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Apache FlinkCEP 实现超时状态监控的步骤详解

Apache FlinkCEP apache 超时状态监控 2022-06-04 23:06:42 786人浏览八月长安

摘要

CEP - Complex Event Processing复杂事件处理。订单下单后超过一定时间还未进行支付确认。打车订单生成后超过一定时间没有确认上车。外卖超过预定送达时间一定时限还没有确认送达。

CEP - Complex Event Processing复杂事件处理。

订单下单后超过一定时间还未进行支付确认。

打车订单生成后超过一定时间没有确认上车。

外卖超过预定送达时间一定时限还没有确认送达。

Apache flinkCEP api

CEPTimeoutEventJob

FlinkCEP源码简析

DataStream和PatternStream

DataStream 一般由相同类型事件或元素组成，一个DataStream可以通过一系列的转换操作如Filter、Map等转换为另一个DataStream。

PatternStream 是对CEP模式匹配的流的抽象，把DataStream和Pattern组合在一块，然后对外提供select和flatSelect等方法。PatternStream并不是DataStream，它提供方法把匹配的模式序列和与其相关联的事件组成的映射（就是Map<模式名称,List<事件>>）发出去，发到SingleOutputStreamOperator里面，SingleOutputStreamOperator是DataStream。

CEPOperatorUtils工具类里的方法和变量使用了「PatternStream」来命名，比如：


public
 
static
 <IN, OUT> 
SingleOutputStreamOperator
<OUT> createPatternStream(...){...}
public

static
 <IN, OUT1, OUT2> 
SingleOutputStreamOperator
<OUT1> createTimeoutPatternStream(...){...}

final
 
SingleOutputStreamOperator
<OUT> patternStream;

SingleOutputStreamOperator


@Public

public
 
class
 
SingleOutputStreamOperator
<T> 
extends
 
DataStream
<T> {...}

PatternStream的构造方法：


PatternStream
(
final
 
DataStream
<T> inputStream, 
final
 
Pattern
<T, ?> pattern) {

  
this
.inputStream = inputStream;

  
this
.pattern = pattern;

  
this
.comparator = 
null
;

}



PatternStream
(
final
 
DataStream
<T> inputStream, 
final
 
Pattern
<T, ?> pattern, 
final
 
EventComparator
<T> comparator) {

  
this
.inputStream = inputStream;

  
this
.pattern = pattern;

  
this
.comparator = comparator;

}

Pattern、Quantifier和EventComparator

Pattern是模式定义的Base Class，Builder模式，定义好的模式会被NFACompiler用来生成NFA。

如果想要自己实现类似next和followedBy这种方法，比如timeEnd，对Pattern进行扩展重写应该是可行的。


public
class
Pattern
<T, F 
extends
 T> {

private
final
String
 name;

private
final
Pattern
<T, ? 
extends
 T> previous;

private
IterativeCondition
<F> condition;

private
Time
 windowTime;

private
Quantifier
 quantifier = 
Quantifier
.one(
ConsumingStrategy
.STRICT);

private
IterativeCondition
<F> untilCondition;

private
Times
 times;
// 匹配到事件之后的跳过策略
private
final
AfterMatchSkipStrategy
 afterMatchSkipStrategy;
  ...
}

Quantifier是用来描述具体模式行为的，主要有三大类：

Single-单一匹配、Looping-循环匹配、Times-一定次数或者次数范围内都能匹配到。

每一个模式Pattern可以是optional可选的（单一匹配或循环匹配），并可以设置ConsumingStrategy。

循环和次数也有一个额外的内部ConsumingStrategy，用在模式中接收的事件之间。


public
class
Quantifier
 {
  ...

public
enum
QuantifierProperty
 {
    SINGLE,
    LOOPING,
    TIMES,
    OPTIONAL,
    GREEDY
  }

public
enum
ConsumingStrategy
 {
    STRICT,
    SKIP_TILL_NEXT,
    SKIP_TILL_ANY,
    NOT_FOLLOW,
    NOT_NEXT
  }

public
static
class
Times
 {
private
final
int
 from;
private
final
int
 to;
private
Times
(
int
 from, 
int
 to) {
Preconditions
.checkArgument(from > 
0
, 
"The from should be a positive number greater than 0."
);
Preconditions
.checkArgument(to >= from, 
"The to should be a number greater than or equal to from: "
 + from + 
"."
);
this
.from = from;
this
.to = to;
    }
public
int
 getFrom() {
return
 from;
    }
public
int
 getTo() {
return
 to;
    }
// 次数范围
public
static
Times
 of(
int
 from, 
int
 to) {
return
new
Times
(from, to);
    }
// 指定具体次数
public
static
Times
 of(
int
 times) {
return
new
Times
(times, times);
    }
@Override
public
boolean
 equals(
Object
 o) {
if
 (
this
 == o) {
return
true
;
      }
if
 (o == 
null
 || getClass() != o.getClass()) {
return
false
;
      }
Times
 times = (
Times
) o;
return
 from == times.from &&
        to == times.to;
    }
@Override
public
int
 hashCode() {
return
Objects
.hash(from, to);
    }
  }
  ...
}

EventComparator，自定义事件比较器，实现EventComparator接口。


public
 
interface
 
EventComparator
<T> 
extends
 
Comparator
<T>, 
Serializable
 {
long
 serialVersionUID = 
1L
;
}

NFACompiler和NFA

NFACompiler提供将Pattern编译成NFA或者NFAFactory的方法，使用NFAFactory可以创建多个NFA。


public
class
NFACompiler
 {
  ...

public
interface
NFAFactory
<T> 
extends
Serializable
 {
    NFA<T> createNFA();
  }
  

private
static
class
NFAFactoryImpl
<T> 
implements
NFAFactory
<T> {
    
private
static
final
long
 serialVersionUID = 
8939783698296714379L
;
    
private
final
long
 windowTime;
private
final
Collection
<
State
<T>> states;
private
final
boolean
 timeoutHandling;
    
private
NFAFactoryImpl
(
long
 windowTime,
Collection
<
State
<T>> states,
boolean
 timeoutHandling) {
      
this
.windowTime = windowTime;
this
.states = states;
this
.timeoutHandling = timeoutHandling;
    }
    
@Override
public
 NFA<T> createNFA() {
// 一个NFA由状态集合、时间窗口的长度和是否处理超时组成
return
new
 NFA<>(states, windowTime, timeoutHandling);
    }
  }
}

NFA：Non-deterministic finite automaton - 非确定的有限（状态）自动机。

更多内容参见

https://zh.wikipedia.org/wiki/非确定有限状态自动机


public
class
 NFA<T> {

private
final
Map
<
String
, 
State
<T>> states;
  

private
final
long
 windowTime;
  

private
final
boolean
 handleTimeout;
  ...
}

PatternSelectFunction和PatternFlatSelectFunction

当一个包含被匹配到的事件的映射能够通过模式名称访问到的时候，PatternSelectFunction的select()方法会被调用。模式名称是由Pattern定义的时候指定的。select()方法恰好返回一个结果，如果需要返回多个结果，则可以实现PatternFlatSelectFunction。


public
 
interface
 
PatternSelectFunction
<IN, OUT> 
extends
 
Function
, 
Serializable
 {



  


  OUT select(
Map
<
String
, 
List
<IN>> pattern) 
throws
 
Exception
;

}

PatternFlatSelectFunction，不是返回一个OUT，而是使用Collector 把匹配到的事件收集起来。


public
interface
PatternFlatSelectFunction
<IN, OUT> 
extends
Function
, 
Serializable
 {
  

void
 flatSelect(
Map
<
String
, 
List
<IN>> pattern, 
Collector
<OUT> out) 
throws
Exception
;
}

SelectTimeoutCepOperator、PatternTimeoutFunction

SelectTimeoutCepOperator是在CEPOperatorUtils中调用createTimeoutPatternStream()方法时创建出来。

SelectTimeoutCepOperator中会被算子迭代调用的方法是proceSSMatchedSequences()和processTimedOutSequences()。

模板方法...对应到抽象类AbstracTKEyedCEPPatternOperator中processEvent()方法和advanceTime()方法。

还有FlatSelectTimeoutCepOperator和对应的PatternFlatTimeoutFunction。


public
class
SelectTimeoutCepOperator
<IN, OUT1, OUT2, KEY>
extends
AbstractKeyedCEPPatternOperator
<IN, KEY, OUT1, 
SelectTimeoutCepOperator
.
SelectWrapper
<IN, OUT1, OUT2>> {
private
OutputTag
<OUT2> timedOutOutputTag;
public
SelectTimeoutCepOperator
(
TypeSerializer
<IN> inputSerializer,
boolean
 isProcessingTime,
NFACompiler
.
NFAFactory
<IN> nfaFactory,
final
EventComparator
<IN> comparator,
AfterMatchSkipStrategy
 skipStrategy,
// 参数命名混淆了flat...包括SelectWrapper类中的成员命名...
PatternSelectFunction
<IN, OUT1> flatSelectFunction,
PatternTimeoutFunction
<IN, OUT2> flatTimeoutFunction,
OutputTag
<OUT2> outputTag,
OutputTag
<IN> lateDataOutputTag) {
super
(
      inputSerializer,
      isProcessingTime,
      nfaFactory,
      comparator,
      skipStrategy,
new
SelectWrapper
<>(flatSelectFunction, flatTimeoutFunction),
      lateDataOutputTag);
this
.timedOutOutputTag = outputTag;
  }
  ...
}
public
interface
PatternTimeoutFunction
<IN, OUT> 
extends
Function
, 
Serializable
 {
  OUT timeout(
Map
<
String
, 
List
<IN>> pattern, 
long
 timeoutTimestamp) 
throws
Exception
;
}
public
interface
PatternFlatTimeoutFunction
<IN, OUT> 
extends
Function
, 
Serializable
 {
void
 timeout(
Map
<
String
, 
List
<IN>> pattern, 
long
 timeoutTimestamp, 
Collector
<OUT> out) 
throws
Exception
;
}

CEP和CEPOperatorUtils

CEP是创建PatternStream的工具类，PatternStream只是DataStream和Pattern的组合。


public
class
 CEP {
  
public
static
 <T> 
PatternStream
<T> pattern(
DataStream
<T> input, 
Pattern
<T, ?> pattern) {
return
new
PatternStream
<>(input, pattern);
  }
  
public
static
 <T> 
PatternStream
<T> pattern(
DataStream
<T> input, 
Pattern
<T, ?> pattern, 
EventComparator
<T> comparator) {
return
new
PatternStream
<>(input, pattern, comparator);
  }
}

CEPOperatorUtils是在PatternStream的select()方法和flatSelect()方法被调用的时候，去创建SingleOutputStreamOperator（DataStream）。


public
class
CEPOperatorUtils
 {
  ...
private
static
 <IN, OUT, K> 
SingleOutputStreamOperator
<OUT> createPatternStream(
final
DataStream
<IN> inputStream,
final
Pattern
<IN, ?> pattern,
final
TypeInfORMation
<OUT> outTypeInfo,
final
boolean
 timeoutHandling,
final
EventComparator
<IN> comparator,
final
OperatorBuilder
<IN, OUT> operatorBuilder) {
final
TypeSerializer
<IN> inputSerializer = inputStream.getType().createSerializer(inputStream.getExecutionConfig());
    
// check whether we use processing time
final
boolean
 isProcessingTime = inputStream.getExecutionEnvironment().getStreamTimeCharacteristic() == 
TimeCharacteristic
.
ProcessingTime
;
    
// compile our pattern into a NFAFactory to instantiate NFAs later on
final
NFACompiler
.
NFAFactory
<IN> nfaFactory = 
NFACompiler
.compileFactory(pattern, timeoutHandling);
    
final
SingleOutputStreamOperator
<OUT> patternStream;
    
if
 (inputStream 
instanceof
KeyedStream
) {
KeyedStream
<IN, K> keyedStream = (
KeyedStream
<IN, K>) inputStream;
      patternStream = keyedStream.transform(
        operatorBuilder.getKeyedOperatorName(),
        outTypeInfo,
        operatorBuilder.build(
          inputSerializer,
          isProcessingTime,
          nfaFactory,
          comparator,
          pattern.getAfterMatchSkipStrategy()));
    } 
else
 {
KeySelector
<IN, 
Byte
> keySelector = 
new
NullByteKeySelector
<>();
      patternStream = inputStream.keyBy(keySelector).transform(
        operatorBuilder.getOperatorName(),
        outTypeInfo,
        operatorBuilder.build(
          inputSerializer,
          isProcessingTime,
          nfaFactory,
          comparator,
          pattern.getAfterMatchSkipStrategy()
        )).forceNonParallel();
    }
    
return
 patternStream;
  }
  ...
}

FlinkCEP实现步骤

IN: DataSource -> DataStream -> Transformations -> DataStream
Pattern: Pattern.begin.where.next.where...times...
PatternStream: CEP.pattern(DataStream, Pattern)
DataStream: PatternStream.select(PatternSelectFunction) PatternStream.flatSelect(PatternSelectFunction)
OUT: DataStream -> Transformations -> DataStream -> DataSink

FlinkCEP匹配超时实现步骤

TimeoutCEP的流需要keyBy，即KeyedStream，如果inputStream不是KeyedStream，会new一个0字节的Key（上面CEPOperatorUtils源码里有提到）。


KeySelector
<IN, 
Byte
> keySelector = 
new
 
NullByteKeySelector
<>();

Pattern最后调用within设置窗口时间。如果是对主键进行分组，一个时间窗口内最多只会匹配出一个超时事件，使用PatternStream.select(...)就可以了。

IN: DataSource -> DataStream -> Transformations -> DataStream -> keyBy -> KeyedStream
Pattern: Pattern.begin.where.next.where...within(Time windowTime)
PatternStream: CEP.pattern(KeyedStream, Pattern)
OutputTag: new OutputTag(...)
SingleOutputStreamOperator: PatternStream.flatSelect(OutputTag, PatternFlatTimeoutFunction, PatternFlatSelectFunction)
DataStream: SingleOutputStreamOperator.getSideOutput(OutputTag)
OUT: DataStream -> Transformations -> DataStream -> DataSink

FlinkCEP超时不足

和Flink窗口聚合类似，如果使用事件时间和依赖事件生成的水印向前推进，需要后续的事件到达，才会触发窗口进行计算和输出结果。

FlinkCEP超时完整demo


public
class
CEPTimeoutEventJob
 {
private
static
final
String
 LOCAL_kafka_BROKER = 
"localhost:9092"
;
private
static
final
String
 GROUP_ID = 
CEPTimeoutEventJob
.
class
.getSimpleName();
private
static
final
String
 GROUP_TOPIC = GROUP_ID;
  
public
static
void
 main(
String
[] args) 
throws
Exception
 {
// 参数
ParameterTool
 params = 
ParameterTool
.fromArgs(args);
    
StreamExecutionEnvironment
 env = 
StreamExecutionEnvironment
.getExecutionEnvironment();
// 使用事件时间
    env.setStreamTimeCharacteristic(
TimeCharacteristic
.
EventTime
);
    env.enableCheckpointing(
5000
);
    env.getCheckpointConfig().enableExternalizedCheckpoints(
CheckpointConfig
.
ExternalizedCheckpointCleanup
.RETAIN_ON_CANCELLATION);
    env.getConfig().disableSysoutLogging();
    env.getConfig().setRestartStrategy(
RestartStrategies
.fixedDelayRestart(
5
, 
10000
));
    
// 不使用POJO的时间
final
AssignerWithPeriodicWatermarks
 extractor = 
new
IngestionTimeExtractor
<POJO>();
    
// 与Kafka Topic的Partition保持一致
    env.setParallelism(
3
);
    
Properties
 kafkaProps = 
new
Properties
();
    kafkaProps.setProperty(
"bootstrap.servers"
, LOCAL_KAFKA_BROKER);
    kafkaProps.setProperty(
"group.id"
, GROUP_ID);
    
// 接入Kafka的消息
FlinkKafkaConsumer011
<POJO> consumer = 
new
FlinkKafkaConsumer011
<>(GROUP_TOPIC, 
new
POJOSchema
(), kafkaProps);
DataStream
<POJO> pojoDataStream = env.addSource(consumer)
        .assignTimestampsAndWatermarks(extractor);
    pojoDataStream.print();
    
// 根据主键aid分组 即对每一个POJO事件进行匹配检测【不同类型的POJO，可以采用不同的within时间】
// 1.
DataStream
<POJO> keyedPojos = pojoDataStream
        .keyBy(
"aid"
);
    
// 从初始化到终态-一个完整的POJO事件序列
// 2.
Pattern
<POJO, POJO> completedPojo =
Pattern
.<POJO>begin(
"init"
)
            .where(
new
SimpleCondition
<POJO>() {
private
static
final
long
 serialVersionUID = -
6847788055093903603L
;
              
@Override
public
boolean
 filter(POJO pojo) 
throws
Exception
 {
return
"02"
.equals(pojo.getAstatus());
              }
            })
            .followedBy(
"end"
)
//            .next("end")
            .where(
new
SimpleCondition
<POJO>() {
private
static
final
long
 serialVersionUID = -
2655089736460847552L
;
              
@Override
public
boolean
 filter(POJO pojo) 
throws
Exception
 {
return
"00"
.equals(pojo.getAstatus()) || 
"01"
.equals(pojo.getAstatus());
              }
            });
    
// 找出1分钟内【便于测试】都没有到终态的事件aid
// 如果针对不同类型有不同within时间，比如有的是超时1分钟，有的可能是超时1个小时 则生成多个PatternStream
// 3.
PatternStream
<POJO> patternStream = CEP.pattern(keyedPojos, completedPojo.within(
Time
.minutes(
1
)));
    
// 定义侧面输出timedout
// 4.
OutputTag
<POJO> timedout = 
new
OutputTag
<POJO>(
"timedout"
) {
private
static
final
long
 serialVersionUID = 
773503794597666247L
;
    };
    
// OutputTag<L> timeoutOutputTag, PatternFlatTimeoutFunction<T, L> patternFlatTimeoutFunction, PatternFlatSelectFunction<T, R> patternFlatSelectFunction
// 5.
SingleOutputStreamOperator
<POJO> timeoutPojos = patternStream.flatSelect(
        timedout,
new
POJOTimedOut
(),
new
FlatSelectNothing
()
    );
    
// 打印输出超时的POJO
// 6.7.
    timeoutPojos.getSideOutput(timedout).print();
    timeoutPojos.print();
    env.execute(
CEPTimeoutEventJob
.
class
.getSimpleName());
  }
  

public
static
class
POJOTimedOut
implements
PatternFlatTimeoutFunction
<POJO, POJO> {
private
static
final
long
 serialVersionUID = -
4214641891396057732L
;
    
@Override
public
void
 timeout(
Map
<
String
, 
List
<POJO>> map, 
long
 l, 
Collector
<POJO> collector) 
throws
Exception
 {
if
 (
null
 != map.get(
"init"
)) {
for
 (POJO pojoInit : map.get(
"init"
)) {
System
.out.println(
"timeout init:"
 + pojoInit.getAid());
          collector.collect(pojoInit);
        }
      }
// 因为end超时了，还没收到end，所以这里是拿不到end的
System
.out.println(
"timeout end: "
 + map.get(
"end"
));
    }
  }
  

public
static
class
FlatSelectNothing
<T> 
implements
PatternFlatSelectFunction
<T, T> {
private
static
final
long
 serialVersionUID = -
3029589950677623844L
;
    
@Override
public
void
 flatSelect(
Map
<
String
, 
List
<T>> pattern, 
Collector
<T> collector) {
System
.out.println(
"flatSelect: "
 + pattern);
    }
  }
}

测试结果（followedBy）：


3
> POJO{aid=
'ID000-0'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563419728242
, energy=
529.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'02'
, createTime=
null
, updateTime=
null
}
3
> POJO{aid=
'ID000-1'
, astyle=
'STYLE000-2'
, aname=
'NAME-1'
, logTime=
1563419728783
, energy=
348.00
, age=
26
, tt=
2019
-
07
-
18
, astatus=
'02'
, createTime=
null
, updateTime=
null
}
3
> POJO{aid=
'ID000-0'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563419749259
, energy=
492.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'00'
, createTime=
null
, updateTime=
null
}
flatSelect: {init=[POJO{aid=
'ID000-0'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563419728242
, energy=
529.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'02'
, createTime=
null
, updateTime=
null
}], 
end
=[POJO{aid=
'ID000-0'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563419749259
, energy=
492.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'00'
, createTime=
null
, updateTime=
null
}]}
timeout init:ID000-
1
3
> POJO{aid=
'ID000-1'
, astyle=
'STYLE000-2'
, aname=
'NAME-1'
, logTime=
1563419728783
, energy=
348.00
, age=
26
, tt=
2019
-
07
-
18
, astatus=
'02'
, createTime=
null
, updateTime=
null
}
timeout 
end
: 
null
3
> POJO{aid=
'ID000-2'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563419829639
, energy=
467.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'03'
, createTime=
null
, updateTime=
null
}
3
> POJO{aid=
'ID000-2'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563419841394
, energy=
107.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'00'
, createTime=
null
, updateTime=
null
}
3
> POJO{aid=
'ID000-3'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563419967721
, energy=
431.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'02'
, createTime=
null
, updateTime=
null
}
3
> POJO{aid=
'ID000-3'
, astyle=
'STYLE000-2'
, aname=
'NAME-0'
, logTime=
1563419979567
, energy=
32.00
, age=
26
, tt=
2019
-
07
-
18
, astatus=
'03'
, createTime=
null
, updateTime=
null
}
3
> POJO{aid=
'ID000-3'
, astyle=
'STYLE000-2'
, aname=
'NAME-0'
, logTime=
1563419993612
, energy=
542.00
, age=
26
, tt=
2019
-
07
-
18
, astatus=
'01'
, createTime=
null
, updateTime=
null
}
flatSelect: {init=[POJO{aid=
'ID000-3'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563419967721
, energy=
431.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'02'
, createTime=
null
, updateTime=
null
}], 
end
=[POJO{aid=
'ID000-3'
, astyle=
'STYLE000-2'
, aname=
'NAME-0'
, logTime=
1563419993612
, energy=
542.00
, age=
26
, tt=
2019
-
07
-
18
, astatus=
'01'
, createTime=
null
, updateTime=
null
}]}
3
> POJO{aid=
'ID000-4'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563420063760
, energy=
122.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'02'
, createTime=
null
, updateTime=
null
}
3
> POJO{aid=
'ID000-4'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563420078008
, energy=
275.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'03'
, createTime=
null
, updateTime=
null
}
timeout init:ID000-
4
3
> POJO{aid=
'ID000-4'
, astyle=
'STYLE000-0'
, aname=
'NAME-0'
, logTime=
1563420063760
, energy=
122.00
, age=
0
, tt=
2019
-
07
-
18
, astatus=
'02'
, createTime=
null
, updateTime=
null
}
timeout 
end
: 
null

总结

以上所述是小编给大家介绍的Apache FlinkCEP 实现超时状态监控的步骤，希望对大家有所帮助，如果大家有任何疑问欢迎给我留言，小编会及时回复大家的！

--结束END--

本文标题: Apache FlinkCEP 实现超时状态监控的步骤详解

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