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authorTaru Karttunen <taruti@taruti.net>2017-09-12 19:06:47 +0300
committerJeremy Stribling <strib@alum.mit.edu>2017-11-27 11:43:01 -0800
commit3834e571da171844efecc4e26fd89082419079a1 (patch)
tree32756a7a66fcf746574393fbba478bc8aac7b368 /storage/filesystem/internal/dotgit/dotgit.go
parent702718fd59be0aa4b8bf8492403c465107ca17af (diff)
downloadgo-git-3834e571da171844efecc4e26fd89082419079a1.tar.gz
Use optionally locking when updating refs
Diffstat (limited to 'storage/filesystem/internal/dotgit/dotgit.go')
-rw-r--r--storage/filesystem/internal/dotgit/dotgit.go62
1 files changed, 53 insertions, 9 deletions
diff --git a/storage/filesystem/internal/dotgit/dotgit.go b/storage/filesystem/internal/dotgit/dotgit.go
index 0c9cd33..e60ffca 100644
--- a/storage/filesystem/internal/dotgit/dotgit.go
+++ b/storage/filesystem/internal/dotgit/dotgit.go
@@ -5,6 +5,7 @@ import (
"bufio"
"errors"
"fmt"
+ "io"
stdioutil "io/ioutil"
"os"
"strings"
@@ -239,7 +240,39 @@ func (d *DotGit) Object(h plumbing.Hash) (billy.File, error) {
return d.fs.Open(file)
}
-func (d *DotGit) SetRef(r *plumbing.Reference) error {
+func (d *DotGit) readReferenceFrom(rd io.Reader, name string) (ref *plumbing.Reference, err error) {
+ b, err := stdioutil.ReadAll(rd)
+ if err != nil {
+ return nil, err
+ }
+
+ line := strings.TrimSpace(string(b))
+ return plumbing.NewReferenceFromStrings(name, line), nil
+}
+
+func (d *DotGit) checkReferenceAndTruncate(f billy.File, old *plumbing.Reference) error {
+ if old == nil {
+ return nil
+ }
+ ref, err := d.readReferenceFrom(f, old.Name().String())
+ if err != nil {
+ return err
+ }
+ if ref.Hash() != old.Hash() {
+ return fmt.Errorf("reference has changed concurrently")
+ }
+ _, err = f.Seek(0, io.SeekStart)
+ if err != nil {
+ return err
+ }
+ err = f.Truncate(0)
+ if err != nil {
+ return err
+ }
+ return nil
+}
+
+func (d *DotGit) SetRef(r, old *plumbing.Reference) error {
var content string
switch r.Type() {
case plumbing.SymbolicReference:
@@ -248,13 +281,30 @@ func (d *DotGit) SetRef(r *plumbing.Reference) error {
content = fmt.Sprintln(r.Hash().String())
}
- f, err := d.fs.Create(r.Name().String())
+ // If we are not checking an old ref, just truncate the file.
+ mode := os.O_RDWR | os.O_CREATE
+ if old == nil {
+ mode |= os.O_TRUNC
+ }
+
+ f, err := d.fs.OpenFile(r.Name().String(), mode, 0666)
if err != nil {
return err
}
defer ioutil.CheckClose(f, &err)
+ err = f.Lock()
+ if err != nil {
+ return err
+ }
+
+ // this is a no-op to call even when old is nil.
+ err = d.checkReferenceAndTruncate(f, old)
+ if err != nil {
+ return err
+ }
+
_, err = f.Write([]byte(content))
return err
}
@@ -493,13 +543,7 @@ func (d *DotGit) readReferenceFile(path, name string) (ref *plumbing.Reference,
}
defer ioutil.CheckClose(f, &err)
- b, err := stdioutil.ReadAll(f)
- if err != nil {
- return nil, err
- }
-
- line := strings.TrimSpace(string(b))
- return plumbing.NewReferenceFromStrings(name, line), nil
+ return d.readReferenceFrom(f, name)
}
// Module return a billy.Filesystem poiting to the module folder