356 lines
11 KiB
Go
356 lines
11 KiB
Go
// 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
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at http://mozilla.org/MPL/2.0/.
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package model
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import (
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"io"
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"os"
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"path/filepath"
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"time"
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"github.com/syncthing/syncthing/lib/protocol"
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"github.com/syncthing/syncthing/lib/sync"
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)
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// A sharedPullerState is kept for each file that is being synced and is kept
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// updated along the way.
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type sharedPullerState struct {
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// Immutable, does not require locking
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file protocol.FileInfo // The new file (desired end state)
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folder string
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tempName string
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realName string
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reused int // Number of blocks reused from temporary file
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ignorePerms bool
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version protocol.Vector // The current (old) version
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sparse bool
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created time.Time
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// Mutable, must be locked for access
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err error // The first error we hit
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fd *os.File // The fd of the temp file
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copyTotal int // Total number of copy actions for the whole job
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pullTotal int // Total number of pull actions for the whole job
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copyOrigin int // Number of blocks copied from the original file
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copyOriginShifted int // Number of blocks copied from the original file but shifted
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copyNeeded int // Number of copy actions still pending
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pullNeeded int // Number of block pulls still pending
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updated time.Time // Time when any of the counters above were last updated
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closed bool // True if the file has been finalClosed.
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available []int32 // Indexes of the blocks that are available in the temporary file
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availableUpdated time.Time // Time when list of available blocks was last updated
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mut sync.RWMutex // Protects the above
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}
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// A momentary state representing the progress of the puller
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type pullerProgress struct {
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Total int `json:"total"`
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Reused int `json:"reused"`
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CopiedFromOrigin int `json:"copiedFromOrigin"`
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CopiedFromOriginShifted int `json:"copiedFromOriginShifted"`
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CopiedFromElsewhere int `json:"copiedFromElsewhere"`
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Pulled int `json:"pulled"`
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Pulling int `json:"pulling"`
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BytesDone int64 `json:"bytesDone"`
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BytesTotal int64 `json:"bytesTotal"`
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}
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// A lockedWriterAt synchronizes WriteAt calls with an external mutex.
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// WriteAt() is goroutine safe by itself, but not against for example Close().
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type lockedWriterAt struct {
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mut *sync.RWMutex
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wr io.WriterAt
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}
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func (w lockedWriterAt) WriteAt(p []byte, off int64) (n int, err error) {
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(*w.mut).Lock()
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defer (*w.mut).Unlock()
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return w.wr.WriteAt(p, off)
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}
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// tempFile returns the fd for the temporary file, reusing an open fd
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// or creating the file as necessary.
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func (s *sharedPullerState) tempFile() (io.WriterAt, error) {
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s.mut.Lock()
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defer s.mut.Unlock()
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// If we've already hit an error, return early
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if s.err != nil {
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return nil, s.err
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}
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// If the temp file is already open, return the file descriptor
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if s.fd != nil {
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return lockedWriterAt{&s.mut, s.fd}, nil
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}
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// Ensure that the parent directory is writable. This is
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// osutil.InWritableDir except we need to do more stuff so we duplicate it
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// here.
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dir := filepath.Dir(s.tempName)
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if info, err := os.Stat(dir); err != nil {
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if os.IsNotExist(err) {
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// XXX: This works around a bug elsewhere, a race condition when
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// things are deleted while being synced. However that happens, we
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// end up with a directory for "foo" with the delete bit, but a
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// file "foo/bar" that we want to sync. We never create the
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// directory, and hence fail to create the file and end up looping
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// forever on it. This breaks that by creating the directory; on
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// next scan it'll be found and the delete bit on it is removed.
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// The user can then clean up as they like...
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l.Infoln("Resurrecting directory", dir)
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if err := os.MkdirAll(dir, 0755); err != nil {
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s.failLocked("resurrect dir", err)
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return nil, err
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}
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} else {
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s.failLocked("dst stat dir", err)
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return nil, err
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}
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} else if info.Mode()&0200 == 0 {
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err := os.Chmod(dir, 0755)
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if !s.ignorePerms && err == nil {
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defer func() {
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err := os.Chmod(dir, info.Mode().Perm())
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if err != nil {
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panic(err)
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}
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}()
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}
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}
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// The permissions to use for the temporary file should be those of the
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// final file, except we need user read & write at minimum. The
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// permissions will be set to the final value later, but in the meantime
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// we don't want to have a temporary file with looser permissions than
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// the final outcome.
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mode := os.FileMode(s.file.Permissions) | 0600
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if s.ignorePerms {
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// When ignorePerms is set we use a very permissive mode and let the
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// system umask filter it.
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mode = 0666
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}
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// Attempt to create the temp file
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// RDWR because of issue #2994.
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flags := os.O_RDWR
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if s.reused == 0 {
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flags |= os.O_CREATE | os.O_EXCL
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} else if !s.ignorePerms {
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// With sufficiently bad luck when exiting or crashing, we may have
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// had time to chmod the temp file to read only state but not yet
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// moved it to it's final name. This leaves us with a read only temp
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// file that we're going to try to reuse. To handle that, we need to
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// make sure we have write permissions on the file before opening it.
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//
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// When ignorePerms is set we trust that the permissions are fine
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// already and make no modification, as we would otherwise override
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// what the umask dictates.
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if err := os.Chmod(s.tempName, mode); err != nil {
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s.failLocked("dst create chmod", err)
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return nil, err
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}
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}
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fd, err := os.OpenFile(s.tempName, flags, mode)
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if err != nil {
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s.failLocked("dst create", err)
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return nil, err
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}
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// Don't truncate symlink files, as that will mean that the path will
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// contain a bunch of nulls.
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if s.sparse && !s.file.IsSymlink() {
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// Truncate sets the size of the file. This creates a sparse file or a
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// space reservation, depending on the underlying filesystem.
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if err := fd.Truncate(s.file.Size); err != nil {
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s.failLocked("dst truncate", err)
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return nil, err
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}
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}
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// Same fd will be used by all writers
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s.fd = fd
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return lockedWriterAt{&s.mut, s.fd}, nil
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}
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// sourceFile opens the existing source file for reading
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func (s *sharedPullerState) sourceFile() (*os.File, error) {
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s.mut.Lock()
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defer s.mut.Unlock()
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// If we've already hit an error, return early
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if s.err != nil {
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return nil, s.err
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}
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// Attempt to open the existing file
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fd, err := os.Open(s.realName)
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if err != nil {
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s.failLocked("src open", err)
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return nil, err
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}
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return fd, nil
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}
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// earlyClose prints a warning message composed of the context and
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// error, and marks the sharedPullerState as failed. Is a no-op when called on
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// an already failed state.
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func (s *sharedPullerState) fail(context string, err error) {
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s.mut.Lock()
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defer s.mut.Unlock()
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s.failLocked(context, err)
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}
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func (s *sharedPullerState) failLocked(context string, err error) {
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if s.err != nil {
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return
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}
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l.Infof("Puller (folder %q, file %q): %s: %v", s.folder, s.file.Name, context, err)
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s.err = err
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}
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func (s *sharedPullerState) failed() error {
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s.mut.RLock()
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err := s.err
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s.mut.RUnlock()
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return err
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}
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func (s *sharedPullerState) copyDone(block protocol.BlockInfo) {
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s.mut.Lock()
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s.copyNeeded--
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s.updated = time.Now()
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s.available = append(s.available, int32(block.Offset/protocol.BlockSize))
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s.availableUpdated = time.Now()
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l.Debugln("sharedPullerState", s.folder, s.file.Name, "copyNeeded ->", s.copyNeeded)
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s.mut.Unlock()
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}
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func (s *sharedPullerState) copiedFromOrigin() {
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s.mut.Lock()
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s.copyOrigin++
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s.updated = time.Now()
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s.mut.Unlock()
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}
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func (s *sharedPullerState) copiedFromOriginShifted() {
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s.mut.Lock()
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s.copyOrigin++
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s.copyOriginShifted++
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s.updated = time.Now()
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s.mut.Unlock()
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}
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func (s *sharedPullerState) pullStarted() {
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s.mut.Lock()
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s.copyTotal--
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s.copyNeeded--
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s.pullTotal++
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s.pullNeeded++
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s.updated = time.Now()
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l.Debugln("sharedPullerState", s.folder, s.file.Name, "pullNeeded start ->", s.pullNeeded)
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s.mut.Unlock()
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}
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func (s *sharedPullerState) pullDone(block protocol.BlockInfo) {
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s.mut.Lock()
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s.pullNeeded--
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s.updated = time.Now()
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s.available = append(s.available, int32(block.Offset/protocol.BlockSize))
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s.availableUpdated = time.Now()
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l.Debugln("sharedPullerState", s.folder, s.file.Name, "pullNeeded done ->", s.pullNeeded)
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s.mut.Unlock()
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}
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// finalClose atomically closes and returns closed status of a file. A true
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// first return value means the file was closed and should be finished, with
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// the error indicating the success or failure of the close. A false first
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// return value indicates the file is not ready to be closed, or is already
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// closed and should in either case not be finished off now.
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func (s *sharedPullerState) finalClose() (bool, error) {
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s.mut.Lock()
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defer s.mut.Unlock()
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if s.closed {
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// Already closed
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return false, nil
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}
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if s.pullNeeded+s.copyNeeded != 0 && s.err == nil {
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// Not done yet, and not errored
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return false, nil
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}
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if s.fd != nil {
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if closeErr := s.fd.Close(); closeErr != nil && s.err == nil {
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// This is our error if we weren't errored before. Otherwise we
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// keep the earlier error.
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s.err = closeErr
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}
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s.fd = nil
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}
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s.closed = true
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return true, s.err
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}
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// Progress returns the momentarily progress for the puller
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func (s *sharedPullerState) Progress() *pullerProgress {
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s.mut.RLock()
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defer s.mut.RUnlock()
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total := s.reused + s.copyTotal + s.pullTotal
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done := total - s.copyNeeded - s.pullNeeded
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return &pullerProgress{
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Total: total,
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Reused: s.reused,
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CopiedFromOrigin: s.copyOrigin,
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CopiedFromElsewhere: s.copyTotal - s.copyNeeded - s.copyOrigin,
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Pulled: s.pullTotal - s.pullNeeded,
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Pulling: s.pullNeeded,
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BytesTotal: blocksToSize(total),
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BytesDone: blocksToSize(done),
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}
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}
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// Updated returns the time when any of the progress related counters was last updated.
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func (s *sharedPullerState) Updated() time.Time {
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s.mut.RLock()
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t := s.updated
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s.mut.RUnlock()
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return t
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}
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// AvailableUpdated returns the time last time list of available blocks was updated
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func (s *sharedPullerState) AvailableUpdated() time.Time {
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s.mut.RLock()
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t := s.availableUpdated
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s.mut.RUnlock()
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return t
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}
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// Available returns blocks available in the current temporary file
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func (s *sharedPullerState) Available() []int32 {
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s.mut.RLock()
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blocks := s.available
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s.mut.RUnlock()
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return blocks
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}
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func blocksToSize(num int) int64 {
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if num < 2 {
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return protocol.BlockSize / 2
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}
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return int64(num-1)*protocol.BlockSize + protocol.BlockSize/2
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}
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