Pin top-level index on partitioned index/filter blocks (facebook#4037)

Summary:
Top-level index in partitioned index/filter blocks are small and could be pinned in memory. So far we use that by cache_index_and_filter_blocks to false. This however make it difficult to keep account of the total memory usage. This patch introduces pin_top_level_index_and_filter which in combination with cache_index_and_filter_blocks=true keeps the top-level index in cache and yet pinned them to avoid cache misses and also cache lookup overhead.
Closes facebook#4037

Differential Revision: D8596218

Pulled By: maysamyabandeh

fbshipit-source-id: 3a5f7f9ca6b4b525b03ff6bd82354881ae974ad2

HISTORY.md

@@ -7,6 +7,7 @@
 ### New Features
 * Changes the format of index blocks by storing the key in their raw form rather than converting them to InternalKey. This saves 8 bytes per index key. The feature is backward compatbile but not forward compatible. It is disabled by default unless format_version 3 or above is used.
 * Improve the performance of iterators doing long range scans by using readahead, when using direct IO.
+* pin_top_level_index_and_filter (default true) in BlockBasedTableOptions can be used in combination with cache_index_and_filter_blocks to prefetch and pin the top-level index of partitioned index and filter blocks in cache. It has no impact when cache_index_and_filter_blocks is false.
 
 ### Bug Fixes
 * fix deadlock with enable_pipelined_write=true and max_successive_merges > 0

db/c.cc

@@ -1985,6 +1985,11 @@ void rocksdb_block_based_options_set_pin_l0_filter_and_index_blocks_in_cache(
   options->rep.pin_l0_filter_and_index_blocks_in_cache = v;
 }
 
+void rocksdb_block_based_options_set_pin_top_level_index_and_filter(
+    rocksdb_block_based_table_options_t* options, unsigned char v) {
+  options->rep.pin_top_level_index_and_filter = v;
+}
+
 void rocksdb_options_set_block_based_table_factory(
     rocksdb_options_t *opt,
     rocksdb_block_based_table_options_t* table_options) {

examples/rocksdb_option_file_example.ini

@@ -138,6 +138,7 @@
   block_restart_interval=16
   cache_index_and_filter_blocks=false
   pin_l0_filter_and_index_blocks_in_cache=false
+  pin_top_level_index_and_filter=false
   index_type=kBinarySearch
   hash_index_allow_collision=true
   flush_block_policy_factory=FlushBlockBySizePolicyFactory

include/rocksdb/c.h

@@ -700,6 +700,9 @@ rocksdb_block_based_options_set_cache_index_and_filter_blocks_with_high_priority
 extern ROCKSDB_LIBRARY_API void
 rocksdb_block_based_options_set_pin_l0_filter_and_index_blocks_in_cache(
     rocksdb_block_based_table_options_t*, unsigned char);
+extern ROCKSDB_LIBRARY_API void
+rocksdb_block_based_options_set_pin_top_level_index_and_filter(
+    rocksdb_block_based_table_options_t*, unsigned char);
 extern ROCKSDB_LIBRARY_API void rocksdb_options_set_block_based_table_factory(
     rocksdb_options_t* opt, rocksdb_block_based_table_options_t* table_options);
 

include/rocksdb/table.h

@@ -77,6 +77,13 @@ struct BlockBasedTableOptions {
   // evicted from cache when the table reader is freed.
   bool pin_l0_filter_and_index_blocks_in_cache = false;
 
+  // If cache_index_and_filter_blocks is true and the below is true, then
+  // the top-level index of partitioned filter and index blocks are stored in
+  // the cache, but a reference is held in the "table reader" object so the
+  // blocks are pinned and only evicted from cache when the table reader is
+  // freed. This is not limited to l0 in LSM tree.
+  bool pin_top_level_index_and_filter = true;
+
   // The index type that will be used for this table.
   enum IndexType : char {
     // A space efficient index block that is optimized for

options/options_settable_test.cc

@@ -140,6 +140,7 @@ TEST_F(OptionsSettableTest, BlockBasedTableOptionsAllFieldsSettable) {
       "cache_index_and_filter_blocks=1;"
       "cache_index_and_filter_blocks_with_high_priority=true;"
       "pin_l0_filter_and_index_blocks_in_cache=1;"
+      "pin_top_level_index_and_filter=1;"
       "index_type=kHashSearch;"
       "checksum=kxxHash;hash_index_allow_collision=1;no_block_cache=1;"
       "block_cache=1M;block_cache_compressed=1k;block_size=1024;"

table/block_based_table_factory.cc

@@ -151,6 +151,9 @@ std::string BlockBasedTableFactory::GetPrintableTableOptions() const {
            "  pin_l0_filter_and_index_blocks_in_cache: %d\n",
            table_options_.pin_l0_filter_and_index_blocks_in_cache);
   ret.append(buffer);
+  snprintf(buffer, kBufferSize, "  pin_top_level_index_and_filter: %d\n",
+           table_options_.pin_top_level_index_and_filter);
+  ret.append(buffer);
   snprintf(buffer, kBufferSize, "  index_type: %d\n",
            table_options_.index_type);
   ret.append(buffer);

table/block_based_table_factory.h

@@ -158,6 +158,10 @@ static std::unordered_map<std::string, OptionTypeInfo>
           OptionType::kBoolean, OptionVerificationType::kNormal, false, 0}},
         {"block_align",
          {offsetof(struct BlockBasedTableOptions, block_align),
+          OptionType::kBoolean, OptionVerificationType::kNormal, false, 0}},
+        {"pin_top_level_index_and_filter",
+         {offsetof(struct BlockBasedTableOptions,
+                   pin_top_level_index_and_filter),
           OptionType::kBoolean, OptionVerificationType::kNormal, false, 0}}};
 #endif  // !ROCKSDB_LITE
 }  // namespace rocksdb

table/block_based_table_reader.cc

@@ -898,17 +898,39 @@ Status BlockBasedTable::Open(const ImmutableCFOptions& ioptions,
                                                 rep->ioptions.info_log);
   }
 
-  const bool pin =
+  // prefetch both index and filters, down to all partitions
+  const bool prefetch_all = prefetch_index_and_filter_in_cache || level == 0;
+  BlockBasedTableOptions::IndexType index_type = new_table->UpdateIndexType();
+  // prefetch the first level of index
+  const bool prefetch_index =
+      prefetch_all ||
+      (table_options.pin_top_level_index_and_filter &&
+       index_type == BlockBasedTableOptions::kTwoLevelIndexSearch);
+  // prefetch the first level of filter
+  const bool prefetch_filter =
+      prefetch_all || (table_options.pin_top_level_index_and_filter &&
+                       rep->filter_type == Rep::FilterType::kPartitionedFilter);
+  // Partition fitlers cannot be enabled without partition indexes
+  assert(!prefetch_index || prefetch_filter);
+  // pin both index and filters, down to all partitions
+  const bool pin_all =
       rep->table_options.pin_l0_filter_and_index_blocks_in_cache && level == 0;
+  // pin the first level of index
+  const bool pin_index =
+      pin_all || (table_options.pin_top_level_index_and_filter &&
+                  index_type == BlockBasedTableOptions::kTwoLevelIndexSearch);
+  // pin the first level of filter
+  const bool pin_filter =
+      pin_all || (table_options.pin_top_level_index_and_filter &&
+                  rep->filter_type == Rep::FilterType::kPartitionedFilter);
   // pre-fetching of blocks is turned on
   // Will use block cache for index/filter blocks access
   // Always prefetch index and filter for level 0
   if (table_options.cache_index_and_filter_blocks) {
-    if (prefetch_index_and_filter_in_cache || level == 0) {
-      assert(table_options.block_cache != nullptr);
+    assert(table_options.block_cache != nullptr);
+    if (prefetch_index) {
       // Hack: Call NewIndexIterator() to implicitly add index to the
       // block_cache
-
       CachableEntry<IndexReader> index_entry;
       bool prefix_extractor_changed = false;
       // check prefix_extractor match only if hash based index is used
@@ -924,27 +946,29 @@ Status BlockBasedTable::Open(const ImmutableCFOptions& ioptions,
         // On success it should give us ownership of the `CachableEntry` by
         // populating `index_entry`.
         assert(index_entry.value != nullptr);
-        index_entry.value->CacheDependencies(pin);
-        if (pin) {
+        if (prefetch_all) {
+          index_entry.value->CacheDependencies(pin_all);
+        }
+        if (pin_index) {
           rep->index_entry = std::move(index_entry);
         } else {
           index_entry.Release(table_options.block_cache.get());
         }
-
-        // Hack: Call GetFilter() to implicitly add filter to the block_cache
-        auto filter_entry = new_table->GetFilter(prefix_extractor);
-        if (filter_entry.value != nullptr) {
-          filter_entry.value->CacheDependencies(pin, prefix_extractor);
-        }
-        // if pin_l0_filter_and_index_blocks_in_cache is true, and this is
-        // a level0 file, then save it in rep_->filter_entry; it will be
-        // released in the destructor only, hence it will be pinned in the
-        // cache while this reader is alive
-        if (pin) {
-          rep->filter_entry = filter_entry;
-        } else {
-          filter_entry.Release(table_options.block_cache.get());
-        }
+      }
+    }
+    if (s.ok() && prefetch_filter) {
+      // Hack: Call GetFilter() to implicitly add filter to the block_cache
+      auto filter_entry = new_table->GetFilter(prefix_extractor);
+      if (filter_entry.value != nullptr && prefetch_all) {
+        filter_entry.value->CacheDependencies(pin_all, prefix_extractor);
+      }
+      // if pin_filter is true then save it in rep_->filter_entry; it will be
+      // released in the destructor only, hence it will be pinned in the
+      // cache while this reader is alive
+      if (pin_filter) {
+        rep->filter_entry = filter_entry;
+      } else {
+        filter_entry.Release(table_options.block_cache.get());
       }
     }
   } else {
@@ -960,7 +984,7 @@ Status BlockBasedTable::Open(const ImmutableCFOptions& ioptions,
       // are hence follow the configuration for pin and prefetch regardless of
       // the value of cache_index_and_filter_blocks
       if (prefetch_index_and_filter_in_cache || level == 0) {
-        rep->index_reader->CacheDependencies(pin);
+        rep->index_reader->CacheDependencies(pin_all);
       }
 
       // Set filter block
@@ -973,7 +997,7 @@ Status BlockBasedTable::Open(const ImmutableCFOptions& ioptions,
         // Refer to the comment above about paritioned indexes always being
         // cached
         if (filter && (prefetch_index_and_filter_in_cache || level == 0)) {
-          filter->CacheDependencies(pin, prefix_extractor);
+          filter->CacheDependencies(pin_all, prefix_extractor);
         }
       }
     } else {
@@ -2419,18 +2443,11 @@ bool BlockBasedTable::TEST_KeyInCache(const ReadOptions& options,
   return in_cache;
 }
 
-// REQUIRES: The following fields of rep_ should have already been populated:
-//  1. file
-//  2. index_handle,
-//  3. options
-//  4. internal_comparator
-//  5. index_type
-Status BlockBasedTable::CreateIndexReader(
-    FilePrefetchBuffer* prefetch_buffer, IndexReader** index_reader,
-    InternalIterator* preloaded_meta_index_iter, int level) {
+BlockBasedTableOptions::IndexType BlockBasedTable::UpdateIndexType() {
   // Some old version of block-based tables don't have index type present in
   // table properties. If that's the case we can safely use the kBinarySearch.
-  auto index_type_on_file = BlockBasedTableOptions::kBinarySearch;
+  BlockBasedTableOptions::IndexType index_type_on_file =
+      BlockBasedTableOptions::kBinarySearch;
   if (rep_->table_properties) {
     auto& props = rep_->table_properties->user_collected_properties;
     auto pos = props.find(BlockBasedTablePropertyNames::kIndexType);
@@ -2441,6 +2458,19 @@ Status BlockBasedTable::CreateIndexReader(
       rep_->index_type = index_type_on_file;
     }
   }
+  return index_type_on_file;
+}
+
+// REQUIRES: The following fields of rep_ should have already been populated:
+//  1. file
+//  2. index_handle,
+//  3. options
+//  4. internal_comparator
+//  5. index_type
+Status BlockBasedTable::CreateIndexReader(
+    FilePrefetchBuffer* prefetch_buffer, IndexReader** index_reader,
+    InternalIterator* preloaded_meta_index_iter, int level) {
+  auto index_type_on_file = UpdateIndexType();
 
   auto file = rep_->file.get();
   const InternalKeyComparator* icomparator = &rep_->internal_comparator;

table/block_based_table_reader.h

@@ -322,6 +322,9 @@ class BlockBasedTable : public TableReader {
 
   void ReadMeta(const Footer& footer);
 
+  // Figure the index type, update it in rep_, and also return it.
+  BlockBasedTableOptions::IndexType UpdateIndexType();
+
   // Create a index reader based on the index type stored in the table.
   // Optionally, user can pass a preloaded meta_index_iter for the index that
   // need to access extra meta blocks for index construction. This parameter
@@ -478,11 +481,12 @@ struct BlockBasedTable::Rep {
   // block to extract prefix without knowing if a key is internal or not.
   unique_ptr<SliceTransform> internal_prefix_transform;
 
-  // only used in level 0 files:
-  // when pin_l0_filter_and_index_blocks_in_cache is true, we do use the
-  // LRU cache, but we always keep the filter & idndex block's handle checked
-  // out here (=we don't call Release()), plus the parsed out objects
-  // the LRU cache will never push flush them out, hence they're pinned
+  // only used in level 0 files when pin_l0_filter_and_index_blocks_in_cache is
+  // true or in all levels when pin_top_level_index_and_filter is set in
+  // combination with partitioned index/filters: then we do use the LRU cache,
+  // but we always keep the filter & index block's handle checked out here (=we
+  // don't call Release()), plus the parsed out objects the LRU cache will never
+  // push flush them out, hence they're pinned
   CachableEntry<FilterBlockReader> filter_entry;
   CachableEntry<IndexReader> index_entry;
   // range deletion meta-block is pinned through reader's lifetime when LRU

table/table_test.cc

@@ -2330,70 +2330,74 @@ TEST_P(BlockBasedTableTest, NoObjectInCacheAfterTableClose) {
         }
         for (bool index_and_filter_in_cache : {true, false}) {
           for (bool pin_l0 : {true, false}) {
-            if (pin_l0 && !index_and_filter_in_cache) {
-              continue;
-            }
-            // Create a table
-            Options opt;
-            unique_ptr<InternalKeyComparator> ikc;
-            ikc.reset(new test::PlainInternalKeyComparator(opt.comparator));
-            opt.compression = kNoCompression;
-            BlockBasedTableOptions table_options = GetBlockBasedTableOptions();
-            table_options.block_size = 1024;
-            table_options.index_type =
-                BlockBasedTableOptions::IndexType::kTwoLevelIndexSearch;
-            table_options.pin_l0_filter_and_index_blocks_in_cache = pin_l0;
-            table_options.partition_filters = partition_filter;
-            table_options.cache_index_and_filter_blocks =
-                index_and_filter_in_cache;
-            // big enough so we don't ever lose cached values.
-            table_options.block_cache = std::shared_ptr<rocksdb::Cache>(
-                new MockCache(16 * 1024 * 1024, 4, false, 0.0));
-            table_options.filter_policy.reset(
-                rocksdb::NewBloomFilterPolicy(10, block_based_filter));
-            opt.table_factory.reset(NewBlockBasedTableFactory(table_options));
-
-            bool convert_to_internal_key = false;
-            TableConstructor c(BytewiseComparator(), convert_to_internal_key,
-                               level);
-            std::string user_key = "k01";
-            std::string key =
-                InternalKey(user_key, 0, kTypeValue).Encode().ToString();
-            c.Add(key, "hello");
-            std::vector<std::string> keys;
-            stl_wrappers::KVMap kvmap;
-            const ImmutableCFOptions ioptions(opt);
-            const MutableCFOptions moptions(opt);
-            c.Finish(opt, ioptions, moptions, table_options, *ikc, &keys,
-                     &kvmap);
-
-            // Doing a read to make index/filter loaded into the cache
-            auto table_reader =
-                dynamic_cast<BlockBasedTable*>(c.GetTableReader());
-            PinnableSlice value;
-            GetContext get_context(opt.comparator, nullptr, nullptr, nullptr,
-                                   GetContext::kNotFound, user_key, &value,
-                                   nullptr, nullptr, nullptr, nullptr);
-            InternalKey ikey(user_key, 0, kTypeValue);
-            auto s = table_reader->Get(ReadOptions(), key, &get_context,
-                                       moptions.prefix_extractor.get());
-            ASSERT_EQ(get_context.State(), GetContext::kFound);
-            ASSERT_STREQ(value.data(), "hello");
-
-            // Close the table
-            c.ResetTableReader();
-
-            auto usage = table_options.block_cache->GetUsage();
-            auto pinned_usage = table_options.block_cache->GetPinnedUsage();
-            // The only usage must be for marked data blocks
-            ASSERT_EQ(usage, MockCache::marked_size_);
-            // There must be some pinned data since PinnableSlice has not
-            // released them yet
-            ASSERT_GT(pinned_usage, 0);
-            // Release pinnable slice reousrces
-            value.Reset();
-            pinned_usage = table_options.block_cache->GetPinnedUsage();
-            ASSERT_EQ(pinned_usage, 0);
+            for (bool pin_top_level : {true, false}) {
+              if (pin_l0 && !index_and_filter_in_cache) {
+                continue;
+              }
+              // Create a table
+              Options opt;
+              unique_ptr<InternalKeyComparator> ikc;
+              ikc.reset(new test::PlainInternalKeyComparator(opt.comparator));
+              opt.compression = kNoCompression;
+              BlockBasedTableOptions table_options =
+                  GetBlockBasedTableOptions();
+              table_options.block_size = 1024;
+              table_options.index_type =
+                  BlockBasedTableOptions::IndexType::kTwoLevelIndexSearch;
+              table_options.pin_l0_filter_and_index_blocks_in_cache = pin_l0;
+              table_options.pin_top_level_index_and_filter = pin_top_level;
+              table_options.partition_filters = partition_filter;
+              table_options.cache_index_and_filter_blocks =
+                  index_and_filter_in_cache;
+              // big enough so we don't ever lose cached values.
+              table_options.block_cache = std::shared_ptr<rocksdb::Cache>(
+                  new MockCache(16 * 1024 * 1024, 4, false, 0.0));
+              table_options.filter_policy.reset(
+                  rocksdb::NewBloomFilterPolicy(10, block_based_filter));
+              opt.table_factory.reset(NewBlockBasedTableFactory(table_options));
+
+              bool convert_to_internal_key = false;
+              TableConstructor c(BytewiseComparator(), convert_to_internal_key,
+                                 level);
+              std::string user_key = "k01";
+              std::string key =
+                  InternalKey(user_key, 0, kTypeValue).Encode().ToString();
+              c.Add(key, "hello");
+              std::vector<std::string> keys;
+              stl_wrappers::KVMap kvmap;
+              const ImmutableCFOptions ioptions(opt);
+              const MutableCFOptions moptions(opt);
+              c.Finish(opt, ioptions, moptions, table_options, *ikc, &keys,
+                       &kvmap);
+
+              // Doing a read to make index/filter loaded into the cache
+              auto table_reader =
+                  dynamic_cast<BlockBasedTable*>(c.GetTableReader());
+              PinnableSlice value;
+              GetContext get_context(opt.comparator, nullptr, nullptr, nullptr,
+                                     GetContext::kNotFound, user_key, &value,
+                                     nullptr, nullptr, nullptr, nullptr);
+              InternalKey ikey(user_key, 0, kTypeValue);
+              auto s = table_reader->Get(ReadOptions(), key, &get_context,
+                                         moptions.prefix_extractor.get());
+              ASSERT_EQ(get_context.State(), GetContext::kFound);
+              ASSERT_STREQ(value.data(), "hello");
+
+              // Close the table
+              c.ResetTableReader();
+
+              auto usage = table_options.block_cache->GetUsage();
+              auto pinned_usage = table_options.block_cache->GetPinnedUsage();
+              // The only usage must be for marked data blocks
+              ASSERT_EQ(usage, MockCache::marked_size_);
+              // There must be some pinned data since PinnableSlice has not
+              // released them yet
+              ASSERT_GT(pinned_usage, 0);
+              // Release pinnable slice reousrces
+              value.Reset();
+              pinned_usage = table_options.block_cache->GetPinnedUsage();
+              ASSERT_EQ(pinned_usage, 0);
+          }
           }
         }
       }