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filelock.go
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filelock.go
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package os
import (
"fmt"
"time"
"cuelang.org/go/cue"
"github.com/gofrs/flock"
"github.com/hofstadter-io/cuetils/flow/context"
)
func init() {
context.Register("os.FileLock", NewFileLock)
context.Register("os.FileUnlock", NewFileUnlock)
}
type FileLock struct {}
func NewFileLock(val cue.Value) (context.Runner, error) {
return &FileLock{}, nil
}
func (T *FileLock) Run(ctx *context.Context) (interface{}, error) {
val := ctx.Value
fn, rw, retry, err := extractConfig(ctx, val)
if err != nil {
return nil, err
}
kn := "hof-filelock."+fn
// check store for existing filelock
var lock *flock.Flock
l, ok := ctx.ValStore.Load(kn)
if !ok {
lock = flock.New(fn)
} else {
lock = l.(*flock.Flock)
}
ctx.ValStore.Store(kn, lock)
if retry == 0 {
if rw {
err = lock.Lock()
} else {
err = lock.RLock()
}
} else {
if rw {
_, err = lock.TryLockContext(ctx.Context, retry)
} else {
_, err = lock.TryRLockContext(ctx.Context, retry)
}
}
return nil, err
}
type FileUnlock struct {}
func NewFileUnlock(val cue.Value) (context.Runner, error) {
return &FileUnlock{}, nil
}
func (T *FileUnlock) Run(ctx *context.Context) (interface{}, error) {
val := ctx.Value
fn, _, _, err := extractConfig(ctx, val)
if err != nil {
return nil, err
}
kn := "hof-filelock."+fn
l, ok := ctx.ValStore.Load(kn)
if !ok {
return nil, fmt.Errorf("unknown filelock: %q", fn)
}
lock := l.(*flock.Flock)
err = lock.Unlock()
return nil, err
}
func extractConfig(ctx *context.Context, val cue.Value) (fn string, rw bool, retry time.Duration, err error) {
ctx.CUELock.Lock()
defer ctx.CUELock.Unlock()
f := val.LookupPath(cue.ParsePath("filename"))
if f.Err() != nil {
return fn, rw, retry, f.Err()
} else if f.Exists() {
fn, err = f.String()
if err != nil {
return fn, rw, retry, err
}
}
r := val.LookupPath(cue.ParsePath("rw"))
if r.Exists() {
rw, err = r.Bool()
if err != nil {
return fn, rw, retry, err
}
}
d := val.LookupPath(cue.ParsePath("retry"))
if d.Exists() {
ds, err := d.String()
if err != nil {
return fn, rw, retry, err
}
retry, err = time.ParseDuration(ds)
if err != nil {
return fn, rw, retry, err
}
}
return fn, rw, retry, err
}