Enabling trivial move in universal compaction

Summary: This change enables trivial move if all the input files are non onverlapping while doing Universal Compaction.

Test Plan: ./compaction_picker_test and db_test ran successfully with the new testcases.

Reviewers: sdong

Reviewed By: sdong

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D40875

HISTORY.md

@@ -8,6 +8,7 @@
 * Several new features on EventListener (see include/rocksdb/listener.h):
  - OnCompationCompleted() now returns per-compaciton job statistics, defined in include/rocksdb/compaction_job_stats.h.
  - Added OnTableFileCreated() and OnTableFileDeleted().
+* Add compaction_options_universal.enable_trivial_move to true, to allow trivial move while performing universal compaction. Trivial move will happen only when all the input files are non overlapping.
 
 ### Public API changes
 * EventListener::OnFlushCompleted() now passes FlushJobInfo instead of a list of parameters.

db/compaction.cc

@@ -167,6 +167,12 @@ bool Compaction::IsTrivialMove() const {
     return false;
   }
 
+  // Used in universal compaction, where trivial move can be done if the
+  // input files are non overlapping
+  if (cfd_->ioptions()->compaction_options_universal.allow_trivial_move) {
+    return is_trivial_move_;
+  }
+
   return (start_level_ != output_level_ && num_input_levels() == 1 &&
           input(0, 0)->fd.GetPathId() == GetOutputPathId() &&
           InputCompressionMatchesOutput() &&

db/compaction.h

@@ -158,6 +158,19 @@ class Compaction {
   // Was this compaction triggered manually by the client?
   bool IsManualCompaction() { return is_manual_compaction_; }
 
+  // Used when allow_trivial_move option is set in
+  // Universal compaction. If all the input files are
+  // non overlapping, then is_trivial_move_ variable
+  // will be set true, else false
+  void set_is_trivial_move(bool trivial_move) {
+    is_trivial_move_ = trivial_move;
+  }
+
+  // Used when allow_trivial_move option is set in
+  // Universal compaction. Returns true, if the input files
+  // are non-overlapping and can be trivially moved.
+  bool is_trivial_move() { return is_trivial_move_; }
+
   // Return the MutableCFOptions that should be used throughout the compaction
   // procedure
   const MutableCFOptions* mutable_cf_options() { return &mutable_cf_options_; }
@@ -238,6 +251,11 @@ class Compaction {
   // Is this compaction requested by the client?
   const bool is_manual_compaction_;
 
+  // True if we can do trivial move in Universal multi level
+  // compaction
+
+  bool is_trivial_move_;
+
   // "level_ptrs_" holds indices into "input_version_->levels_", where each
   // index remembers which file of an associated level we are currently used
   // to check KeyNotExistsBeyondOutputLevel() for deletion operation.

db/compaction_picker.cc

@@ -15,6 +15,7 @@
 
 #include <inttypes.h>
 #include <limits>
+#include <queue>
 #include <string>
 #include <utility>
 
@@ -37,6 +38,64 @@ uint64_t TotalCompensatedFileSize(const std::vector<FileMetaData*>& files) {
   return sum;
 }
 
+// Used in universal compaction when trivial move is enabled.
+// This structure is used for the construction of min heap
+// that contains the file meta data, the level of the file
+// and the index of the file in that level
+
+struct InputFileInfo {
+  FileMetaData* f;
+  unsigned int level;
+  unsigned int index;
+};
+
+// Used in universal compaction when trivial move is enabled.
+// This comparator is used for the construction of min heap
+// based on the smallest key of the file.
+struct UserKeyComparator {
+  explicit UserKeyComparator(const Comparator* ucmp) { ucmp_ = ucmp; }
+
+  bool operator()(InputFileInfo i1, InputFileInfo i2) const {
+    return (ucmp_->Compare(i1.f->smallest.user_key(),
+                           i2.f->smallest.user_key()) > 0);
+  }
+
+ private:
+  const Comparator* ucmp_;
+};
+
+typedef std::priority_queue<InputFileInfo, std::vector<InputFileInfo>,
+                            UserKeyComparator> SmallestKeyHeap;
+
+// This function creates the heap that is used to find if the files are
+// overlapping during universal compaction when the allow_trivial_move
+// is set.
+SmallestKeyHeap create_level_heap(Compaction* c, const Comparator* ucmp) {
+  SmallestKeyHeap smallest_key_priority_q =
+      SmallestKeyHeap(UserKeyComparator(ucmp));
+
+  InputFileInfo input_file;
+
+  for (unsigned int l = 0; l < c->num_input_levels(); l++) {
+    if (c->num_input_files(l) != 0) {
+      if (l == 0 && c->start_level() == 0) {
+        for (size_t i = 0; i < c->num_input_files(0); i++) {
+          input_file.f = c->input(0, i);
+          input_file.level = 0;
+          input_file.index = i;
+          smallest_key_priority_q.push(std::move(input_file));
+        }
+      } else {
+        input_file.f = c->input(l, 0);
+        input_file.level = l;
+        input_file.index = 0;
+        smallest_key_priority_q.push(std::move(input_file));
+      }
+    }
+  }
+  return smallest_key_priority_q;
+}
+
 }  // anonymous namespace
 
 // Determine compression type, based on user options, level of the output
@@ -1106,6 +1165,50 @@ void GetSmallestLargestSeqno(const std::vector<FileMetaData*>& files,
 }  // namespace
 #endif
 
+// Algorithm that checks to see if there are any overlapping
+// files in the input
+bool CompactionPicker::IsInputNonOverlapping(Compaction* c) {
+  auto comparator = icmp_->user_comparator();
+  int first_iter = 1;
+
+  InputFileInfo prev, curr, next;
+
+  SmallestKeyHeap smallest_key_priority_q =
+      create_level_heap(c, icmp_->user_comparator());
+
+  while (!smallest_key_priority_q.empty()) {
+    curr = smallest_key_priority_q.top();
+    smallest_key_priority_q.pop();
+
+    if (first_iter) {
+      prev = curr;
+      first_iter = 0;
+    } else {
+      if (comparator->Compare(prev.f->largest.user_key(),
+                              curr.f->smallest.user_key()) >= 0) {
+        // found overlapping files, return false
+        return false;
+      }
+      assert(comparator->Compare(curr.f->largest.user_key(),
+                                 prev.f->largest.user_key()) > 0);
+      prev = curr;
+    }
+
+    next.f = nullptr;
+
+    if (curr.level != 0 && curr.index < c->num_input_files(curr.level) - 1) {
+      next.f = c->input(curr.level, curr.index + 1);
+      next.level = curr.level;
+      next.index = curr.index + 1;
+    }
+
+    if (next.f) {
+      smallest_key_priority_q.push(std::move(next));
+    }
+  }
+  return true;
+}
+
 // Universal style of compaction. Pick files that are contiguous in
 // time-range to compact.
 //
@@ -1168,6 +1271,10 @@ Compaction* UniversalCompactionPicker::PickCompaction(
     return nullptr;
   }
 
+  if (ioptions_.compaction_options_universal.allow_trivial_move == true) {
+    c->set_is_trivial_move(IsInputNonOverlapping(c));
+  }
+
 // validate that all the chosen files of L0 are non overlapping in time
 #ifndef NDEBUG
   SequenceNumber prev_smallest_seqno = 0U;

db/compaction_picker.h

@@ -105,6 +105,12 @@ class CompactionPicker {
       const VersionStorageInfo* vstorage,
       const CompactionOptions& compact_options) const;
 
+  // Used in universal compaction when the enabled_trivial_move
+  // option is set. Checks whether there are any overlapping files
+  // in the input. Returns true if the input files are non
+  // overlapping.
+  bool IsInputNonOverlapping(Compaction* c);
+
  protected:
   int NumberLevels() const { return ioptions_.num_levels; }
 

db/compaction_picker_test.cc

@@ -77,6 +77,8 @@ class CompactionPickerTest : public testing::Test {
     f->fd = FileDescriptor(file_number, path_id, file_size);
     f->smallest = InternalKey(smallest, smallest_seq, kTypeValue);
     f->largest = InternalKey(largest, largest_seq, kTypeValue);
+    f->smallest_seqno = smallest_seq;
+    f->largest_seqno = largest_seq;
     f->compensated_file_size = file_size;
     f->refs = 0;
     vstorage_->AddFile(level, f);
@@ -365,6 +367,64 @@ TEST_F(CompactionPickerTest, NeedsCompactionUniversal) {
               vstorage_->CompactionScore(0) >= 1);
   }
 }
+// Tests if the files can be trivially moved in multi level
+// universal compaction when allow_trivial_move option is set
+// In this test as the input files overlaps, they cannot
+// be trivially moved.
+
+TEST_F(CompactionPickerTest, CannotTrivialMoveUniversal) {
+  const uint64_t kFileSize = 100000;
+
+  ioptions_.compaction_options_universal.allow_trivial_move = true;
+  NewVersionStorage(1, kCompactionStyleUniversal);
+  UniversalCompactionPicker universal_compaction_picker(ioptions_, &icmp_);
+  // must return false when there's no files.
+  ASSERT_EQ(universal_compaction_picker.NeedsCompaction(vstorage_.get()),
+            false);
+
+  NewVersionStorage(3, kCompactionStyleUniversal);
+
+  Add(0, 1U, "150", "200", kFileSize, 0, 500, 550);
+  Add(0, 2U, "201", "250", kFileSize, 0, 401, 450);
+  Add(0, 4U, "260", "300", kFileSize, 0, 260, 300);
+  Add(1, 5U, "100", "151", kFileSize, 0, 200, 251);
+  Add(1, 3U, "301", "350", kFileSize, 0, 101, 150);
+  Add(2, 6U, "120", "200", kFileSize, 0, 20, 100);
+
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(
+      universal_compaction_picker.PickCompaction(
+          cf_name_, mutable_cf_options_, vstorage_.get(), &log_buffer_));
+
+  ASSERT_TRUE(!compaction->is_trivial_move());
+}
+// Tests if the files can be trivially moved in multi level
+// universal compaction when allow_trivial_move option is set
+// In this test as the input files doesn't overlaps, they should
+// be trivially moved.
+TEST_F(CompactionPickerTest, AllowsTrivialMoveUniversal) {
+  const uint64_t kFileSize = 100000;
+
+  ioptions_.compaction_options_universal.allow_trivial_move = true;
+  UniversalCompactionPicker universal_compaction_picker(ioptions_, &icmp_);
+
+  NewVersionStorage(3, kCompactionStyleUniversal);
+
+  Add(0, 1U, "150", "200", kFileSize, 0, 500, 550);
+  Add(0, 2U, "201", "250", kFileSize, 0, 401, 450);
+  Add(0, 4U, "260", "300", kFileSize, 0, 260, 300);
+  Add(1, 5U, "010", "080", kFileSize, 0, 200, 251);
+  Add(2, 3U, "301", "350", kFileSize, 0, 101, 150);
+
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(
+      universal_compaction_picker.PickCompaction(
+          cf_name_, mutable_cf_options_, vstorage_.get(), &log_buffer_));
+
+  ASSERT_TRUE(compaction->is_trivial_move());
+}
 
 TEST_F(CompactionPickerTest, NeedsCompactionFIFO) {
   NewVersionStorage(1, kCompactionStyleFIFO);

db/db_impl.cc

@@ -2538,8 +2538,12 @@ Status DBImpl::BackgroundCompaction(bool* madeProgress, JobContext* job_context,
     // Move files to next level
     int32_t moved_files = 0;
     int64_t moved_bytes = 0;
-    for (size_t i = 0; i < c->num_input_files(0); i++) {
-      FileMetaData* f = c->input(0, i);
+    for (unsigned int l = 0; l < c->num_input_levels(); l++) {
+      if (l == static_cast<unsigned int>(c->output_level())) {
+        continue;
+      }
+      for (size_t i = 0; i < c->num_input_files(l); i++) {
+        FileMetaData* f = c->input(l, i);
         c->edit()->DeleteFile(c->level(), f->fd.GetNumber());
         c->edit()->AddFile(c->output_level(), f->fd.GetNumber(),
                            f->fd.GetPathId(), f->fd.GetFileSize(), f->smallest,
@@ -2548,11 +2552,13 @@ Status DBImpl::BackgroundCompaction(bool* madeProgress, JobContext* job_context,
 
         LogToBuffer(log_buffer,
                     "[%s] Moving #%" PRIu64 " to level-%d %" PRIu64 " bytes\n",
-                  c->column_family_data()->GetName().c_str(), f->fd.GetNumber(),
-                  c->output_level(), f->fd.GetFileSize());
+                    c->column_family_data()->GetName().c_str(),
+                    f->fd.GetNumber(), c->output_level(), f->fd.GetFileSize());
         ++moved_files;
         moved_bytes += f->fd.GetFileSize();
       }
+    }
+
     status = versions_->LogAndApply(c->column_family_data(),
                                     *c->mutable_cf_options(), c->edit(),
                                     &mutex_, directories_.GetDbDir());

db/db_test.cc

@@ -4528,7 +4528,50 @@ TEST_P(DBTestUniversalCompactionMultiLevels, UniversalCompactionMultiLevels) {
     ASSERT_EQ(Get(1, Key(i % num_keys)), Key(i));
   }
 }
+// Tests universal compaction with trivial move enabled
+TEST_P(DBTestUniversalCompactionMultiLevels, UniversalCompactionTrivialMove) {
+  int32_t trivial_move = 0;
+  int32_t non_trivial_move = 0;
+  rocksdb::SyncPoint::GetInstance()->SetCallBack(
+      "DBImpl::BackgroundCompaction:TrivialMove",
+      [&](void* arg) { trivial_move++; });
+  rocksdb::SyncPoint::GetInstance()->SetCallBack(
+      "DBImpl::BackgroundCompaction:NonTrivial",
+      [&](void* arg) { non_trivial_move++; });
+  rocksdb::SyncPoint::GetInstance()->EnableProcessing();
 
+  Options options;
+  options.compaction_style = kCompactionStyleUniversal;
+  options.compaction_options_universal.allow_trivial_move = true;
+  options.num_levels = 3;
+  options.write_buffer_size = 100 << 10;  // 100KB
+  options.level0_file_num_compaction_trigger = 3;
+  options.max_background_compactions = 1;
+  options.target_file_size_base = 32 * 1024;
+  options = CurrentOptions(options);
+  DestroyAndReopen(options);
+  CreateAndReopenWithCF({"pikachu"}, options);
+
+  // Trigger compaction if size amplification exceeds 110%
+  options.compaction_options_universal.max_size_amplification_percent = 110;
+  options = CurrentOptions(options);
+  ReopenWithColumnFamilies({"default", "pikachu"}, options);
+
+  Random rnd(301);
+  int num_keys = 15000;
+  for (int i = 0; i < num_keys; i++) {
+    ASSERT_OK(Put(1, Key(i), Key(i)));
+  }
+  std::vector<std::string> values;
+
+  ASSERT_OK(Flush(1));
+  dbfull()->TEST_WaitForCompact();
+
+  ASSERT_GT(trivial_move, 0);
+  ASSERT_EQ(non_trivial_move, 0);
+
+  rocksdb::SyncPoint::GetInstance()->DisableProcessing();
+}
 INSTANTIATE_TEST_CASE_P(DBTestUniversalCompactionMultiLevels,
                         DBTestUniversalCompactionMultiLevels,
                         ::testing::Values(3, 20));

include/rocksdb/universal_compaction.h

@@ -69,6 +69,11 @@ class CompactionOptionsUniversal {
   // Default: kCompactionStopStyleTotalSize
   CompactionStopStyle stop_style;
 
+  // Option to optimize the universal multi level compaction by enabling
+  // trivial move for non overlapping files.
+  // Default: false
+  bool allow_trivial_move;
+
   // Default set of parameters
   CompactionOptionsUniversal()
       : size_ratio(1),
@@ -76,7 +81,8 @@ class CompactionOptionsUniversal {
         max_merge_width(UINT_MAX),
         max_size_amplification_percent(200),
         compression_size_percent(-1),
-        stop_style(kCompactionStopStyleTotalSize) {}
+        stop_style(kCompactionStopStyleTotalSize),
+        allow_trivial_move(false) {}
 };
 
 }  // namespace rocksdb