options.go

// Copyright 2011 The LevelDB-Go and Pebble Authors. All rights reserved. Use
// of this source code is governed by a BSD-style license that can be found in
// the LICENSE file.

package pebble

import "github.com/petermattis/pebble/internal/base"

// Compression exports the base.Compression type.
type Compression = base.Compression

// Exported Compression constants.
const (
	DefaultCompression = base.DefaultCompression
	NoCompression      = base.NoCompression
	SnappyCompression  = base.SnappyCompression
)

// FilterType exports the base.FilterType type.
type FilterType = base.FilterType

// Exported TableFilter constants.
const (
	TableFilter = base.TableFilter
)

// FilterWriter exports the base.FilterWriter type.
type FilterWriter = base.FilterWriter

// FilterPolicy exports the base.FilterPolicy type.
type FilterPolicy = base.FilterPolicy

// TableFormat exports the base.TableFormat type.
type TableFormat = base.TableFormat

// Exported TableFormat constants.
const (
	TableFormatRocksDBv2 = base.TableFormatRocksDBv2
	TableFormatLevelDB   = base.TableFormatLevelDB
)

// TablePropertyCollector exports the base.TablePropertyCollector type.
type TablePropertyCollector = base.TablePropertyCollector

// LevelOptions exports the base.LevelOptions type.
type LevelOptions = base.LevelOptions

// Options exports the base.Options type.
type Options = base.Options

// IterOptions hold the optional per-query parameters for NewIter.
//
// Like Options, a nil *IterOptions is valid and means to use the default
// values.
type IterOptions struct {
	// LowerBound specifies the smallest key (inclusive) that the iterator will
	// return during iteration. If the iterator is seeked or iterated past this
	// boundary the iterator will return Valid()==false. Setting LowerBound
	// effectively truncates the key space visible to the iterator.
	LowerBound []byte
	// UpperBound specifies the largest key (exclusive) that the iterator will
	// return during iteration. If the iterator is seeked or iterated past this
	// boundary the iterator will return Valid()==false. Setting UpperBound
	// effectively truncates the key space visible to the iterator.
	UpperBound []byte
	// TableFilter can be used to filter the tables that are scanned during
	// iteration based on the user properties. Return true to scan the table and
	// false to skip scanning.
	TableFilter func(userProps map[string]string) bool
}

// GetLowerBound returns the LowerBound or nil if the receiver is nil.
func (o *IterOptions) GetLowerBound() []byte {
	if o == nil {
		return nil
	}
	return o.LowerBound
}

// GetUpperBound returns the UpperBound or nil if the receiver is nil.
func (o *IterOptions) GetUpperBound() []byte {
	if o == nil {
		return nil
	}
	return o.UpperBound
}

// WriteOptions hold the optional per-query parameters for Set and Delete
// operations.
//
// Like Options, a nil *WriteOptions is valid and means to use the default
// values.
type WriteOptions struct {
	// Sync is whether to sync underlying writes from the OS buffer cache
	// through to actual disk, if applicable. Setting Sync can result in
	// slower writes.
	//
	// If false, and the machine crashes, then some recent writes may be lost.
	// Note that if it is just the process that crashes (and the machine does
	// not) then no writes will be lost.
	//
	// In other words, Sync being false has the same semantics as a write
	// system call. Sync being true means write followed by fsync.
	//
	// The default value is true.
	Sync bool
}

// Sync specifies the default write options for writes which synchronize to
// disk.
var Sync = &WriteOptions{Sync: true}

// NoSync specifies the default write options for writes which do not
// synchronize to disk.
var NoSync = &WriteOptions{Sync: false}

// GetSync returns the Sync value or true if the receiver is nil.
func (o *WriteOptions) GetSync() bool {
	return o == nil || o.Sync
}