133 lines
3.2 KiB
Go
133 lines
3.2 KiB
Go
// Copyright 2019 Sorint.lab
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package sequence
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import (
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"context"
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"encoding/json"
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"fmt"
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"math"
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"strconv"
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"strings"
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"time"
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"agola.io/agola/internal/etcd"
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errors "golang.org/x/xerrors"
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)
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type Sequence struct {
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Epoch uint64
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C uint64
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}
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func (s *Sequence) String() string {
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// 1<<64 -1 in base 32 is "fvvvvvvvvvvvv" and uses 13 chars
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return fmt.Sprintf("%013s-%013s", strconv.FormatUint(s.Epoch, 32), strconv.FormatUint(s.C, 32))
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}
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func (s *Sequence) Reverse() *Sequence {
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return &Sequence{
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Epoch: math.MaxUint64 - s.Epoch,
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C: math.MaxUint64 - s.C,
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}
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}
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func Parse(s string) (*Sequence, error) {
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if len(s) != 13*2+1 {
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return nil, errors.Errorf("bad sequence %q string length", s)
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}
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parts := strings.Split(s, "-")
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if len(parts) != 2 {
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return nil, errors.Errorf("bad sequence %q", s)
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}
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epoch, err := strconv.ParseUint(parts[0], 32, 64)
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if err != nil {
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return nil, errors.Errorf("cannot parse sequence epoch %q: %w", epoch, err)
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}
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c, err := strconv.ParseUint(parts[1], 32, 64)
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if err != nil {
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return nil, errors.Errorf("cannot parse sequence count %q: %w", c, err)
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}
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return &Sequence{
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Epoch: epoch,
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C: c,
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}, nil
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}
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func (s *Sequence) EqualEpoch(s2 *Sequence) bool {
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return s.Epoch == s2.Epoch
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}
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func CurSequence(ctx context.Context, e *etcd.Store, key string) (*Sequence, bool, error) {
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resp, err := e.Get(ctx, key, 0)
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if err != nil && err != etcd.ErrKeyNotFound {
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return nil, false, err
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}
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if err == etcd.ErrKeyNotFound {
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return nil, false, nil
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}
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seq := &Sequence{}
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if err != etcd.ErrKeyNotFound {
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kv := resp.Kvs[0]
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if err := json.Unmarshal(kv.Value, &seq); err != nil {
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return nil, false, err
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}
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}
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return seq, true, nil
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}
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func IncSequence(ctx context.Context, e *etcd.Store, key string) (*Sequence, error) {
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resp, err := e.Get(ctx, key, 0)
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if err != nil && err != etcd.ErrKeyNotFound {
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return nil, err
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}
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var revision int64
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seq := &Sequence{}
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if err != etcd.ErrKeyNotFound {
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kv := resp.Kvs[0]
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if err := json.Unmarshal(kv.Value, &seq); err != nil {
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return nil, err
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}
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revision = kv.ModRevision
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}
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// if the epoch is zero then this is a new etcd cluster. This will happen on
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// first creation or if the etcd cluster is recreated. The epoch is used to
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// keep the seq incremental and we assume the new epoch will always be greater
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// than the previous ones (it not then there was a big backward time drift)
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//
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// TODO(sgotti) check that the new epoch is greater then previous ones???
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if seq.Epoch == 0 {
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seq.Epoch = uint64(time.Now().Unix())
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}
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seq.C++
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seqj, err := json.Marshal(seq)
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if err != nil {
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return nil, err
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}
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_, err = e.AtomicPut(ctx, key, seqj, revision, nil)
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if err != nil {
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return nil, err
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}
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return seq, nil
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}
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