Delete files in multiple ranges at once

Summary:
Using `DeleteFilesInRange` to delete files in a lot of ranges can be slow, because
`VersionSet::LogAndApply` is expensive.

This PR adds a new `DeleteFilesInRange` function to delete files in multiple
ranges at once.

Close https://github.com/facebook/rocksdb/issues/2951
Closes https://github.com/facebook/rocksdb/pull/3431

Differential Revision: D6849228

Pulled By: ajkr

fbshipit-source-id: daeedcabd8def4b1d9ee95a58266dee77b5d68cb

HISTORY.md

@@ -2,9 +2,11 @@
 ## Unreleased
 ### Public API Change
 * Iterator::SeekForPrev is now a pure virtual method. This is to prevent user who implement the Iterator interface fail to implement SeekForPrev by mistake.
+- Add `include_end` option to make the range end exclusive when `include_end == false` in `DeleteFilesInRange()`.
 
 ### New Features
 * Improve the performance of iterators doing long range scans by using readahead.
+- Add new function `DeleteFilesInRanges()` to delete files in multiple ranges at once for better performance.
 
 ### Bug Fixes
 * Fix `DisableFileDeletions()` followed by `GetSortedWalFiles()` to not return obsolete WAL files that `PurgeObsoleteFiles()` is going to delete.

db/convenience.cc

@@ -19,9 +19,17 @@ void CancelAllBackgroundWork(DB* db, bool wait) {
 }
 
 Status DeleteFilesInRange(DB* db, ColumnFamilyHandle* column_family,
-                          const Slice* begin, const Slice* end) {
+                          const Slice* begin, const Slice* end,
+                          bool include_end) {
+  RangePtr range(begin, end);
+  return DeleteFilesInRanges(db, column_family, &range, 1, include_end);
+}
+
+Status DeleteFilesInRanges(DB* db, ColumnFamilyHandle* column_family,
+                           const RangePtr* ranges, size_t n,
+                           bool include_end) {
   return (static_cast_with_check<DBImpl, DB>(db->GetRootDB()))
-      ->DeleteFilesInRange(column_family, begin, end);
+      ->DeleteFilesInRanges(column_family, ranges, n, include_end);
 }
 
 Status VerifySstFileChecksum(const Options& options,

db/db_compaction_test.cc

@@ -1517,6 +1517,122 @@ TEST_F(DBCompactionTest, DeleteFileRange) {
   ASSERT_GT(old_num_files, new_num_files);
 }
 
+TEST_F(DBCompactionTest, DeleteFilesInRanges) {
+  Options options = CurrentOptions();
+  options.write_buffer_size = 10 * 1024 * 1024;
+  options.max_bytes_for_level_multiplier = 2;
+  options.num_levels = 4;
+  options.max_background_compactions = 3;
+  options.disable_auto_compactions = true;
+
+  DestroyAndReopen(options);
+  int32_t value_size = 10 * 1024;  // 10 KB
+
+  Random rnd(301);
+  std::map<int32_t, std::string> values;
+
+  // file [0 => 100), [100 => 200), ... [900, 1000)
+  for (auto i = 0; i < 10; i++) {
+    for (auto j = 0; j < 100; j++) {
+      auto k = i * 100 + j;
+      values[k] = RandomString(&rnd, value_size);
+      ASSERT_OK(Put(Key(k), values[k]));
+    }
+    ASSERT_OK(Flush());
+  }
+  ASSERT_EQ("10", FilesPerLevel(0));
+  CompactRangeOptions compact_options;
+  compact_options.change_level = true;
+  compact_options.target_level = 2;
+  ASSERT_OK(db_->CompactRange(compact_options, nullptr, nullptr));
+  ASSERT_EQ("0,0,10", FilesPerLevel(0));
+
+  // file [0 => 100), [200 => 300), ... [800, 900)
+  for (auto i = 0; i < 10; i+=2) {
+    for (auto j = 0; j < 100; j++) {
+      auto k = i * 100 + j;
+      ASSERT_OK(Put(Key(k), values[k]));
+    }
+    ASSERT_OK(Flush());
+  }
+  ASSERT_EQ("5,0,10", FilesPerLevel(0));
+  ASSERT_OK(dbfull()->TEST_CompactRange(0, nullptr, nullptr));
+  ASSERT_EQ("0,5,10", FilesPerLevel(0));
+
+  // Delete files in range [0, 299] (inclusive)
+  {
+    auto begin_str1 = Key(0), end_str1 = Key(100);
+    auto begin_str2 = Key(100), end_str2 = Key(200);
+    auto begin_str3 = Key(200), end_str3 = Key(299);
+    Slice begin1(begin_str1), end1(end_str1);
+    Slice begin2(begin_str2), end2(end_str2);
+    Slice begin3(begin_str3), end3(end_str3);
+    std::vector<RangePtr> ranges;
+    ranges.push_back(RangePtr(&begin1, &end1));
+    ranges.push_back(RangePtr(&begin2, &end2));
+    ranges.push_back(RangePtr(&begin3, &end3));
+    ASSERT_OK(DeleteFilesInRanges(db_, db_->DefaultColumnFamily(),
+                                  ranges.data(), ranges.size()));
+    ASSERT_EQ("0,3,7", FilesPerLevel(0));
+
+    // Keys [0, 300) should not exist.
+    for (auto i = 0; i < 300; i++) {
+      ReadOptions ropts;
+      std::string result;
+      auto s = db_->Get(ropts, Key(i), &result);
+      ASSERT_TRUE(s.IsNotFound());
+    }
+    for (auto i = 300; i < 1000; i++) {
+      ASSERT_EQ(Get(Key(i)), values[i]);
+    }
+  }
+
+  // Delete files in range [600, 999) (exclusive)
+  {
+    auto begin_str1 = Key(600), end_str1 = Key(800);
+    auto begin_str2 = Key(700), end_str2 = Key(900);
+    auto begin_str3 = Key(800), end_str3 = Key(999);
+    Slice begin1(begin_str1), end1(end_str1);
+    Slice begin2(begin_str2), end2(end_str2);
+    Slice begin3(begin_str3), end3(end_str3);
+    std::vector<RangePtr> ranges;
+    ranges.push_back(RangePtr(&begin1, &end1));
+    ranges.push_back(RangePtr(&begin2, &end2));
+    ranges.push_back(RangePtr(&begin3, &end3));
+    ASSERT_OK(DeleteFilesInRanges(db_, db_->DefaultColumnFamily(),
+                                  ranges.data(), ranges.size(), false));
+    ASSERT_EQ("0,1,4", FilesPerLevel(0));
+
+    // Keys [600, 900) should not exist.
+    for (auto i = 600; i < 900; i++) {
+      ReadOptions ropts;
+      std::string result;
+      auto s = db_->Get(ropts, Key(i), &result);
+      ASSERT_TRUE(s.IsNotFound());
+    }
+    for (auto i = 300; i < 600; i++) {
+      ASSERT_EQ(Get(Key(i)), values[i]);
+    }
+    for (auto i = 900; i < 1000; i++) {
+      ASSERT_EQ(Get(Key(i)), values[i]);
+    }
+  }
+
+  // Delete all files.
+  {
+    RangePtr range;
+    ASSERT_OK(DeleteFilesInRanges(db_, db_->DefaultColumnFamily(), &range, 1));
+    ASSERT_EQ("", FilesPerLevel(0));
+
+    for (auto i = 0; i < 1000; i++) {
+      ReadOptions ropts;
+      std::string result;
+      auto s = db_->Get(ropts, Key(i), &result);
+      ASSERT_TRUE(s.IsNotFound());
+    }
+  }
+}
+
 TEST_F(DBCompactionTest, DeleteFileRangeFileEndpointsOverlapBug) {
   // regression test for #2833: groups of files whose user-keys overlap at the
   // endpoints could be split by `DeleteFilesInRange`. This caused old data to

db/db_impl.cc

@@ -2138,19 +2138,22 @@ Status DBImpl::DeleteFile(std::string name) {
   return status;
 }
 
-Status DBImpl::DeleteFilesInRange(ColumnFamilyHandle* column_family,
-                                  const Slice* begin, const Slice* end) {
+Status DBImpl::DeleteFilesInRanges(ColumnFamilyHandle* column_family,
+                                   const RangePtr* ranges, size_t n,
+                                   bool include_end) {
   Status status;
   auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family);
   ColumnFamilyData* cfd = cfh->cfd();
   VersionEdit edit;
-  std::vector<FileMetaData*> deleted_files;
+  std::set<FileMetaData*> deleted_files;
   JobContext job_context(next_job_id_.fetch_add(1), true);
   {
     InstrumentedMutexLock l(&mutex_);
     Version* input_version = cfd->current();
 
     auto* vstorage = input_version->storage_info();
+    for (size_t r = 0; r < n; r++) {
+      auto begin = ranges[r].start, end = ranges[r].limit;
       for (int i = 1; i < cfd->NumberLevels(); i++) {
         if (vstorage->LevelFiles(i).empty() ||
             !vstorage->OverlapInLevel(i, begin, end)) {
@@ -2180,12 +2183,20 @@ Status DBImpl::DeleteFilesInRange(ColumnFamilyHandle* column_family,
           if (level_file->being_compacted) {
             continue;
           }
+          if (deleted_files.find(level_file) != deleted_files.end()) {
+            continue;
+          }
+          if (!include_end && end != nullptr &&
+              cfd->user_comparator()->Compare(level_file->largest.user_key(), *end) == 0) {
+            continue;
+          }
           edit.SetColumnFamily(cfd->GetID());
           edit.DeleteFile(i, level_file->fd.GetNumber());
-        deleted_files.push_back(level_file);
+          deleted_files.insert(level_file);
           level_file->being_compacted = true;
         }
       }
+    }
     if (edit.GetDeletedFiles().empty()) {
       job_context.Clean();
       return Status::OK();

db/db_impl.h

@@ -247,8 +247,9 @@ class DBImpl : public DB {
       const TransactionLogIterator::ReadOptions&
           read_options = TransactionLogIterator::ReadOptions()) override;
   virtual Status DeleteFile(std::string name) override;
-  Status DeleteFilesInRange(ColumnFamilyHandle* column_family,
-                            const Slice* begin, const Slice* end);
+  Status DeleteFilesInRanges(ColumnFamilyHandle* column_family,
+                             const RangePtr* ranges, size_t n,
+                             bool include_end = true);
 
   virtual void GetLiveFilesMetaData(
       std::vector<LiveFileMetaData>* metadata) override;

include/rocksdb/convenience.h

@@ -329,7 +329,15 @@ void CancelAllBackgroundWork(DB* db, bool wait = false);
 // in the range.
 // Snapshots before the delete might not see the data in the given range.
 Status DeleteFilesInRange(DB* db, ColumnFamilyHandle* column_family,
-                          const Slice* begin, const Slice* end);
+                          const Slice* begin, const Slice* end,
+                          bool include_end = true);
+
+// Delete files in multiple ranges at once
+// Delete files in a lot of ranges one at a time can be slow, use this API for
+// better performance in that case.
+Status DeleteFilesInRanges(DB* db, ColumnFamilyHandle* column_family,
+                           const RangePtr* ranges, size_t n,
+                           bool include_end = true);
 
 // Verify the checksum of file
 Status VerifySstFileChecksum(const Options& options,

include/rocksdb/db.h

@@ -100,6 +100,14 @@ struct Range {
   Range(const Slice& s, const Slice& l) : start(s), limit(l) { }
 };
 
+struct RangePtr {
+  const Slice* start;
+  const Slice* limit;
+
+  RangePtr() : start(nullptr), limit(nullptr) { }
+  RangePtr(const Slice* s, const Slice* l) : start(s), limit(l) { }
+};
+
 // A collections of table properties objects, where
 //  key: is the table's file name.
 //  value: the table properties object of the given table.