Add 'user friendly' datastore API.

service/datastore/datastore.go

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package datastore
+
+import (
+        "fmt"
+        "reflect"
+
+        "github.com/luci/luci-go/common/errors"
+)
+
+type datastoreImpl struct{ RawInterface }
+
+var _ Interface = (*datastoreImpl)(nil)
+
+func (d *datastoreImpl) KeyForObj(src interface{}) Key {
+        ret, err := d.KeyForObjErr(src)
+        if err != nil {
+                panic(err)
+        }
+        return ret
+}
+
+func (d *datastoreImpl) KeyForObjErr(src interface{}) (Key, error) {
+        return newKeyObjErr(d.NewKey, src)
+}
+
+func (d *datastoreImpl) Run(q Query, proto interface{}, cb RunCB) error {
+        if _, ok := proto.(*Key); ok {
+                return d.RawInterface.Run(q.KeysOnly(), func(k Key, _ PropertyMap, gc func() (Cursor, error)) bool {
+                        return cb(k, gc)
+                })
+        }
+
+        mat := parseArg(reflect.TypeOf(proto))
+        if !mat.valid || mat.newElem == nil {
+                return fmt.Errorf("invalid Run proto type: %T", proto)
+        }
+
+        innerErr := error(nil)
+        err := d.RawInterface.Run(q, func(k Key, pm PropertyMap, gc func() (Cursor, error)) bool {
+                itm := mat.newElem()
+                if innerErr = mat.setPM(itm, pm); innerErr != nil {
+                        return false
+                }
+                mat.setKey(itm, k)
+                return cb(itm.Interface(), gc)
+        })
+        if err == nil {
+                err = innerErr
+        }
+        return err
+}
+
+func (d *datastoreImpl) GetAll(q Query, dst interface{}) error {
+        v := reflect.ValueOf(dst)
+        if v.Kind() != reflect.Ptr {
+                return fmt.Errorf("invalid GetAll dst: must have a ptr-to-slice: %T", dst)
+        }
+        if !v.IsValid() || v.IsNil() {
+                return errors.New("invalid GetAll dst: <nil>")
+        }
+
+        if keys, ok := dst.(*[]Key); ok {
+                return d.RawInterface.Run(q.KeysOnly(), func(k Key, _ PropertyMap, _ func() (Cursor, error)) bool {
+                        *keys = append(*keys, k)
+                        return true
+                })
+        }
+
+        slice := v.Elem()
+        mat := parseMultiArg(slice.Type())
+        if !mat.valid || mat.newElem == nil {
+                return fmt.Errorf("invalid GetAll input type: %T", dst)
+        }
+
+        lme := errors.LazyMultiError{Size: slice.Len()}
+        i := 0
+        err := d.RawInterface.Run(q, func(k Key, pm PropertyMap, _ func() (Cursor, error)) bool {
+                slice.Set(reflect.Append(slice, mat.newElem()))
+                itm := slice.Index(i)
+                mat.setKey(itm, k)
+                lme.Assign(i, mat.setPM(itm, pm))
+                i++
+                return true
+        })
+        if err == nil {
+                err = lme.Get()
+        }
+        return err
+}
+
+func isOkType(v reflect.Type) bool {
+        if v.Implements(typeOfPropertyLoadSaver) {
+                return true
+        }
+        if v.Kind() == reflect.Ptr && v.Elem().Kind() == reflect.Struct {
+                return true
+        }
+        return false
+}
+
+func (d *datastoreImpl) Get(dst interface{}) (err error) {
+        if !isOkType(reflect.TypeOf(dst)) {
+                return fmt.Errorf("invalid Get input type: %T", dst)
+        }
+        return errors.SingleError(d.GetMulti([]interface{}{dst}))
+}
+
+func (d *datastoreImpl) Put(src interface{}) (err error) {
+        if !isOkType(reflect.TypeOf(src)) {

[Vadim Sh., 2015/08/03 21:25:12]

so Put requires passing values by pointer? Does it makes sense to allow pass by
value (e.g. if key is already set)?

[iannucci, 2015/08/03 21:51:48]

Yeah, it requires pass by pointer. It COULD make sense to pass by value if they
key is already set... but not really. Note that PutMulti also requires
pass-by-pointer (even in the []S type cases, the slice acts like a pointer-to-S)

+                return fmt.Errorf("invalid Put input type: %T", src)
+        }
+        return errors.SingleError(d.PutMulti([]interface{}{src}))
+}
+
+func (d *datastoreImpl) Delete(key Key) (err error) {
+        return errors.SingleError(d.DeleteMulti([]Key{key}))
+}
+
+func (d *datastoreImpl) GetMulti(dst interface{}) error {
+        slice := reflect.ValueOf(dst)
+        mat := parseMultiArg(slice.Type())
+        if !mat.valid {
+                return fmt.Errorf("invalid GetMulti input type: %T", dst)
+        }
+
+        keys, err := mat.GetKeys(d.NewKey, slice)
+        if err != nil {
+                return err
+        }
+
+        lme := errors.LazyMultiError{Size: len(keys)}
+        i := 0
+        err = d.RawInterface.GetMulti(keys, func(pm PropertyMap, err error) {
+                if !lme.Assign(i, err) {
+                        lme.Assign(i, mat.setPM(slice.Index(i), pm))
+                }
+                i++
+        })
+
+        if err == nil {
+                err = lme.Get()
+        }
+        return err
+}
+
+func (d *datastoreImpl) PutMulti(src interface{}) error {
+        slice := reflect.ValueOf(src)
+        mat := parseMultiArg(slice.Type())
+        if !mat.valid {
+                return fmt.Errorf("invalid PutMulti input type: %T", src)
+        }
+
+        keys, err := mat.GetKeys(d.NewKey, slice)
+        if err != nil {
+                return err
+        }
+
+        vals, err := mat.GetPMs(slice)
+        if err != nil {
+                return err
+        }
+
+        lme := errors.LazyMultiError{Size: len(keys)}
+        i := 0
+        err = d.RawInterface.PutMulti(keys, vals, func(key Key, err error) {
+                if key != keys[i] {
+                        mat.setKey(slice.Index(i), key)
+                }
+                lme.Assign(i, err)
+                i++
+        })
+
+        if err == nil {
+                err = lme.Get()
+        }
+        return err
+}
+
+func (d *datastoreImpl) DeleteMulti(keys []Key) (err error) {
+        lme := errors.LazyMultiError{Size: len(keys)}
+        i := 0
+        extErr := d.RawInterface.DeleteMulti(keys, func(internalErr error) {
+                lme.Assign(i, internalErr)
+                i++
+        })
+        err = lme.Get()
+        if err == nil {
+                err = extErr
+        }
+        return
+}
+
+func (d *datastoreImpl) Raw() RawInterface {
+        return d.RawInterface
+}