rclone/fs/march/march.go
Nick Craig-Wood 11da2a6c9b Break the fs package up into smaller parts.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.

The new code layout is documented in CONTRIBUTING.
2018-01-15 17:51:14 +00:00

406 lines
10 KiB
Go

// Package march traverses two directories in lock step
package march
import (
"path"
"sort"
"strings"
"sync"
"github.com/ncw/rclone/fs"
"github.com/ncw/rclone/fs/filter"
"github.com/ncw/rclone/fs/list"
"github.com/ncw/rclone/fs/walk"
"golang.org/x/net/context"
"golang.org/x/text/unicode/norm"
)
// March holds the data used to traverse two Fs simultaneously,
// calling callback for each match
type March struct {
// parameters
ctx context.Context
fdst fs.Fs
fsrc fs.Fs
dir string
callback Marcher
// internal state
srcListDir listDirFn // function to call to list a directory in the src
dstListDir listDirFn // function to call to list a directory in the dst
transforms []matchTransformFn
}
// Marcher is called on each match
type Marcher interface {
// SrcOnly is called for a DirEntry found only in the source
SrcOnly(src fs.DirEntry) (recurse bool)
// DstOnly is called for a DirEntry found only in the destination
DstOnly(dst fs.DirEntry) (recurse bool)
// Match is called for a DirEntry found both in the source and destination
Match(dst, src fs.DirEntry) (recurse bool)
}
// New sets up a march over fsrc, and fdst calling back callback for each match
func New(ctx context.Context, fdst, fsrc fs.Fs, dir string, callback Marcher) *March {
m := &March{
ctx: ctx,
fdst: fdst,
fsrc: fsrc,
dir: dir,
callback: callback,
}
m.srcListDir = m.makeListDir(fsrc, false)
m.dstListDir = m.makeListDir(fdst, filter.Active.Opt.DeleteExcluded)
// Now create the matching transform
// ..normalise the UTF8 first
m.transforms = append(m.transforms, norm.NFC.String)
// ..if destination is caseInsensitive then make it lower case
// case Insensitive | src | dst | lower case compare |
// | No | No | No |
// | Yes | No | No |
// | No | Yes | Yes |
// | Yes | Yes | Yes |
if fdst.Features().CaseInsensitive {
m.transforms = append(m.transforms, strings.ToLower)
}
return m
}
// list a directory into entries, err
type listDirFn func(dir string) (entries fs.DirEntries, err error)
// makeListDir makes a listing function for the given fs and includeAll flags
func (m *March) makeListDir(f fs.Fs, includeAll bool) listDirFn {
if !fs.Config.UseListR || f.Features().ListR == nil {
return func(dir string) (entries fs.DirEntries, err error) {
return list.DirSorted(f, includeAll, dir)
}
}
var (
mu sync.Mutex
started bool
dirs walk.DirTree
dirsErr error
)
return func(dir string) (entries fs.DirEntries, err error) {
mu.Lock()
defer mu.Unlock()
if !started {
dirs, dirsErr = walk.NewDirTree(f, m.dir, includeAll, fs.Config.MaxDepth)
started = true
}
if dirsErr != nil {
return nil, dirsErr
}
entries, ok := dirs[dir]
if !ok {
err = fs.ErrorDirNotFound
} else {
delete(dirs, dir)
}
return entries, err
}
}
// listDirJob describe a directory listing that needs to be done
type listDirJob struct {
srcRemote string
dstRemote string
srcDepth int
dstDepth int
noSrc bool
noDst bool
}
// Run starts the matching process off
func (m *March) Run() {
srcDepth := fs.Config.MaxDepth
if srcDepth < 0 {
srcDepth = fs.MaxLevel
}
dstDepth := srcDepth
if filter.Active.Opt.DeleteExcluded {
dstDepth = fs.MaxLevel
}
// Start some directory listing go routines
var wg sync.WaitGroup // sync closing of go routines
var traversing sync.WaitGroup // running directory traversals
in := make(chan listDirJob, fs.Config.Checkers)
for i := 0; i < fs.Config.Checkers; i++ {
wg.Add(1)
go func() {
defer wg.Done()
for {
select {
case <-m.ctx.Done():
return
case job, ok := <-in:
if !ok {
return
}
jobs := m.processJob(job)
if len(jobs) > 0 {
traversing.Add(len(jobs))
go func() {
// Now we have traversed this directory, send these
// jobs off for traversal in the background
for _, newJob := range jobs {
in <- newJob
}
}()
}
traversing.Done()
}
}
}()
}
// Start the process
traversing.Add(1)
in <- listDirJob{
srcRemote: m.dir,
srcDepth: srcDepth - 1,
dstRemote: m.dir,
dstDepth: dstDepth - 1,
}
traversing.Wait()
close(in)
wg.Wait()
}
// Check to see if the context has been cancelled
func (m *March) aborting() bool {
select {
case <-m.ctx.Done():
return true
default:
}
return false
}
// matchEntry is an entry plus transformed name
type matchEntry struct {
entry fs.DirEntry
leaf string
name string
}
// matchEntries contains many matchEntry~s
type matchEntries []matchEntry
// Len is part of sort.Interface.
func (es matchEntries) Len() int { return len(es) }
// Swap is part of sort.Interface.
func (es matchEntries) Swap(i, j int) { es[i], es[j] = es[j], es[i] }
// Less is part of sort.Interface.
//
// Compare in order (name, leaf, remote)
func (es matchEntries) Less(i, j int) bool {
ei, ej := &es[i], &es[j]
if ei.name == ej.name {
if ei.leaf == ej.leaf {
return ei.entry.Remote() < ej.entry.Remote()
}
return ei.leaf < ej.leaf
}
return ei.name < ej.name
}
// Sort the directory entries by (name, leaf, remote)
//
// We use a stable sort here just in case there are
// duplicates. Assuming the remote delivers the entries in a
// consistent order, this will give the best user experience
// in syncing as it will use the first entry for the sync
// comparison.
func (es matchEntries) sort() {
sort.Stable(es)
}
// make a matchEntries from a newMatch entries
func newMatchEntries(entries fs.DirEntries, transforms []matchTransformFn) matchEntries {
es := make(matchEntries, len(entries))
for i := range es {
es[i].entry = entries[i]
name := path.Base(entries[i].Remote())
es[i].leaf = name
for _, transform := range transforms {
name = transform(name)
}
es[i].name = name
}
es.sort()
return es
}
// matchPair is a matched pair of direntries returned by matchListings
type matchPair struct {
src, dst fs.DirEntry
}
// matchTransformFn converts a name into a form which is used for
// comparison in matchListings.
type matchTransformFn func(name string) string
// Process the two listings, matching up the items in the two slices
// using the transform function on each name first.
//
// Into srcOnly go Entries which only exist in the srcList
// Into dstOnly go Entries which only exist in the dstList
// Into matches go matchPair's of src and dst which have the same name
//
// This checks for duplicates and checks the list is sorted.
func matchListings(srcListEntries, dstListEntries fs.DirEntries, transforms []matchTransformFn) (srcOnly fs.DirEntries, dstOnly fs.DirEntries, matches []matchPair) {
srcList := newMatchEntries(srcListEntries, transforms)
dstList := newMatchEntries(dstListEntries, transforms)
for iSrc, iDst := 0, 0; ; iSrc, iDst = iSrc+1, iDst+1 {
var src, dst fs.DirEntry
var srcName, dstName string
if iSrc < len(srcList) {
src = srcList[iSrc].entry
srcName = srcList[iSrc].name
}
if iDst < len(dstList) {
dst = dstList[iDst].entry
dstName = dstList[iDst].name
}
if src == nil && dst == nil {
break
}
if src != nil && iSrc > 0 {
prev := srcList[iSrc-1].name
if srcName == prev {
fs.Logf(src, "Duplicate %s found in source - ignoring", fs.DirEntryType(src))
iDst-- // ignore the src and retry the dst
continue
} else if srcName < prev {
// this should never happen since we sort the listings
panic("Out of order listing in source")
}
}
if dst != nil && iDst > 0 {
prev := dstList[iDst-1].name
if dstName == prev {
fs.Logf(dst, "Duplicate %s found in destination - ignoring", fs.DirEntryType(dst))
iSrc-- // ignore the dst and retry the src
continue
} else if dstName < prev {
// this should never happen since we sort the listings
panic("Out of order listing in destination")
}
}
if src != nil && dst != nil {
if srcName < dstName {
dst = nil
iDst-- // retry the dst
} else if srcName > dstName {
src = nil
iSrc-- // retry the src
}
}
// Debugf(nil, "src = %v, dst = %v", src, dst)
switch {
case src == nil && dst == nil:
// do nothing
case src == nil:
dstOnly = append(dstOnly, dst)
case dst == nil:
srcOnly = append(srcOnly, src)
default:
matches = append(matches, matchPair{src: src, dst: dst})
}
}
return
}
// processJob processes a listDirJob listing the source and
// destination directories, comparing them and returning a slice of
// more jobs
//
// returns errors using processError
func (m *March) processJob(job listDirJob) (jobs []listDirJob) {
var (
srcList, dstList fs.DirEntries
srcListErr, dstListErr error
wg sync.WaitGroup
)
// List the src and dst directories
if !job.noSrc {
wg.Add(1)
go func() {
defer wg.Done()
srcList, srcListErr = m.srcListDir(job.srcRemote)
}()
}
if !job.noDst {
wg.Add(1)
go func() {
defer wg.Done()
dstList, dstListErr = m.dstListDir(job.dstRemote)
}()
}
// Wait for listings to complete and report errors
wg.Wait()
if srcListErr != nil {
fs.Errorf(job.srcRemote, "error reading source directory: %v", srcListErr)
fs.CountError(srcListErr)
return nil
}
if dstListErr == fs.ErrorDirNotFound {
// Copy the stuff anyway
} else if dstListErr != nil {
fs.Errorf(job.dstRemote, "error reading destination directory: %v", dstListErr)
fs.CountError(dstListErr)
return nil
}
// Work out what to do and do it
srcOnly, dstOnly, matches := matchListings(srcList, dstList, m.transforms)
for _, src := range srcOnly {
if m.aborting() {
return nil
}
recurse := m.callback.SrcOnly(src)
if recurse && job.srcDepth > 0 {
jobs = append(jobs, listDirJob{
srcRemote: src.Remote(),
srcDepth: job.srcDepth - 1,
noDst: true,
})
}
}
for _, dst := range dstOnly {
if m.aborting() {
return nil
}
recurse := m.callback.DstOnly(dst)
if recurse && job.dstDepth > 0 {
jobs = append(jobs, listDirJob{
dstRemote: dst.Remote(),
dstDepth: job.dstDepth - 1,
noSrc: true,
})
}
}
for _, match := range matches {
if m.aborting() {
return nil
}
recurse := m.callback.Match(match.dst, match.src)
if recurse && job.srcDepth > 0 && job.dstDepth > 0 {
jobs = append(jobs, listDirJob{
srcRemote: match.src.Remote(),
dstRemote: match.dst.Remote(),
srcDepth: job.srcDepth - 1,
dstDepth: job.dstDepth - 1,
})
}
}
return jobs
}