mirror of
https://github.com/go-gitea/gitea.git
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240 lines
4.7 KiB
Go
240 lines
4.7 KiB
Go
// Copyright (c) 2013, 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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"errors"
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"sync/atomic"
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"time"
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"github.com/syndtr/goleveldb/leveldb/journal"
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"github.com/syndtr/goleveldb/leveldb/memdb"
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"github.com/syndtr/goleveldb/leveldb/storage"
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)
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var (
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errHasFrozenMem = errors.New("has frozen mem")
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)
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type memDB struct {
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db *DB
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*memdb.DB
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ref int32
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}
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func (m *memDB) getref() int32 {
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return atomic.LoadInt32(&m.ref)
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}
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func (m *memDB) incref() {
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atomic.AddInt32(&m.ref, 1)
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}
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func (m *memDB) decref() {
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if ref := atomic.AddInt32(&m.ref, -1); ref == 0 {
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// Only put back memdb with std capacity.
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if m.Capacity() == m.db.s.o.GetWriteBuffer() {
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m.Reset()
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m.db.mpoolPut(m.DB)
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}
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m.db = nil
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m.DB = nil
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} else if ref < 0 {
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panic("negative memdb ref")
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}
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}
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// Get latest sequence number.
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func (db *DB) getSeq() uint64 {
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return atomic.LoadUint64(&db.seq)
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}
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// Atomically adds delta to seq.
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func (db *DB) addSeq(delta uint64) {
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atomic.AddUint64(&db.seq, delta)
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}
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func (db *DB) setSeq(seq uint64) {
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atomic.StoreUint64(&db.seq, seq)
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}
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func (db *DB) sampleSeek(ikey internalKey) {
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v := db.s.version()
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if v.sampleSeek(ikey) {
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// Trigger table compaction.
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db.compTrigger(db.tcompCmdC)
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}
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v.release()
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}
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func (db *DB) mpoolPut(mem *memdb.DB) {
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if !db.isClosed() {
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select {
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case db.memPool <- mem:
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default:
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}
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}
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}
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func (db *DB) mpoolGet(n int) *memDB {
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var mdb *memdb.DB
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select {
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case mdb = <-db.memPool:
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default:
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}
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if mdb == nil || mdb.Capacity() < n {
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mdb = memdb.New(db.s.icmp, maxInt(db.s.o.GetWriteBuffer(), n))
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}
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return &memDB{
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db: db,
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DB: mdb,
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}
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}
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func (db *DB) mpoolDrain() {
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ticker := time.NewTicker(30 * time.Second)
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for {
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select {
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case <-ticker.C:
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select {
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case <-db.memPool:
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default:
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}
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case <-db.closeC:
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ticker.Stop()
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// Make sure the pool is drained.
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select {
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case <-db.memPool:
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case <-time.After(time.Second):
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}
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close(db.memPool)
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return
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}
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}
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}
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// Create new memdb and froze the old one; need external synchronization.
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// newMem only called synchronously by the writer.
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func (db *DB) newMem(n int) (mem *memDB, err error) {
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fd := storage.FileDesc{Type: storage.TypeJournal, Num: db.s.allocFileNum()}
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w, err := db.s.stor.Create(fd)
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if err != nil {
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db.s.reuseFileNum(fd.Num)
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return
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}
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db.memMu.Lock()
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defer db.memMu.Unlock()
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if db.frozenMem != nil {
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return nil, errHasFrozenMem
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}
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if db.journal == nil {
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db.journal = journal.NewWriter(w)
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} else {
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db.journal.Reset(w)
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db.journalWriter.Close()
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db.frozenJournalFd = db.journalFd
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}
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db.journalWriter = w
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db.journalFd = fd
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db.frozenMem = db.mem
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mem = db.mpoolGet(n)
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mem.incref() // for self
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mem.incref() // for caller
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db.mem = mem
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// The seq only incremented by the writer. And whoever called newMem
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// should hold write lock, so no need additional synchronization here.
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db.frozenSeq = db.seq
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return
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}
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// Get all memdbs.
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func (db *DB) getMems() (e, f *memDB) {
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db.memMu.RLock()
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defer db.memMu.RUnlock()
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if db.mem != nil {
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db.mem.incref()
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} else if !db.isClosed() {
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panic("nil effective mem")
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}
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if db.frozenMem != nil {
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db.frozenMem.incref()
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}
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return db.mem, db.frozenMem
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}
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// Get effective memdb.
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func (db *DB) getEffectiveMem() *memDB {
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db.memMu.RLock()
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defer db.memMu.RUnlock()
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if db.mem != nil {
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db.mem.incref()
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} else if !db.isClosed() {
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panic("nil effective mem")
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}
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return db.mem
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}
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// Check whether we has frozen memdb.
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func (db *DB) hasFrozenMem() bool {
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db.memMu.RLock()
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defer db.memMu.RUnlock()
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return db.frozenMem != nil
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}
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// Get frozen memdb.
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func (db *DB) getFrozenMem() *memDB {
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db.memMu.RLock()
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defer db.memMu.RUnlock()
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if db.frozenMem != nil {
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db.frozenMem.incref()
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}
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return db.frozenMem
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}
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// Drop frozen memdb; assume that frozen memdb isn't nil.
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func (db *DB) dropFrozenMem() {
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db.memMu.Lock()
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if err := db.s.stor.Remove(db.frozenJournalFd); err != nil {
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db.logf("journal@remove removing @%d %q", db.frozenJournalFd.Num, err)
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} else {
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db.logf("journal@remove removed @%d", db.frozenJournalFd.Num)
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}
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db.frozenJournalFd = storage.FileDesc{}
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db.frozenMem.decref()
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db.frozenMem = nil
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db.memMu.Unlock()
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}
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// Clear mems ptr; used by DB.Close().
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func (db *DB) clearMems() {
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db.memMu.Lock()
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db.mem = nil
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db.frozenMem = nil
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db.memMu.Unlock()
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}
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// Set closed flag; return true if not already closed.
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func (db *DB) setClosed() bool {
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return atomic.CompareAndSwapUint32(&db.closed, 0, 1)
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}
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// Check whether DB was closed.
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func (db *DB) isClosed() bool {
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return atomic.LoadUint32(&db.closed) != 0
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}
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// Check read ok status.
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func (db *DB) ok() error {
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if db.isClosed() {
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return ErrClosed
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}
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return nil
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}
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