foundationdb/recipes/go-recipes/indirect.go

132 lines
3.2 KiB
Go

/*
* indirect.go
*
* This source file is part of the FoundationDB open source project
*
* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package main
import (
"fmt"
"log"
"github.com/apple/foundationdb/bindings/go/src/fdb"
"github.com/apple/foundationdb/bindings/go/src/fdb/directory"
"github.com/apple/foundationdb/bindings/go/src/fdb/subspace"
"github.com/apple/foundationdb/bindings/go/src/fdb/tuple"
)
func clear_subspace(trtr fdb.Transactor, sub subspace.Subspace) error {
_, err := trtr.Transact(func(tr fdb.Transaction) (interface{}, error) {
tr.ClearRange(sub)
return nil, nil
})
return err
}
func print_subspace(trtr fdb.Transactor, sub subspace.Subspace) {
trtr.Transact(func(tr fdb.Transaction) (interface{}, error) {
k := tr.GetRange(sub, fdb.RangeOptions{0, -1, false}).Iterator()
for k.Advance() {
fmt.Println(_unpack(k.MustGet().Value))
}
return nil, nil
})
}
func _pack(t interface{}) []byte {
return tuple.Tuple{t}.Pack()
}
func _unpack(t []byte) tuple.Tuple {
i, e := tuple.Unpack(t)
if e != nil {
return nil
}
return i
}
type Workspace struct {
Dir directory.Directory
db fdb.Database
}
func (wrkspc Workspace) _Update(trtr fdb.Transactor) {
trtr.Transact(func(tr fdb.Transaction) (interface{}, error) {
_, err := wrkspc.Dir.Remove(tr, []string{"current"})
if err != nil {
log.Fatal(err)
}
_, err = wrkspc.Dir.Move(tr, []string{"new"}, []string{"current"})
return nil, err
})
}
func (wrkspc Workspace) GetCurrent() (dir directory.DirectorySubspace, err error) {
dir, err = wrkspc.Dir.CreateOrOpen(wrkspc.db, []string{"current"}, nil)
return
}
func (wrkspc Workspace) Session(foo func(directory.DirectorySubspace)) (err error) {
newdir, err := wrkspc.Dir.CreateOrOpen(wrkspc.db, []string{"new"}, nil)
if err != nil {
return
}
foo(newdir)
wrkspc._Update(wrkspc.db)
return
}
func main() {
fdb.MustAPIVersion(710)
db := fdb.MustOpenDefault()
WorkspaceDemoDir, err := directory.CreateOrOpen(db, []string{"Workspace"}, nil)
if err != nil {
log.Fatal(err)
}
clear_subspace(db, WorkspaceDemoDir)
w := Workspace{WorkspaceDemoDir, db}
current, err := w.GetCurrent()
clear_subspace(db, current)
db.Transact(func(tr fdb.Transaction) (interface{}, error) {
tr.Set(current.Pack(tuple.Tuple{"a"}), _pack("Hello"))
return nil, nil
})
print_subspace(db, current)
w.Session(func(dir directory.DirectorySubspace) {
db.Transact(func(tr fdb.Transaction) (interface{}, error) {
tr.Set(dir.Pack(tuple.Tuple{"b"}), _pack("World"))
return nil, nil
})
})
current, err = w.GetCurrent()
if err != nil {
log.Fatal(err)
}
print_subspace(db, current)
}