Revert "Add support for caching bloomfilters (#1204)"

This reverts commit 4676ca9.

Reading bloom filters from the cache leads to severe preformance
degradation.
Result of read bench tool
1. With bloom filters in cache
	Average read speed		: 97.37 KB/s
	Total bytes read in 1 minute	: 3.7 MB

2. With bloom filters stored in memory (no cache)
	Average read speed		: 41.3833 MB/s
	Total bytes read in 1 minute	: 2.4 GB

Author: Ibrahim Jarif

table/builder_test.go

@@ -57,7 +57,7 @@ func TestTableIndex(t *testing.T) {
 		keysCount := 10000
 		for _, opt := range opts {
 			builder := NewTableBuilder(opt)
-			filename := fmt.Sprintf("%s%c%d.sst", os.TempDir(), os.PathSeparator, rand.Uint32())
+			filename := fmt.Sprintf("%s%c%d.sst", os.TempDir(), os.PathSeparator, rand.Int63())
 			f, err := y.OpenSyncedFile(filename, true)
 			require.NoError(t, err)
 

table/table.go

@@ -18,7 +18,6 @@ package table
 
 import (
 	"crypto/aes"
-	"encoding/binary"
 	"fmt"
 	"io"
 	"math"
@@ -82,7 +81,7 @@ type TableInterface interface {
 	DoesNotHave(hash uint64) bool
 }
 
-// Table represents a loaded table file with the info we have about it.
+// Table represents a loaded table file with the info we have about it
 type Table struct {
 	sync.Mutex
 
@@ -98,11 +97,10 @@ type Table struct {
 	smallest, biggest []byte // Smallest and largest keys (with timestamps).
 	id                uint64 // file id, part of filename
 
+	bf       *z.Bloom
 	Checksum []byte
 	// Stores the total size of key-values stored in this table (including the size on vlog).
 	estimatedSize uint64
-	indexStart    int
-	indexLen      int
 
 	IsInmemory bool // Set to true if the table is on level 0 and opened in memory.
 	opt        *Options
@@ -148,13 +146,6 @@ func (t *Table) DecrRef() error {
 		if err := os.Remove(filename); err != nil {
 			return err
 		}
-		// Delete all blocks from the cache.
-		for i := range t.blockIndex {
-			t.opt.Cache.Del(t.blockCacheKey(i))
-		}
-		// Delete bloom filter from the cache.
-		t.opt.Cache.Del(t.bfCacheKey())
-
 	}
 	return nil
 }
@@ -345,12 +336,10 @@ func (t *Table) readIndex() error {
 	// Read index size from the footer.
 	readPos -= 4
 	buf = t.readNoFail(readPos, 4)
-	t.indexLen = int(y.BytesToU32(buf))
-
+	indexLen := int(y.BytesToU32(buf))
 	// Read index.
-	readPos -= t.indexLen
-	t.indexStart = readPos
-	data := t.readNoFail(readPos, t.indexLen)
+	readPos -= indexLen
+	data := t.readNoFail(readPos, indexLen)
 
 	if err := y.VerifyChecksum(data, expectedChk); err != nil {
 		return y.Wrapf(err, "failed to verify checksum for table: %s", t.Filename())
@@ -369,18 +358,11 @@ func (t *Table) readIndex() error {
 	y.Check(err)
 
 	t.estimatedSize = index.EstimatedSize
-	t.blockIndex = index.Offsets
-
-	// Avoid the cost of unmarshalling the bloom filters if the cache is absent.
-	if t.opt.Cache != nil {
-		var bf *z.Bloom
-		if bf, err = z.JSONUnmarshal(index.BloomFilter); err != nil {
-			return y.Wrapf(err, "failed to unmarshal bloom filter for the table %d in Table.readIndex",
-				t.id)
-		}
-
-		t.opt.Cache.Set(t.bfCacheKey(), bf, int64(len(index.BloomFilter)))
+	if t.bf, err = z.JSONUnmarshal(index.BloomFilter); err != nil {
+		return y.Wrapf(err, "failed to unmarshal bloom filter for the table %d in Table.readIndex",
+			t.id)
 	}
+	t.blockIndex = index.Offsets
 	return nil
 }
 
@@ -461,25 +443,10 @@ func (t *Table) block(idx int) (*block, error) {
 	return blk, nil
 }
 
-// bfCacheKey returns the cache key for bloom filter.
-func (t *Table) bfCacheKey() []byte {
-	y.AssertTrue(t.id < math.MaxUint32)
-	buf := make([]byte, 4)
-	binary.BigEndian.PutUint32(buf, uint32(t.id))
-
-	// Without the "bf" prefix, we will have conflict with the blockCacheKey.
-	return append([]byte("bf"), buf...)
-}
-
-func (t *Table) blockCacheKey(idx int) []byte {
-	y.AssertTrue(t.id < math.MaxUint32)
+func (t *Table) blockCacheKey(idx int) uint64 {
+	y.AssertTrue(t.ID() < math.MaxUint32)
 	y.AssertTrue(uint32(idx) < math.MaxUint32)
-
-	buf := make([]byte, 8)
-	// Assume t.ID does not overflow uint32.
-	binary.BigEndian.PutUint32(buf[:4], uint32(t.ID()))
-	binary.BigEndian.PutUint32(buf[4:], uint32(idx))
-	return buf
+	return (t.ID() << 32) | uint64(idx)
 }
 
 // EstimatedSize returns the total size of key-values stored in this table (including the
@@ -503,44 +470,7 @@ func (t *Table) ID() uint64 { return t.id }
 
 // DoesNotHave returns true if (but not "only if") the table does not have the key hash.
 // It does a bloom filter lookup.
-func (t *Table) DoesNotHave(hash uint64) bool {
-	var bf *z.Bloom
-
-	// Return fast if cache is absent.
-	if t.opt.Cache == nil {
-		bf, _ := t.readBloomFilter()
-		return !bf.Has(hash)
-	}
-
-	// Check if the bloomfilter exists in the cache.
-	if b, ok := t.opt.Cache.Get(t.bfCacheKey()); b != nil && ok {
-		bf = b.(*z.Bloom)
-		return !bf.Has(hash)
-	}
-
-	bf, sz := t.readBloomFilter()
-	t.opt.Cache.Set(t.bfCacheKey(), bf, int64(sz))
-	return !bf.Has(hash)
-}
-
-// readBloomFilter reads the bloom filter from the SST and returns its length
-// along with the bloom filter.
-func (t *Table) readBloomFilter() (*z.Bloom, int) {
-	// Read bloom filter from the SST.
-	data := t.readNoFail(t.indexStart, t.indexLen)
-	index := pb.TableIndex{}
-	var err error
-	// Decrypt the table index if it is encrypted.
-	if t.shouldDecrypt() {
-		data, err = t.decrypt(data)
-		y.Check(err)
-	}
-	y.Check(proto.Unmarshal(data, &index))
-
-	bf, err := z.JSONUnmarshal(index.BloomFilter)
-	y.Check(err)
-	return bf, len(index.BloomFilter)
-}
+func (t *Table) DoesNotHave(hash uint64) bool { return !t.bf.Has(hash) }
 
 // VerifyChecksum verifies checksum for all blocks of table. This function is called by
 // OpenTable() function. This function is also called inside levelsController.VerifyChecksum().

table/table_test.go

@@ -77,9 +77,13 @@ func buildTable(t *testing.T, keyValues [][]string, opts Options) *os.File {
 	defer b.Close()
 	// TODO: Add test for file garbage collection here. No files should be left after the tests here.
 
-	filename := fmt.Sprintf("%s%s%d.sst", os.TempDir(), string(os.PathSeparator), rand.Uint32())
+	filename := fmt.Sprintf("%s%s%d.sst", os.TempDir(), string(os.PathSeparator), rand.Int63())
 	f, err := y.CreateSyncedFile(filename, true)
-	require.NoError(t, err)
+	if t != nil {
+		require.NoError(t, err)
+	} else {
+		y.Check(err)
+	}
 
 	sort.Slice(keyValues, func(i, j int) bool {
 		return keyValues[i][0] < keyValues[j][0]