go/sqlite3
1
0
Fork 0
mirror of https://github.com/ncruces/go-sqlite3.git synced 2026-01-11 21:49:13 +00:00
Code Issues Packages Projects Releases Wiki Activity

Dot file locking. (#179)

Browse Source
This commit is contained in:
Nuno Cruces
2024-10-30 12:20:21 +00:00
committed by GitHub
parent 1ad1608228
commit b2e8636227
14 changed files with 178 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
.github/workflows/test.yml vendored
View File

@@ -9,6 +9,10 @@ on:
- '**.wasm.bz2'
pull_request:
branches: [ "main" ]
paths:
- '**.go'
- '**.wasm'
- '**.wasm.bz2'
workflow_dispatch:
jobs:
@@ -52,6 +56,10 @@ jobs:
run: go test -v -tags sqlite3_flock ./...
if: matrix.os == 'macos-latest'
- name: Test dot locks
run: go test -v -tags sqlite3_dotlk ./...
if: matrix.os == 'macos-latest'
- name: Test no shared memory
run: go test -v -tags sqlite3_noshm ./...
if: matrix.os == 'ubuntu-latest'

2
internal/util/mmap.go
View File

@@ -1,4 +1,4 @@
//go:build unix && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_noshm || sqlite3_nosys)
//go:build unix && !(sqlite3_noshm || sqlite3_nosys)
package util

2
internal/util/mmap_other.go
View File

@@ -1,4 +1,4 @@
//go:build !unix || !(386 || arm || amd64 || arm64 || riscv64 || ppc64le) || sqlite3_noshm || sqlite3_nosys
//go:build !unix || sqlite3_noshm || sqlite3_nosys
package util

19
vfs/README.md
View File

@@ -19,20 +19,19 @@ POSIX advisory locks, which SQLite uses on Unix, are
On Linux and macOS, this package uses
[OFD locks](https://www.gnu.org/software/libc/manual/html_node/Open-File-Description-Locks.html)
to synchronize access to database files.
OFD locks are fully compatible with POSIX advisory locks.
This package can also use
[BSD locks](https://man.freebsd.org/cgi/man.cgi?query=flock&sektion=2),
albeit with reduced concurrency (`BEGIN IMMEDIATE` behaves like `BEGIN EXCLUSIVE`).
On BSD, macOS, and illumos, BSD locks are fully compatible with POSIX advisory locks;
on Linux and z/OS, they are fully functional, but incompatible;
elsewhere, they are very likely broken.
BSD locks are the default on BSD and illumos,
but you can opt into them with the `sqlite3_flock` build tag.
On Windows, this package uses `LockFileEx` and `UnlockFileEx`,
like SQLite.
You can also opt into a cross platform locking implementation
with the `sqlite3_dotlk` build tag.
Otherwise, file locking is not supported, and you must use
[`nolock=1`](https://sqlite.org/uri.html#urinolock)
(or [`immutable=1`](https://sqlite.org/uri.html#uriimmutable))
@@ -86,8 +85,8 @@ The implementation is compatible with SQLite's
### Build Tags
The VFS can be customized with a few build tags:
- `sqlite3_flock` forces the use of BSD locks; it can be used on z/OS to enable locking,
and elsewhere to test BSD locks.
- `sqlite3_flock` forces the use of BSD locks.
- `sqlite3_dotlk` forces the use of dot-file locks.
- `sqlite3_nosys` prevents importing [`x/sys`](https://pkg.go.dev/golang.org/x/sys);
disables locking _and_ shared memory on all platforms.
- `sqlite3_noshm` disables shared memory on all platforms.
@@ -96,17 +95,19 @@ The VFS can be customized with a few build tags:
> The default configuration of this package is compatible with the standard
> [Unix and Windows SQLite VFSes](https://sqlite.org/vfs.html#multiple_vfses);
> `sqlite3_flock` builds are compatible with the
> [`unix-flock` VFS](https://sqlite.org/compile.html#enable_locking_style).
> [`unix-flock` VFS](https://sqlite.org/compile.html#enable_locking_style);
> `sqlite3_dotlk` builds are compatible with the
> [`unix-dotfile` VFS](https://sqlite.org/compile.html#enable_locking_style).
> If incompatible file locking is used, accessing databases concurrently with
> _other_ SQLite libraries will eventually corrupt data.
### Custom VFSes
- [`github.com/ncruces/go-sqlite3/vfs/adiantum`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs/adiantum)
wraps a VFS to offer encryption at rest.
- [`github.com/ncruces/go-sqlite3/vfs/memdb`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs/memdb)
implements an in-memory VFS.
- [`github.com/ncruces/go-sqlite3/vfs/readervfs`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs/readervfs)
implements a VFS for immutable databases.
- [`github.com/ncruces/go-sqlite3/vfs/adiantum`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs/adiantum)
wraps a VFS to offer encryption at rest.
- [`github.com/ncruces/go-sqlite3/vfs/xts`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs/xts)
wraps a VFS to offer encryption at rest.

13
vfs/file.go
View File

@@ -35,10 +35,10 @@ func testSymlinks(path string) error {
func (vfsOS) Delete(path string, syncDir bool) error {
err := os.Remove(path)
if errors.Is(err, fs.ErrNotExist) {
return _IOERR_DELETE_NOENT
}
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
return _IOERR_DELETE_NOENT
}
return err
}
if runtime.GOOS != "windows" && syncDir {
@@ -151,6 +151,7 @@ func (f *vfsFile) Close() error {
if f.shm != nil {
f.shm.Close()
}
f.Unlock(LOCK_NONE)
return f.File.Close()
}
@@ -206,10 +207,10 @@ func (f *vfsFile) HasMoved() (bool, error) {
return false, err
}
pi, err := os.Stat(f.Name())
if errors.Is(err, fs.ErrNotExist) {
return true, nil
}
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
return true, nil
}
return false, err
}
return !os.SameFile(fi, pi), nil

2
vfs/lock.go
View File

@@ -1,4 +1,4 @@
//go:build (linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && !sqlite3_nosys
//go:build ((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk
package vfs

2
vfs/lock_other.go
View File

@@ -1,4 +1,4 @@
//go:build !(linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) || sqlite3_nosys
//go:build !(((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk)
package vfs

2
vfs/os_bsd.go
View File

@@ -1,4 +1,4 @@
//go:build (freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && !sqlite3_nosys
//go:build ((freebsd || openbsd || netbsd || dragonfly || illumos) && !(sqlite3_dotlk || sqlite3_nosys)) || sqlite3_flock
package vfs

143
vfs/os_dotlk.go Normal file
View File

@@ -0,0 +1,143 @@
//go:build sqlite3_dotlk
package vfs
import (
"errors"
"io/fs"
"os"
"sync"
)
var (
// +checklocks:vfsDotLocksMtx
vfsDotLocks = map[string]*vfsDotLocker{}
vfsDotLocksMtx sync.Mutex
)
type vfsDotLocker struct {
shared int // +checklocks:vfsDotLocksMtx
pending *os.File // +checklocks:vfsDotLocksMtx
reserved *os.File // +checklocks:vfsDotLocksMtx
}
func osGetSharedLock(file *os.File) _ErrorCode {
vfsDotLocksMtx.Lock()
defer vfsDotLocksMtx.Unlock()
name := file.Name()
locker := vfsDotLocks[name]
if locker == nil {
err := os.Mkdir(name+".lock", 0777)
if errors.Is(err, fs.ErrExist) {
return _BUSY // Another process has the lock.
}
if err != nil {
return _IOERR_LOCK
}
locker = &vfsDotLocker{}
vfsDotLocks[name] = locker
}
if locker.pending != nil {
return _BUSY
}
locker.shared++
return _OK
}
func osGetReservedLock(file *os.File) _ErrorCode {
vfsDotLocksMtx.Lock()
defer vfsDotLocksMtx.Unlock()
name := file.Name()
locker := vfsDotLocks[name]
if locker == nil {
return _IOERR_LOCK
}
if locker.reserved != nil && locker.reserved != file {
return _BUSY
}
locker.reserved = file
return _OK
}
func osGetExclusiveLock(file *os.File, _ *LockLevel) _ErrorCode {
vfsDotLocksMtx.Lock()
defer vfsDotLocksMtx.Unlock()
name := file.Name()
locker := vfsDotLocks[name]
if locker == nil {
return _IOERR_LOCK
}
if locker.pending != nil && locker.pending != file {
return _BUSY
}
locker.pending = file
if locker.shared > 1 {
return _BUSY
}
return _OK
}
func osDowngradeLock(file *os.File, _ LockLevel) _ErrorCode {
vfsDotLocksMtx.Lock()
defer vfsDotLocksMtx.Unlock()
name := file.Name()
locker := vfsDotLocks[name]
if locker == nil {
return _IOERR_UNLOCK
}
if locker.reserved == file {
locker.reserved = nil
}
if locker.pending == file {
locker.pending = nil
}
return _OK
}
func osReleaseLock(file *os.File, state LockLevel) _ErrorCode {
vfsDotLocksMtx.Lock()
defer vfsDotLocksMtx.Unlock()
name := file.Name()
locker := vfsDotLocks[name]
if locker == nil {
return _IOERR_UNLOCK
}
if locker.shared == 1 {
err := os.Remove(name + ".lock")
if err != nil && !errors.Is(err, fs.ErrNotExist) {
return _IOERR_UNLOCK
}
delete(vfsDotLocks, name)
}
if locker.reserved == file {
locker.reserved = nil
}
if locker.pending == file {
locker.pending = nil
}
locker.shared--
return _OK
}
func osCheckReservedLock(file *os.File) (bool, _ErrorCode) {
vfsDotLocksMtx.Lock()
defer vfsDotLocksMtx.Unlock()
name := file.Name()
locker := vfsDotLocks[name]
if locker == nil {
return false, _OK
}
return locker.reserved != nil, _OK
}

2
vfs/os_ofd.go
View File

@@ -1,4 +1,4 @@
//go:build (linux || darwin) && !(sqlite3_flock || sqlite3_nosys)
//go:build (linux || darwin) && !(sqlite3_flock || sqlite3_dotlk || sqlite3_nosys)
package vfs

2
vfs/os_windows.go
View File

@@ -1,4 +1,4 @@
//go:build !sqlite3_nosys
//go:build !(sqlite3_dotlk || sqlite3_nosys)
package vfs

2
vfs/shm.go
View File

@@ -1,4 +1,4 @@
//go:build (darwin || linux || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_noshm || sqlite3_nosys)
//go:build (darwin || linux || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_dotlk || sqlite3_noshm || sqlite3_nosys)
package vfs

2
vfs/shm_bsd.go
View File

@@ -1,4 +1,4 @@
//go:build (freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_noshm || sqlite3_nosys)
//go:build (freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_dotlk || sqlite3_noshm || sqlite3_nosys)
package vfs

2
vfs/shm_other.go
View File

@@ -1,4 +1,4 @@
//go:build !(darwin || linux || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) || !(386 || arm || amd64 || arm64 || riscv64 || ppc64le) || sqlite3_noshm || sqlite3_nosys
//go:build !(darwin || linux || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) || !(386 || arm || amd64 || arm64 || riscv64 || ppc64le) || sqlite3_dotlk || sqlite3_noshm || sqlite3_nosys
package vfs