134 lines
2.8 KiB
Go
134 lines
2.8 KiB
Go
package source
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import (
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"sort"
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)
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// Direction is either up or down.
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type Direction string
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const (
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Down Direction = "down"
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Up Direction = "up"
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)
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// Migration is a helper struct for source drivers that need to
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// build the full directory tree in memory.
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// Migration is fully independent from migrate.Migration.
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type Migration struct {
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// Version is the version of this migration.
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Version uint
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// Identifier can be any string that helps identifying
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// this migration in the source.
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Identifier string
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// Direction is either Up or Down.
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Direction Direction
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// Raw holds the raw location path to this migration in source.
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// ReadUp and ReadDown will use this.
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Raw string
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}
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// Migrations wraps Migration and has an internal index
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// to keep track of Migration order.
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type Migrations struct {
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index uintSlice
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migrations map[uint]map[Direction]*Migration
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}
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func NewMigrations() *Migrations {
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return &Migrations{
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index: make(uintSlice, 0),
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migrations: make(map[uint]map[Direction]*Migration),
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}
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}
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func (i *Migrations) Append(m *Migration) (ok bool) {
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if m == nil {
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return false
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}
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if i.migrations[m.Version] == nil {
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i.migrations[m.Version] = make(map[Direction]*Migration)
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}
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// reject duplicate versions
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if _, dup := i.migrations[m.Version][m.Direction]; dup {
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return false
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}
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i.migrations[m.Version][m.Direction] = m
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i.buildIndex()
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return true
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}
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func (i *Migrations) buildIndex() {
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i.index = make(uintSlice, 0, len(i.migrations))
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for version := range i.migrations {
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i.index = append(i.index, version)
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}
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sort.Slice(i.index, func(x, y int) bool {
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return i.index[x] < i.index[y]
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})
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}
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func (i *Migrations) First() (version uint, ok bool) {
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if len(i.index) == 0 {
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return 0, false
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}
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return i.index[0], true
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}
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func (i *Migrations) Prev(version uint) (prevVersion uint, ok bool) {
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pos := i.findPos(version)
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if pos >= 1 && len(i.index) > pos-1 {
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return i.index[pos-1], true
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}
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return 0, false
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}
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func (i *Migrations) Next(version uint) (nextVersion uint, ok bool) {
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pos := i.findPos(version)
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if pos >= 0 && len(i.index) > pos+1 {
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return i.index[pos+1], true
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}
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return 0, false
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}
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func (i *Migrations) Up(version uint) (m *Migration, ok bool) {
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if _, ok := i.migrations[version]; ok {
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if mx, ok := i.migrations[version][Up]; ok {
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return mx, true
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}
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}
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return nil, false
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}
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func (i *Migrations) Down(version uint) (m *Migration, ok bool) {
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if _, ok := i.migrations[version]; ok {
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if mx, ok := i.migrations[version][Down]; ok {
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return mx, true
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}
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}
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return nil, false
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}
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func (i *Migrations) findPos(version uint) int {
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if len(i.index) > 0 {
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ix := i.index.Search(version)
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if ix < len(i.index) && i.index[ix] == version {
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return ix
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}
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}
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return -1
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}
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type uintSlice []uint
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func (s uintSlice) Search(x uint) int {
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return sort.Search(len(s), func(i int) bool { return s[i] >= x })
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}
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