Python 通过thrift接口连接Hbase读取存储数据

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Python 通过thrift接口连接Hbase读取存储数据

原创 2013年03月14日 23:23:41

标签：
thrift /
Hbase /
python /
并行拓展 /
failover

介绍：

Hbase：开源的分布式数据库

资料介绍:http://www.oschina.net/p/hbase

Thrift:一个软件框架，用来进行可扩展且跨语言的服务的开发。最初由Facebook开发，作为Hadoop的一个工具，提供跨语言服务开发；

资料介绍：http://dongxicheng.org/search-engine/thrift-guide/

官方使用手册：http://download.csdn.net/detail/wyjzt999/5141006从安装到使用都很全面

我们项目里客户端是用python开发，因此需要Thrift提供server端，经过thrift对Hbase进行数据读写操作，性能非常不错，并且可以在Hadoop集群上做并行拓展，稳定性高，Facebook内部通信也是采用thrift来做；

首先学习一下Hbase的表结构：

Row Key

Row key行键 (Row key)可以是任意字符串(最大长度是 64KB，实际应用中长度一般为 10-100bytes)，在hbase内部，row key保存为字节数组。

列族 (column family)

hbase表中的每个列，都归属与某个列族。列族是表的chema的一部分(而列不是)，必须在使用表之前定义。列名都以列族作为前缀。例如courses:history ， courses:math 都属于 courses 这个列族。

时间戳

HBase中通过row和columns确定的为一个存贮单元称为cell。每个 cell都保存着同一份数据的多个版本。版本通过时间戳来索引。时间戳的类型是 64位整型。时间戳可以由hbase(在数据写入时自动 )赋值，此时时间戳是精确到毫秒的当前系统时间。时间戳也可以由客户显式赋值。如果应用程序要避免数据版本冲突，就必须自己生成具有唯一性的时间戳。每个 cell中，不同版本的数据按照时间倒序排序，即最新的数据排在最前面。

为了避免数据存在过多版本造成的的管理 (包括存贮和索引)负担，hbase提供了两种数据版本回收方式。一是保存数据的最后n个版本，二是保存最近一段时间内的版本（比如最近七天）。用户可以针对每个列族进行设置。

对Hbase而言，表结构设计会对系统的性能以及开销上造成很大的区别;

1.首先建立与thriftserver端的连接

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from thrift import Thrift
from thrift.transport import TSocket, TTransport
from thrift.protocol import TBinaryProtocol
from hbase import Hbase
#server端地址和端口
transport = TSocket.TSocket(host, port)
#可以设置超时
transport.setTimeout(5000)
#设置传输方式（TFramedTransport或TBufferedTransport）
trans = TTransport.TBufferedTransport(transport)
#设置传输协议
protocol = TBinaryProtocol.TBinaryProtocol(trans)
#确定客户端
client = Hbase.Client(protocol)
#打开连接
transport.open()

2.然后就可以做具体的操作，比如查表，删表，插入Row Key等等

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from hbase.ttypes import ColumnDescriptor, Mutation, BatchMutation, TRegionInfo
from hbase.ttypes import IOError, AlreadyExists
#获取表名
client.getTableNames()
#创建新表
_TABLE = "keyword"

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demo = ColumnDescriptor(name='data:',maxVersions = 10)#列族data能保留最近的10个数据，每个列名后面要跟:号
createTable(_TABLE, [demo])

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#创建列名2个data:url data:word
tmp1= [Mutation(column="data:url", value="www.baidu.com")]
tmp2= [Mutation(column="data:word", value="YaGer")]
#新建2个列 (表名，行键，列名)
client.mutateRow(_TABLE, row, tmp1)
client.mutateRow(_TABLE, row, tmp1)

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#从表中取数据
#通过最大版本数取数据
client.getByMaxver(_TABLE,'00001','data:word', 10)#一次取10个版本
#取列族内数据
client.getColumns(_TABLE, '00001')

3.支持thrift并行拓展和失效转移Failover机制

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#file name：hbaseconn.py
#! /usr/bin/env python
# -*- coding: utf-8 -*-
#提供建立连接的方法和取数据操作的方法
import logging
import traceback
import time,sys
from unittest import TestCase, main
import socket
from thrift import Thrift
from thrift.transport import TSocket
from thrift.transport import TTransport
from thrift.protocol import TBinaryProtocol
from hbase import Hbase
from hbase.ttypes import IOError as HbaseIOError, AlreadyExists
from hbase.ttypes import ColumnDescriptor, Mutation, BatchMutation
_TABLE = 'thrift_check'
_ROW = 'test_for_thrift'
_DATA = 'data:word'
_VALUE = 'Flag'
class DbConnError(Exception):
"""Conn Db exception.
Timeout or any except for connection from low layer api
"""
pass
class Connection:
def __init__(self, trans, client, addr, port):
self.trans = trans
self.client = client
self.hp = addr
self.port = port
pass
class CenterDb:
@classmethod
def open(cls, host_port):
cls.tc_list = []
for hp in host_port:
trans, client = cls._open(*hp)
cls.tc_list.append(Connection(trans, client, hp[0], hp[1]))
return cls.tc_list
@classmethod
def _open(cls, host, port):
transport = TSocket.TSocket(host, port)
transport.setTimeout(5000)
trans = TTransport.TBufferedTransport(transport)
protocol = TBinaryProtocol.TBinaryProtocol(trans)
client = Hbase.Client(protocol)
ok = False
try:
trans.open()
ok = True
except TSocket.TTransportException, e:
logerr('CenterDb(Hbase) Open error(%s, %d)' % (host, port))
ok = False
else:
pass
# dbg('CenterDb connected (%s, %d)' % (host, port))
return trans, client
@classmethod
def _initTable(cls, client):
dat = ColumnDescriptor(name = 'data', maxVersions = 1)
tmp = [Mutation(column = _DATA, value = _VALUE)]
try:
client.createTable(_TABLE, [dat])
client.mutateRow(_TABLE, _ROW, tmp)
dbg("Create Table For Thrift Test Success!")
return True
except AlreadyExists:
return True
return False
@classmethod
def _get(cls, client):
client.getVer(_TABLE,_ROW,_DATA, 1)
return True
@classmethod
def _reconnect(cls, trans):
trans.close()
trans.open()
def __init__(self, transport, client):
self.t = transport
self.c = client
def __str__(self):
return 'CenterDb.open(%s, %d)' % (self.t, self.c)
def __del__(self):
self.t.close()
def getColumns(self, table, row):
tr_list = []
tr_list = self._failover('getRow', table, row)
if (not tr_list):
return {}
return tr_list[0].columns

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#file name: thriftmanage.py
#! /usr/bin/python
# -*- coding: utf-8 -*-
#提供管理thrift连接的方法
#建一个线程循环检测thrift的可使用性，非连接池
import logging
import time,sys,random
import threading
from hbase import Hbase
from hbase.ttypes import IOError as HbaseIOError
from hbase.ttypes import ColumnDescriptor, Mutation, BatchMutation
import hbaseconn
from hbaseconn import CenterDb
class Failover(threading.Thread):
def __init__(self,serverid, serverlist):
threading.Thread.__init__(self)
self.serverlist = serverlist
self.serverid = serverid
self.lenlist = len(serverlist)
self.conn_list = []
self.invalid_con_list = []
'''''
cur_conn : now oper is using
my_conn : this schd server should use
[(trans1,client1),(trans2,client2),...]
'''
self.cur_conn = None
self.my_conn = None
self._makeConn()
self._getConn()
self._init_for_check()
self.switched_flag = False
def _makeConn(self):
'''''make all the conntion to thrift serverlist
'''
self.conn_list = CenterDb.open(self.serverlist)
def _getConn(self):
'''''get only one connection from the conn_list,confirm cur_conn and my_conn
'''
self.cur_conn = self.my_conn = self.conn_list[(int(self.serverid) % self.lenlist)]
self.other_conn = self.conn_list[:]
self.other_conn.remove(self.my_conn)
return True
def _init_for_check(self):
'''''init _TABLLE test_for_flag
'''
try:
if not CenterDb._initTable( self.my_conn.client ):
dbg("Error In Create Table For Thrift Test!")
except Exception, e:
dbg("init_for_check thrift:%s" % e)
'''''make the only conn for check proc
'''
self.check_conn = CenterDb.open( ((self.my_conn.hp, self.my_conn.port),))[0]
def _switch(self):
'''''when my_conn failed, choose the other client randomly;
when my_conn is reset OK, cur_conn will use my_conn again
'''
#print 'Schd%s come in _switch' % self.serverid
if 0 == len(self.other_conn):
return False
trycount = 0
while True:
try:
if trycount == 3*self.lenlist :#try 3*length times
return False
tmp_conn = random.choice(self.other_conn)
#CenterDb._reconnect(tmp_conn.trans)
#DEBUG
if self._checker(tmp_conn):
self.cur_conn = tmp_conn
dbg('Schd%s _switch cur_conn: %s' % (self.serverid, self.cur_conn.hp))
return True
else:
trycount += 1
logerr('Schd%s _switch for %d times' % (self.serverid, trycount))
CenterDb._reconnect(tmp_conn.trans)#close this trans and try again;breakdown early
if self._checker(tmp_conn):
self.cur_conn = tmp_conn
return True
else:
continue#can't be used
except Exception, e:
continue
def _failover(self,oper, *args, **kwargs):
result = []
try :
result = getattr(self.cur_conn.client, oper)(*args, **kwargs)
return result
except HbaseIOError, e:
logerr("_failover : %s " % e)
except Exception, e:
logerr( 'Schd%s _failover : Connect to %s thrift Server closed! Choose another......Reason:%s ' % \
(self.serverid, self.cur_conn.hp, e))
self.cur_conn.trans.close()
self.switched_flag = True
if self._switch():
logerr('Schd%s _failover : Now using %s server' % (self.serverid, self.cur_conn.hp))
result = getattr(self.cur_conn.client, oper)(*args, **kwargs)
else:
logerr( 'Schd%s _failover : Switch 3 rotate Find No Healthy Thrift server !' % self.serverid)
return result
def getByMaxver(self, table, row, column, max_ver):
"""Get cell list by ver
Get cell list no more than max versions
Args:
table: table name
row: row key
column: column name
max_ver: max version to retrieve cell
"""
cell_list = []
start_time = time.time()
cell_list = self._failover('getVer', table, row, column, max_ver)
if (not cell_list):
return []
take = time.time() - start_time
if take > 0.015:
logerr('Hbase over 15ms:take %s ms' % str("%.3f" % (take*1000)))
return map(lambda x: (x.value, x.timestamp), cell_list)
def getColumns(self, table, row):
tr_list = []
tr_list = self._failover('getRow', table, row)
if (not tr_list):
return {}
return tr_list[0].columns
def _checker(self,conn):
'''''check my_conn , be sure it is connected and get data OK
'''
try:
if conn.trans.isOpen():
CenterDb._get(conn.client)
return True
else:
return False
except Exception, e:
logerr( 'Schd%s _checker : Connect to %s closed! Please Restart now..... Reason: %s ' % \
(self.serverid, conn.hp, e))
return False
def _restart(self):
'''''if my_conn failed, restart it's trans
'''
while True:
#print 'come in _restart %s ' % self.my_conn.hp
self.my_conn.trans.close()
self.check_conn.trans.close()
try:
time.sleep(2)
self.my_conn.trans.open()
self.check_conn.trans.open()
if self.my_conn.trans.isOpen() and self.check_conn.trans.isOpen():
CenterDb._get(self.check_conn.client)
#self.check_conn.client.getVer('keywordurl','test_for_thrift','data:word', 1)
return True
else: continue
except Exception, e:
logerr('Schd%s _restart : Connect to %s is not restart yet ... Reason:%s ' % \
(self.serverid, self.my_conn.hp, e))
self.my_conn.trans.close()
self.check_conn.trans.close()
continue
def run(self):
while True:
time.sleep(1)
if self._checker(self.check_conn) and (not self.switched_flag):
continue
else:
if self._restart():
logerr( 'Schd%s Connection from %s to my:%s Recovered ! ' % \
(self.serverid,self.cur_conn.hp,self.my_conn.hp))
self.cur_conn = self.my_conn
self.switched_flag = False
continue

使用thrift生成的代码中提供的方法有：
void enableTable(Bytes tableName)
void disableTable(Bytes tableName)
bool isTableEnabled(Bytes tableName)
void compact(Bytes tableNameOrRegionName)
void majorCompact(Bytes tableNameOrRegionName)
getTableNames()
getColumnDescriptors(Text tableName)
getTableRegions(Text tableName)
void createTable(Text tableName, columnFamilies)
void deleteTable(Text tableName)
get(Text tableName, Text row, Text column)
getVer(Text tableName, Text row, Text column, i32 numVersions)
getVerTs(Text tableName, Text row, Text column, i64 timestamp, i32 numVersions)
getRow(Text tableName, Text row)
getRowWithColumns(Text tableName, Text row, columns)
getRowTs(Text tableName, Text row, i64 timestamp)
getRowWithColumnsTs(Text tableName, Text row, columns, i64 timestamp)
getRows(Text tableName, rows)
getRowsWithColumns(Text tableName, rows, columns)
getRowsTs(Text tableName, rows, i64 timestamp)
getRowsWithColumnsTs(Text tableName, rows, columns, i64 timestamp)
void mutateRow(Text tableName, Text row, mutations)
void mutateRowTs(Text tableName, Text row, mutations, i64 timestamp)
void mutateRows(Text tableName, rowBatches)
void mutateRowsTs(Text tableName, rowBatches, i64 timestamp)
i64 atomicIncrement(Text tableName, Text row, Text column, i64 value)
void deleteAll(Text tableName, Text row, Text column)
void deleteAllTs(Text tableName, Text row, Text column, i64 timestamp)
void deleteAllRow(Text tableName, Text row)
void deleteAllRowTs(Text tableName, Text row, i64 timestamp)
ScannerID scannerOpenWithScan(Text tableName, TScan scan)
ScannerID scannerOpen(Text tableName, Text startRow, columns)
ScannerID scannerOpenWithStop(Text tableName, Text startRow, Text stopRow, columns)
ScannerID scannerOpenWithPrefix(Text tableName, Text startAndPrefix, columns)
ScannerID scannerOpenTs(Text tableName, Text startRow, columns, i64 timestamp)
ScannerID scannerOpenWithStopTs(Text tableName, Text startRow, Text stopRow, columns, i64 timestamp)
scannerGet(ScannerID id)
scannerGetList(ScannerID id, i32 nbRows)
void scannerClose(ScannerID id)

参考：http://yannramin.com/2008/07/19/using-facebook-thrift-with-python-and-hbase/