Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 960 insertions, 0 deletions

diff --git a/src/rocksdb/table/block.cc b/src/rocksdb/table/block.cc
new file mode 100644
index 00000000..7c83ebb6
--- /dev/null
+++ b/src/rocksdb/table/block.cc
@@ -0,0 +1,960 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// 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.
+//
+// Decodes the blocks generated by block_builder.cc.
+
+#include "table/block.h"
+#include <algorithm>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "monitoring/perf_context_imp.h"
+#include "port/port.h"
+#include "port/stack_trace.h"
+#include "rocksdb/comparator.h"
+#include "table/block_prefix_index.h"
+#include "table/data_block_footer.h"
+#include "table/format.h"
+#include "util/coding.h"
+#include "util/logging.h"
+
+namespace rocksdb {
+
+// Helper routine: decode the next block entry starting at "p",
+// storing the number of shared key bytes, non_shared key bytes,
+// and the length of the value in "*shared", "*non_shared", and
+// "*value_length", respectively.  Will not derefence past "limit".
+//
+// If any errors are detected, returns nullptr.  Otherwise, returns a
+// pointer to the key delta (just past the three decoded values).
+struct DecodeEntry {
+  inline const char* operator()(const char* p, const char* limit,
+                                uint32_t* shared, uint32_t* non_shared,
+                                uint32_t* value_length) {
+    // We need 2 bytes for shared and non_shared size. We also need one more
+    // byte either for value size or the actual value in case of value delta
+    // encoding.
+    assert(limit - p >= 3);
+    *shared = reinterpret_cast<const unsigned char*>(p)[0];
+    *non_shared = reinterpret_cast<const unsigned char*>(p)[1];
+    *value_length = reinterpret_cast<const unsigned char*>(p)[2];
+    if ((*shared | *non_shared | *value_length) < 128) {
+      // Fast path: all three values are encoded in one byte each
+      p += 3;
+    } else {
+      if ((p = GetVarint32Ptr(p, limit, shared)) == nullptr) return nullptr;
+      if ((p = GetVarint32Ptr(p, limit, non_shared)) == nullptr) return nullptr;
+      if ((p = GetVarint32Ptr(p, limit, value_length)) == nullptr) {
+        return nullptr;
+      }
+    }
+
+    // Using an assert in place of "return null" since we should not pay the
+    // cost of checking for corruption on every single key decoding
+    assert(!(static_cast<uint32_t>(limit - p) < (*non_shared + *value_length)));
+    return p;
+  }
+};
+
+// Helper routine: similar to DecodeEntry but does not have assertions.
+// Instead, returns nullptr so that caller can detect and report failure.
+struct CheckAndDecodeEntry {
+  inline const char* operator()(const char* p, const char* limit,
+                                uint32_t* shared, uint32_t* non_shared,
+                                uint32_t* value_length) {
+    // We need 2 bytes for shared and non_shared size. We also need one more
+    // byte either for value size or the actual value in case of value delta
+    // encoding.
+    if (limit - p < 3) {
+      return nullptr;
+    }
+    *shared = reinterpret_cast<const unsigned char*>(p)[0];
+    *non_shared = reinterpret_cast<const unsigned char*>(p)[1];
+    *value_length = reinterpret_cast<const unsigned char*>(p)[2];
+    if ((*shared | *non_shared | *value_length) < 128) {
+      // Fast path: all three values are encoded in one byte each
+      p += 3;
+    } else {
+      if ((p = GetVarint32Ptr(p, limit, shared)) == nullptr) return nullptr;
+      if ((p = GetVarint32Ptr(p, limit, non_shared)) == nullptr) return nullptr;
+      if ((p = GetVarint32Ptr(p, limit, value_length)) == nullptr) {
+        return nullptr;
+      }
+    }
+
+    if (static_cast<uint32_t>(limit - p) < (*non_shared + *value_length)) {
+      return nullptr;
+    }
+    return p;
+  }
+};
+
+struct DecodeKey {
+  inline const char* operator()(const char* p, const char* limit,
+                                uint32_t* shared, uint32_t* non_shared) {
+    uint32_t value_length;
+    return DecodeEntry()(p, limit, shared, non_shared, &value_length);
+  }
+};
+
+// In format_version 4, which is used by index blocks, the value size is not
+// encoded before the entry, as the value is known to be the handle with the
+// known size.
+struct DecodeKeyV4 {
+  inline const char* operator()(const char* p, const char* limit,
+                                uint32_t* shared, uint32_t* non_shared) {
+    // We need 2 bytes for shared and non_shared size. We also need one more
+    // byte either for value size or the actual value in case of value delta
+    // encoding.
+    if (limit - p < 3) return nullptr;
+    *shared = reinterpret_cast<const unsigned char*>(p)[0];
+    *non_shared = reinterpret_cast<const unsigned char*>(p)[1];
+    if ((*shared | *non_shared) < 128) {
+      // Fast path: all three values are encoded in one byte each
+      p += 2;
+    } else {
+      if ((p = GetVarint32Ptr(p, limit, shared)) == nullptr) return nullptr;
+      if ((p = GetVarint32Ptr(p, limit, non_shared)) == nullptr) return nullptr;
+    }
+    return p;
+  }
+};
+
+void DataBlockIter::Next() {
+  assert(Valid());
+  ParseNextDataKey<DecodeEntry>();
+}
+
+void DataBlockIter::NextOrReport() {
+  assert(Valid());
+  ParseNextDataKey<CheckAndDecodeEntry>();
+}
+
+void IndexBlockIter::Next() {
+  assert(Valid());
+  ParseNextIndexKey();
+}
+
+void IndexBlockIter::Prev() {
+  assert(Valid());
+  // Scan backwards to a restart point before current_
+  const uint32_t original = current_;
+  while (GetRestartPoint(restart_index_) >= original) {
+    if (restart_index_ == 0) {
+      // No more entries
+      current_ = restarts_;
+      restart_index_ = num_restarts_;
+      return;
+    }
+    restart_index_--;
+  }
+  SeekToRestartPoint(restart_index_);
+  do {
+    if (!ParseNextIndexKey()) {
+      break;
+    }
+    // Loop until end of current entry hits the start of original entry
+  } while (NextEntryOffset() < original);
+}
+
+// Similar to IndexBlockIter::Prev but also caches the prev entries
+void DataBlockIter::Prev() {
+  assert(Valid());
+
+  assert(prev_entries_idx_ == -1 ||
+         static_cast<size_t>(prev_entries_idx_) < prev_entries_.size());
+  // Check if we can use cached prev_entries_
+  if (prev_entries_idx_ > 0 &&
+      prev_entries_[prev_entries_idx_].offset == current_) {
+    // Read cached CachedPrevEntry
+    prev_entries_idx_--;
+    const CachedPrevEntry& current_prev_entry =
+        prev_entries_[prev_entries_idx_];
+
+    const char* key_ptr = nullptr;
+    if (current_prev_entry.key_ptr != nullptr) {
+      // The key is not delta encoded and stored in the data block
+      key_ptr = current_prev_entry.key_ptr;
+      key_pinned_ = true;
+    } else {
+      // The key is delta encoded and stored in prev_entries_keys_buff_
+      key_ptr = prev_entries_keys_buff_.data() + current_prev_entry.key_offset;
+      key_pinned_ = false;
+    }
+    const Slice current_key(key_ptr, current_prev_entry.key_size);
+
+    current_ = current_prev_entry.offset;
+    key_.SetKey(current_key, false /* copy */);
+    value_ = current_prev_entry.value;
+
+    return;
+  }
+
+  // Clear prev entries cache
+  prev_entries_idx_ = -1;
+  prev_entries_.clear();
+  prev_entries_keys_buff_.clear();
+
+  // Scan backwards to a restart point before current_
+  const uint32_t original = current_;
+  while (GetRestartPoint(restart_index_) >= original) {
+    if (restart_index_ == 0) {
+      // No more entries
+      current_ = restarts_;
+      restart_index_ = num_restarts_;
+      return;
+    }
+    restart_index_--;
+  }
+
+  SeekToRestartPoint(restart_index_);
+
+  do {
+    if (!ParseNextDataKey<DecodeEntry>()) {
+      break;
+    }
+    Slice current_key = key();
+
+    if (key_.IsKeyPinned()) {
+      // The key is not delta encoded
+      prev_entries_.emplace_back(current_, current_key.data(), 0,
+                                 current_key.size(), value());
+    } else {
+      // The key is delta encoded, cache decoded key in buffer
+      size_t new_key_offset = prev_entries_keys_buff_.size();
+      prev_entries_keys_buff_.append(current_key.data(), current_key.size());
+
+      prev_entries_.emplace_back(current_, nullptr, new_key_offset,
+                                 current_key.size(), value());
+    }
+    // Loop until end of current entry hits the start of original entry
+  } while (NextEntryOffset() < original);
+  prev_entries_idx_ = static_cast<int32_t>(prev_entries_.size()) - 1;
+}
+
+void DataBlockIter::Seek(const Slice& target) {
+  Slice seek_key = target;
+  PERF_TIMER_GUARD(block_seek_nanos);
+  if (data_ == nullptr) {  // Not init yet
+    return;
+  }
+  uint32_t index = 0;
+  bool ok = BinarySeek<DecodeKey>(seek_key, 0, num_restarts_ - 1, &index,
+                                  comparator_);
+
+  if (!ok) {
+    return;
+  }
+  SeekToRestartPoint(index);
+  // Linear search (within restart block) for first key >= target
+
+  while (true) {
+    if (!ParseNextDataKey<DecodeEntry>() || Compare(key_, seek_key) >= 0) {
+      return;
+    }
+  }
+}
+
+// Optimized Seek for point lookup for an internal key `target`
+// target = "seek_user_key @ type | seqno".
+//
+// For any type other than kTypeValue, kTypeDeletion, kTypeSingleDeletion,
+// or kTypeBlobIndex, this function behaves identically as Seek().
+//
+// For any type in kTypeValue, kTypeDeletion, kTypeSingleDeletion,
+// or kTypeBlobIndex:
+//
+// If the return value is FALSE, iter location is undefined, and it means:
+// 1) there is no key in this block falling into the range:
+//    ["seek_user_key @ type | seqno", "seek_user_key @ kTypeDeletion | 0"],
+//    inclusive; AND
+// 2) the last key of this block has a greater user_key from seek_user_key
+//
+// If the return value is TRUE, iter location has two possibilies:
+// 1) If iter is valid, it is set to a location as if set by BinarySeek. In
+//    this case, it points to the first key_ with a larger user_key or a
+//    matching user_key with a seqno no greater than the seeking seqno.
+// 2) If the iter is invalid, it means that either all the user_key is less
+//    than the seek_user_key, or the block ends with a matching user_key but
+//    with a smaller [ type | seqno ] (i.e. a larger seqno, or the same seqno
+//    but larger type).
+bool DataBlockIter::SeekForGetImpl(const Slice& target) {
+  Slice user_key = ExtractUserKey(target);
+  uint32_t map_offset = restarts_ + num_restarts_ * sizeof(uint32_t);
+  uint8_t entry = data_block_hash_index_->Lookup(data_, map_offset, user_key);
+
+  if (entry == kCollision) {
+    // HashSeek not effective, falling back
+    Seek(target);
+    return true;
+  }
+
+  if (entry == kNoEntry) {
+    // Even if we cannot find the user_key in this block, the result may
+    // exist in the next block. Consider this exmpale:
+    //
+    // Block N:    [aab@100, ... , app@120]
+    // bounary key: axy@50 (we make minimal assumption about a boundary key)
+    // Block N+1:  [axy@10, ...   ]
+    //
+    // If seek_key = axy@60, the search will starts from Block N.
+    // Even if the user_key is not found in the hash map, the caller still
+    // have to conntinue searching the next block.
+    //
+    // In this case, we pretend the key is the the last restart interval.
+    // The while-loop below will search the last restart interval for the
+    // key. It will stop at the first key that is larger than the seek_key,
+    // or to the end of the block if no one is larger.
+    entry = static_cast<uint8_t>(num_restarts_ - 1);
+  }
+
+  uint32_t restart_index = entry;
+
+  // check if the key is in the restart_interval
+  assert(restart_index < num_restarts_);
+  SeekToRestartPoint(restart_index);
+
+  const char* limit = nullptr;
+  if (restart_index_ + 1 < num_restarts_) {
+    limit = data_ + GetRestartPoint(restart_index_ + 1);
+  } else {
+    limit = data_ + restarts_;
+  }
+
+  while (true) {
+    // Here we only linear seek the target key inside the restart interval.
+    // If a key does not exist inside a restart interval, we avoid
+    // further searching the block content accross restart interval boundary.
+    //
+    // TODO(fwu): check the left and write boundary of the restart interval
+    // to avoid linear seek a target key that is out of range.
+    if (!ParseNextDataKey<DecodeEntry>(limit) || Compare(key_, target) >= 0) {
+      // we stop at the first potential matching user key.
+      break;
+    }
+  }
+
+  if (current_ == restarts_) {
+    // Search reaches to the end of the block. There are three possibilites:
+    // 1) there is only one user_key match in the block (otherwise collsion).
+    //    the matching user_key resides in the last restart interval, and it
+    //    is the last key of the restart interval and of the block as well.
+    //    ParseNextDataKey() skiped it as its [ type | seqno ] is smaller.
+    //
+    // 2) The seek_key is not found in the HashIndex Lookup(), i.e. kNoEntry,
+    //    AND all existing user_keys in the restart interval are smaller than
+    //    seek_user_key.
+    //
+    // 3) The seek_key is a false positive and happens to be hashed to the
+    //    last restart interval, AND all existing user_keys in the restart
+    //    interval are smaller than seek_user_key.
+    //
+    // The result may exist in the next block each case, so we return true.
+    return true;
+  }
+
+  if (user_comparator_->Compare(key_.GetUserKey(), user_key) != 0) {
+    // the key is not in this block and cannot be at the next block either.
+    return false;
+  }
+
+  // Here we are conservative and only support a limited set of cases
+  ValueType value_type = ExtractValueType(key_.GetKey());
+  if (value_type != ValueType::kTypeValue &&
+      value_type != ValueType::kTypeDeletion &&
+      value_type != ValueType::kTypeSingleDeletion &&
+      value_type != ValueType::kTypeBlobIndex) {
+    Seek(target);
+    return true;
+  }
+
+  // Result found, and the iter is correctly set.
+  return true;
+}
+
+void IndexBlockIter::Seek(const Slice& target) {
+  Slice seek_key = target;
+  if (!key_includes_seq_) {
+    seek_key = ExtractUserKey(target);
+  }
+  PERF_TIMER_GUARD(block_seek_nanos);
+  if (data_ == nullptr) {  // Not init yet
+    return;
+  }
+  uint32_t index = 0;
+  bool ok = false;
+  if (prefix_index_) {
+    ok = PrefixSeek(target, &index);
+  } else if (value_delta_encoded_) {
+    ok = BinarySeek<DecodeKeyV4>(seek_key, 0, num_restarts_ - 1, &index,
+                                 comparator_);
+  } else {
+    ok = BinarySeek<DecodeKey>(seek_key, 0, num_restarts_ - 1, &index,
+                               comparator_);
+  }
+
+  if (!ok) {
+    return;
+  }
+  SeekToRestartPoint(index);
+  // Linear search (within restart block) for first key >= target
+
+  while (true) {
+    if (!ParseNextIndexKey() || Compare(key_, seek_key) >= 0) {
+      return;
+    }
+  }
+}
+
+void DataBlockIter::SeekForPrev(const Slice& target) {
+  PERF_TIMER_GUARD(block_seek_nanos);
+  Slice seek_key = target;
+  if (data_ == nullptr) {  // Not init yet
+    return;
+  }
+  uint32_t index = 0;
+  bool ok = BinarySeek<DecodeKey>(seek_key, 0, num_restarts_ - 1, &index,
+                                  comparator_);
+
+  if (!ok) {
+    return;
+  }
+  SeekToRestartPoint(index);
+  // Linear search (within restart block) for first key >= seek_key
+
+  while (ParseNextDataKey<DecodeEntry>() && Compare(key_, seek_key) < 0) {
+  }
+  if (!Valid()) {
+    SeekToLast();
+  } else {
+    while (Valid() && Compare(key_, seek_key) > 0) {
+      Prev();
+    }
+  }
+}
+
+void DataBlockIter::SeekToFirst() {
+  if (data_ == nullptr) {  // Not init yet
+    return;
+  }
+  SeekToRestartPoint(0);
+  ParseNextDataKey<DecodeEntry>();
+}
+
+void DataBlockIter::SeekToFirstOrReport() {
+  if (data_ == nullptr) {  // Not init yet
+    return;
+  }
+  SeekToRestartPoint(0);
+  ParseNextDataKey<CheckAndDecodeEntry>();
+}
+
+void IndexBlockIter::SeekToFirst() {
+  if (data_ == nullptr) {  // Not init yet
+    return;
+  }
+  SeekToRestartPoint(0);
+  ParseNextIndexKey();
+}
+
+void DataBlockIter::SeekToLast() {
+  if (data_ == nullptr) {  // Not init yet
+    return;
+  }
+  SeekToRestartPoint(num_restarts_ - 1);
+  while (ParseNextDataKey<DecodeEntry>() && NextEntryOffset() < restarts_) {
+    // Keep skipping
+  }
+}
+
+void IndexBlockIter::SeekToLast() {
+  if (data_ == nullptr) {  // Not init yet
+    return;
+  }
+  SeekToRestartPoint(num_restarts_ - 1);
+  while (ParseNextIndexKey() && NextEntryOffset() < restarts_) {
+    // Keep skipping
+  }
+}
+
+template <class TValue>
+void BlockIter<TValue>::CorruptionError() {
+  current_ = restarts_;
+  restart_index_ = num_restarts_;
+  status_ = Status::Corruption("bad entry in block");
+  key_.Clear();
+  value_.clear();
+}
+
+template <typename DecodeEntryFunc>
+bool DataBlockIter::ParseNextDataKey(const char* limit) {
+  current_ = NextEntryOffset();
+  const char* p = data_ + current_;
+  if (!limit) {
+    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;
+  p = DecodeEntryFunc()(p, limit, &shared, &non_shared, &value_length);
+  if (p == nullptr || key_.Size() < shared) {
+    CorruptionError();
+    return false;
+  } else {
+    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;
+    }
+
+    if (global_seqno_ != kDisableGlobalSequenceNumber) {
+      // If we are reading a file with a global sequence number we should
+      // expect that all encoded sequence numbers are zeros and any value
+      // type is kTypeValue, kTypeMerge, kTypeDeletion, or kTypeRangeDeletion.
+      assert(GetInternalKeySeqno(key_.GetInternalKey()) == 0);
+
+      ValueType value_type = ExtractValueType(key_.GetKey());
+      assert(value_type == ValueType::kTypeValue ||
+             value_type == ValueType::kTypeMerge ||
+             value_type == ValueType::kTypeDeletion ||
+             value_type == ValueType::kTypeRangeDeletion);
+
+      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) {
+    // In BlockBuilder, we have ensured a block with HashIndex is less than
+    // kMaxBlockSizeSupportedByHashIndex (64KiB).
+    //
+    // Therefore, if we encounter a block with a size > 64KiB, the block
+    // cannot have HashIndex. So the footer will directly interpreted as
+    // num_restarts.
+    //
+    // Such check is for backward compatibility. We can ensure legacy block
+    // with a vary large num_restarts i.e. >= 0x80000000 can be interpreted
+    // correctly as no HashIndex even if the MSB of num_restarts is set.
+    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() {
+  // This sync point can be re-enabled if RocksDB can control the
+  // initialization order of any/all static options created by the user.
+  // 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
+    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*/,
+                                  bool block_contents_pinned,
+                                  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(), block_contents_pinned,
+        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,
+                                   bool block_contents_pinned,
+                                   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,
+                         block_contents_pinned,
+                         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