move serializer into Interface

Signed-off-by: Thomas Jungblut <[email protected]>

db.go

@@ -135,9 +135,8 @@ type DB struct {
 	rwtx     *Tx
 	txs      []*Tx
 
-	freelist           fl.Interface
-	freelistSerializer fl.Serializable
-	freelistLoad       sync.Once
+	freelist     fl.Interface
+	freelistLoad sync.Once
 
 	pagePool sync.Pool
 
@@ -192,7 +191,6 @@ func Open(path string, mode os.FileMode, options *Options) (db *DB, err error) {
 	db.NoFreelistSync = options.NoFreelistSync
 	db.PreLoadFreelist = options.PreLoadFreelist
 	db.FreelistType = options.FreelistType
-	db.freelistSerializer = fl.Serializer{}
 	db.Mlock = options.Mlock
 
 	// Set default values for later DB operations.
@@ -425,7 +423,7 @@ func (db *DB) loadFreelist() {
 			db.freelist.Init(db.freepages())
 		} else {
 			// Read free list from freelist page.
-			db.freelistSerializer.Read(db.freelist, db.page(db.meta().Freelist()))
+			db.freelist.Read(db.page(db.meta().Freelist()))
 		}
 		db.stats.FreePageN = db.freelist.FreeCount()
 		db.stats.PendingPageN = db.freelist.PendingCount()

internal/freelist/array.go

@@ -111,6 +111,6 @@ func NewArrayFreelist() Interface {
 		},
 	}
 	// this loopy reference allows us to share the span merging via interfaces
-	a.shared.spanMerger = a
+	a.shared.sharedInterface = a
 	return a
 }

internal/freelist/freelist.go

@@ -6,7 +6,21 @@ import (
 	"go.etcd.io/bbolt/internal/common"
 )
 
+type ReadWriter interface {
+	// Read calls Init with the page ids stored in te given page.
+	Read(page *common.Page)
+
+	// Write writes the freelist into the given page.
+	Write(page *common.Page)
+
+	// EstimatedWritePageSize returns the size of the freelist after serialization in Write.
+	// This should never underestimate the size.
+	EstimatedWritePageSize() int
+}
+
 type Interface interface {
+	ReadWriter
+
 	// Init initializes this freelist with the given list of pages.
 	Init(ids common.Pgids)
 
@@ -58,8 +72,8 @@ func Copyall(f Interface, dst []common.Pgid) {
 }
 
 // Reload reads the freelist from a page and filters out pending items.
-func Reload(s Serializable, f Interface, p *common.Page) {
-	s.Read(f, p)
+func Reload(f Interface, p *common.Page) {
+	f.Read(p)
 	NoSyncReload(f, p.FreelistPageIds())
 }
 

internal/freelist/freelist_test.go

@@ -6,6 +6,7 @@ import (
 	"reflect"
 	"sort"
 	"testing"
+	"unsafe"
 
 	"go.etcd.io/bbolt/internal/common"
 )
@@ -178,6 +179,52 @@ func TestFreelist_releaseRange(t *testing.T) {
 	}
 }
 
+// Ensure that a freelist can deserialize from a freelist page.
+func TestFreelist_read(t *testing.T) {
+	// Create a page.
+	var buf [4096]byte
+	page := (*common.Page)(unsafe.Pointer(&buf[0]))
+	page.SetFlags(common.FreelistPageFlag)
+	page.SetCount(2)
+
+	// Insert 2 page ids.
+	ids := (*[3]common.Pgid)(unsafe.Pointer(uintptr(unsafe.Pointer(page)) + unsafe.Sizeof(*page)))
+	ids[0] = 23
+	ids[1] = 50
+
+	// Deserialize page into a freelist.
+	f := newTestFreelist()
+	f.Read(page)
+
+	// Ensure that there are two page ids in the freelist.
+	if exp := common.Pgids([]common.Pgid{23, 50}); !reflect.DeepEqual(exp, f.FreePageIds()) {
+		t.Fatalf("exp=%v; got=%v", exp, f.FreePageIds())
+	}
+}
+
+// Ensure that a freelist can serialize into a freelist page.
+func TestFreelist_write(t *testing.T) {
+	// Create a freelist and write it to a page.
+	var buf [4096]byte
+	f := newTestFreelist()
+
+	f.Init([]common.Pgid{12, 39})
+	f.pendingPageIds()[100] = &txPending{ids: []common.Pgid{28, 11}}
+	f.pendingPageIds()[101] = &txPending{ids: []common.Pgid{3}}
+	p := (*common.Page)(unsafe.Pointer(&buf[0]))
+	f.Write(p)
+
+	// Read the page back out.
+	f2 := newTestFreelist()
+	f2.Read(p)
+
+	// Ensure that the freelist is correct.
+	// All pages should be present and in reverse order.
+	if exp := common.Pgids([]common.Pgid{3, 11, 12, 28, 39}); !reflect.DeepEqual(exp, f2.FreePageIds()) {
+		t.Fatalf("exp=%v; got=%v", exp, f2.FreePageIds())
+	}
+}
+
 func Benchmark_FreelistRelease10K(b *testing.B)    { benchmark_FreelistRelease(b, 10000) }
 func Benchmark_FreelistRelease100K(b *testing.B)   { benchmark_FreelistRelease(b, 100000) }
 func Benchmark_FreelistRelease1000K(b *testing.B)  { benchmark_FreelistRelease(b, 1000000) }

internal/freelist/hashmap.go

@@ -296,6 +296,6 @@ func NewHashMapFreelist() Interface {
 		backwardMap: make(map[common.Pgid]uint64),
 	}
 	// this loopy reference allows us to share the span merging via interfaces
-	hm.shared.spanMerger = hm
+	hm.shared.sharedInterface = hm
 	return hm
 }

internal/freelist/shared.go

@@ -2,11 +2,18 @@ package freelist
 
 import (
 	"fmt"
-
 	"go.etcd.io/bbolt/internal/common"
+	"sort"
+	"unsafe"
 )
 
-type spanMerger interface {
+type sharedInterface interface {
+	// Init initializes this freelist with the given list of pages.
+	Init(ids common.Pgids)
+	// Count returns the number of free and pending pages.
+	Count() int
+	// FreePageIds returns all free pages.
+	FreePageIds() common.Pgids
 	// mergeSpans is merging the given pages into the freelist
 	mergeSpans(ids common.Pgids)
 }
@@ -18,7 +25,7 @@ type txPending struct {
 }
 
 type shared struct {
-	spanMerger
+	sharedInterface
 
 	allocs  map[common.Pgid]common.Txid // mapping of Txid that allocated a pgid.
 	cache   map[common.Pgid]struct{}    // fast lookup of all free and pending page ids.
@@ -96,7 +103,7 @@ func (t *shared) Rollback(txid common.Txid) {
 	}
 	// Remove pages from pending list and mark as free if allocated by txid.
 	delete(t.pending, txid)
-	t.spanMerger.mergeSpans(m)
+	t.sharedInterface.mergeSpans(m)
 }
 
 func (t *shared) Release(txid common.Txid) {
@@ -144,6 +151,72 @@ func (t *shared) ReleaseRange(begin, end common.Txid) {
 	t.mergeSpans(m)
 }
 
+func (t *shared) Read(p *common.Page) {
+	if !p.IsFreelistPage() {
+		panic(fmt.Sprintf("invalid freelist page: %d, page type is %s", p.Id(), p.Typ()))
+	}
+
+	ids := p.FreelistPageIds()
+
+	// Copy the list of page ids from the freelist.
+	if len(ids) == 0 {
+		t.Init(nil)
+	} else {
+		// copy the ids, so we don't modify on the freelist page directly
+		idsCopy := make([]common.Pgid, len(ids))
+		copy(idsCopy, ids)
+		// Make sure they're sorted.
+		sort.Sort(common.Pgids(idsCopy))
+
+		t.Init(idsCopy)
+	}
+}
+
+func (t *shared) EstimatedWritePageSize() int {
+	n := t.Count()
+	if n >= 0xFFFF {
+		// The first element will be used to store the count. See freelist.write.
+		n++
+	}
+	return int(common.PageHeaderSize) + (int(unsafe.Sizeof(common.Pgid(0))) * n)
+}
+
+func (t *shared) Write(p *common.Page) {
+	// Combine the old free pgids and pgids waiting on an open transaction.
+
+	// Update the header flag.
+	p.SetFlags(common.FreelistPageFlag)
+
+	// The page.count can only hold up to 64k elements so if we overflow that
+	// number then we handle it by putting the size in the first element.
+	l := t.Count()
+	if l == 0 {
+		p.SetCount(uint16(l))
+	} else if l < 0xFFFF {
+		p.SetCount(uint16(l))
+		data := common.UnsafeAdd(unsafe.Pointer(p), unsafe.Sizeof(*p))
+		ids := unsafe.Slice((*common.Pgid)(data), l)
+		t.copyall(ids)
+	} else {
+		p.SetCount(0xFFFF)
+		data := common.UnsafeAdd(unsafe.Pointer(p), unsafe.Sizeof(*p))
+		ids := unsafe.Slice((*common.Pgid)(data), l+1)
+		ids[0] = common.Pgid(l)
+		t.copyall(ids[1:])
+	}
+}
+
+// Copyall copies a list of all free ids and all pending ids in one sorted list.
+// f.count returns the minimum length required for dst.
+func (t *shared) copyall(dst []common.Pgid) {
+	m := make(common.Pgids, 0, t.PendingCount())
+	for _, txp := range t.pendingPageIds() {
+		m = append(m, txp.ids...)
+	}
+	sort.Sort(m)
+	common.Mergepgids(dst, t.FreePageIds(), m)
+}
+
 // reindex rebuilds the free cache based on available and pending free lists.
 func (t *shared) reindex(free common.Pgids, pending map[common.Txid]*txPending) {
 	t.cache = make(map[common.Pgid]struct{}, len(free))