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