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Add MaxInputLevel() to CompactionPicker

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Summary:
Having if-then branch for different compaction strategies is considered
hacky and make CompactionPicker less pluggable.  This diff removes two
of such if-then branches in version_set.cc by adding MaxInputLevel() to
CompactionPicker.

    // Given the current number of levels, returns the lowest allowed level
    // for compaction input.
    virtual int MaxInputLevel(int current_num_levels) const;

Test Plan:
make db_test
export ROCKSDB_TESTS=Compaction
./db_test

Reviewers: igor, sdong, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D19971
This commit is contained in:
Yueh-Hsuan Chiang 2014-07-17 18:01:04 -07:00
parent 2f289dccf3
commit 052ddbe0e2
2 changed files with 27 additions and 12 deletions
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20
db/compaction_picker.h
View file

@ -52,6 +52,10 @@ class CompactionPicker {
const InternalKey* end,
InternalKey** compaction_end);
// Given the current number of levels, returns the lowest allowed level
// for compaction input.
virtual int MaxInputLevel(int current_num_levels) const = 0;
// Free up the files that participated in a compaction
void ReleaseCompactionFiles(Compaction* c, Status status);
@ -135,6 +139,11 @@ class UniversalCompactionPicker : public CompactionPicker {
virtual Compaction* PickCompaction(Version* version,
LogBuffer* log_buffer) override;
// The maxinum allowed input level. Always return 0.
virtual int MaxInputLevel(int current_num_levels) const override {
return 0;
}
private:
// Pick Universal compaction to limit read amplification
Compaction* PickCompactionUniversalReadAmp(Version* version, double score,
@ -159,6 +168,12 @@ class LevelCompactionPicker : public CompactionPicker {
virtual Compaction* PickCompaction(Version* version,
LogBuffer* log_buffer) override;
// Returns current_num_levels - 2, meaning the last level cannot be
// compaction input level.
virtual int MaxInputLevel(int current_num_levels) const override {
return current_num_levels - 2;
}
private:
// For the specfied level, pick a compaction.
// Returns nullptr if there is no compaction to be done.
@ -180,6 +195,11 @@ class FIFOCompactionPicker : public CompactionPicker {
int output_level, const InternalKey* begin,
const InternalKey* end,
InternalKey** compaction_end) override;
// The maxinum allowed input level. Always return 0.
virtual int MaxInputLevel(int current_num_levels) const override {
return 0;
}
};
} // namespace rocksdb

19
db/version_set.cc
View file

@ -929,13 +929,10 @@ void Version::ComputeCompactionScore(
double max_score = 0;
int max_score_level = 0;
int num_levels_to_check =
(cfd_->options()->compaction_style != kCompactionStyleUniversal &&
cfd_->options()->compaction_style != kCompactionStyleFIFO)
? NumberLevels() - 1
: 1;
int max_input_level =
cfd_->compaction_picker()->MaxInputLevel(NumberLevels());
for (int level = 0; level < num_levels_to_check; level++) {
for (int level = 0; level <= max_input_level; level++) {
double score;
if (level == 0) {
// We treat level-0 specially by bounding the number of files
@ -1084,12 +1081,10 @@ bool Version::NeedsCompaction() const {
// ending up with nothing to do. We can improve it later.
// TODO(sdong): improve this function to be accurate for universal
// compactions.
int num_levels_to_check =
(cfd_->options()->compaction_style != kCompactionStyleUniversal &&
cfd_->options()->compaction_style != kCompactionStyleFIFO)
? NumberLevels() - 1
: 1;
for (int i = 0; i < num_levels_to_check; i++) {
int max_input_level =
cfd_->compaction_picker()->MaxInputLevel(NumberLevels());
for (int i = 0; i <= max_input_level; i++) {
if (compaction_score_[i] >= 1) {
return true;
}