com.google.cloud.dataflow.sdk.transforms.windowing.PaneInfo Maven / Gradle / Ivy
/*
* Copyright (C) 2015 Google Inc.
*
* Licensed 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 com.google.cloud.dataflow.sdk.transforms.windowing;
import com.google.cloud.dataflow.sdk.coders.AtomicCoder;
import com.google.cloud.dataflow.sdk.coders.Coder;
import com.google.cloud.dataflow.sdk.coders.CoderException;
import com.google.cloud.dataflow.sdk.transforms.GroupByKey;
import com.google.cloud.dataflow.sdk.util.VarInt;
import com.google.common.base.MoreObjects;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Objects;
/**
* Provides information about the pane this value belongs to. Every pane is implicitly associated
* with a window.
*
* Note: This does not uniquely identify a pane, and should not be used for comparisons.
*/
public final class PaneInfo {
/**
* Enumerates the possibilities for how the timing of this pane firing related to the watermark.
*/
public enum Timing {
/** Pane was fired before the watermark passed the end of the window. */
EARLY,
/** First pane fired after the watermark passed the end of the window. */
ON_TIME,
/** Panes fired after the {@code ON_TIME} firing. */
LATE,
/**
* This element was not produced in a triggered pane and its relation to the watermark is
* unknown.
*/
UNKNOWN;
// NOTE: Do not add fields or re-order them. The ordinal is used as part of
// the encoding.
}
private static byte encodedByte(boolean isFirst, boolean isLast, Timing timing) {
byte result = 0x0;
if (isFirst) {
result |= 1;
}
if (isLast) {
result |= 2;
}
result |= timing.ordinal() << 2;
return result;
}
private static final ImmutableMap BYTE_TO_PANE_INFO;
static {
ImmutableMap.Builder decodingBuilder = ImmutableMap.builder();
for (Timing timing : Timing.values()) {
long onTimeIndex = timing == Timing.EARLY ? -1 : 0;
register(decodingBuilder, new PaneInfo(true, true, timing, 0, onTimeIndex));
register(decodingBuilder, new PaneInfo(true, false, timing, 0, onTimeIndex));
register(decodingBuilder, new PaneInfo(false, true, timing, -1, onTimeIndex));
register(decodingBuilder, new PaneInfo(false, false, timing, -1, onTimeIndex));
}
BYTE_TO_PANE_INFO = decodingBuilder.build();
}
private static void register(ImmutableMap.Builder builder, PaneInfo info) {
builder.put(info.encodedByte, info);
}
private final byte encodedByte;
private final boolean isFirst;
private final boolean isLast;
private final Timing timing;
private final long index;
private final long nonSpeculativeIndex;
/**
* {@code PaneInfo} to use for elements on (and before) initial window assignemnt (including
* elements read from sources) before they have passed through a {@link GroupByKey} and are
* associated with a particular trigger firing.
*/
public static final PaneInfo NO_FIRING =
PaneInfo.createPane(true, true, Timing.UNKNOWN, 0, 0);
/**
* {@code PaneInfo} to use when there will be exactly one firing and it is on time.
*/
public static final PaneInfo ON_TIME_AND_ONLY_FIRING =
PaneInfo.createPane(true, true, Timing.ON_TIME, 0, 0);
private PaneInfo(boolean isFirst, boolean isLast, Timing timing, long index, long onTimeIndex) {
this.encodedByte = encodedByte(isFirst, isLast, timing);
this.isFirst = isFirst;
this.isLast = isLast;
this.timing = timing;
this.index = index;
this.nonSpeculativeIndex = onTimeIndex;
}
public static PaneInfo createPane(boolean isFirst, boolean isLast, Timing timing) {
Preconditions.checkArgument(isFirst, "Indices must be provided for non-first pane info.");
return createPane(isFirst, isLast, timing, 0, timing == Timing.EARLY ? -1 : 0);
}
/**
* Factory method to create a {@link PaneInfo} with the specified parameters.
*/
public static PaneInfo createPane(
boolean isFirst, boolean isLast, Timing timing, long index, long onTimeIndex) {
if (isFirst || timing == Timing.UNKNOWN) {
return Preconditions.checkNotNull(
BYTE_TO_PANE_INFO.get(encodedByte(isFirst, isLast, timing)));
} else {
return new PaneInfo(isFirst, isLast, timing, index, onTimeIndex);
}
}
public static PaneInfo decodePane(byte encodedPane) {
return Preconditions.checkNotNull(BYTE_TO_PANE_INFO.get(encodedPane));
}
/**
* Return true if there is no timing information for the current {@link PaneInfo}.
* This typically indicates that the current element has not been assigned to
* windows or passed through an operation that executes triggers yet.
*/
public boolean isUnknown() {
return Timing.UNKNOWN.equals(timing);
}
/**
* Return true if this is the first pane produced for the associated window.
*/
public boolean isFirst() {
return isFirst;
}
/**
* Return true if this is the last pane that will be produced in the associated window.
*/
public boolean isLast() {
return isLast;
}
/**
* Return true if this is the last pane that will be produced in the associated window.
*/
public Timing getTiming() {
return timing;
}
/**
* The zero-based index of this trigger firing that produced this pane. i.e.
* 0 for the first time the timer fires, 1 for the next time, etc.
*
* A given (key, window, pane-index) is guaranteed to be unique in the
* output of a group-by-key operation.
*/
public long getIndex() {
return index;
}
/**
* The zero-based index of this trigger firing among non-speculative panes, i.e.
* 0 for the first non-{@link Timing#EARLY} timer firing, 1 for the next one, etc.
*
*
Always -1 for speculative data.
*/
public long getNonSpeculativeIndex() {
return nonSpeculativeIndex;
}
int getEncodedByte() {
return encodedByte;
}
@Override
public int hashCode() {
return Objects.hash(encodedByte, index, nonSpeculativeIndex);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
// Simple PaneInfos are interned.
return true;
} else if (obj instanceof PaneInfo) {
PaneInfo that = (PaneInfo) obj;
return this.encodedByte == that.encodedByte
&& this.index == that.index
&& this.nonSpeculativeIndex == that.nonSpeculativeIndex;
} else {
return false;
}
}
@Override
public String toString() {
return MoreObjects.toStringHelper(getClass())
.omitNullValues()
.add("isFirst", isFirst ? true : null)
.add("isLast", isLast ? true : null)
.add("timing", timing)
.add("index", index)
.add("onTimeIndex", nonSpeculativeIndex != -1 ? nonSpeculativeIndex : null)
.toString();
}
/**
* A Coder for encoding PaneInfo instances.
*/
public static class PaneInfoCoder extends AtomicCoder {
private static final long serialVersionUID = 0;
private static enum Encoding {
FIRST,
ONE_INDEX,
TWO_INDICES;
// NOTE: Do not reorder fields. The ordinal is used as part of
// the encoding.
public final byte tag;
private Encoding() {
assert ordinal() < 16;
tag = (byte) (ordinal() << 4);
}
public static Encoding fromTag(byte b) {
return Encoding.values()[b >> 4];
}
}
private Encoding chooseEncoding(PaneInfo value) {
if (value.index == 0 && value.nonSpeculativeIndex == 0 || value.timing == Timing.UNKNOWN) {
return Encoding.FIRST;
} else if (value.index == value.nonSpeculativeIndex || value.timing == Timing.EARLY) {
return Encoding.ONE_INDEX;
} else {
return Encoding.TWO_INDICES;
}
}
public static final PaneInfoCoder INSTANCE = new PaneInfoCoder();
@Override
public void encode(PaneInfo value, final OutputStream outStream, Coder.Context context)
throws CoderException, IOException {
Encoding encoding = chooseEncoding(value);
switch (chooseEncoding(value)) {
case FIRST:
outStream.write(value.encodedByte);
break;
case ONE_INDEX:
outStream.write(value.encodedByte | encoding.tag);
VarInt.encode(value.index, outStream);
break;
case TWO_INDICES:
outStream.write(value.encodedByte | encoding.tag);
VarInt.encode(value.index, outStream);
VarInt.encode(value.nonSpeculativeIndex, outStream);
break;
default:
throw new CoderException("Unknown encoding " + encoding);
}
}
@Override
public PaneInfo decode(final InputStream inStream, Coder.Context context)
throws CoderException, IOException {
byte keyAndTag = (byte) inStream.read();
PaneInfo base = BYTE_TO_PANE_INFO.get((byte) (keyAndTag & 0x0F));
long index, onTimeIndex;
switch (Encoding.fromTag(keyAndTag)) {
case FIRST:
return base;
case ONE_INDEX:
index = VarInt.decodeLong(inStream);
onTimeIndex = base.timing == Timing.EARLY ? -1 : index;
break;
case TWO_INDICES:
index = VarInt.decodeLong(inStream);
onTimeIndex = VarInt.decodeLong(inStream);
break;
default:
throw new CoderException("Unknown encoding " + (keyAndTag & 0xF0));
}
return new PaneInfo(base.isFirst, base.isLast, base.timing, index, onTimeIndex);
}
}
}