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[RocksDB] Compaction Filter Cleanup

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Summary: This hopefully gives the right semantics to compaction filter. Will write a small wiki to explain the ideas.

Test Plan: make check; db_stress

Reviewers: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11121
This commit is contained in:
Haobo Xu 2013-06-06 10:31:37 -07:00
parent 7a5f71d19a
commit 1afdf28701
1 changed files with 38 additions and 25 deletions
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63
db/db_impl.cc
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@ -1641,12 +1641,14 @@ Status DBImpl::DoCompactionWork(CompactionState* compact) {
SequenceNumber visible_at_tip = 0;
SequenceNumber earliest_snapshot;
SequenceNumber latest_snapshot = 0;
snapshots_.getAll(compact->existing_snapshots);
if (compact->existing_snapshots.size() == 0) {
// optimize for fast path if there are no snapshots
visible_at_tip = versions_->LastSequence();
earliest_snapshot = visible_at_tip;
} else {
latest_snapshot = compact->existing_snapshots.back();
// Add the current seqno as the 'latest' virtual
// snapshot to the end of this list.
compact->existing_snapshots.push_back(versions_->LastSequence());
@ -1680,6 +1682,7 @@ Status DBImpl::DoCompactionWork(CompactionState* compact) {
kMaxSequenceNumber;
SequenceNumber visible_in_snapshot = kMaxSequenceNumber;
std::string compaction_filter_value;
std::vector<char> delete_key; // for compaction filter
MergeHelper merge(user_comparator(), options_.merge_operator,
options_.info_log.get(),
false /* internal key corruption is expected */);
@ -1727,6 +1730,41 @@ Status DBImpl::DoCompactionWork(CompactionState* compact) {
has_current_user_key = true;
last_sequence_for_key = kMaxSequenceNumber;
visible_in_snapshot = kMaxSequenceNumber;
// apply the compaction filter to the first occurrence of the user key
if (options_.compaction_filter &&
ikey.type == kTypeValue &&
(visible_at_tip || ikey.sequence > latest_snapshot)) {
// 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 delete marker.
bool value_changed = false;
compaction_filter_value.clear();
bool to_delete =
options_.compaction_filter->Filter(compact->compaction->level(),
ikey.user_key, value,
&compaction_filter_value,
&value_changed);
if (to_delete) {
// make a copy of the original key
delete_key.assign(key.data(), key.data() + key.size());
// convert it to a delete
UpdateInternalKey(&delete_key[0], delete_key.size(),
ikey.sequence, kTypeDeletion);
// anchor the key again
key = Slice(&delete_key[0], delete_key.size());
// needed because ikey is backed by key
ParseInternalKey(key, &ikey);
// no value associated with delete
value.clear();
RecordTick(options_.statistics, COMPACTION_KEY_DROP_USER);
} else if (value_changed) {
value = compaction_filter_value;
}
}
}
// If there are no snapshots, then this kv affect visibility at tip.
@ -1773,31 +1811,6 @@ Status DBImpl::DoCompactionWork(CompactionState* compact) {
key = merge.key();
ParseInternalKey(key, &ikey);
value = merge.value();
} else if (options_.compaction_filter &&
ikey.type != kTypeDeletion &&
visible_at_tip) {
// If the user has specified a compaction filter and there are no
// outstanding external snapshots, then invoke the filter.
// If the return value of the compaction filter is true,
// drop this key from the output.
assert(ikey.type == kTypeValue);
assert(!drop);
bool value_changed = false;
compaction_filter_value.clear();
drop = options_.compaction_filter->Filter(compact->compaction->level(),
ikey.user_key, value,
&compaction_filter_value,
&value_changed);
// Another example of statistics update without holding the lock
// TODO: clean it up
if (drop) {
RecordTick(options_.statistics, COMPACTION_KEY_DROP_USER);
}
// If the application wants to change the value, then do so here.
if (value_changed) {
value = compaction_filter_value;
}
}
last_sequence_for_key = ikey.sequence;