lostluck commented on a change in pull request #11197: [BEAM-8292] Portable Reshuffle for Go SDK URL: https://github.com/apache/beam/pull/11197#discussion_r397314344
########## File path: sdks/go/pkg/beam/core/runtime/exec/reshuffle.go ########## @@ -0,0 +1,170 @@ +// 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 ( + "bytes" + "context" + "fmt" + "io" + "math/rand" + + "github.com/apache/beam/sdks/go/pkg/beam/core/graph/coder" + "github.com/apache/beam/sdks/go/pkg/beam/internal/errors" +) + +// ReshuffleInput is a Node. +type ReshuffleInput struct { + UID UnitID + SID StreamID + Coder *coder.Coder // Coder for the input PCollection. + Seed int64 + Out Node + + r *rand.Rand + enc ElementEncoder + wEnc WindowEncoder + b bytes.Buffer + // ret is a cached allocations for passing to the next Unit. Units never modify the passed in FullValue. + ret FullValue +} + +// ID returns the unit debug id. +func (n *ReshuffleInput) ID() UnitID { + return n.UID +} + +// Up initializes the value and window encoders, and the random source. +func (n *ReshuffleInput) Up(ctx context.Context) error { + n.enc = MakeElementEncoder(coder.SkipW(n.Coder)) + n.wEnc = MakeWindowEncoder(n.Coder.Window) + n.r = rand.New(rand.NewSource(n.Seed)) + return nil +} + +// StartBundle is a no-op. +func (n *ReshuffleInput) StartBundle(ctx context.Context, id string, data DataContext) error { + return MultiStartBundle(ctx, id, data, n.Out) +} + +func (n *ReshuffleInput) ProcessElement(ctx context.Context, value *FullValue, values ...ReStream) error { + n.b.Reset() + if err := EncodeWindowedValueHeader(n.wEnc, value.Windows, value.Timestamp, &n.b); err != nil { + return err + } + if err := n.enc.Encode(value, &n.b); err != nil { + return errors.WithContextf(err, "encoding element %v with coder %v", value, n.Coder) + } + n.ret = FullValue{Elm: n.r.Int(), Elm2: n.b.Bytes(), Timestamp: value.Timestamp} + if err := n.Out.ProcessElement(ctx, &n.ret); err != nil { + return err + } + return nil +} + +// FinishBundle propagates finish bundle, and clears cached state. +func (n *ReshuffleInput) FinishBundle(ctx context.Context) error { + n.b = bytes.Buffer{} + n.ret = FullValue{} + return MultiFinishBundle(ctx, n.Out) +} + +// Down is a no-op. +func (n *ReshuffleInput) Down(ctx context.Context) error { + return nil +} + +func (n *ReshuffleInput) String() string { + return fmt.Sprintf("ReshuffleInput[%v] Coder:%v", n.SID, n.Coder) +} + +// ReshuffleOutput is a Node. +type ReshuffleOutput struct { + UID UnitID + SID StreamID + Coder *coder.Coder // Coder for the receiving PCollection. + Out Node + + b bytes.Buffer + dec ElementDecoder + wDec WindowDecoder + ret FullValue +} + +// ID returns the unit debug id. +func (n *ReshuffleOutput) ID() UnitID { + return n.UID +} + +// Up initializes the value and window encoders, and the random source. +func (n *ReshuffleOutput) Up(ctx context.Context) error { + n.dec = MakeElementDecoder(coder.SkipW(n.Coder)) + n.wDec = MakeWindowDecoder(n.Coder.Window) + return nil +} + +// StartBundle is a no-op. +func (n *ReshuffleOutput) StartBundle(ctx context.Context, id string, data DataContext) error { + return MultiStartBundle(ctx, id, data, n.Out) +} + +func (n *ReshuffleOutput) ProcessElement(ctx context.Context, value *FullValue, values ...ReStream) error { + // Marshal the pieces into a temporary buffer since they must be transmitted on FnAPI as a single + // unit. + vs, err := values[0].Open() Review comment: This is the Go SDK future proofing itself, against CoGBK supporting multiple datastreams from the runner. Functionally, only datasource.go would need to change in that case. You can see a comment to that effect in datasource.go, and then nearly everything else deals with the values streams properly under that assumption. In this case, we know that if this code is being used, it's coming from a single GBK, which means there's only a single stream of values, and then since we're framework side, we just handle the stream directly. In that way, it's similar to how we're handling CoGBKs presently, with synthetic inject and expand steps to get to the right number of joined streams, even though the Runner is only providing us with a single data stream for the grouped data. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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