introduce a freelist interface

This introduces an interface for the freelist, splits it into two concrete
implementations.

fixes etcd-io#773

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

allocate_test.go

@@ -4,32 +4,36 @@ import (
  "testing"
 
  "go.etcd.io/bbolt/internal/common"
+ "go.etcd.io/bbolt/internal/freelist"
 )
 
 func TestTx_allocatePageStats(t *testing.T) {
- f := newTestFreelist()
- ids := []common.Pgid{2, 3}
- f.readIDs(ids)
+ for n, f := range map[string]freelist.Interface{"hashmap": freelist.NewHashMapFreelist(), "array": freelist.NewArrayFreelist()} {
+ t.Run(n, func(t *testing.T) {
+ ids := []common.Pgid{2, 3}
+ f.Init(ids)
 
- tx := &Tx{
- db: &DB{
- freelist: f,
- pageSize: common.DefaultPageSize,
- },
- meta: &common.Meta{},
- pages: make(map[common.Pgid]*common.Page),
- }
+  tx := &Tx{
+  db: &DB{
+  freelist: f,
+  pageSize: common.DefaultPageSize,
+  },
+  meta: &common.Meta{},
+  pages: make(map[common.Pgid]*common.Page),
+  }
 
- txStats := tx.Stats()
- prePageCnt := txStats.GetPageCount()
- allocateCnt := f.free_count()
+  txStats := tx.Stats()
+  prePageCnt := txStats.GetPageCount()
+  allocateCnt := f.FreeCount()
 
- if _, err := tx.allocate(allocateCnt); err != nil {
- t.Fatal(err)
- }
+  if _, err := tx.allocate(allocateCnt); err != nil {
+  t.Fatal(err)
+  }
 
- txStats = tx.Stats()
- if txStats.GetPageCount() != prePageCnt+int64(allocateCnt) {
- t.Errorf("Allocated %d but got %d page in stats", allocateCnt, txStats.GetPageCount())
+ txStats = tx.Stats()
+ if txStats.GetPageCount() != prePageCnt+int64(allocateCnt) {
+ t.Errorf("Allocated %d but got %d page in stats", allocateCnt, txStats.GetPageCount())
+ }
+ })
  }
 }

bucket.go

@@ -903,7 +903,7 @@ func (b *Bucket) free() {
  var tx = b.tx
  b.forEachPageNode(func(p *common.Page, n *node, _ int) {
  if p != nil {
- tx.db.freelist.free(tx.meta.Txid(), p)
+ tx.db.freelist.Free(tx.meta.Txid(), p)
  } else {
  n.free()
  }

bucket_test.go

@@ -430,6 +430,9 @@ func TestBucket_Delete_FreelistOverflow(t *testing.T) {
  if reopenFreePages := db.Stats().FreePageN; freePages != reopenFreePages {
  t.Fatalf("expected %d free pages, got %+v", freePages, db.Stats())
  }
+ if reopenPendingPages := db.Stats().PendingPageN; reopenPendingPages != 0 {
+ t.Fatalf("expected no pending pages, got %+v", db.Stats())
+ }
 }
 
 // Ensure that deleting of non-existing key is a no-op.

cmd/bbolt/command_version.go

@@ -5,6 +5,7 @@ import (
  "runtime"
 
  "github.com/spf13/cobra"
+
  "go.etcd.io/bbolt/version"
 )
 

db.go

@@ -12,6 +12,7 @@ import (
 
  berrors "go.etcd.io/bbolt/errors"
  "go.etcd.io/bbolt/internal/common"
+ fl "go.etcd.io/bbolt/internal/freelist"
 )
 
 // The time elapsed between consecutive file locking attempts.
@@ -133,7 +134,7 @@ type DB struct {
  rwtx *Tx
  txs []*Tx
 
- freelist *freelist
+ freelist fl.Interface
  freelistLoad sync.Once
 
  pagePool sync.Pool
@@ -418,12 +419,12 @@ func (db *DB) loadFreelist() {
  db.freelist = newFreelist(db.FreelistType)
  if !db.hasSyncedFreelist() {
  // Reconstruct free list by scanning the DB.
- db.freelist.readIDs(db.freepages())
+ db.freelist.Init(db.freepages())
  } else {
  // Read free list from freelist page.
- db.freelist.read(db.page(db.meta().Freelist()))
+ db.freelist.Read(db.page(db.meta().Freelist()))
  }
- db.stats.FreePageN = db.freelist.free_count()
+ db.stats.FreePageN = db.freelist.FreeCount()
  })
 }
 
@@ -797,7 +798,7 @@ func (db *DB) beginTx() (*Tx, error) {
  db.txs = append(db.txs, t)
  n := len(db.txs)
  if db.freelist != nil {
- db.freelist.addReadonlyTXID(t.meta.Txid())
+ db.freelist.AddReadonlyTXID(t.meta.Txid())
  }
 
  // Unlock the meta pages.
@@ -843,7 +844,7 @@ func (db *DB) beginRWTx() (*Tx, error) {
  t := &Tx{writable: true}
  t.init(db)
  db.rwtx = t
- db.freelist.freePages()
+ db.freelist.ReleasePendingPages()
  return t, nil
 }
 
@@ -867,7 +868,7 @@ func (db *DB) removeTx(tx *Tx) {
  }
  n := len(db.txs)
  if db.freelist != nil {
- db.freelist.removeReadonlyTXID(tx.meta.Txid())
+ db.freelist.RemoveReadonlyTXID(tx.meta.Txid())
  }
 
  // Unlock the meta pages.
@@ -1155,7 +1156,7 @@ func (db *DB) allocate(txid common.Txid, count int) (*common.Page, error) {
  p.SetOverflow(uint32(count - 1))
 
  // Use pages from the freelist if they are available.
- p.SetId(db.freelist.allocate(txid, count))
+ p.SetId(db.freelist.Allocate(txid, count))
  if p.Id() != 0 {
  return p, nil
  }
@@ -1261,6 +1262,13 @@ func (db *DB) freepages() []common.Pgid {
  return fids
 }
 
+func newFreelist(freelistType FreelistType) fl.Interface {
+ if freelistType == FreelistMapType {
+ return fl.NewHashMapFreelist()
+ }
+ return fl.NewArrayFreelist()
+}
+
 // Options represents the options that can be set when opening a database.
 type Options struct {
  // Timeout is the amount of time to wait to obtain a file lock.