| // 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 iKey |
| 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 iKey) 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) |
| } |