flume-Thrift-source

Thrift IDL
Flume Thrift IDL在client包里面，定义如下：

namespace java org.apache.flume.thrift

struct ThriftFlumeEvent {
1: required map <string, string> headers,
2: required binary body,
}

enum Status {
OK,
FAILED,
ERROR,
UNKNOWN
}

service ThriftSourceProtocol {
Status append(1: ThriftFlumeEvent event),
Status appendBatch(1: list<ThriftFlumeEvent> events),
}注意:event在C#里面是关键字，所以利用Thrift编译器生成客户端的接口时，要把所有event关键字改成其他的、比如events.

Thrift Service
Flume的Source分两种:

?实现PollableSource接口
通过SinkRunner管理Source
?实现EventDrivenSource接口
可以自己接受数据、发送到channel。比如ThriftSource
Flume Thrift Service的实现类在core包

public class ThriftSource extends AbstractSource implements Configurable,
EventDrivenSource {
public static final String CONFIG_THREADS = "threads";
public static final String CONFIG_BIND = "bind";
public static final String CONFIG_PORT = "port";
private Integer port;
private String bindAddress;
private int maxThreads = 0;
private SourceCounter sourceCounter;
private TServer server;
private TServerTransport serverTransport;
private ExecutorService servingExecutor;
public void start() {
//创建工作者线程池
...
args.protocolFactory(new TCompactProtocol.Factory());
args.inputTransportFactory(new TFastFramedTransport.Factory());
args.outputTransportFactory(new TFastFramedTransport.Factory());

//ThriftSourceProtocol是Flume Thrift Service的真正实现
args.processor(new ThriftSourceProtocol
.Processor<ThriftSourceHandler>(new ThriftSourceHandler()));
/**
* Start serving.
*/
servingExecutor.submit(new Runnable() {
@Override
public void run() {
server.serve();
}
});
...
}Flume Thrift Service真正的实现类是内部类ThriftSourceHandler

private class ThriftSourceHandler implements ThriftSourceProtocol.Iface {

@Override
public Status append(ThriftFlumeEvent event) throws TException {
Event flumeEvent = EventBuilder.withBody(event.getBody(),
event.getHeaders());

sourceCounter.incrementAppendReceivedCount();
sourceCounter.incrementEventReceivedCount();

try {
//传给channel
getChannelProcessor().processEvent(flumeEvent);
} catch (ChannelException ex) {
logger.warn("Thrift source " + getName() + " could not append events " +
"to the channel.", ex);
return Status.FAILED;
}
sourceCounter.incrementAppendAcceptedCount();
sourceCounter.incrementEventAcceptedCount();
return Status.OK;
}

@Override
public Status appendBatch(List<ThriftFlumeEvent> events) throws TException {
sourceCounter.incrementAppendBatchReceivedCount();
sourceCounter.addToEventReceivedCount(events.size());

List<Event> flumeEvents = Lists.newArrayList();
for(ThriftFlumeEvent event : events) {
flumeEvents.add(EventBuilder.withBody(event.getBody(),
event.getHeaders()));
}

try {
getChannelProcessor().processEventBatch(flumeEvents);
} catch (ChannelException ex) {
logger.warn("Thrift source %s could not append events to the " +
"channel.", getName());
return Status.FAILED;
}

sourceCounter.incrementAppendBatchAcceptedCount();
sourceCounter.addToEventAcceptedCount(events.size());
return Status.OK;
}
}