--- /dev/null
+// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package leveldb
+
+import (
+ "sync/atomic"
+
+ "github.com/syndtr/goleveldb/leveldb/iterator"
+ "github.com/syndtr/goleveldb/leveldb/memdb"
+ "github.com/syndtr/goleveldb/leveldb/opt"
+)
+
+func (s *session) pickMemdbLevel(umin, umax []byte, maxLevel int) int {
+ v := s.version()
+ defer v.release()
+ return v.pickMemdbLevel(umin, umax, maxLevel)
+}
+
+func (s *session) flushMemdb(rec *sessionRecord, mdb *memdb.DB, maxLevel int) (int, error) {
+ // Create sorted table.
+ iter := mdb.NewIterator(nil)
+ defer iter.Release()
+ t, n, err := s.tops.createFrom(iter)
+ if err != nil {
+ return 0, err
+ }
+
+ // Pick level other than zero can cause compaction issue with large
+ // bulk insert and delete on strictly incrementing key-space. The
+ // problem is that the small deletion markers trapped at lower level,
+ // while key/value entries keep growing at higher level. Since the
+ // key-space is strictly incrementing it will not overlaps with
+ // higher level, thus maximum possible level is always picked, while
+ // overlapping deletion marker pushed into lower level.
+ // See: https://github.com/syndtr/goleveldb/issues/127.
+ flushLevel := s.pickMemdbLevel(t.imin.ukey(), t.imax.ukey(), maxLevel)
+ rec.addTableFile(flushLevel, t)
+
+ s.logf("memdb@flush created L%d@%d N·%d S·%s %q:%q", flushLevel, t.fd.Num, n, shortenb(int(t.size)), t.imin, t.imax)
+ return flushLevel, nil
+}
+
+// Pick a compaction based on current state; need external synchronization.
+func (s *session) pickCompaction() *compaction {
+ v := s.version()
+
+ var sourceLevel int
+ var t0 tFiles
+ if v.cScore >= 1 {
+ sourceLevel = v.cLevel
+ cptr := s.getCompPtr(sourceLevel)
+ tables := v.levels[sourceLevel]
+ for _, t := range tables {
+ if cptr == nil || s.icmp.Compare(t.imax, cptr) > 0 {
+ t0 = append(t0, t)
+ break
+ }
+ }
+ if len(t0) == 0 {
+ t0 = append(t0, tables[0])
+ }
+ } else {
+ if p := atomic.LoadPointer(&v.cSeek); p != nil {
+ ts := (*tSet)(p)
+ sourceLevel = ts.level
+ t0 = append(t0, ts.table)
+ } else {
+ v.release()
+ return nil
+ }
+ }
+
+ return newCompaction(s, v, sourceLevel, t0)
+}
+
+// Create compaction from given level and range; need external synchronization.
+func (s *session) getCompactionRange(sourceLevel int, umin, umax []byte, noLimit bool) *compaction {
+ v := s.version()
+
+ if sourceLevel >= len(v.levels) {
+ v.release()
+ return nil
+ }
+
+ t0 := v.levels[sourceLevel].getOverlaps(nil, s.icmp, umin, umax, sourceLevel == 0)
+ if len(t0) == 0 {
+ v.release()
+ return nil
+ }
+
+ // Avoid compacting too much in one shot in case the range is large.
+ // But we cannot do this for level-0 since level-0 files can overlap
+ // and we must not pick one file and drop another older file if the
+ // two files overlap.
+ if !noLimit && sourceLevel > 0 {
+ limit := int64(v.s.o.GetCompactionSourceLimit(sourceLevel))
+ total := int64(0)
+ for i, t := range t0 {
+ total += t.size
+ if total >= limit {
+ s.logf("table@compaction limiting F·%d -> F·%d", len(t0), i+1)
+ t0 = t0[:i+1]
+ break
+ }
+ }
+ }
+
+ return newCompaction(s, v, sourceLevel, t0)
+}
+
+func newCompaction(s *session, v *version, sourceLevel int, t0 tFiles) *compaction {
+ c := &compaction{
+ s: s,
+ v: v,
+ sourceLevel: sourceLevel,
+ levels: [2]tFiles{t0, nil},
+ maxGPOverlaps: int64(s.o.GetCompactionGPOverlaps(sourceLevel)),
+ tPtrs: make([]int, len(v.levels)),
+ }
+ c.expand()
+ c.save()
+ return c
+}
+
+// compaction represent a compaction state.
+type compaction struct {
+ s *session
+ v *version
+
+ sourceLevel int
+ levels [2]tFiles
+ maxGPOverlaps int64
+
+ gp tFiles
+ gpi int
+ seenKey bool
+ gpOverlappedBytes int64
+ imin, imax internalKey
+ tPtrs []int
+ released bool
+
+ snapGPI int
+ snapSeenKey bool
+ snapGPOverlappedBytes int64
+ snapTPtrs []int
+}
+
+func (c *compaction) save() {
+ c.snapGPI = c.gpi
+ c.snapSeenKey = c.seenKey
+ c.snapGPOverlappedBytes = c.gpOverlappedBytes
+ c.snapTPtrs = append(c.snapTPtrs[:0], c.tPtrs...)
+}
+
+func (c *compaction) restore() {
+ c.gpi = c.snapGPI
+ c.seenKey = c.snapSeenKey
+ c.gpOverlappedBytes = c.snapGPOverlappedBytes
+ c.tPtrs = append(c.tPtrs[:0], c.snapTPtrs...)
+}
+
+func (c *compaction) release() {
+ if !c.released {
+ c.released = true
+ c.v.release()
+ }
+}
+
+// Expand compacted tables; need external synchronization.
+func (c *compaction) expand() {
+ limit := int64(c.s.o.GetCompactionExpandLimit(c.sourceLevel))
+ vt0 := c.v.levels[c.sourceLevel]
+ vt1 := tFiles{}
+ if level := c.sourceLevel + 1; level < len(c.v.levels) {
+ vt1 = c.v.levels[level]
+ }
+
+ t0, t1 := c.levels[0], c.levels[1]
+ imin, imax := t0.getRange(c.s.icmp)
+ // We expand t0 here just incase ukey hop across tables.
+ t0 = vt0.getOverlaps(t0, c.s.icmp, imin.ukey(), imax.ukey(), c.sourceLevel == 0)
+ if len(t0) != len(c.levels[0]) {
+ imin, imax = t0.getRange(c.s.icmp)
+ }
+ t1 = vt1.getOverlaps(t1, c.s.icmp, imin.ukey(), imax.ukey(), false)
+ // Get entire range covered by compaction.
+ amin, amax := append(t0, t1...).getRange(c.s.icmp)
+
+ // See if we can grow the number of inputs in "sourceLevel" without
+ // changing the number of "sourceLevel+1" files we pick up.
+ if len(t1) > 0 {
+ exp0 := vt0.getOverlaps(nil, c.s.icmp, amin.ukey(), amax.ukey(), c.sourceLevel == 0)
+ if len(exp0) > len(t0) && t1.size()+exp0.size() < limit {
+ xmin, xmax := exp0.getRange(c.s.icmp)
+ exp1 := vt1.getOverlaps(nil, c.s.icmp, xmin.ukey(), xmax.ukey(), false)
+ if len(exp1) == len(t1) {
+ c.s.logf("table@compaction expanding L%d+L%d (F·%d S·%s)+(F·%d S·%s) -> (F·%d S·%s)+(F·%d S·%s)",
+ c.sourceLevel, c.sourceLevel+1, len(t0), shortenb(int(t0.size())), len(t1), shortenb(int(t1.size())),
+ len(exp0), shortenb(int(exp0.size())), len(exp1), shortenb(int(exp1.size())))
+ imin, imax = xmin, xmax
+ t0, t1 = exp0, exp1
+ amin, amax = append(t0, t1...).getRange(c.s.icmp)
+ }
+ }
+ }
+
+ // Compute the set of grandparent files that overlap this compaction
+ // (parent == sourceLevel+1; grandparent == sourceLevel+2)
+ if level := c.sourceLevel + 2; level < len(c.v.levels) {
+ c.gp = c.v.levels[level].getOverlaps(c.gp, c.s.icmp, amin.ukey(), amax.ukey(), false)
+ }
+
+ c.levels[0], c.levels[1] = t0, t1
+ c.imin, c.imax = imin, imax
+}
+
+// Check whether compaction is trivial.
+func (c *compaction) trivial() bool {
+ return len(c.levels[0]) == 1 && len(c.levels[1]) == 0 && c.gp.size() <= c.maxGPOverlaps
+}
+
+func (c *compaction) baseLevelForKey(ukey []byte) bool {
+ for level := c.sourceLevel + 2; level < len(c.v.levels); level++ {
+ tables := c.v.levels[level]
+ for c.tPtrs[level] < len(tables) {
+ t := tables[c.tPtrs[level]]
+ if c.s.icmp.uCompare(ukey, t.imax.ukey()) <= 0 {
+ // We've advanced far enough.
+ if c.s.icmp.uCompare(ukey, t.imin.ukey()) >= 0 {
+ // Key falls in this file's range, so definitely not base level.
+ return false
+ }
+ break
+ }
+ c.tPtrs[level]++
+ }
+ }
+ return true
+}
+
+func (c *compaction) shouldStopBefore(ikey internalKey) bool {
+ for ; c.gpi < len(c.gp); c.gpi++ {
+ gp := c.gp[c.gpi]
+ if c.s.icmp.Compare(ikey, gp.imax) <= 0 {
+ break
+ }
+ if c.seenKey {
+ c.gpOverlappedBytes += gp.size
+ }
+ }
+ c.seenKey = true
+
+ if c.gpOverlappedBytes > c.maxGPOverlaps {
+ // Too much overlap for current output; start new output.
+ c.gpOverlappedBytes = 0
+ return true
+ }
+ return false
+}
+
+// Creates an iterator.
+func (c *compaction) newIterator() iterator.Iterator {
+ // Creates iterator slice.
+ icap := len(c.levels)
+ if c.sourceLevel == 0 {
+ // Special case for level-0.
+ icap = len(c.levels[0]) + 1
+ }
+ its := make([]iterator.Iterator, 0, icap)
+
+ // Options.
+ ro := &opt.ReadOptions{
+ DontFillCache: true,
+ Strict: opt.StrictOverride,
+ }
+ strict := c.s.o.GetStrict(opt.StrictCompaction)
+ if strict {
+ ro.Strict |= opt.StrictReader
+ }
+
+ for i, tables := range c.levels {
+ if len(tables) == 0 {
+ continue
+ }
+
+ // Level-0 is not sorted and may overlaps each other.
+ if c.sourceLevel+i == 0 {
+ for _, t := range tables {
+ its = append(its, c.s.tops.newIterator(t, nil, ro))
+ }
+ } else {
+ it := iterator.NewIndexedIterator(tables.newIndexIterator(c.s.tops, c.s.icmp, nil, ro), strict)
+ its = append(its, it)
+ }
+ }
+
+ return iterator.NewMergedIterator(its, c.s.icmp, strict)
+}
OSDN Git Service
