syncthing/lib/model/sharedpullerstate.go

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// Copyright (C) 2014 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package model
import (
"encoding/binary"
"io"
"time"
"github.com/pkg/errors"
"github.com/syncthing/syncthing/lib/fs"
"github.com/syncthing/syncthing/lib/osutil"
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"github.com/syncthing/syncthing/lib/protocol"
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"github.com/syncthing/syncthing/lib/sync"
)
// A sharedPullerState is kept for each file that is being synced and is kept
// updated along the way.
type sharedPullerState struct {
// Immutable, does not require locking
file protocol.FileInfo // The new file (desired end state)
fs fs.Filesystem
folder string
tempName string
realName string
reused int // Number of blocks reused from temporary file
ignorePerms bool
hasCurFile bool // Whether curFile is set
curFile protocol.FileInfo // The file as it exists now in our database
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sparse bool
created time.Time
fsync bool
// Mutable, must be locked for access
err error // The first error we hit
writer *lockedWriterAt // Wraps fd to prevent fd closing at the same time as writing
copyTotal int // Total number of copy actions for the whole job
pullTotal int // Total number of pull actions for the whole job
copyOrigin int // Number of blocks copied from the original file
copyOriginShifted int // Number of blocks copied from the original file but shifted
copyNeeded int // Number of copy actions still pending
pullNeeded int // Number of block pulls still pending
updated time.Time // Time when any of the counters above were last updated
closed bool // True if the file has been finalClosed.
available []int // Indexes of the blocks that are available in the temporary file
availableUpdated time.Time // Time when list of available blocks was last updated
mut sync.RWMutex // Protects the above
}
func newSharedPullerState(file protocol.FileInfo, fs fs.Filesystem, folderID, tempName string, blocks []protocol.BlockInfo, reused []int, ignorePerms, hasCurFile bool, curFile protocol.FileInfo, sparse bool, fsync bool) *sharedPullerState {
return &sharedPullerState{
file: file,
fs: fs,
folder: folderID,
tempName: tempName,
realName: file.Name,
copyTotal: len(blocks),
copyNeeded: len(blocks),
reused: len(reused),
updated: time.Now(),
available: reused,
availableUpdated: time.Now(),
ignorePerms: ignorePerms,
hasCurFile: hasCurFile,
curFile: curFile,
mut: sync.NewRWMutex(),
sparse: sparse,
fsync: fsync,
created: time.Now(),
}
}
// A momentary state representing the progress of the puller
type pullerProgress struct {
Total int `json:"total"`
Reused int `json:"reused"`
CopiedFromOrigin int `json:"copiedFromOrigin"`
CopiedFromOriginShifted int `json:"copiedFromOriginShifted"`
CopiedFromElsewhere int `json:"copiedFromElsewhere"`
Pulled int `json:"pulled"`
Pulling int `json:"pulling"`
BytesDone int64 `json:"bytesDone"`
BytesTotal int64 `json:"bytesTotal"`
}
// lockedWriterAt adds a lock to protect from closing the fd at the same time as writing.
// WriteAt() is goroutine safe by itself, but not against for example Close().
type lockedWriterAt struct {
mut sync.RWMutex
fd fs.File
}
// WriteAt itself is goroutine safe, thus just needs to acquire a read-lock to
// prevent closing concurrently (see SyncClose).
func (w *lockedWriterAt) WriteAt(p []byte, off int64) (n int, err error) {
w.mut.RLock()
defer w.mut.RUnlock()
return w.fd.WriteAt(p, off)
}
// SyncClose ensures that no more writes are happening before going ahead and
// syncing and closing the fd, thus needs to acquire a write-lock.
func (w *lockedWriterAt) SyncClose(fsync bool) error {
w.mut.Lock()
defer w.mut.Unlock()
if fsync {
if err := w.fd.Sync(); err != nil {
// Sync() is nice if it works but not worth failing the
// operation over if it fails.
l.Debugf("fsync failed: %v", err)
}
}
return w.fd.Close()
}
// tempFile returns the fd for the temporary file, reusing an open fd
// or creating the file as necessary.
func (s *sharedPullerState) tempFile() (*lockedWriterAt, error) {
s.mut.Lock()
defer s.mut.Unlock()
// If we've already hit an error, return early
if s.err != nil {
return nil, s.err
}
// If the temp file is already open, return the file descriptor
if s.writer != nil {
return s.writer, nil
}
if err := s.addWriterLocked(); err != nil {
s.failLocked(err)
return nil, err
}
return s.writer, nil
}
func (s *sharedPullerState) addWriterLocked() error {
return inWritableDir(s.tempFileInWritableDir, s.fs, s.tempName, s.ignorePerms)
}
// tempFileInWritableDir should only be called from tempFile.
func (s *sharedPullerState) tempFileInWritableDir(_ string) error {
// The permissions to use for the temporary file should be those of the
// final file, except we need user read & write at minimum. The
// permissions will be set to the final value later, but in the meantime
// we don't want to have a temporary file with looser permissions than
// the final outcome.
mode := fs.FileMode(s.file.Permissions) | 0600
if s.ignorePerms {
// When ignorePerms is set we use a very permissive mode and let the
// system umask filter it.
mode = 0666
}
// Attempt to create the temp file
// RDWR because of issue #2994.
flags := fs.OptReadWrite
if s.reused == 0 {
flags |= fs.OptCreate | fs.OptExclusive
} else if !s.ignorePerms {
// With sufficiently bad luck when exiting or crashing, we may have
// had time to chmod the temp file to read only state but not yet
// moved it to its final name. This leaves us with a read only temp
// file that we're going to try to reuse. To handle that, we need to
// make sure we have write permissions on the file before opening it.
//
// When ignorePerms is set we trust that the permissions are fine
// already and make no modification, as we would otherwise override
// what the umask dictates.
if err := s.fs.Chmod(s.tempName, mode); err != nil {
return errors.Wrap(err, "setting perms on temp file")
}
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}
fd, err := s.fs.OpenFile(s.tempName, flags, mode)
if err != nil {
return errors.Wrap(err, "opening temp file")
}
// Hide the temporary file
s.fs.Hide(s.tempName)
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// Don't truncate symlink files, as that will mean that the path will
// contain a bunch of nulls.
if s.sparse && !s.file.IsSymlink() {
size := s.file.Size
// Trailer added to encrypted files
if len(s.file.Encrypted) > 0 {
size += encryptionTrailerSize(s.file)
}
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// Truncate sets the size of the file. This creates a sparse file or a
// space reservation, depending on the underlying filesystem.
if err := fd.Truncate(size); err != nil {
// The truncate call failed. That can happen in some cases when
// space reservation isn't possible or over some network
// filesystems... This generally doesn't matter.
if s.reused > 0 {
// ... but if we are attempting to reuse a file we have a
// corner case when the old file is larger than the new one
// and we can't just overwrite blocks and let the old data
// linger at the end. In this case we attempt a delete of
// the file and hope for better luck next time, when we
// should come around with s.reused == 0.
fd.Close()
if remErr := s.fs.Remove(s.tempName); remErr != nil {
l.Debugln("failed to remove temporary file:", remErr)
}
return err
}
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}
}
// Same fd will be used by all writers
s.writer = &lockedWriterAt{sync.NewRWMutex(), fd}
return nil
}
// fail sets the error on the puller state compose of error, and marks the
// sharedPullerState as failed. Is a no-op when called on an already failed state.
func (s *sharedPullerState) fail(err error) {
s.mut.Lock()
defer s.mut.Unlock()
s.failLocked(err)
}
func (s *sharedPullerState) failLocked(err error) {
if s.err != nil || err == nil {
return
}
s.err = err
}
func (s *sharedPullerState) failed() error {
s.mut.RLock()
err := s.err
s.mut.RUnlock()
return err
}
func (s *sharedPullerState) copyDone(block protocol.BlockInfo) {
s.mut.Lock()
s.copyNeeded--
s.updated = time.Now()
s.available = append(s.available, int(block.Offset/int64(s.file.BlockSize())))
s.availableUpdated = time.Now()
Implement facility based logger, debugging via REST API This implements a new debug/trace infrastructure based on a slightly hacked up logger. Instead of the traditional "if debug { ... }" I've rewritten the logger to have no-op Debugln and Debugf, unless debugging has been enabled for a given "facility". The "facility" is just a string, typically a package name. This will be slightly slower than before; but not that much as it's mostly a function call that returns immediately. For the cases where it matters (the Debugln takes a hex.Dump() of something for example, and it's not in a very occasional "if err != nil" branch) there is an l.ShouldDebug(facility) that is fast enough to be used like the old "if debug". The point of all this is that we can now toggle debugging for the various packages on and off at runtime. There's a new method /rest/system/debug that can be POSTed a set of facilities to enable and disable debug for, or GET from to get a list of facilities with descriptions and their current debug status. Similarly a /rest/system/log?since=... can grab the latest log entries, up to 250 of them (hardcoded constant in main.go) plus the initial few. Not implemented in this commit (but planned) is a simple debug GUI available on /debug that shows the current log in an easily pasteable format and has checkboxes to enable the various debug facilities. The debug instructions to a user then becomes "visit this URL, check these boxes, reproduce your problem, copy and paste the log". The actual log viewer on the hypothetical /debug URL can poll regularly for new log entries and this bypass the 250 line limit. The existing STTRACE=foo variable is still obeyed and just sets the start state of the system.
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l.Debugln("sharedPullerState", s.folder, s.file.Name, "copyNeeded ->", s.copyNeeded)
s.mut.Unlock()
}
func (s *sharedPullerState) copiedFromOrigin() {
s.mut.Lock()
s.copyOrigin++
s.updated = time.Now()
s.mut.Unlock()
}
func (s *sharedPullerState) copiedFromOriginShifted() {
s.mut.Lock()
s.copyOrigin++
s.copyOriginShifted++
s.updated = time.Now()
s.mut.Unlock()
}
func (s *sharedPullerState) pullStarted() {
s.mut.Lock()
s.copyTotal--
s.copyNeeded--
s.pullTotal++
s.pullNeeded++
s.updated = time.Now()
Implement facility based logger, debugging via REST API This implements a new debug/trace infrastructure based on a slightly hacked up logger. Instead of the traditional "if debug { ... }" I've rewritten the logger to have no-op Debugln and Debugf, unless debugging has been enabled for a given "facility". The "facility" is just a string, typically a package name. This will be slightly slower than before; but not that much as it's mostly a function call that returns immediately. For the cases where it matters (the Debugln takes a hex.Dump() of something for example, and it's not in a very occasional "if err != nil" branch) there is an l.ShouldDebug(facility) that is fast enough to be used like the old "if debug". The point of all this is that we can now toggle debugging for the various packages on and off at runtime. There's a new method /rest/system/debug that can be POSTed a set of facilities to enable and disable debug for, or GET from to get a list of facilities with descriptions and their current debug status. Similarly a /rest/system/log?since=... can grab the latest log entries, up to 250 of them (hardcoded constant in main.go) plus the initial few. Not implemented in this commit (but planned) is a simple debug GUI available on /debug that shows the current log in an easily pasteable format and has checkboxes to enable the various debug facilities. The debug instructions to a user then becomes "visit this URL, check these boxes, reproduce your problem, copy and paste the log". The actual log viewer on the hypothetical /debug URL can poll regularly for new log entries and this bypass the 250 line limit. The existing STTRACE=foo variable is still obeyed and just sets the start state of the system.
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l.Debugln("sharedPullerState", s.folder, s.file.Name, "pullNeeded start ->", s.pullNeeded)
s.mut.Unlock()
}
func (s *sharedPullerState) pullDone(block protocol.BlockInfo) {
s.mut.Lock()
s.pullNeeded--
s.updated = time.Now()
s.available = append(s.available, int(block.Offset/int64(s.file.BlockSize())))
s.availableUpdated = time.Now()
Implement facility based logger, debugging via REST API This implements a new debug/trace infrastructure based on a slightly hacked up logger. Instead of the traditional "if debug { ... }" I've rewritten the logger to have no-op Debugln and Debugf, unless debugging has been enabled for a given "facility". The "facility" is just a string, typically a package name. This will be slightly slower than before; but not that much as it's mostly a function call that returns immediately. For the cases where it matters (the Debugln takes a hex.Dump() of something for example, and it's not in a very occasional "if err != nil" branch) there is an l.ShouldDebug(facility) that is fast enough to be used like the old "if debug". The point of all this is that we can now toggle debugging for the various packages on and off at runtime. There's a new method /rest/system/debug that can be POSTed a set of facilities to enable and disable debug for, or GET from to get a list of facilities with descriptions and their current debug status. Similarly a /rest/system/log?since=... can grab the latest log entries, up to 250 of them (hardcoded constant in main.go) plus the initial few. Not implemented in this commit (but planned) is a simple debug GUI available on /debug that shows the current log in an easily pasteable format and has checkboxes to enable the various debug facilities. The debug instructions to a user then becomes "visit this URL, check these boxes, reproduce your problem, copy and paste the log". The actual log viewer on the hypothetical /debug URL can poll regularly for new log entries and this bypass the 250 line limit. The existing STTRACE=foo variable is still obeyed and just sets the start state of the system.
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l.Debugln("sharedPullerState", s.folder, s.file.Name, "pullNeeded done ->", s.pullNeeded)
s.mut.Unlock()
}
// finalClose atomically closes and returns closed status of a file. A true
// first return value means the file was closed and should be finished, with
// the error indicating the success or failure of the close. A false first
// return value indicates the file is not ready to be closed, or is already
// closed and should in either case not be finished off now.
func (s *sharedPullerState) finalClose() (bool, error) {
s.mut.Lock()
defer s.mut.Unlock()
if s.closed {
// Already closed
return false, nil
}
if s.pullNeeded+s.copyNeeded != 0 && s.err == nil {
// Not done yet, and not errored
return false, nil
}
if len(s.file.Encrypted) > 0 {
if err := s.finalizeEncrypted(); err != nil && s.err == nil {
// This is our error as we weren't errored before.
s.err = err
}
}
if s.writer != nil {
if err := s.writer.SyncClose(s.fsync); err != nil && s.err == nil {
// This is our error as we weren't errored before.
s.err = err
}
s.writer = nil
}
s.closed = true
// Unhide the temporary file when we close it, as it's likely to
// immediately be renamed to the final name. If this is a failed temp
// file we will also unhide it, but I'm fine with that as we're now
// leaving it around for potentially quite a while.
s.fs.Unhide(s.tempName)
return true, s.err
}
// finalizeEncrypted adds a trailer to the encrypted file containing the
// serialized FileInfo and the length of that FileInfo. When initializing a
// folder from encrypted data we can extract this FileInfo from the end of
// the file and regain the original metadata.
func (s *sharedPullerState) finalizeEncrypted() error {
if s.writer == nil {
if err := s.addWriterLocked(); err != nil {
return err
}
}
_, err := writeEncryptionTrailer(s.file, s.writer)
return err
}
// Returns the size of the written trailer.
func writeEncryptionTrailer(file protocol.FileInfo, writer io.WriterAt) (int64, error) {
// Here the file is in native format, while encryption happens in
// wire format (always slashes).
wireFile := file
wireFile.Name = osutil.NormalizedFilename(wireFile.Name)
trailerSize := encryptionTrailerSize(wireFile)
bs := make([]byte, trailerSize)
n, err := wireFile.MarshalTo(bs)
if err != nil {
return 0, err
}
binary.BigEndian.PutUint32(bs[n:], uint32(n))
bs = bs[:n+4]
if _, err := writer.WriteAt(bs, wireFile.Size); err != nil {
return 0, err
}
return trailerSize, nil
}
func encryptionTrailerSize(file protocol.FileInfo) int64 {
return int64(file.ProtoSize()) + 4
}
// Progress returns the momentarily progress for the puller
func (s *sharedPullerState) Progress() *pullerProgress {
s.mut.RLock()
defer s.mut.RUnlock()
total := s.reused + s.copyTotal + s.pullTotal
done := total - s.copyNeeded - s.pullNeeded
file := len(s.file.Blocks)
return &pullerProgress{
Total: total,
Reused: s.reused,
CopiedFromOrigin: s.copyOrigin,
CopiedFromElsewhere: s.copyTotal - s.copyNeeded - s.copyOrigin,
Pulled: s.pullTotal - s.pullNeeded,
Pulling: s.pullNeeded,
BytesTotal: blocksToSize(total, file, s.file.BlockSize(), s.file.Size),
BytesDone: blocksToSize(done, file, s.file.BlockSize(), s.file.Size),
}
}
// Updated returns the time when any of the progress related counters was last updated.
func (s *sharedPullerState) Updated() time.Time {
s.mut.RLock()
t := s.updated
s.mut.RUnlock()
return t
}
// AvailableUpdated returns the time last time list of available blocks was updated
func (s *sharedPullerState) AvailableUpdated() time.Time {
s.mut.RLock()
t := s.availableUpdated
s.mut.RUnlock()
return t
}
// Available returns blocks available in the current temporary file
func (s *sharedPullerState) Available() []int {
s.mut.RLock()
blocks := s.available
s.mut.RUnlock()
return blocks
}
func blocksToSize(blocks, blocksInFile, blockSize int, fileSize int64) int64 {
// The last/only block has somewhere between 1 and blockSize bytes. We do
// not know whether the smaller block is part of the blocks and use an
// estimate assuming a random chance that the small block is contained.
if blocksInFile == 0 {
return 0
}
return int64(blocks)*int64(blockSize) - (int64(blockSize)-fileSize%int64(blockSize))*int64(blocks)/int64(blocksInFile)
}