通过Thrift source向Flume发送数据的Python实现

目前Flume支持Thrift source，即通过一个Thrift服务来收集数据（这一点和scribe是一样的），然后通过相应的channel发送到sink中去。以下是具体的实现过程:


环境：Python 2.7.5/CDH4.3 Flume 1.3/Thrift 0.9/
首先，我们需要一个Thrift协议的Python Flume客户端的模块，这个模块可以根据Thrift的定义自动生成。你应该先从Cloudera的网站上下载到CDH4.3中的Flume tarball ：

wget http://archive.cloudera.com/cdh4/cdh/4/

下载到本地之后解压，在目录flume-ng-sdk\src\main\thrift下有Thrift对应的定义文件，并用它来生成对应的客户端模块：

tar xzvf flume-ng-1.3.0-cdh4.3.0.tar.gz
cd apache-flume-1.3.0-cdh4.3.0-bin\flume-ng-sdk\src\main\thrift
thrift --gen py flume.thrit

你会在当前目录下得到一个叫做gen-py的目录，我们将其更名为genpy之后，放到Python的系统模块路径中去：

mv gen-py/ /usr/local/lib/python2.7/site-packages/genpy

此时，你就可以通过以下过程来引用这个模块了：

[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from genpy import flume
>>> dir(flume)
['__all__', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__']
>>> 

下面，就是利用这模块来封装一个客户端模块，注意Flume的Thrift source服务端使用的协议是继承自TCompactProtocol的TTupleProtocol:

public final class TTupleProtocol extends TCompactProtocol {...

在Thrift Python模块中，只有两种可选协议：TCompactProtocol, TBinaryProtocol， 很显然我们需要使用前一种协议，如果使用TBinaryProtocol，会在服务器端报以下错误：

18 Jul 2013 18:25:29,447 ERROR [pool-5-thread-4] (org.apache.thrift.server.TThreadPoolServer$WorkerProcess.run:213)  - Thrift error occurred d
uring processing of message.
org.apache.thrift.protocol.TProtocolException: Expected protocol id ffffff82 but got ffffff80
        at org.apache.thrift.protocol.TCompactProtocol.readMessageBegin(TCompactProtocol.java:472)
        at org.apache.thrift.TBaseProcessor.process(TBaseProcessor.java:27)
        at org.apache.thrift.server.TThreadPoolServer$WorkerProcess.run(TThreadPoolServer.java:206)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
        at java.lang.Thread.run(Thread.java:662)

在客户端会有以下的报错

Traceback (most recent call last):
  File "pyflume.py", line 65, in 
    flume_client.send({'a':'hello', 'b':'world'}, 'events under hello world')
  File "pyflume.py", line 53, in send
    self.client.append(event)
  File "/usr/local/lib/python2.7/site-packages/genpy/flume/ThriftSourceProtocol.py", line 49, in append
    return self.recv_append()
  File "/usr/local/lib/python2.7/site-packages/genpy/flume/ThriftSourceProtocol.py", line 60, in recv_append
    (fname, mtype, rseqid) = self._iprot.readMessageBegin()
  File "/usr/local/lib/python2.7/site-packages/thrift/protocol/TBinaryProtocol.py", line 126, in readMessageBegin
    sz = self.readI32()
  File "/usr/local/lib/python2.7/site-packages/thrift/protocol/TBinaryProtocol.py", line 206, in readI32
    buff = self.trans.readAll(4)
  File "/usr/local/lib/python2.7/site-packages/thrift/transport/TTransport.py", line 58, in readAll
    chunk = self.read(sz - have)
  File "/usr/local/lib/python2.7/site-packages/thrift/transport/TTransport.py", line 271, in read
    self.readFrame()
  File "/usr/local/lib/python2.7/site-packages/thrift/transport/TTransport.py", line 275, in readFrame
    buff = self.__trans.readAll(4)
  File "/usr/local/lib/python2.7/site-packages/thrift/transport/TTransport.py", line 58, in readAll
    chunk = self.read(sz - have)
  File "/usr/local/lib/python2.7/site-packages/thrift/transport/TSocket.py", line 118, in read
    message='TSocket read 0 bytes')
thrift.transport.TTransport.TTransportException: TSocket read 0 bytes

以下就是具体的实现代码，大家可以参考修改：

#coding=utf-8
'''
Created on 2013-07-18


@author: Felix
'''
from genpy.flume import ThriftSourceProtocol
from genpy.flume.ttypes import ThriftFlumeEvent


from thrift.transport import TTransport, TSocket
from thrift.protocol import TCompactProtocol


class _Transport(object):
    def __init__(self, thrift_host, thrift_port, timeout=None, unix_socket=None):
        self.thrift_host = thrift_host
        self.thrift_port = thrift_port
        self.timeout = timeout
        self.unix_socket = unix_socket
        
        self._socket = TSocket.TSocket(self.thrift_host, self.thrift_port, self.unix_socket)
        self._transport_factory = TTransport.TFramedTransportFactory()
        self._transport = self._transport_factory.getTransport(self._socket)
        
    def connect(self):
        try:
            if self.timeout:
                self._socket.setTimeout(self.timeout)
            if not self.is_open():
                self._transport = self._transport_factory.getTransport(self._socket)
                self._transport.open()
        except Exception, e:
            print(e)
            self.close()
    
    def is_open(self):
        return self._transport.isOpen()
    
    def get_transport(self):
        return self._transport
    
    def close(self):
        self._transport.close()
        
class FlumeClient(object):
    def __init__(self, thrift_host, thrift_port, timeout=None, unix_socket=None):
        self._transObj = _Transport(thrift_host, thrift_port, timeout=timeout, unix_socket=unix_socket)
        self._protocol = TCompactProtocol.TCompactProtocol(trans=self._transObj.get_transport())
        self.client = ThriftSourceProtocol.Client(iprot=self._protocol, oprot=self._protocol)
        self._transObj.connect()
        
    def send(self, event):
        try:
            self.client.append(event)
        except Exception, e:
            print(e)
        finally:
            self._transObj.connect()
    
    def send_batch(self, events):
        try:
            self.client.appendBatch(events)
        except Exception, e:
            print(e)
        finally:
            self._transObj.connect()
    
    def close(self):
        self._transObj.close()
    
if __name__ == '__main__':
    import random
    flume_client = FlumeClient('192.168.1.141', 4141)
    event = ThriftFlumeEvent({'a':'hello', 'b':'world'}, 'events under hello world2')
    events = [ThriftFlumeEvent({'a':'hello', 'b':'world'}, 'events under hello world%s' % random.randint(0, 1000)) for _ in range(100)]
    
    flume_client.send(event)
    flume_client.send_batch(events)
    flume_client.close()

    
        


以上代码也在github上：https://github.com/sinolambda/pyflume