576d2d6c60
Summary: If IsInSnapshot(seq2, snapshot) determines that the snapshot is released, the future queries IsInSnapshot(seq1, snapshot) could still return a definitive answer of true if for example seq1 is too old that is determined visible in all snapshots. This violates a recently added assert statement to compaction iterator. The patch relaxes the assert. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4969 Differential Revision: D14030998 Pulled By: maysamyabandeh fbshipit-source-id: 6db53db0e37d0a20e8997ef2c1004b8627614ab9
705 lines
30 KiB
C++
705 lines
30 KiB
C++
// 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).
|
|
|
|
#include "db/compaction_iterator.h"
|
|
|
|
#include "db/snapshot_checker.h"
|
|
#include "port/likely.h"
|
|
#include "rocksdb/listener.h"
|
|
#include "table/internal_iterator.h"
|
|
#include "util/sync_point.h"
|
|
|
|
#define DEFINITELY_IN_SNAPSHOT(seq, snapshot) \
|
|
((seq) <= (snapshot) && \
|
|
(snapshot_checker_ == nullptr || \
|
|
LIKELY(snapshot_checker_->CheckInSnapshot((seq), (snapshot)) == \
|
|
SnapshotCheckerResult::kInSnapshot)))
|
|
|
|
#define DEFINITELY_NOT_IN_SNAPSHOT(seq, snapshot) \
|
|
((seq) > (snapshot) || \
|
|
(snapshot_checker_ != nullptr && \
|
|
UNLIKELY(snapshot_checker_->CheckInSnapshot((seq), (snapshot)) == \
|
|
SnapshotCheckerResult::kNotInSnapshot)))
|
|
|
|
#define IN_EARLIEST_SNAPSHOT(seq) \
|
|
((seq) <= earliest_snapshot_ && \
|
|
(snapshot_checker_ == nullptr || LIKELY(IsInEarliestSnapshot(seq))))
|
|
|
|
namespace rocksdb {
|
|
|
|
CompactionIterator::CompactionIterator(
|
|
InternalIterator* input, const Comparator* cmp, MergeHelper* merge_helper,
|
|
SequenceNumber last_sequence, std::vector<SequenceNumber>* snapshots,
|
|
SequenceNumber earliest_write_conflict_snapshot,
|
|
const SnapshotChecker* snapshot_checker, Env* env,
|
|
bool report_detailed_time, bool expect_valid_internal_key,
|
|
CompactionRangeDelAggregator* range_del_agg, const Compaction* compaction,
|
|
const CompactionFilter* compaction_filter,
|
|
const std::atomic<bool>* shutting_down,
|
|
const SequenceNumber preserve_deletes_seqnum)
|
|
: CompactionIterator(
|
|
input, cmp, merge_helper, last_sequence, snapshots,
|
|
earliest_write_conflict_snapshot, snapshot_checker, env,
|
|
report_detailed_time, expect_valid_internal_key, range_del_agg,
|
|
std::unique_ptr<CompactionProxy>(
|
|
compaction ? new CompactionProxy(compaction) : nullptr),
|
|
compaction_filter, shutting_down, preserve_deletes_seqnum) {}
|
|
|
|
CompactionIterator::CompactionIterator(
|
|
InternalIterator* input, const Comparator* cmp, MergeHelper* merge_helper,
|
|
SequenceNumber /*last_sequence*/, std::vector<SequenceNumber>* snapshots,
|
|
SequenceNumber earliest_write_conflict_snapshot,
|
|
const SnapshotChecker* snapshot_checker, Env* env,
|
|
bool report_detailed_time, bool expect_valid_internal_key,
|
|
CompactionRangeDelAggregator* range_del_agg,
|
|
std::unique_ptr<CompactionProxy> compaction,
|
|
const CompactionFilter* compaction_filter,
|
|
const std::atomic<bool>* shutting_down,
|
|
const SequenceNumber preserve_deletes_seqnum)
|
|
: input_(input),
|
|
cmp_(cmp),
|
|
merge_helper_(merge_helper),
|
|
snapshots_(snapshots),
|
|
earliest_write_conflict_snapshot_(earliest_write_conflict_snapshot),
|
|
snapshot_checker_(snapshot_checker),
|
|
env_(env),
|
|
report_detailed_time_(report_detailed_time),
|
|
expect_valid_internal_key_(expect_valid_internal_key),
|
|
range_del_agg_(range_del_agg),
|
|
compaction_(std::move(compaction)),
|
|
compaction_filter_(compaction_filter),
|
|
shutting_down_(shutting_down),
|
|
preserve_deletes_seqnum_(preserve_deletes_seqnum),
|
|
current_user_key_sequence_(0),
|
|
current_user_key_snapshot_(0),
|
|
merge_out_iter_(merge_helper_),
|
|
current_key_committed_(false) {
|
|
assert(compaction_filter_ == nullptr || compaction_ != nullptr);
|
|
assert(snapshots_ != nullptr);
|
|
bottommost_level_ =
|
|
compaction_ == nullptr ? false : compaction_->bottommost_level();
|
|
if (compaction_ != nullptr) {
|
|
level_ptrs_ = std::vector<size_t>(compaction_->number_levels(), 0);
|
|
}
|
|
if (snapshots_->size() == 0) {
|
|
// optimize for fast path if there are no snapshots
|
|
visible_at_tip_ = true;
|
|
earliest_snapshot_iter_ = snapshots_->end();
|
|
earliest_snapshot_ = kMaxSequenceNumber;
|
|
latest_snapshot_ = 0;
|
|
} else {
|
|
visible_at_tip_ = false;
|
|
earliest_snapshot_iter_ = snapshots_->begin();
|
|
earliest_snapshot_ = snapshots_->at(0);
|
|
latest_snapshot_ = snapshots_->back();
|
|
}
|
|
#ifndef NDEBUG
|
|
// findEarliestVisibleSnapshot assumes this ordering.
|
|
for (size_t i = 1; i < snapshots_->size(); ++i) {
|
|
assert(snapshots_->at(i - 1) < snapshots_->at(i));
|
|
}
|
|
#endif
|
|
input_->SetPinnedItersMgr(&pinned_iters_mgr_);
|
|
TEST_SYNC_POINT_CALLBACK("CompactionIterator:AfterInit", compaction_.get());
|
|
}
|
|
|
|
CompactionIterator::~CompactionIterator() {
|
|
// input_ Iteartor lifetime is longer than pinned_iters_mgr_ lifetime
|
|
input_->SetPinnedItersMgr(nullptr);
|
|
}
|
|
|
|
void CompactionIterator::ResetRecordCounts() {
|
|
iter_stats_.num_record_drop_user = 0;
|
|
iter_stats_.num_record_drop_hidden = 0;
|
|
iter_stats_.num_record_drop_obsolete = 0;
|
|
iter_stats_.num_record_drop_range_del = 0;
|
|
iter_stats_.num_range_del_drop_obsolete = 0;
|
|
iter_stats_.num_optimized_del_drop_obsolete = 0;
|
|
}
|
|
|
|
void CompactionIterator::SeekToFirst() {
|
|
NextFromInput();
|
|
PrepareOutput();
|
|
}
|
|
|
|
void CompactionIterator::Next() {
|
|
// If there is a merge output, return it before continuing to process the
|
|
// input.
|
|
if (merge_out_iter_.Valid()) {
|
|
merge_out_iter_.Next();
|
|
|
|
// Check if we returned all records of the merge output.
|
|
if (merge_out_iter_.Valid()) {
|
|
key_ = merge_out_iter_.key();
|
|
value_ = merge_out_iter_.value();
|
|
bool valid_key __attribute__((__unused__));
|
|
valid_key = ParseInternalKey(key_, &ikey_);
|
|
// MergeUntil stops when it encounters a corrupt key and does not
|
|
// include them in the result, so we expect the keys here to be valid.
|
|
assert(valid_key);
|
|
// Keep current_key_ in sync.
|
|
current_key_.UpdateInternalKey(ikey_.sequence, ikey_.type);
|
|
key_ = current_key_.GetInternalKey();
|
|
ikey_.user_key = current_key_.GetUserKey();
|
|
valid_ = true;
|
|
} else {
|
|
// We consumed all pinned merge operands, release pinned iterators
|
|
pinned_iters_mgr_.ReleasePinnedData();
|
|
// MergeHelper moves the iterator to the first record after the merged
|
|
// records, so even though we reached the end of the merge output, we do
|
|
// not want to advance the iterator.
|
|
NextFromInput();
|
|
}
|
|
} else {
|
|
// Only advance the input iterator if there is no merge output and the
|
|
// iterator is not already at the next record.
|
|
if (!at_next_) {
|
|
input_->Next();
|
|
}
|
|
NextFromInput();
|
|
}
|
|
|
|
if (valid_) {
|
|
// Record that we've outputted a record for the current key.
|
|
has_outputted_key_ = true;
|
|
}
|
|
|
|
PrepareOutput();
|
|
}
|
|
|
|
void CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
|
|
Slice* skip_until) {
|
|
if (compaction_filter_ != nullptr &&
|
|
(ikey_.type == kTypeValue || ikey_.type == kTypeBlobIndex)) {
|
|
// If the user has specified a compaction filter and the sequence
|
|
// number is greater than any external snapshot, then invoke the
|
|
// filter. If the return value of the compaction filter is true,
|
|
// replace the entry with a deletion marker.
|
|
CompactionFilter::Decision filter;
|
|
compaction_filter_value_.clear();
|
|
compaction_filter_skip_until_.Clear();
|
|
CompactionFilter::ValueType value_type =
|
|
ikey_.type == kTypeValue ? CompactionFilter::ValueType::kValue
|
|
: CompactionFilter::ValueType::kBlobIndex;
|
|
// Hack: pass internal key to BlobIndexCompactionFilter since it needs
|
|
// to get sequence number.
|
|
Slice& filter_key = ikey_.type == kTypeValue ? ikey_.user_key : key_;
|
|
{
|
|
StopWatchNano timer(env_, report_detailed_time_);
|
|
filter = compaction_filter_->FilterV2(
|
|
compaction_->level(), filter_key, value_type, value_,
|
|
&compaction_filter_value_, compaction_filter_skip_until_.rep());
|
|
iter_stats_.total_filter_time +=
|
|
env_ != nullptr && report_detailed_time_ ? timer.ElapsedNanos() : 0;
|
|
}
|
|
|
|
if (filter == CompactionFilter::Decision::kRemoveAndSkipUntil &&
|
|
cmp_->Compare(*compaction_filter_skip_until_.rep(), ikey_.user_key) <=
|
|
0) {
|
|
// Can't skip to a key smaller than the current one.
|
|
// Keep the key as per FilterV2 documentation.
|
|
filter = CompactionFilter::Decision::kKeep;
|
|
}
|
|
|
|
if (filter == CompactionFilter::Decision::kRemove) {
|
|
// convert the current key to a delete; key_ is pointing into
|
|
// current_key_ at this point, so updating current_key_ updates key()
|
|
ikey_.type = kTypeDeletion;
|
|
current_key_.UpdateInternalKey(ikey_.sequence, kTypeDeletion);
|
|
// no value associated with delete
|
|
value_.clear();
|
|
iter_stats_.num_record_drop_user++;
|
|
} else if (filter == CompactionFilter::Decision::kChangeValue) {
|
|
value_ = compaction_filter_value_;
|
|
} else if (filter == CompactionFilter::Decision::kRemoveAndSkipUntil) {
|
|
*need_skip = true;
|
|
compaction_filter_skip_until_.ConvertFromUserKey(kMaxSequenceNumber,
|
|
kValueTypeForSeek);
|
|
*skip_until = compaction_filter_skip_until_.Encode();
|
|
}
|
|
}
|
|
}
|
|
|
|
void CompactionIterator::NextFromInput() {
|
|
at_next_ = false;
|
|
valid_ = false;
|
|
|
|
while (!valid_ && input_->Valid() && !IsShuttingDown()) {
|
|
key_ = input_->key();
|
|
value_ = input_->value();
|
|
iter_stats_.num_input_records++;
|
|
|
|
if (!ParseInternalKey(key_, &ikey_)) {
|
|
// If `expect_valid_internal_key_` is false, return the corrupted key
|
|
// and let the caller decide what to do with it.
|
|
// TODO(noetzli): We should have a more elegant solution for this.
|
|
if (expect_valid_internal_key_) {
|
|
assert(!"Corrupted internal key not expected.");
|
|
status_ = Status::Corruption("Corrupted internal key not expected.");
|
|
break;
|
|
}
|
|
key_ = current_key_.SetInternalKey(key_);
|
|
has_current_user_key_ = false;
|
|
current_user_key_sequence_ = kMaxSequenceNumber;
|
|
current_user_key_snapshot_ = 0;
|
|
iter_stats_.num_input_corrupt_records++;
|
|
valid_ = true;
|
|
break;
|
|
}
|
|
TEST_SYNC_POINT_CALLBACK("CompactionIterator:ProcessKV", &ikey_);
|
|
|
|
// Update input statistics
|
|
if (ikey_.type == kTypeDeletion || ikey_.type == kTypeSingleDeletion) {
|
|
iter_stats_.num_input_deletion_records++;
|
|
}
|
|
iter_stats_.total_input_raw_key_bytes += key_.size();
|
|
iter_stats_.total_input_raw_value_bytes += value_.size();
|
|
|
|
// If need_skip is true, we should seek the input iterator
|
|
// to internal key skip_until and continue from there.
|
|
bool need_skip = false;
|
|
// Points either into compaction_filter_skip_until_ or into
|
|
// merge_helper_->compaction_filter_skip_until_.
|
|
Slice skip_until;
|
|
|
|
// Check whether the user key changed. After this if statement current_key_
|
|
// is a copy of the current input key (maybe converted to a delete by the
|
|
// compaction filter). ikey_.user_key is pointing to the copy.
|
|
if (!has_current_user_key_ ||
|
|
!cmp_->Equal(ikey_.user_key, current_user_key_)) {
|
|
// First occurrence of this user key
|
|
// Copy key for output
|
|
key_ = current_key_.SetInternalKey(key_, &ikey_);
|
|
current_user_key_ = ikey_.user_key;
|
|
has_current_user_key_ = true;
|
|
has_outputted_key_ = false;
|
|
current_user_key_sequence_ = kMaxSequenceNumber;
|
|
current_user_key_snapshot_ = 0;
|
|
current_key_committed_ = KeyCommitted(ikey_.sequence);
|
|
|
|
// Apply the compaction filter to the first committed version of the user
|
|
// key.
|
|
if (current_key_committed_) {
|
|
InvokeFilterIfNeeded(&need_skip, &skip_until);
|
|
}
|
|
} else {
|
|
// Update the current key to reflect the new sequence number/type without
|
|
// copying the user key.
|
|
// TODO(rven): Compaction filter does not process keys in this path
|
|
// Need to have the compaction filter process multiple versions
|
|
// if we have versions on both sides of a snapshot
|
|
current_key_.UpdateInternalKey(ikey_.sequence, ikey_.type);
|
|
key_ = current_key_.GetInternalKey();
|
|
ikey_.user_key = current_key_.GetUserKey();
|
|
|
|
// Note that newer version of a key is ordered before older versions. If a
|
|
// newer version of a key is committed, so as the older version. No need
|
|
// to query snapshot_checker_ in that case.
|
|
if (UNLIKELY(!current_key_committed_)) {
|
|
assert(snapshot_checker_ != nullptr);
|
|
current_key_committed_ = KeyCommitted(ikey_.sequence);
|
|
// Apply the compaction filter to the first committed version of the
|
|
// user key.
|
|
if (current_key_committed_) {
|
|
InvokeFilterIfNeeded(&need_skip, &skip_until);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (UNLIKELY(!current_key_committed_)) {
|
|
assert(snapshot_checker_ != nullptr);
|
|
valid_ = true;
|
|
break;
|
|
}
|
|
|
|
// If there are no snapshots, then this kv affect visibility at tip.
|
|
// Otherwise, search though all existing snapshots to find the earliest
|
|
// snapshot that is affected by this kv.
|
|
SequenceNumber last_sequence __attribute__((__unused__));
|
|
last_sequence = current_user_key_sequence_;
|
|
current_user_key_sequence_ = ikey_.sequence;
|
|
SequenceNumber last_snapshot = current_user_key_snapshot_;
|
|
SequenceNumber prev_snapshot = 0; // 0 means no previous snapshot
|
|
current_user_key_snapshot_ =
|
|
visible_at_tip_
|
|
? earliest_snapshot_
|
|
: findEarliestVisibleSnapshot(ikey_.sequence, &prev_snapshot);
|
|
|
|
if (need_skip) {
|
|
// This case is handled below.
|
|
} else if (clear_and_output_next_key_) {
|
|
// In the previous iteration we encountered a single delete that we could
|
|
// not compact out. We will keep this Put, but can drop it's data.
|
|
// (See Optimization 3, below.)
|
|
assert(ikey_.type == kTypeValue);
|
|
assert(current_user_key_snapshot_ == last_snapshot);
|
|
|
|
value_.clear();
|
|
valid_ = true;
|
|
clear_and_output_next_key_ = false;
|
|
} else if (ikey_.type == kTypeSingleDeletion) {
|
|
// We can compact out a SingleDelete if:
|
|
// 1) We encounter the corresponding PUT -OR- we know that this key
|
|
// doesn't appear past this output level
|
|
// =AND=
|
|
// 2) We've already returned a record in this snapshot -OR-
|
|
// there are no earlier earliest_write_conflict_snapshot.
|
|
//
|
|
// Rule 1 is needed for SingleDelete correctness. Rule 2 is needed to
|
|
// allow Transactions to do write-conflict checking (if we compacted away
|
|
// all keys, then we wouldn't know that a write happened in this
|
|
// snapshot). If there is no earlier snapshot, then we know that there
|
|
// are no active transactions that need to know about any writes.
|
|
//
|
|
// Optimization 3:
|
|
// If we encounter a SingleDelete followed by a PUT and Rule 2 is NOT
|
|
// true, then we must output a SingleDelete. In this case, we will decide
|
|
// to also output the PUT. While we are compacting less by outputting the
|
|
// PUT now, hopefully this will lead to better compaction in the future
|
|
// when Rule 2 is later true (Ie, We are hoping we can later compact out
|
|
// both the SingleDelete and the Put, while we couldn't if we only
|
|
// outputted the SingleDelete now).
|
|
// In this case, we can save space by removing the PUT's value as it will
|
|
// never be read.
|
|
//
|
|
// Deletes and Merges are not supported on the same key that has a
|
|
// SingleDelete as it is not possible to correctly do any partial
|
|
// compaction of such a combination of operations. The result of mixing
|
|
// those operations for a given key is documented as being undefined. So
|
|
// we can choose how to handle such a combinations of operations. We will
|
|
// try to compact out as much as we can in these cases.
|
|
// We will report counts on these anomalous cases.
|
|
|
|
// The easiest way to process a SingleDelete during iteration is to peek
|
|
// ahead at the next key.
|
|
ParsedInternalKey next_ikey;
|
|
input_->Next();
|
|
|
|
// Check whether the next key exists, is not corrupt, and is the same key
|
|
// as the single delete.
|
|
if (input_->Valid() && ParseInternalKey(input_->key(), &next_ikey) &&
|
|
cmp_->Equal(ikey_.user_key, next_ikey.user_key)) {
|
|
// Check whether the next key belongs to the same snapshot as the
|
|
// SingleDelete.
|
|
if (prev_snapshot == 0 ||
|
|
DEFINITELY_NOT_IN_SNAPSHOT(next_ikey.sequence, prev_snapshot)) {
|
|
if (next_ikey.type == kTypeSingleDeletion) {
|
|
// We encountered two SingleDeletes in a row. This could be due to
|
|
// unexpected user input.
|
|
// Skip the first SingleDelete and let the next iteration decide how
|
|
// to handle the second SingleDelete
|
|
|
|
// First SingleDelete has been skipped since we already called
|
|
// input_->Next().
|
|
++iter_stats_.num_record_drop_obsolete;
|
|
++iter_stats_.num_single_del_mismatch;
|
|
} else if (has_outputted_key_ ||
|
|
DEFINITELY_IN_SNAPSHOT(
|
|
ikey_.sequence, earliest_write_conflict_snapshot_)) {
|
|
// Found a matching value, we can drop the single delete and the
|
|
// value. It is safe to drop both records since we've already
|
|
// outputted a key in this snapshot, or there is no earlier
|
|
// snapshot (Rule 2 above).
|
|
|
|
// Note: it doesn't matter whether the second key is a Put or if it
|
|
// is an unexpected Merge or Delete. We will compact it out
|
|
// either way. We will maintain counts of how many mismatches
|
|
// happened
|
|
if (next_ikey.type != kTypeValue &&
|
|
next_ikey.type != kTypeBlobIndex) {
|
|
++iter_stats_.num_single_del_mismatch;
|
|
}
|
|
|
|
++iter_stats_.num_record_drop_hidden;
|
|
++iter_stats_.num_record_drop_obsolete;
|
|
// Already called input_->Next() once. Call it a second time to
|
|
// skip past the second key.
|
|
input_->Next();
|
|
} else {
|
|
// Found a matching value, but we cannot drop both keys since
|
|
// there is an earlier snapshot and we need to leave behind a record
|
|
// to know that a write happened in this snapshot (Rule 2 above).
|
|
// Clear the value and output the SingleDelete. (The value will be
|
|
// outputted on the next iteration.)
|
|
|
|
// Setting valid_ to true will output the current SingleDelete
|
|
valid_ = true;
|
|
|
|
// Set up the Put to be outputted in the next iteration.
|
|
// (Optimization 3).
|
|
clear_and_output_next_key_ = true;
|
|
}
|
|
} else {
|
|
// We hit the next snapshot without hitting a put, so the iterator
|
|
// returns the single delete.
|
|
valid_ = true;
|
|
}
|
|
} else {
|
|
// We are at the end of the input, could not parse the next key, or hit
|
|
// a different key. The iterator returns the single delete if the key
|
|
// possibly exists beyond the current output level. We set
|
|
// has_current_user_key to false so that if the iterator is at the next
|
|
// key, we do not compare it again against the previous key at the next
|
|
// iteration. If the next key is corrupt, we return before the
|
|
// comparison, so the value of has_current_user_key does not matter.
|
|
has_current_user_key_ = false;
|
|
if (compaction_ != nullptr && IN_EARLIEST_SNAPSHOT(ikey_.sequence) &&
|
|
compaction_->KeyNotExistsBeyondOutputLevel(ikey_.user_key,
|
|
&level_ptrs_)) {
|
|
// Key doesn't exist outside of this range.
|
|
// Can compact out this SingleDelete.
|
|
++iter_stats_.num_record_drop_obsolete;
|
|
++iter_stats_.num_single_del_fallthru;
|
|
if (!bottommost_level_) {
|
|
++iter_stats_.num_optimized_del_drop_obsolete;
|
|
}
|
|
} else {
|
|
// Output SingleDelete
|
|
valid_ = true;
|
|
}
|
|
}
|
|
|
|
if (valid_) {
|
|
at_next_ = true;
|
|
}
|
|
} else if (last_snapshot == current_user_key_snapshot_ ||
|
|
(last_snapshot > 0 &&
|
|
last_snapshot < current_user_key_snapshot_)) {
|
|
// If the earliest snapshot is which this key is visible in
|
|
// is the same as the visibility of a previous instance of the
|
|
// same key, then this kv is not visible in any snapshot.
|
|
// Hidden by an newer entry for same user key
|
|
//
|
|
// Note: Dropping this key will not affect TransactionDB write-conflict
|
|
// checking since there has already been a record returned for this key
|
|
// in this snapshot.
|
|
assert(last_sequence >= current_user_key_sequence_);
|
|
|
|
// Note2: if last_snapshot < current_user_key_snapshot, it can only
|
|
// mean last_snapshot is released between we process last value and
|
|
// this value, and findEarliestVisibleSnapshot returns the next snapshot
|
|
// as current_user_key_snapshot. In this case last value and current
|
|
// value are both in current_user_key_snapshot currently.
|
|
// Although last_snapshot is released we might still get a definitive
|
|
// response when key sequence number changes, e.g., when seq is determined
|
|
// too old and visible in all snapshots.
|
|
assert(last_snapshot == current_user_key_snapshot_ ||
|
|
(snapshot_checker_ != nullptr &&
|
|
snapshot_checker_->CheckInSnapshot(current_user_key_sequence_,
|
|
last_snapshot) !=
|
|
SnapshotCheckerResult::kNotInSnapshot));
|
|
|
|
++iter_stats_.num_record_drop_hidden; // (A)
|
|
input_->Next();
|
|
} else if (compaction_ != nullptr && ikey_.type == kTypeDeletion &&
|
|
IN_EARLIEST_SNAPSHOT(ikey_.sequence) &&
|
|
ikeyNotNeededForIncrementalSnapshot() &&
|
|
compaction_->KeyNotExistsBeyondOutputLevel(ikey_.user_key,
|
|
&level_ptrs_)) {
|
|
// TODO(noetzli): This is the only place where we use compaction_
|
|
// (besides the constructor). We should probably get rid of this
|
|
// dependency and find a way to do similar filtering during flushes.
|
|
//
|
|
// For this user key:
|
|
// (1) there is no data in higher levels
|
|
// (2) data in lower levels will have larger sequence numbers
|
|
// (3) data in layers that are being compacted here and have
|
|
// smaller sequence numbers will be dropped in the next
|
|
// few iterations of this loop (by rule (A) above).
|
|
// Therefore this deletion marker is obsolete and can be dropped.
|
|
//
|
|
// Note: Dropping this Delete will not affect TransactionDB
|
|
// write-conflict checking since it is earlier than any snapshot.
|
|
//
|
|
// It seems that we can also drop deletion later than earliest snapshot
|
|
// given that:
|
|
// (1) The deletion is earlier than earliest_write_conflict_snapshot, and
|
|
// (2) No value exist earlier than the deletion.
|
|
++iter_stats_.num_record_drop_obsolete;
|
|
if (!bottommost_level_) {
|
|
++iter_stats_.num_optimized_del_drop_obsolete;
|
|
}
|
|
input_->Next();
|
|
} else if ((ikey_.type == kTypeDeletion) && bottommost_level_ &&
|
|
ikeyNotNeededForIncrementalSnapshot()) {
|
|
// Handle the case where we have a delete key at the bottom most level
|
|
// We can skip outputting the key iff there are no subsequent puts for this
|
|
// key
|
|
ParsedInternalKey next_ikey;
|
|
input_->Next();
|
|
// Skip over all versions of this key that happen to occur in the same snapshot
|
|
// range as the delete
|
|
while (input_->Valid() && ParseInternalKey(input_->key(), &next_ikey) &&
|
|
cmp_->Equal(ikey_.user_key, next_ikey.user_key) &&
|
|
(prev_snapshot == 0 ||
|
|
DEFINITELY_NOT_IN_SNAPSHOT(next_ikey.sequence, prev_snapshot))) {
|
|
input_->Next();
|
|
}
|
|
// If you find you still need to output a row with this key, we need to output the
|
|
// delete too
|
|
if (input_->Valid() && ParseInternalKey(input_->key(), &next_ikey) &&
|
|
cmp_->Equal(ikey_.user_key, next_ikey.user_key)) {
|
|
valid_ = true;
|
|
at_next_ = true;
|
|
}
|
|
} else if (ikey_.type == kTypeMerge) {
|
|
if (!merge_helper_->HasOperator()) {
|
|
status_ = Status::InvalidArgument(
|
|
"merge_operator is not properly initialized.");
|
|
return;
|
|
}
|
|
|
|
pinned_iters_mgr_.StartPinning();
|
|
// We know the merge type entry is not hidden, otherwise we would
|
|
// have hit (A)
|
|
// We encapsulate the merge related state machine in a different
|
|
// object to minimize change to the existing flow.
|
|
Status s = merge_helper_->MergeUntil(input_, range_del_agg_,
|
|
prev_snapshot, bottommost_level_);
|
|
merge_out_iter_.SeekToFirst();
|
|
|
|
if (!s.ok() && !s.IsMergeInProgress()) {
|
|
status_ = s;
|
|
return;
|
|
} else if (merge_out_iter_.Valid()) {
|
|
// NOTE: key, value, and ikey_ refer to old entries.
|
|
// These will be correctly set below.
|
|
key_ = merge_out_iter_.key();
|
|
value_ = merge_out_iter_.value();
|
|
bool valid_key __attribute__((__unused__));
|
|
valid_key = ParseInternalKey(key_, &ikey_);
|
|
// MergeUntil stops when it encounters a corrupt key and does not
|
|
// include them in the result, so we expect the keys here to valid.
|
|
assert(valid_key);
|
|
// Keep current_key_ in sync.
|
|
current_key_.UpdateInternalKey(ikey_.sequence, ikey_.type);
|
|
key_ = current_key_.GetInternalKey();
|
|
ikey_.user_key = current_key_.GetUserKey();
|
|
valid_ = true;
|
|
} else {
|
|
// all merge operands were filtered out. reset the user key, since the
|
|
// batch consumed by the merge operator should not shadow any keys
|
|
// coming after the merges
|
|
has_current_user_key_ = false;
|
|
pinned_iters_mgr_.ReleasePinnedData();
|
|
|
|
if (merge_helper_->FilteredUntil(&skip_until)) {
|
|
need_skip = true;
|
|
}
|
|
}
|
|
} else {
|
|
// 1. new user key -OR-
|
|
// 2. different snapshot stripe
|
|
bool should_delete = range_del_agg_->ShouldDelete(
|
|
key_, RangeDelPositioningMode::kForwardTraversal);
|
|
if (should_delete) {
|
|
++iter_stats_.num_record_drop_hidden;
|
|
++iter_stats_.num_record_drop_range_del;
|
|
input_->Next();
|
|
} else {
|
|
valid_ = true;
|
|
}
|
|
}
|
|
|
|
if (need_skip) {
|
|
input_->Seek(skip_until);
|
|
}
|
|
}
|
|
|
|
if (!valid_ && IsShuttingDown()) {
|
|
status_ = Status::ShutdownInProgress();
|
|
}
|
|
}
|
|
|
|
void CompactionIterator::PrepareOutput() {
|
|
// Zeroing out the sequence number leads to better compression.
|
|
// If this is the bottommost level (no files in lower levels)
|
|
// and the earliest snapshot is larger than this seqno
|
|
// and the userkey differs from the last userkey in compaction
|
|
// then we can squash the seqno to zero.
|
|
//
|
|
// This is safe for TransactionDB write-conflict checking since transactions
|
|
// only care about sequence number larger than any active snapshots.
|
|
//
|
|
// Can we do the same for levels above bottom level as long as
|
|
// KeyNotExistsBeyondOutputLevel() return true?
|
|
if ((compaction_ != nullptr && !compaction_->allow_ingest_behind()) &&
|
|
ikeyNotNeededForIncrementalSnapshot() && bottommost_level_ && valid_ &&
|
|
IN_EARLIEST_SNAPSHOT(ikey_.sequence) && ikey_.type != kTypeMerge) {
|
|
assert(ikey_.type != kTypeDeletion && ikey_.type != kTypeSingleDeletion);
|
|
ikey_.sequence = 0;
|
|
current_key_.UpdateInternalKey(0, ikey_.type);
|
|
}
|
|
}
|
|
|
|
inline SequenceNumber CompactionIterator::findEarliestVisibleSnapshot(
|
|
SequenceNumber in, SequenceNumber* prev_snapshot) {
|
|
assert(snapshots_->size());
|
|
auto snapshots_iter = std::lower_bound(
|
|
snapshots_->begin(), snapshots_->end(), in);
|
|
if (snapshots_iter == snapshots_->begin()) {
|
|
*prev_snapshot = 0;
|
|
} else {
|
|
*prev_snapshot = *std::prev(snapshots_iter);
|
|
assert(*prev_snapshot < in);
|
|
}
|
|
if (snapshot_checker_ == nullptr) {
|
|
return snapshots_iter != snapshots_->end()
|
|
? *snapshots_iter : kMaxSequenceNumber;
|
|
}
|
|
bool has_released_snapshot = !released_snapshots_.empty();
|
|
for (; snapshots_iter != snapshots_->end(); ++snapshots_iter) {
|
|
auto cur = *snapshots_iter;
|
|
assert(in <= cur);
|
|
// Skip if cur is in released_snapshots.
|
|
if (has_released_snapshot && released_snapshots_.count(cur) > 0) {
|
|
continue;
|
|
}
|
|
auto res = snapshot_checker_->CheckInSnapshot(in, cur);
|
|
if (res == SnapshotCheckerResult::kInSnapshot) {
|
|
return cur;
|
|
} else if (res == SnapshotCheckerResult::kSnapshotReleased) {
|
|
released_snapshots_.insert(cur);
|
|
}
|
|
*prev_snapshot = cur;
|
|
}
|
|
return kMaxSequenceNumber;
|
|
}
|
|
|
|
// used in 2 places - prevents deletion markers to be dropped if they may be
|
|
// needed and disables seqnum zero-out in PrepareOutput for recent keys.
|
|
inline bool CompactionIterator::ikeyNotNeededForIncrementalSnapshot() {
|
|
return (!compaction_->preserve_deletes()) ||
|
|
(ikey_.sequence < preserve_deletes_seqnum_);
|
|
}
|
|
|
|
bool CompactionIterator::IsInEarliestSnapshot(SequenceNumber sequence) {
|
|
assert(snapshot_checker_ != nullptr);
|
|
assert(earliest_snapshot_ == kMaxSequenceNumber ||
|
|
(earliest_snapshot_iter_ != snapshots_->end() &&
|
|
*earliest_snapshot_iter_ == earliest_snapshot_));
|
|
auto in_snapshot =
|
|
snapshot_checker_->CheckInSnapshot(sequence, earliest_snapshot_);
|
|
while (UNLIKELY(in_snapshot == SnapshotCheckerResult::kSnapshotReleased)) {
|
|
// Avoid the the current earliest_snapshot_ being return as
|
|
// earliest visible snapshot for the next value. So if a value's sequence
|
|
// is zero-ed out by PrepareOutput(), the next value will be compact out.
|
|
released_snapshots_.insert(earliest_snapshot_);
|
|
earliest_snapshot_iter_++;
|
|
|
|
if (earliest_snapshot_iter_ == snapshots_->end()) {
|
|
earliest_snapshot_ = kMaxSequenceNumber;
|
|
} else {
|
|
earliest_snapshot_ = *earliest_snapshot_iter_;
|
|
}
|
|
in_snapshot =
|
|
snapshot_checker_->CheckInSnapshot(sequence, earliest_snapshot_);
|
|
}
|
|
assert(in_snapshot != SnapshotCheckerResult::kSnapshotReleased);
|
|
return in_snapshot == SnapshotCheckerResult::kInSnapshot;
|
|
}
|
|
|
|
} // namespace rocksdb
|