leveldb: version now locks individual files (fixes #161)
This way version doesn't need to locks successive versions.
So that intermediate files generated during compaction can
be released right away, even if old versions still being used.
diff --git a/leveldb/session.go b/leveldb/session.go
index f3e7477..ad68a87 100644
--- a/leveldb/session.go
+++ b/leveldb/session.go
@@ -47,6 +47,7 @@
o *cachedOptions
icmp *iComparer
tops *tOps
+ fileRef map[int64]int
manifest *journal.Writer
manifestWriter storage.Writer
@@ -69,6 +70,7 @@
s = &session{
stor: stor,
storLock: storLock,
+ fileRef: make(map[int64]int),
}
s.setOptions(o)
s.tops = newTableOps(s)
diff --git a/leveldb/session_util.go b/leveldb/session_util.go
index 34ad617..9232893 100644
--- a/leveldb/session_util.go
+++ b/leveldb/session_util.go
@@ -39,6 +39,18 @@
return storage.FileDesc{storage.TypeTemp, num}
}
+func (s *session) addFileRef(fd storage.FileDesc, ref int) int {
+ ref += s.fileRef[fd.Num]
+ if ref > 0 {
+ s.fileRef[fd.Num] = ref
+ } else if ref == 0 {
+ delete(s.fileRef, fd.Num)
+ } else {
+ panic(fmt.Sprintf("negative ref: %v", fd))
+ }
+ return ref
+}
+
// Session state.
// Get current version. This will incr version ref, must call
@@ -46,7 +58,7 @@
func (s *session) version() *version {
s.vmu.Lock()
defer s.vmu.Unlock()
- s.stVersion.ref++
+ s.stVersion.incref()
return s.stVersion
}
@@ -59,14 +71,15 @@
// Set current version to v.
func (s *session) setVersion(v *version) {
s.vmu.Lock()
- v.ref = 1 // Holds by session.
- if old := s.stVersion; old != nil {
- v.ref++ // Holds by old version.
- old.next = v
- old.releaseNB()
+ defer s.vmu.Unlock()
+ // Hold by session. It is important to call this first before releasing
+ // current version, otherwise the still used files might get released.
+ v.incref()
+ if s.stVersion != nil {
+ // Release current version.
+ s.stVersion.releaseNB()
}
s.stVersion = v
- s.vmu.Unlock()
}
// Get current unused file number.
diff --git a/leveldb/version.go b/leveldb/version.go
index c60f12c..73f272a 100644
--- a/leveldb/version.go
+++ b/leveldb/version.go
@@ -34,44 +34,48 @@
cSeek unsafe.Pointer
- closing bool
- ref int
- // Succeeding version.
- next *version
+ closing bool
+ ref int
+ released bool
}
func newVersion(s *session) *version {
return &version{s: s}
}
+func (v *version) incref() {
+ if v.released {
+ panic("already released")
+ }
+
+ v.ref++
+ if v.ref == 1 {
+ // Incr file ref.
+ for _, tt := range v.levels {
+ for _, t := range tt {
+ v.s.addFileRef(t.fd, 1)
+ }
+ }
+ }
+}
+
func (v *version) releaseNB() {
v.ref--
if v.ref > 0 {
return
- }
- if v.ref < 0 {
+ } else if v.ref < 0 {
panic("negative version ref")
}
- nextTables := make(map[int64]bool)
- for _, tt := range v.next.levels {
- for _, t := range tt {
- num := t.fd.Num
- nextTables[num] = true
- }
- }
-
for _, tt := range v.levels {
for _, t := range tt {
- num := t.fd.Num
- if _, ok := nextTables[num]; !ok {
+ if v.s.addFileRef(t.fd, -1) == 0 {
v.s.tops.remove(t)
}
}
}
- v.next.releaseNB()
- v.next = nil
+ v.released = true
}
func (v *version) release() {
