Update diff interface to use callback
The change computation will be done on the callers thread and use callbacks rather than running a goroutine and returning a channel. Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
This commit is contained in:
Derek McGowan
parent
aa3be3b0fe
commit
65e8c07847
3 changed files with 164 additions and 219 deletions
250
fs/diff.go
250
fs/diff.go
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@ -5,7 +5,8 @@ import (
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"os"
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"path/filepath"
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"strings"
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"sync"
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"golang.org/x/sync/errgroup"
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"github.com/Sirupsen/logrus"
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)
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@ -43,14 +44,13 @@ func (k ChangeKind) String() string {
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// Change represents single change between a diff and its parent.
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type Change struct {
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Kind ChangeKind
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Path string
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FileInfo os.FileInfo
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Source string
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Kind ChangeKind
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Path string
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}
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// Changes returns a stream of changes between the provided upper
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// directory and lower directory.
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// Changes computes changes between lower and upper calling the
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// given change function for each computed change. Callbacks
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// will be done serialially and order by path name.
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//
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// Changes are ordered by name and should be appliable in the
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// order in which they received.
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@ -71,70 +71,22 @@ type Change struct {
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// nanosecond values where one of those values is zero, the files will
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// be considered unchanged if the content is the same. This behavior
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// is to account for timestamp truncation during archiving.
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func Changes(ctx context.Context, upper, lower string) (context.Context, <-chan Change) {
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var (
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changes = make(chan Change)
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retCtx, cancel = context.WithCancel(ctx)
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)
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cc := &changeContext{
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Context: retCtx,
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func Changes(ctx context.Context, upper, lower string, ch func(Change, os.FileInfo) error) error {
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if lower == "" {
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logrus.Debugf("Using single walk diff for %s", upper)
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return addDirChanges(ctx, ch, upper)
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} else if diffOptions := detectDirDiff(upper, lower); diffOptions != nil {
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logrus.Debugf("Using single walk diff for %s from %s", diffOptions.diffDir, lower)
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return diffDirChanges(ctx, ch, lower, diffOptions)
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}
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go func() {
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var err error
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if lower == "" {
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logrus.Debugf("Using single walk diff for %s", upper)
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err = addDirChanges(ctx, changes, upper)
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} else if diffOptions := detectDirDiff(upper, lower); diffOptions != nil {
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logrus.Debugf("Using single walk diff for %s from %s", diffOptions.diffDir, lower)
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err = diffDirChanges(ctx, changes, lower, diffOptions)
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} else {
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logrus.Debugf("Using double walk diff for %s from %s", upper, lower)
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err = doubleWalkDiff(ctx, changes, upper, lower)
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}
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if err != nil {
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cc.errL.Lock()
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cc.err = err
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cc.errL.Unlock()
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cancel()
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}
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close(changes)
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}()
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return cc, changes
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logrus.Debugf("Using double walk diff for %s from %s", upper, lower)
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return doubleWalkDiff(ctx, ch, upper, lower)
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}
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// changeContext wraps a context to allow setting an error
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// directly from a change streamer to allow streams canceled
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// due to errors to propagate the error to the caller.
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type changeContext struct {
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context.Context
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type changeFn func(Change, os.FileInfo) error
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err error
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errL sync.Mutex
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}
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func (cc *changeContext) Err() error {
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cc.errL.Lock()
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if cc.err != nil {
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return cc.err
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}
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cc.errL.Unlock()
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return cc.Context.Err()
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}
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func sendChange(ctx context.Context, changes chan<- Change, change Change) error {
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select {
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case <-ctx.Done():
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return ctx.Err()
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case changes <- change:
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return nil
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}
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}
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func addDirChanges(ctx context.Context, changes chan<- Change, root string) error {
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func addDirChanges(ctx context.Context, changes changeFn, root string) error {
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return filepath.Walk(root, func(path string, f os.FileInfo, err error) error {
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if err != nil {
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return err
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@ -154,13 +106,11 @@ func addDirChanges(ctx context.Context, changes chan<- Change, root string) erro
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}
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change := Change{
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Path: path,
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Kind: ChangeKindAdd,
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FileInfo: f,
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Source: filepath.Join(root, path),
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Path: path,
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Kind: ChangeKindAdd,
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}
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return sendChange(ctx, changes, change)
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return changes(change, f)
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})
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}
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@ -173,7 +123,7 @@ type diffDirOptions struct {
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}
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// diffDirChanges walks the diff directory and compares changes against the lower.
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func diffDirChanges(ctx context.Context, changes chan<- Change, lower string, o *diffDirOptions) error {
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func diffDirChanges(ctx context.Context, changes changeFn, lower string, o *diffDirOptions) error {
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changedDirs := make(map[string]struct{})
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return filepath.Walk(o.diffDir, func(path string, f os.FileInfo, err error) error {
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if err != nil {
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@ -215,11 +165,10 @@ func diffDirChanges(ctx context.Context, changes chan<- Change, lower string, o
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if deletedFile != "" {
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change.Path = deletedFile
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change.Kind = ChangeKindDelete
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f = nil
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} else {
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// Otherwise, the file was added
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change.Kind = ChangeKindAdd
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change.FileInfo = f
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change.Source = filepath.Join(o.diffDir, path)
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// ...Unless it already existed in a lower, in which case, it's a modification
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stat, err := os.Stat(filepath.Join(lower, path))
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@ -256,105 +205,108 @@ func diffDirChanges(ctx context.Context, changes chan<- Change, lower string, o
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return err
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}
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dirChange := Change{
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Path: parent,
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Kind: ChangeKindModify,
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FileInfo: pi,
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Source: filepath.Join(o.diffDir, parent),
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Path: parent,
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Kind: ChangeKindModify,
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}
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if err := sendChange(ctx, changes, dirChange); err != nil {
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if err := changes(dirChange, pi); err != nil {
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return err
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}
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changedDirs[parent] = struct{}{}
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}
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}
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return sendChange(ctx, changes, change)
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return changes(change, f)
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})
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}
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// doubleWalkDiff walks both directories to create a diff
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func doubleWalkDiff(ctx context.Context, changes chan<- Change, upper, lower string) (err error) {
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pathCtx, cancel := context.WithCancel(ctx)
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defer func() {
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if err != nil {
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cancel()
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}
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}()
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func doubleWalkDiff(ctx context.Context, changes changeFn, upper, lower string) (err error) {
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g, ctx := errgroup.WithContext(ctx)
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var (
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w1 = pathWalker(pathCtx, lower)
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w2 = pathWalker(pathCtx, upper)
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c1 = make(chan *currentPath)
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c2 = make(chan *currentPath)
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f1, f2 *currentPath
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rmdir string
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)
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g.Go(func() error {
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defer close(c1)
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return pathWalk(ctx, lower, c1)
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})
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g.Go(func() error {
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defer close(c2)
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return pathWalk(ctx, upper, c2)
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})
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g.Go(func() error {
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for c1 != nil || c2 != nil {
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if f1 == nil && c1 != nil {
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f1, err = nextPath(ctx, c1)
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if err != nil {
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return err
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}
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if f1 == nil {
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c1 = nil
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}
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}
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for w1 != nil || w2 != nil {
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if f1 == nil && w1 != nil {
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f1, err = nextPath(w1)
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if err != nil {
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return err
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if f2 == nil && c2 != nil {
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f2, err = nextPath(ctx, c2)
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if err != nil {
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return err
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}
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if f2 == nil {
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c2 = nil
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}
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}
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if f1 == nil {
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w1 = nil
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if f1 == nil && f2 == nil {
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continue
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}
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}
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if f2 == nil && w2 != nil {
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f2, err = nextPath(w2)
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if err != nil {
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return err
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}
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if f2 == nil {
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w2 = nil
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}
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}
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if f1 == nil && f2 == nil {
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continue
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}
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c := pathChange(f1, f2)
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switch c.Kind {
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case ChangeKindAdd:
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if rmdir != "" {
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rmdir = ""
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}
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c.FileInfo = f2.f
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c.Source = filepath.Join(upper, c.Path)
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f2 = nil
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case ChangeKindDelete:
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// Check if this file is already removed by being
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// under of a removed directory
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if rmdir != "" && strings.HasPrefix(f1.path, rmdir) {
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var f os.FileInfo
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c := pathChange(f1, f2)
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switch c.Kind {
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case ChangeKindAdd:
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if rmdir != "" {
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rmdir = ""
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}
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f = f2.f
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f2 = nil
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case ChangeKindDelete:
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// Check if this file is already removed by being
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// under of a removed directory
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if rmdir != "" && strings.HasPrefix(f1.path, rmdir) {
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f1 = nil
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continue
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} else if rmdir == "" && f1.f.IsDir() {
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rmdir = f1.path + string(os.PathSeparator)
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} else if rmdir != "" {
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rmdir = ""
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}
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f1 = nil
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continue
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} else if rmdir == "" && f1.f.IsDir() {
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rmdir = f1.path + string(os.PathSeparator)
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} else if rmdir != "" {
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rmdir = ""
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case ChangeKindModify:
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same, err := sameFile(f1, f2)
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if err != nil {
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return err
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}
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if f1.f.IsDir() && !f2.f.IsDir() {
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rmdir = f1.path + string(os.PathSeparator)
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} else if rmdir != "" {
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rmdir = ""
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}
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f = f2.f
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f1 = nil
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f2 = nil
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if same {
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continue
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}
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}
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f1 = nil
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case ChangeKindModify:
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same, err := sameFile(f1, f2)
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if err != nil {
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if err := changes(c, f); err != nil {
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return err
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}
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if f1.f.IsDir() && !f2.f.IsDir() {
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rmdir = f1.path + string(os.PathSeparator)
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} else if rmdir != "" {
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rmdir = ""
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}
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c.FileInfo = f2.f
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c.Source = filepath.Join(upper, c.Path)
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f1 = nil
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f2 = nil
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if same {
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continue
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}
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}
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if err := sendChange(ctx, changes, c); err != nil {
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return err
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}
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}
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return nil
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})
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return nil
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return g.Wait()
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}
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