/
12splittabledofns.go
69 lines (57 loc) · 2.03 KB
/
12splittabledofns.go
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// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You 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 snippets
import (
"time"
"github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf"
"github.com/apache/beam/sdks/v2/go/pkg/beam/io/rtrackers/offsetrange"
)
type Record struct{}
type SomeService struct {
ThrottlingErr error
}
func (s *SomeService) readNextRecords(position interface{}) ([]Record, error) {
return []Record{}, nil
}
type checkpointingSplittableDoFn struct {
ExternalService SomeService
}
// [START self_checkpoint]
func (fn *checkpointingSplittableDoFn) ProcessElement(rt *sdf.LockRTracker, emit func(Record)) (sdf.ProcessContinuation, error) {
position := rt.GetRestriction().(offsetrange.Restriction).Start
for {
records, err := fn.ExternalService.readNextRecords(position)
if err != nil {
if err == fn.ExternalService.ThrottlingErr {
// Resume at a later time to avoid throttling.
return sdf.ResumeProcessingIn(60 * time.Second), nil
}
return sdf.StopProcessing(), err
}
if len(records) == 0 {
// Wait for data to be available.
return sdf.ResumeProcessingIn(10 * time.Second), nil
}
for _, record := range records {
if !rt.TryClaim(position) {
// Records have been claimed, finish processing.
return sdf.StopProcessing(), nil
}
position += 1
emit(record)
}
}
}
// [END self_checkpoint]