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ds.go
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ds.go
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package kv
import (
"context"
"fmt"
"path/filepath"
"sync"
"cloud.google.com/go/datastore"
)
type dsKv struct {
mu sync.Mutex
ctx context.Context
nameSpace string
client *datastore.Client
}
type Buffer struct {
Valid bool
Value []byte
}
func newDataStoreKv(ctx context.Context, projectID, nameSpace string) (*dsKv, func() error, error) {
client, err := datastore.NewClient(ctx, projectID)
if err != nil {
return nil, nil, err
}
f := func() error {
return client.Close()
}
return &dsKv{
ctx: ctx,
nameSpace: nameSpace,
client: client,
}, f, nil
}
func (d *dsKv) Get(key string) ([]byte, error) {
if len(key) == 0 {
return nil, fmt.Errorf("key cannot be empty")
}
keys := splitKey(key, d.nameSpace)
var parent *datastore.Key
var child *datastore.Key
for i := range keys {
child = datastore.NameKey(d.nameSpace, filepath.Join(keys[:i+1]...), parent)
if err := d.client.Get(d.ctx, child, new(Buffer)); err != nil {
return nil, err
}
parent = child
}
b := new(Buffer)
if err := d.client.Get(d.ctx, child, b); err != nil {
return nil, err
}
if !b.Valid {
return nil, fmt.Errorf("invalid key. key points to a bucket and not a value")
}
return b.Value, nil
}
func (d *dsKv) Set(key string, val []byte) error {
d.mu.Lock()
defer d.mu.Unlock()
if len(key) == 0 {
return fmt.Errorf("cannot set empty key")
}
if val == nil {
return fmt.Errorf("val cannot be nil, use zero value instead")
}
var parent *datastore.Key
var child *datastore.Key
keys := splitKey(key, d.nameSpace)
for i := range keys {
i := i
child = datastore.NameKey(d.nameSpace, filepath.Join(keys[:i+1]...), parent)
err := d.client.Get(d.ctx, child, new(Buffer))
switch err {
// if the key does not exist, then put one
case datastore.ErrNoSuchEntity, datastore.ErrInvalidKey:
child, err = d.client.Put(d.ctx, child, new(Buffer))
if err != nil {
return err
}
case nil:
default:
return err
}
parent = child
}
b := new(Buffer)
b.Value = val
b.Valid = true
_, err := d.client.Put(d.ctx, child, b)
return err
}
func (d *dsKv) Delete(key string) error {
d.mu.Lock()
defer d.mu.Unlock()
keys, err := d.enumerate(key)
if err != nil {
return err
}
for _, key := range keys {
if err := d.client.Delete(context.Background(), key); err != nil {
return err
}
}
return nil
}
func (d *dsKv) enumerate(key string) ([]*datastore.Key, error) {
if len(key) == 0 {
return nil, fmt.Errorf("key cannot be empty")
}
keys := splitKey(key, d.nameSpace)
var parent *datastore.Key
var child *datastore.Key
for i := range keys {
child = datastore.NameKey(d.nameSpace, filepath.Join(keys[:i+1]...), parent)
if err := d.client.Get(d.ctx, child, new(Buffer)); err != nil {
return nil, err
}
parent = child
}
q := datastore.NewQuery("test").Ancestor(child).KeysOnly()
return d.client.GetAll(context.Background(), q, nil)
}
func (d *dsKv) Enumerate(key string) ([]string, error) {
keys, err := d.enumerate(key)
if err != nil {
return nil, err
}
var outKeys []string
for _, key := range keys {
b := new(Buffer)
if err := d.client.Get(context.Background(), key, b); err != nil {
return nil, err
} else {
if b.Valid {
outKeys = append(outKeys, key.Name)
}
}
}
return outKeys, nil
}