[
https://issues.apache.org/jira/browse/BEAM-3286?focusedWorklogId=133292&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-133292
]
ASF GitHub Bot logged work on BEAM-3286:
----------------------------------------
Author: ASF GitHub Bot
Created on: 09/Aug/18 21:36
Start Date: 09/Aug/18 21:36
Worklog Time Spent: 10m
Work Description: lostluck commented on a change in pull request #6197:
[BEAM-3286] Add preliminary Go support for side input
URL: https://github.com/apache/beam/pull/6197#discussion_r209083489
##########
File path: sdks/go/pkg/beam/core/runtime/exec/sideinput.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 exec
+
+import (
+ "context"
+ "fmt"
+ "io"
+
+ "github.com/apache/beam/sdks/go/pkg/beam/core/graph/coder"
+ "github.com/apache/beam/sdks/go/pkg/beam/core/typex"
+)
+
+// This file contains support for side input.
+
+const IterableSideInputKey = ""
+
+// SideInputAdapter provides a concrete ReStream from a low-level side input
reader. It
+// encapsulates StreamID and coding as needed.
+type SideInputAdapter interface {
+ NewIterable(ctx context.Context, reader SideInputReader, w
typex.Window) (ReStream, error)
+}
+
+type sideInputAdapter struct {
+ sid StreamID
+ wc WindowEncoder
+ kc ElementEncoder
+ ec ElementDecoder
+}
+
+// NewSideInputAdapter returns a side input adapter for the given StreamID and
coder.
+// It expects a W<KV<K,V>> coder, because the protocol supports MultiSet
access only.
+func NewSideInputAdapter(sid StreamID, c *coder.Coder) SideInputAdapter {
+ if !coder.IsW(c) || !coder.IsKV(coder.SkipW(c)) {
+ panic(fmt.Sprintf("expected WKV coder for side input: %v", c))
+ }
+
+ wc := MakeWindowEncoder(c.Window)
+ kc := MakeElementEncoder(coder.SkipW(c).Components[0])
+ ec := MakeElementDecoder(coder.SkipW(c).Components[1])
+ return &sideInputAdapter{sid: sid, wc: wc, kc: kc, ec: ec}
+}
+
+func (s *sideInputAdapter) NewIterable(ctx context.Context, reader
SideInputReader, w typex.Window) (ReStream, error) {
+ key, err := EncodeElement(s.kc, []byte(IterableSideInputKey))
+ if err != nil {
+ return nil, err
+ }
+ win, err := EncodeWindow(s.wc, w)
+ if err != nil {
+ return nil, err
+ }
+ return &proxyReStream{
+ open: func() (Stream, error) {
+ r, err := reader.Open(ctx, s.sid, key, win)
+ if err != nil {
+ return nil, err
+ }
+ return &elementStream{r: r, ec: s.ec}, nil
+ },
+ }, nil
+}
+
+func (s *sideInputAdapter) String() string {
+ return fmt.Sprintf("SideInputAdapter[%v]", s.sid)
+}
+
+// proxyReStream is a simple wrapper of an open function.
+type proxyReStream struct {
+ open func() (Stream, error)
+}
+
+func (p *proxyReStream) Open() (Stream, error) {
+ return p.open()
+}
+
+// elementStream exposes a Stream from decoding elements.
+type elementStream struct {
+ r io.ReadCloser
+ ec ElementDecoder
+}
+
+func (s *elementStream) Close() error {
+ return s.r.Close()
+}
+
+func (s *elementStream) Read() (FullValue, error) {
+ // We should see a stream of unwindowed values -- no sizes, no key.
+ return s.ec.Decode(s.r)
+}
+
+// FixedKey transform any value into KV<K, V> for a fixed K.
+type FixedKey struct {
Review comment:
Consider not exporting this, unless necessary.
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Issue Time Tracking
-------------------
Worklog Id: (was: 133292)
Time Spent: 1h 20m (was: 1h 10m)
> Go SDK support for portable side input
> --------------------------------------
>
> Key: BEAM-3286
> URL: https://issues.apache.org/jira/browse/BEAM-3286
> Project: Beam
> Issue Type: Sub-task
> Components: sdk-go
> Reporter: Henning Rohde
> Assignee: Henning Rohde
> Priority: Major
> Labels: portability
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
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