (!ParseNextDataKey()) {
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break;
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}
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Slice current_key = key();
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if (key_.IsKeyPinned()) {
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// The key is not delta encoded
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prev_entries_.emplace_back(current_, current_key.data(), 0,
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current_key.size(), value());
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} else {
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// The key is delta encoded, cache decoded key in buffer
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size_t new_key_offset = prev_entries_keys_buff_.size();
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prev_entries_keys_buff_.append(current_key.data(), current_key.size());
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prev_entries_.emplace_back(current_, nullptr, new_key_offset,
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current_key.size(), value());
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}
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// Loop until end of current entry hits the start of original entry
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} while (NextEntryOffset() < original);
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prev_entries_idx_ = static_cast<int32_t>(prev_entries_.size()) - 1;
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}
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void DataBlockIter::Seek(const Slice& target) {
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Slice seek_key = target;
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PERF_TIMER_GUARD(block_seek_nanos);
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if (data_ == nullptr) { // Not init yet
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return;
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}
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uint32_t index = 0;
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bool ok = BinarySeek<DecodeKey>(seek_key, 0, num_restarts_ - 1, &index,
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comparator_);
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if (!ok) {
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return;
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}
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SeekToRestartPoint(index);
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// Linear search (within restart block) for first key >= target
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while (true) {
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if (!ParseNextDataKey() || Compare(key_, seek_key) >= 0) {
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return;
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}
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}
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}
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// Optimized Seek for point lookup for an internal key `target`
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// target = "seek_user_key @ type | seqno".
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//
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// For any type other than kTypeValue, kTypeDeletion, kTypeSingleDeletion,
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// or kTypeBlobIndex, this function behaves identically as Seek().
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//
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// For any type in kTypeValue, kTypeDeletion, kTypeSingleDeletion,
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// or kTypeBlobIndex:
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//
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// If the return value is FALSE, iter location is undefined, and it means:
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// 1) there is no key in this block falling into the range:
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// ["seek_user_key @ type | seqno", "seek_user_key @ type | 0"],
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// inclusive; AND
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// 2) the last key of this block has a greater user_key from seek_user_key
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//
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// If the return value is TRUE, iter location has two possibilies:
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// 1) If iter is valid, it is set to a location as if set by BinarySeek. In
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// this case, it points to the first key_ with a larger user_key or a
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// matching user_key with a seqno no greater than the seeking seqno.
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// 2) If the iter is invalid, it means either the block has no such user_key,
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// or the block ends with a matching user_key but with a larger seqno.
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bool DataBlockIter::SeekForGetImpl(const Slice& target) {
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Slice user_key = ExtractUserKey(target);
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uint32_t map_offset = restarts_ + num_restarts_ * sizeof(uint32_t);
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uint8_t entry = data_block_hash_index_->Lookup(data_, map_offset, user_key);
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if (entry == kNoEntry) {
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// Even if we cannot find the user_key in this block, the result may
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// exist in the next block. Consider this exmpale:
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//
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// Block N: [aab@100, ... , app@120]
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// bounary key: axy@50 (we make minimal assumption about a boundary key)
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// Block N+1: [axy@10, ... ]
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//
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// If seek_key = axy@60, the search will starts from Block N.
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// Even if the user_key is not found in the hash map, the caller still
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// have to conntinue searching the next block. So we invalidate the
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// iterator to tell the caller to go on.
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current_ = restarts_; // Invalidate the iter
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return true;
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}
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if (entry == kCollision) {
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// HashSeek not effective, falling back
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Seek(target);
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return true;
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}
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uint32_t restart_index = entry;
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// check if the key is in the restart_interval
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assert(restart_index < num_restarts_);
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SeekToRestartPoint(restart_index);
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const char* limit = nullptr;
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if (restart_index_ + 1 < num_restarts_) {
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limit = data_ + GetRestartPoint(restart_index_ + 1);
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} else {
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limit = data_ + restarts_;
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}
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while (true) {
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// Here we only linear seek the target key inside the restart interval.
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// If a key does not exist inside a restart interval, we avoid
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// further searching the block content accross restart interval boundary.
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//
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// TODO(fwu): check the left and write boundary of the restart interval
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// to avoid linear seek a target key that is out of range.
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if (!ParseNextDataKey(limit) || Compare(key_, target) >= 0) {
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// we stop at the first potential matching user key.
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break;
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}
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}
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if (current_ == restarts_) {
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// Search reaches to the end of the block. There are two possibilites;
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// 1) there is only one user_key match in the block (otherwise collsion).
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// the matching user_key resides in the last restart interval.
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// it is the last key of the restart interval and of the block too.
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// ParseNextDataKey() skiped it as its seqno is newer.
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//
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// 2) The seek_key is a false positive and got hashed to the last restart
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// interval.
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// All existing keys in the restart interval are less than seek_key.
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//
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// The result may exist in the next block in either case, so may_exist is
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// returned as true.
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return true;
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}
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if (user_comparator_->Compare(key_.GetUserKey(), user_key) != 0) {
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// the key is not in this block and cannot be at the next block either.
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// return false to tell the caller to break from the top-level for-loop
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return false;
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}
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// Here we are conservative and only support a limited set of cases
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ValueType value_type = ExtractValueType(key_.GetKey());
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if (value_type != ValueType::kTypeValue &&
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value_type != ValueType::kTypeDeletion &&
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value_type != ValueType::kTypeSingleDeletion &&
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value_type != ValueType::kTypeBlobIndex) {
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Seek(target);
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return true;
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}
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// Result found, and the iter is correctly set.
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return true;
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}
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void IndexBlockIter::Seek(const Slice& target) {
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Slice seek_key = target;
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if (!key_includes_seq_) {
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seek_key = ExtractUserKey(target);
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}
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PERF_TIMER_GUARD(block_seek_nanos);
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if (data_ == nullptr) { // Not init yet
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return;
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}
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uint32_t index = 0;
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bool ok = false;
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if (prefix_index_) {
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ok = PrefixSeek(target, &index);
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} else if (value_delta_encoded_) {
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ok = BinarySeek<DecodeKeyV4>(seek_key, 0, num_restarts_ - 1, &index,
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active_comparator_);
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} else {
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ok = BinarySeek<DecodeKey>(seek_key, 0, num_restarts_ - 1, &index,
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active_comparator_);
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}
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if (!ok) {
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return;
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}
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SeekToRestartPoint(index);
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// Linear search (within restart block) for first key >= target
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while (true) {
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if (!ParseNextIndexKey() || Compare(key_, seek_key) >= 0) {
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return;
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}
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}
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}
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void DataBlockIter::SeekForPrev(const Slice& target) {
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PERF_TIMER_GUARD(block_seek_nanos);
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Slice seek_key = target;
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if (data_ == nullptr) { // Not init yet
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return;
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}
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uint32_t index = 0;
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bool ok = BinarySeek<DecodeKey>(seek_key, 0, num_restarts_ - 1, &index,
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comparator_);
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if (!ok) {
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return;
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}
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SeekToRestartPoint(index);
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// Linear search (within restart block) for first key >= seek_key
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while (ParseNextDataKey() && Compare(key_, seek_key) < 0) {
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}
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if (!Valid()) {
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SeekToLast();
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} else {
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while (Valid() && Compare(key_, seek_key) > 0) {
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Prev();
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}
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}
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}
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void DataBlockIter::SeekToFirst() {
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if (data_ == nullptr) { // Not init yet
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return;
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}
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SeekToRestartPoint(0);
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ParseNextDataKey();
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}
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void IndexBlockIter::SeekToFirst() {
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if (data_ == nullptr) { // Not init yet
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return;
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}
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SeekToRestartPoint(0);
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ParseNextIndexKey();
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}
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void DataBlockIter::SeekToLast() {
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if (data_ == nullptr) { // Not init yet
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return;
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}
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SeekToRestartPoint(num_restarts_ - 1);
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while (ParseNextDataKey() && NextEntryOffset() < restarts_) {
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// Keep skipping
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}
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}
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void IndexBlockIter::SeekToLast() {
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if (data_ == nullptr) { // Not init yet
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return;
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}
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SeekToRestartPoint(num_restarts_ - 1);
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while (ParseNextIndexKey() && NextEntryOffset() < restarts_) {
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// Keep skipping
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}
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}
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template <class TValue>
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void BlockIter<TValue>::CorruptionError() {
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current_ = restarts_;
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restart_index_ = num_restarts_;
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status_ = Status::Corruption("bad entry in block");
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key_.Clear();
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value_.clear();
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}
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bool DataBlockIter::ParseNextDataKey(const char* limit) {
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current_ = NextEntryOffset();
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const char* p = data_ + current_;
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if (!limit) {
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limit = data_ + restarts_; // Restarts come right after data
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}
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if (p >= limit) {
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// No more entries to return. Mark as invalid.
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current_ = restarts_;
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restart_index_ = num_restarts_;
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return false;
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}
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// Decode next entry
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uint32_t shared, non_shared, value_length;
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p = DecodeEntry()(p, limit, &shared, &non_shared, &value_length);
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if (p == nullptr || key_.Size() < shared) {
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CorruptionError();
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return false;
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} else {
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if (shared == 0) {
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// If this key dont share any bytes with prev key then we dont need
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// to decode it and can use it's address in the block directly.
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key_.SetKey(Slice(p, non_shared), false /* copy */);
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key_pinned_ = true;
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} else {
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// This key share `shared` bytes with prev key, we need to decode it
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key_.TrimAppend(shared, p, non_shared);
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key_pinned_ = false;
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}
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if (global_seqno_ != kDisableGlobalSequenceNumber) {
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// If we are reading a file with a global sequence number we should
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// expect that all encoded sequence numbers are zeros and any value
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// type is kTypeValue, kTypeMerge, kTypeDeletion, or kTypeRangeDeletion.
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assert(GetInternalKeySeqno(key_.GetInternalKey()) == 0);
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ValueType value_type = ExtractValueType(key_.GetKey());
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assert(value_type == ValueType::kTypeValue ||
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value_type == ValueType::kTypeMerge ||
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value_type == ValueType::kTypeDeletion ||
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value_type == ValueType::kTypeRangeDeletion);
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|
|
|
if (key_pinned_) {
|
|
// TODO(tec): Investigate updating the seqno in the loaded block
|
|
// directly instead of doing a copy and update.
|
|
|
|
// We cannot use the key address in the block directly because
|
|
// we have a global_seqno_ that will overwrite the encoded one.
|
|
key_.OwnKey();
|
|
key_pinned_ = false;
|
|
}
|
|
|
|
key_.UpdateInternalKey(global_seqno_, value_type);
|
|
}
|
|
|
|
value_ = Slice(p + non_shared, value_length);
|
|
if (shared == 0) {
|
|
while (restart_index_ + 1 < num_restarts_ &&
|
|
GetRestartPoint(restart_index_ + 1) < current_) {
|
|
++restart_index_;
|
|
}
|
|
}
|
|
// else we are in the middle of a restart interval and the restart_index_
|
|
// thus has not changed
|
|
return true;
|
|
}
|
|
}
|
|
|
|
bool IndexBlockIter::ParseNextIndexKey() {
|
|
current_ = NextEntryOffset();
|
|
const char* p = data_ + current_;
|
|
const char* limit = data_ + restarts_; // Restarts come right after data
|
|
if (p >= limit) {
|
|
// No more entries to return. Mark as invalid.
|
|
current_ = restarts_;
|
|
restart_index_ = num_restarts_;
|
|
return false;
|
|
}
|
|
|
|
// Decode next entry
|
|
uint32_t shared, non_shared, value_length;
|
|
if (value_delta_encoded_) {
|
|
p = DecodeKeyV4()(p, limit, &shared, &non_shared);
|
|
value_length = 0;
|
|
} else {
|
|
p = DecodeEntry()(p, limit, &shared, &non_shared, &value_length);
|
|
}
|
|
if (p == nullptr || key_.Size() < shared) {
|
|
CorruptionError();
|
|
return false;
|
|
}
|
|
if (shared == 0) {
|
|
// If this key dont share any bytes with prev key then we dont need
|
|
// to decode it and can use it's address in the block directly.
|
|
key_.SetKey(Slice(p, non_shared), false /* copy */);
|
|
key_pinned_ = true;
|
|
} else {
|
|
// This key share `shared` bytes with prev key, we need to decode it
|
|
key_.TrimAppend(shared, p, non_shared);
|
|
key_pinned_ = false;
|
|
}
|
|
value_ = Slice(p + non_shared, value_length);
|
|
if (shared == 0) {
|
|
while (restart_index_ + 1 < num_restarts_ &&
|
|
GetRestartPoint(restart_index_ + 1) < current_) {
|
|
++restart_index_;
|
|
}
|
|
}
|
|
// else we are in the middle of a restart interval and the restart_index_
|
|
// thus has not changed
|
|
if (value_delta_encoded_) {
|
|
assert(value_length == 0);
|
|
DecodeCurrentValue(shared);
|
|
}
|
|
return true;
|
|
}
|
|
|
|
// The format:
|
|
// restart_point 0: k, v (off, sz), k, v (delta-sz), ..., k, v (delta-sz)
|
|
// restart_point 1: k, v (off, sz), k, v (delta-sz), ..., k, v (delta-sz)
|
|
// ...
|
|
// restart_point n-1: k, v (off, sz), k, v (delta-sz), ..., k, v (delta-sz)
|
|
// where, k is key, v is value, and its encoding is in parenthesis.
|
|
// The format of each key is (shared_size, non_shared_size, shared, non_shared)
|
|
// The format of each value, i.e., block hanlde, is (offset, size) whenever the
|
|
// shared_size is 0, which included the first entry in each restart point.
|
|
// Otherwise the format is delta-size = block handle size - size of last block
|
|
// handle.
|
|
void IndexBlockIter::DecodeCurrentValue(uint32_t shared) {
|
|
assert(value_delta_encoded_);
|
|
const char* limit = data_ + restarts_;
|
|
if (shared == 0) {
|
|
uint64_t o, s;
|
|
const char* newp = GetVarint64Ptr(value_.data(), limit, &o);
|
|
assert(newp);
|
|
newp = GetVarint64Ptr(newp, limit, &s);
|
|
assert(newp);
|
|
decoded_value_ = BlockHandle(o, s);
|
|
value_ = Slice(value_.data(), newp - value_.data());
|
|
} else {
|
|
uint64_t next_value_base =
|
|
decoded_value_.offset() + decoded_value_.size() + kBlockTrailerSize;
|
|
int64_t delta;
|
|
const char* newp = GetVarsignedint64Ptr(value_.data(), limit, &delta);
|
|
decoded_value_ =
|
|
BlockHandle(next_value_base, decoded_value_.size() + delta);
|
|
value_ = Slice(value_.data(), newp - value_.data());
|
|
}
|
|
}
|
|
|
|
// Binary search in restart array to find the first restart point that
|
|
// is either the last restart point with a key less than target,
|
|
// which means the key of next restart point is larger than target, or
|
|
// the first restart point with a key = target
|
|
template <class TValue>
|
|
template <typename DecodeKeyFunc>
|
|
bool BlockIter<TValue>::BinarySeek(const Slice& target, uint32_t left,
|
|
uint32_t right, uint32_t* index,
|
|
const Comparator* comp) {
|
|
assert(left <= right);
|
|
|
|
while (left < right) {
|
|
uint32_t mid = (left + right + 1) / 2;
|
|
uint32_t region_offset = GetRestartPoint(mid);
|
|
uint32_t shared, non_shared;
|
|
const char* key_ptr = DecodeKeyFunc()(
|
|
data_ + region_offset, data_ + restarts_, &shared, &non_shared);
|
|
if (key_ptr == nullptr || (shared != 0)) {
|
|
CorruptionError();
|
|
return false;
|
|
}
|
|
Slice mid_key(key_ptr, non_shared);
|
|
int cmp = comp->Compare(mid_key, target);
|
|
if (cmp < 0) {
|
|
// Key at "mid" is smaller than "target". Therefore all
|
|
// blocks before "mid" are uninteresting.
|
|
left = mid;
|
|
} else if (cmp > 0) {
|
|
// Key at "mid" is >= "target". Therefore all blocks at or
|
|
// after "mid" are uninteresting.
|
|
right = mid - 1;
|
|
} else {
|
|
left = right = mid;
|
|
}
|
|
}
|
|
|
|
*index = left;
|
|
return true;
|
|
}
|
|
|
|
// Compare target key and the block key of the block of `block_index`.
|
|
// Return -1 if error.
|
|
int IndexBlockIter::CompareBlockKey(uint32_t block_index, const Slice& target) {
|
|
uint32_t region_offset = GetRestartPoint(block_index);
|
|
uint32_t shared, non_shared;
|
|
const char* key_ptr =
|
|
value_delta_encoded_
|
|
? DecodeKeyV4()(data_ + region_offset, data_ + restarts_, &shared,
|
|
&non_shared)
|
|
: DecodeKey()(data_ + region_offset, data_ + restarts_, &shared,
|
|
&non_shared);
|
|
if (key_ptr == nullptr || (shared != 0)) {
|
|
CorruptionError();
|
|
return 1; // Return target is smaller
|
|
}
|
|
Slice block_key(key_ptr, non_shared);
|
|
return Compare(block_key, target);
|
|
}
|
|
|
|
// Binary search in block_ids to find the first block
|
|
// with a key >= target
|
|
bool IndexBlockIter::BinaryBlockIndexSeek(const Slice& target,
|
|
uint32_t* block_ids, uint32_t left,
|
|
uint32_t right, uint32_t* index) {
|
|
assert(left <= right);
|
|
uint32_t left_bound = left;
|
|
|
|
while (left <= right) {
|
|
uint32_t mid = (right + left) / 2;
|
|
|
|
int cmp = CompareBlockKey(block_ids[mid], target);
|
|
if (!status_.ok()) {
|
|
return false;
|
|
}
|
|
if (cmp < 0) {
|
|
// Key at "target" is larger than "mid". Therefore all
|
|
// blocks before or at "mid" are uninteresting.
|
|
left = mid + 1;
|
|
} else {
|
|
// Key at "target" is <= "mid". Therefore all blocks
|
|
// after "mid" are uninteresting.
|
|
// If there is only one block left, we found it.
|
|
if (left == right) break;
|
|
right = mid;
|
|
}
|
|
}
|
|
|
|
if (left == right) {
|
|
// In one of the two following cases:
|
|
// (1) left is the first one of block_ids
|
|
// (2) there is a gap of blocks between block of `left` and `left-1`.
|
|
// we can further distinguish the case of key in the block or key not
|
|
// existing, by comparing the target key and the key of the previous
|
|
// block to the left of the block found.
|
|
if (block_ids[left] > 0 &&
|
|
(left == left_bound || block_ids[left - 1] != block_ids[left] - 1) &&
|
|
CompareBlockKey(block_ids[left] - 1, target) > 0) {
|
|
current_ = restarts_;
|
|
return false;
|
|
}
|
|
|
|
*index = block_ids[left];
|
|
return true;
|
|
} else {
|
|
assert(left > right);
|
|
// Mark iterator invalid
|
|
current_ = restarts_;
|
|
return false;
|
|
}
|
|
}
|
|
|
|
bool IndexBlockIter::PrefixSeek(const Slice& target, uint32_t* index) {
|
|
assert(prefix_index_);
|
|
Slice seek_key = target;
|
|
if (!key_includes_seq_) {
|
|
seek_key = ExtractUserKey(target);
|
|
}
|
|
uint32_t* block_ids = nullptr;
|
|
uint32_t num_blocks = prefix_index_->GetBlocks(target, &block_ids);
|
|
|
|
if (num_blocks == 0) {
|
|
current_ = restarts_;
|
|
return false;
|
|
} else {
|
|
return BinaryBlockIndexSeek(seek_key, block_ids, 0, num_blocks - 1, index);
|
|
}
|
|
}
|
|
|
|
uint32_t Block::NumRestarts() const {
|
|
assert(size_ >= 2*sizeof(uint32_t));
|
|
uint32_t block_footer = DecodeFixed32(data_ + size_ - sizeof(uint32_t));
|
|
uint32_t num_restarts = block_footer;
|
|
if (size_ > kMaxBlockSizeSupportedByHashIndex) {
|
|
// We ensure a block with HashIndex is less than 64KiB in BlockBuilder.
|
|
// Therefore the footer cannot be encoded as a packed index type and
|
|
// num_restarts.
|
|
// Such check can ensure legacy block with a vary large num_restarts
|
|
// i.e. >= 0x10000000 can be interpreted correctly as no HashIndex.
|
|
// If a legacy block hash a num_restarts >= 0x10000000, size_ will be
|
|
// much large than 64KiB.
|
|
return num_restarts;
|
|
}
|
|
BlockBasedTableOptions::DataBlockIndexType index_type;
|
|
UnPackIndexTypeAndNumRestarts(block_footer, &index_type, &num_restarts);
|
|
return num_restarts;
|
|
}
|
|
|
|
BlockBasedTableOptions::DataBlockIndexType Block::IndexType() const {
|
|
assert(size_ >= 2 * sizeof(uint32_t));
|
|
if (size_ > kMaxBlockSizeSupportedByHashIndex) {
|
|
// The check is for the same reason as that in NumRestarts()
|
|
return BlockBasedTableOptions::kDataBlockBinarySearch;
|
|
}
|
|
uint32_t block_footer = DecodeFixed32(data_ + size_ - sizeof(uint32_t));
|
|
uint32_t num_restarts = block_footer;
|
|
BlockBasedTableOptions::DataBlockIndexType index_type;
|
|
UnPackIndexTypeAndNumRestarts(block_footer, &index_type, &num_restarts);
|
|
return index_type;
|
|
}
|
|
|
|
Block::~Block() { TEST_SYNC_POINT("Block::~Block"); }
|
|
|
|
Block::Block(BlockContents&& contents, SequenceNumber _global_seqno,
|
|
size_t read_amp_bytes_per_bit, Statistics* statistics)
|
|
: contents_(std::move(contents)),
|
|
data_(contents_.data.data()),
|
|
size_(contents_.data.size()),
|
|
restart_offset_(0),
|
|
num_restarts_(0),
|
|
global_seqno_(_global_seqno) {
|
|
TEST_SYNC_POINT("Block::Block:0");
|
|
if (size_ < sizeof(uint32_t)) {
|
|
size_ = 0; // Error marker
|
|
} else {
|
|
// Should only decode restart points for uncompressed blocks
|
|
if (compression_type() == kNoCompression) {
|
|
num_restarts_ = NumRestarts();
|
|
switch (IndexType()) {
|
|
case BlockBasedTableOptions::kDataBlockBinarySearch:
|
|
restart_offset_ = static_cast<uint32_t>(size_) -
|
|
(1 + num_restarts_) * sizeof(uint32_t);
|
|
if (restart_offset_ > size_ - sizeof(uint32_t)) {
|
|
// The size is too small for NumRestarts() and therefore
|
|
// restart_offset_ wrapped around.
|
|
size_ = 0;
|
|
}
|
|
break;
|
|
case BlockBasedTableOptions::kDataBlockBinaryAndHash:
|
|
if (size_ < sizeof(uint32_t) /* block footer */ +
|
|
sizeof(uint16_t) /* NUM_BUCK */) {
|
|
size_ = 0;
|
|
break;
|
|
}
|
|
|
|
uint16_t map_offset;
|
|
data_block_hash_index_.Initialize(
|
|
contents.data.data(),
|
|
static_cast<uint16_t>(
|
|
contents.data.size() - sizeof(uint32_t)), /*chop off
|
|
NUM_RESTARTS*/
|
|
&map_offset);
|
|
|
|
restart_offset_ = map_offset - num_restarts_ * sizeof(uint32_t);
|
|
|
|
if (restart_offset_ > map_offset) {
|
|
// map_offset is too small for NumRestarts() and
|
|
// therefore restart_offset_ wrapped around.
|
|
size_ = 0;
|
|
break;
|
|
}
|
|
break;
|
|
default:
|
|
size_ = 0; // Error marker
|
|
}
|
|
}
|
|
}
|
|
if (read_amp_bytes_per_bit != 0 && statistics && size_ != 0) {
|
|
read_amp_bitmap_.reset(new BlockReadAmpBitmap(
|
|
restart_offset_, read_amp_bytes_per_bit, statistics));
|
|
}
|
|
}
|
|
|
|
template <>
|
|
DataBlockIter* Block::NewIterator(const Comparator* cmp, const Comparator* ucmp,
|
|
DataBlockIter* iter, Statistics* stats,
|
|
bool /*total_order_seek*/,
|
|
bool /*key_includes_seq*/,
|
|
bool /*value_is_full*/,
|
|
BlockPrefixIndex* /*prefix_index*/) {
|
|
DataBlockIter* ret_iter;
|
|
if (iter != nullptr) {
|
|
ret_iter = iter;
|
|
} else {
|
|
ret_iter = new DataBlockIter;
|
|
}
|
|
if (size_ < 2 * sizeof(uint32_t)) {
|
|
ret_iter->Invalidate(Status::Corruption("bad block contents"));
|
|
return ret_iter;
|
|
}
|
|
if (num_restarts_ == 0) {
|
|
// Empty block.
|
|
ret_iter->Invalidate(Status::OK());
|
|
return ret_iter;
|
|
} else {
|
|
ret_iter->Initialize(
|
|
cmp, ucmp, data_, restart_offset_, num_restarts_, global_seqno_,
|
|
read_amp_bitmap_.get(), cachable(),
|
|
data_block_hash_index_.Valid() ? &data_block_hash_index_ : nullptr);
|
|
if (read_amp_bitmap_) {
|
|
if (read_amp_bitmap_->GetStatistics() != stats) {
|
|
// DB changed the Statistics pointer, we need to notify read_amp_bitmap_
|
|
read_amp_bitmap_->SetStatistics(stats);
|
|
}
|
|
}
|
|
}
|
|
|
|
return ret_iter;
|
|
}
|
|
|
|
template <>
|
|
IndexBlockIter* Block::NewIterator(const Comparator* cmp,
|
|
const Comparator* ucmp, IndexBlockIter* iter,
|
|
Statistics* /*stats*/, bool total_order_seek,
|
|
bool key_includes_seq, bool value_is_full,
|
|
BlockPrefixIndex* prefix_index) {
|
|
IndexBlockIter* ret_iter;
|
|
if (iter != nullptr) {
|
|
ret_iter = iter;
|
|
} else {
|
|
ret_iter = new IndexBlockIter;
|
|
}
|
|
if (size_ < 2 * sizeof(uint32_t)) {
|
|
ret_iter->Invalidate(Status::Corruption("bad block contents"));
|
|
return ret_iter;
|
|
}
|
|
if (num_restarts_ == 0) {
|
|
// Empty block.
|
|
ret_iter->Invalidate(Status::OK());
|
|
return ret_iter;
|
|
} else {
|
|
BlockPrefixIndex* prefix_index_ptr =
|
|
total_order_seek ? nullptr : prefix_index;
|
|
ret_iter->Initialize(cmp, ucmp, data_, restart_offset_, num_restarts_,
|
|
prefix_index_ptr, key_includes_seq, value_is_full,
|
|
cachable(), nullptr /* data_block_hash_index */);
|
|
}
|
|
|
|
return ret_iter;
|
|
}
|
|
|
|
size_t Block::ApproximateMemoryUsage() const {
|
|
size_t usage = usable_size();
|
|
#ifdef ROCKSDB_MALLOC_USABLE_SIZE
|
|
usage += malloc_usable_size((void*)this);
|
|
#else
|
|
usage += sizeof(*this);
|
|
#endif // ROCKSDB_MALLOC_USABLE_SIZE
|
|
if (read_amp_bitmap_) {
|
|
usage += read_amp_bitmap_->ApproximateMemoryUsage();
|
|
}
|
|
return usage;
|
|
}
|
|
|
|
} // namespace rocksdb
|