/
windowing.go
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/
windowing.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 beam
import (
"fmt"
"time"
"github.com/apache/beam/sdks/v2/go/pkg/beam/core/graph"
"github.com/apache/beam/sdks/v2/go/pkg/beam/core/graph/window"
"github.com/apache/beam/sdks/v2/go/pkg/beam/core/graph/window/trigger"
"github.com/apache/beam/sdks/v2/go/pkg/beam/internal/errors"
)
type WindowIntoOption interface {
windowIntoOption()
}
type windowTrigger struct {
trigger trigger.Trigger
}
func (t windowTrigger) windowIntoOption() {}
// Trigger applies the given trigger to the window.
func Trigger(tr trigger.Trigger) WindowIntoOption {
return windowTrigger{trigger: tr}
}
type accumulationMode struct {
mode window.AccumulationMode
}
func (m accumulationMode) windowIntoOption() {}
// PanesAccumulate applies an Accumulating AccumulationMode to the window.
// After a pane fires, already processed elements will accumulate and
// elements will be repeated in subseqent firings for the window.
func PanesAccumulate() WindowIntoOption {
return accumulationMode{mode: window.Accumulating}
}
// PanesDiscard applies a Discarding AccumulationMode to the window.
// After a pane fires, already processed elements will be discarded
// and not included in later firings for the window.
func PanesDiscard() WindowIntoOption {
return accumulationMode{mode: window.Discarding}
}
type allowedLateness struct {
delay time.Duration
}
func (m allowedLateness) windowIntoOption() {}
// AllowedLateness configures for how long data may arrive after the end of a window.
func AllowedLateness(delay time.Duration) WindowIntoOption {
return allowedLateness{delay: delay}
}
// WindowInto applies the windowing strategy to each element.
func WindowInto(s Scope, ws *window.Fn, col PCollection, opts ...WindowIntoOption) PCollection {
return Must(TryWindowInto(s, ws, col, opts...))
}
// TryWindowInto attempts to insert a WindowInto transform.
func TryWindowInto(s Scope, wfn *window.Fn, col PCollection, opts ...WindowIntoOption) (PCollection, error) {
if !s.IsValid() {
return PCollection{}, errors.New("invalid scope")
}
if !col.IsValid() {
return PCollection{}, errors.New("invalid input pcollection")
}
ws := window.WindowingStrategy{Fn: wfn, Trigger: trigger.DefaultTrigger{}}
for _, opt := range opts {
switch opt := opt.(type) {
case windowTrigger:
// TODO(BEAM-3304): call validation on trigger construction here
// so local errors can be returned to the user in their pipeline
// context instead of at pipeline translation time.
ws.Trigger = opt.trigger
case accumulationMode:
ws.AccumulationMode = opt.mode
case allowedLateness:
ws.AllowedLateness = int(opt.delay / time.Millisecond)
default:
panic(fmt.Sprintf("Unknown WindowInto option type: %T: %v", opt, opt))
}
}
edge := graph.NewWindowInto(s.real, s.scope, &ws, col.n)
ret := PCollection{edge.Output[0].To}
return ret, nil
}