[GitHub] [beam] christogav commented on a diff in pull request #26042: [Go SDK] Spanner Batched Reads

["christogav (via GitHub)" <gi...@apache.org>]

christogav commented on code in PR #26042:
URL: https://github.com/apache/beam/pull/26042#discussion_r1168262492


##########
sdks/go/pkg/beam/io/spannerio/common.go:
##########
@@ -0,0 +1,58 @@
+// 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 spannerio provides an API for reading and writing resouces to
+// Google Spanner datastores.
+package spannerio
+
+import (
+	"cloud.google.com/go/spanner"
+	"context"
+	"fmt"
+)

Review Comment:
   Corrected.



##########
sdks/go/pkg/beam/io/spannerio/generate_partitions.go:
##########
@@ -0,0 +1,149 @@
+// 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 spannerio provides an API for reading and writing resources to
+// Google Spanner datastores.
+package spannerio
+
+import (
+	"cloud.google.com/go/spanner"
+	"context"
+	"fmt"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/register"
+)
+
+func init() {
+	register.DoFn3x1[context.Context, []byte, func(read *PartitionedRead), error]((*generatePartitionsFn)(nil))
+	register.Emitter1[*PartitionedRead]()
+}
+
+type generatePartitionsFn struct {
+	spannerFn
+	Query     string            `json:"query"`   // Table is the table identifier.
+	Options   queryBatchOptions `json:"options"` // Options specifies additional query execution options.
+	generator partitionGenerator
+}
+
+func (f *generatePartitionsFn) Setup(ctx context.Context) error {
+	err := f.spannerFn.Setup(ctx)
+
+	if f.generator == nil {
+		f.generator = newPartitionGenerator(f.client)
+	}
+
+	return err
+}
+
+func (f *generatePartitionsFn) Teardown() {
+	f.spannerFn.Teardown()
+}
+
+func partitionOptions(options queryBatchOptions) spanner.PartitionOptions {
+	partitionOptions := spanner.PartitionOptions{}
+
+	if options.MaxPartitions != 0 {
+		partitionOptions.MaxPartitions = options.MaxPartitions
+	}
+
+	return partitionOptions
+}
+
+// GeneratePartitions generates read partitions to support batched reading from Spanner.
+func GeneratePartitions(s beam.Scope, db string, query string, options ...func(*queryBatchOptions) error) beam.PCollection {
+	s.Scope("spanner.GeneratePartitions")
+
+	fn := newGeneratePartitionsFn(db, query, options...)
+	return fn.generatePartitions(s)
+}
+
+func newGeneratePartitionsFn(
+	db string,
+	query string,
+	options ...func(*queryBatchOptions) error,
+) *generatePartitionsFn {
+	if db == "" {
+		panic("no database provided")
+	}
+
+	opts := queryBatchOptions{}
+	for _, opt := range options {
+		if err := opt(&opts); err != nil {
+			panic(err)
+		}
+	}
+
+	return &generatePartitionsFn{
+		spannerFn: newSpannerFn(db),
+		Query:     query,
+		Options:   opts,
+	}
+}
+
+func (f *generatePartitionsFn) generatePartitions(s beam.Scope) beam.PCollection {
+	imp := beam.Impulse(s)
+	return beam.ParDo(s, f, imp)
+}
+
+func (f *generatePartitionsFn) ProcessElement(ctx context.Context, _ []byte, emit func(*PartitionedRead)) error {
+	txnId, partitions := f.generator.generate(ctx, f.Options.TimestampBound, f.Query, partitionOptions(f.Options))
+
+	for _, p := range partitions {
+		emit(NewPartitionedRead(txnId, p))
+	}
+
+	return nil
+}
+
+type partitionGenerator interface {
+	generate(
+		ctx context.Context,
+		tb spanner.TimestampBound,
+		query string,
+		opts spanner.PartitionOptions,
+	) (spanner.BatchReadOnlyTransactionID, []*spanner.Partition)
+}
+
+type partitionGeneratorImpl struct {
+	client *spanner.Client
+}
+
+func newPartitionGenerator(client *spanner.Client) partitionGenerator {
+	return &partitionGeneratorImpl{client}
+}
+
+func (g *partitionGeneratorImpl) generate(
+	ctx context.Context,
+	tb spanner.TimestampBound,
+	query string,
+	opts spanner.PartitionOptions,
+) (spanner.BatchReadOnlyTransactionID, []*spanner.Partition) {
+	txn, err := g.client.BatchReadOnlyTransaction(ctx, tb)
+	if err != nil {
+		panic("unable to create batch read only transaction: " + err.Error())
+	}
+	defer txn.Close()
+
+	if txn == nil {
+		panic("unable to create a spanner transaction")
+	}

Review Comment:
   Removed.



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