Golang Directory.MakeLock方法代码示例

/*
Constructs a new IndexWriter per the settings given in conf. If you want to
make "live" changes to this writer instance, use Config().

NOTE: after this writer is created, the given configuration instance cannot be
passed to another writer. If you intend to do so, you should clone it
beforehand.
*/
func NewIndexWriter(d store.Directory, conf *IndexWriterConfig) (w *IndexWriter, err error) {
	ans := &IndexWriter{
		Locker:         &sync.Mutex{},
		ClosingControl: newClosingControl(),

		segmentsToMerge: make(map[*SegmentInfoPerCommit]bool),
		mergeExceptions: make([]*OneMerge, 0),
		doAfterFlush:    func() error { return nil },
		doBeforeFlush:   func() error { return nil },
		commitLock:      &sync.Mutex{},
		fullFlushLock:   &sync.Mutex{},

		config:         newLiveIndexWriterConfigFrom(conf),
		directory:      d,
		analyzer:       conf.analyzer,
		infoStream:     conf.infoStream,
		mergePolicy:    conf.mergePolicy,
		mergeScheduler: conf.mergeScheduler,
		codec:          conf.codec,

		bufferedDeletesStream: newBufferedDeletesStream(conf.infoStream),
		poolReaders:           conf.readerPooling,

		writeLock: d.MakeLock(WRITE_LOCK_NAME),
	}
	ans.readerPool = newReaderPool(ans)
	ans.MergeControl = newMergeControl(conf.infoStream, ans.readerPool)

	conf.setIndexWriter(ans)
	ans.mergePolicy.SetIndexWriter(ans)

	// obtain write lock
	if ok, err := ans.writeLock.ObtainWithin(conf.writeLockTimeout); !ok || err != nil {
		if err != nil {
			return nil, err
		}
		return nil, errors.New(fmt.Sprintf("Index locked for write: %v", ans.writeLock))
	}

	var success bool = false
	defer func() {
		if !success {
			if ans.infoStream.IsEnabled("IW") {
				ans.infoStream.Message("IW", "init: hit exception on init; releasing write lock")
			}
			ans.writeLock.Release() // don't mask the original exception
			ans.writeLock = nil
		}
	}()

	var create bool
	switch conf.openMode {
	case OPEN_MODE_CREATE:
		create = true
	case OPEN_MODE_APPEND:
		create = false
	default:
		// CREATE_OR_APPEND - create only if an index does not exist
		ok, err := IsIndexExists(d)
		if err != nil {
			return nil, err
		}
		create = !ok
	}

	// If index is too old, reading the segments will return
	// IndexFormatTooOldError
	ans.segmentInfos = &SegmentInfos{}

	var initialIndexExists bool = true

	if create {
		// Try to read first. This is to allow create against an index
		// that's currently open for searching. In this case we write the
		// next segments_N file with no segments:
		err = ans.segmentInfos.ReadAll(d)
		if err == nil {
			ans.segmentInfos.Clear()
		} else {
			// Likely this means it's a fresh directory
			initialIndexExists = false
			err = nil
		}

		// Record that we have a change (zero out all segments) pending:
		ans.changed()
	} else {
		err = ans.segmentInfos.ReadAll(d)
		if err != nil {
			return
		}

//.........这里部分代码省略.........