码迷,mamicode.com
首页 > 其他好文 > 详细

cassandra cqlsh代码分析

时间:2014-08-26 11:37:45      阅读:332      评论:0      收藏:0      [点我收藏+]

标签:cassandra   代码分析   集群   大数据   nosql   

1.  cqlsh代码流程

1)   start入口

bin/cqlsh

-main-

->main(*read_options(sys.argv[1:],os.environ))

->def main(options, hostname, port):

->shell.cmdloop()

->cmdloop(self):  //进入了cmd loop

 

2)   select入口

bin/cqlsh

a)     def do_select(self, parsed):  

 tracing_was_enabled = self.tracing_enabled

        ksname = parsed.get_binding(‘ksname‘)

        stop_tracing =ksname == ‘system_traces‘ or (ksname is None and self.current_keyspace ==‘system_traces‘)

       self.tracing_enabled = self.tracing_enabled and not stop_tracing

        statement =parsed.extract_orig()

       with_default_limit = parsed.get_binding(‘limit‘) is None

        ifwith_default_limit:

           statement = "%s LIMIT %d;" % (statement[:-1], DEFAULT_SELECT_LIMIT)

        self.perform_statement(statement,with_default_limit=with_default_limit) #进入查询过程

       self.tracing_enabled = tracing_was_enabled

可以使用tracing 开关,在shell命令行通过如下命令打开

b)      self.perform_statement(statement, decoder=ErrorHandlingSchemaDecoder, with_default_limit=with_default_limit);

c)      perform_statement_untraced(self, statement, decoder=None,with_default_limit=False)

untraced 的状态下解析代码;

d)     self.cursor.execute(statement, decoder=decoder)#执行代码;

->self.cursor= self.conn.cursor()

     -> self.conn = cql.connect(hostname, port, user=username,password=password,

                                  cql_version=cqlver, transport=transport); #cqlsh打开的时候连接集群

e)     import cql 是在 lib/cql-internal-only-1.4.1.zip 模块里面实现的;

f)       open connection.py ;

  ->def cursor(self):

        if notself.open_socket:

           raise ProgrammingError("Connection has been closed.")

        curs =self.cursorclass(self)

       curs.compression = self.compression

       curs.consistency_level = self.consistency_level

        return curs

g)     open cursor.py

-> def execute(self, cql_query,params={}, decoder=None, consistency_level=None):

        # note that‘decoder‘ here is actually the decoder class, not the

        # instance tobe used for decoding. bad naming, but it‘s in use now.

        ifisinstance(cql_query, unicode):

           raise ValueError("CQL query must be bytes, not unicode")

       self.pre_execution_setup() #执行环节设置

        prepared_q =self.prepare_inline(cql_query, params)   

        cl =consistency_level or self.consistency_level

        response =self.get_response(prepared_q, cl)  #获得执行结果

        returnself.process_execution_results(response, decoder=decoder)

h)     下载代码需要深入分析

  查找.get_response的分析过程

i)      $ grep ‘get_response‘ ./* 
./cursor.py: response =self.get_response(prepared_q, cl) 
./cursor.py: response =self.get_response_prepared(prepared_query, params, cl) 
./native.py: def get_response(self, query,consistency_level): 
./native.py: def get_response_prepared(self,prepared_query, params, consistency_level): 
./thrifteries.py: def get_response(self,cql_query, consistency_level):  #经过测试,该文件实现了前面的功能;
./thrifteries.py: def get_response_prepared(self,prepared_query, params, consistency_level):

 

j)      ./thrifteries.py: defget_response(self, cql_query, consistency_level): 

 def get_response(self, cql_query,consistency_level):

       compressed_q, compress = self.compress_query_text(cql_query)  //语句进行了压缩

        print"thrift_getresponse"

        cl =getattr(ConsistencyLevel, consistency_level)

        if self.use_cql3_methods:   #cassandra 默认为cql3.0

           doquery = self._connection.client.execute_cql3_query   #获得执行方法

           return self.handle_cql_execution_errors(doquery, compressed_q, compress,cl)  //

        else:   #查看方法执行过程

           doquery = self._connection.client.execute_cql_query 

           return self.handle_cql_execution_errors(doquery, compressed_q, compress)

k)     def handle_cql_execution_errors(self, executor, *args, **kwargs):

        try:

           return executor(*args, **kwargs) //调用executor方法执行出来结果,所有需要关注executor方法

        exceptInvalidRequestException, ire:

           raise cql.ProgrammingError("Bad Request: %s" % ire.why)

        exceptSchemaDisagreementException, sde:

           raise cql.IntegrityError("Schema versions disagree, (try againlater).")

        exceptUnavailableException:

           raise cql.OperationalError("Unable to complete request: one or "

                                     "more nodes were unavailable.")

        exceptTimedOutException:

           raise cql.OperationalError("Request did not complete within rpc_timeout.")

        exceptTApplicationException, tapp:

 

l)       doquery =self._connection.client.execute_prepared_cql3_query

[ lib]$ grep -r ‘prepare_cql3_query‘./cql-1.4.1/* 
./cql-1.4.1/cql/thrifteries.py: doquery =self._connection.client.prepare_cql3_query 
./cql-1.4.1/cql/cassandra/Cassandra.py: defprepare_cql3_query(self, query, compression): 
./cql-1.4.1/cql/cassandra/Cassandra.py: defprepare_cql3_query(self, query, compression): 
./cql-1.4.1/cql/cassandra/Cassandra.py:self.send_prepare_cql3_query(query, compression) 
./cql-1.4.1/cql/cassandra/Cassandra.py: returnself.recv_prepare_cql3_query() 
./cql-1.4.1/cql/cassandra/Cassandra.py: defsend_prepare_cql3_query(self, query, compression): 
./cql-1.4.1/cql/cassandra/Cassandra.py:self._oprot.writeMessageBegin(‘prepare_cql3_query‘, TMessageType.CALL,self._seqid) 
./cql-1.4.1/cql/cassandra/Cassandra.py: args =prepare_cql3_query_args() 
./cql-1.4.1/cql/cassandra/Cassandra.py: def recv_prepare_cql3_query(self,): 
./cql-1.4.1/cql/cassandra/Cassandra.py: result =prepare_cql3_query_result() 
./cql-1.4.1/cql/cassandra/Cassandra.py: raiseTApplicationException(TApplicationException.MISSING_RESULT,"prepare_cql3_query failed: unknown result"); 
./cql-1.4.1/cql/cassandra/Cassandra.py:self._processMap["prepare_cql3_query"] =Processor.process_prepare_cql3_query 
./cql-1.4.1/cql/cassandra/Cassandra.py: defprocess_prepare_cql3_query(self, seqid, iprot, oprot): 
./cql-1.4.1/cql/cassandra/Cassandra.py: args =prepare_cql3_query_args() 
./cql-1.4.1/cql/cassandra/Cassandra.py: result =prepare_cql3_query_result() 
./cql-1.4.1/cql/cassandra/Cassandra.py:result.success = self._handler.prepare_cql3_query(args.query, args.compression) 
./cql-1.4.1/cql/cassandra/Cassandra.py:oprot.writeMessageBegin("prepare_cql3_query", TMessageType.REPLY,seqid) 
./cql-1.4.1/cql/cassandra/Cassandra.py:classprepare_cql3_query_args: 
./cql-1.4.1/cql/cassandra/Cassandra.py:oprot.writeStructBegin(‘prepare_cql3_query_args‘) 
./cql-1.4.1/cql/cassandra/Cassandra.py:classprepare_cql3_query_result: 
./cql-1.4.1/cql/cassandra/Cassandra.py:oprot.writeStructBegin(‘prepare_cql3_query_result‘)

m)     open cql-1.4.1/cql/cassandra/Cassandra.py

 def execute_cql3_query(self, query,compression, consistency):

    """

    Parameters:

     - query

     - compression

     - consistency

    """

    print"execute_cql3_query(self, query, compression, consistency)"

   self.send_execute_cql3_query(query, compression, consistency)  #发送请求

    returnself.recv_execute_cql3_query()  #接受请求

n)       def send_execute_cql3_query(self,query, compression, consistency):

   self._oprot.writeMessageBegin(‘execute_cql3_query‘, TMessageType.CALL,self._seqid)

    args =execute_cql3_query_args()

    args.query = query

    args.compression =compression

    args.consistency =consistency

    args.write(self._oprot)

   self._oprot.writeMessageEnd()

    self._oprot.trans.flush()

 

消息内容如下

|   string           |       32bit      |  32bit     |

|  execute_cql3_query‘|TMessageType.CAL| self._seqid |

 -------------------args----------------------------------

end

 

将请求类型发送到thrift端口,有固定的通信协议。

o)      grep -r ‘writeMessage‘  ./*

./lib/thrift/protocol/TProtocol.py:  def writeMessageBegin(self, name, ttype,seqid):

./lib/thrift/protocol/TProtocol.py:  def writeMessageEnd(self):

./lib/thrift/protocol/TJSONProtocol.py: defwriteMessageBegin(self, name, request_type, seqid):

./lib/thrift/protocol/TJSONProtocol.py:  def writeMessageEnd(self):

./lib/thrift/protocol/TJSONProtocol.py: defwriteMessageBegin(self, name, request_type, seqid):

./lib/thrift/protocol/TJSONProtocol.py:    def writeMessageEnd(self):

./lib/thrift/protocol/TBinaryProtocol.py:  def writeMessageBegin(self, name, type,seqid):

./lib/thrift/protocol/TBinaryProtocol.py:  def writeMessageEnd(self):

使用了thrift接口写入端口信息

p)          vim./lib/thrift/protocol/TBinaryProtocol.py

def writeMessageBegin(self, name, type,seqid):

   if self.strictWrite:

     self.writeI32(TBinaryProtocol.VERSION_1 | type)

     self.writeString(name)

     self.writeI32(seqid)

   else:

     self.writeString(name)

     self.writeByte(type)

     self.writeI32(seqid)

q)      vimlib/cql-1.4.1/cql/cassandra/Cassandra.py

def write(self,oprot):

    if oprot.__class__ ==TBinaryProtocol.TBinaryProtocolAccelerated and self.thrift_spec is not None andfastbinary is n

ot None:

     oprot.trans.write(fastbinary.encode_binary(self, (self.__class__,self.thrift_spec)))

      return

    oprot.writeStructBegin(‘execute_cql3_query_args‘)

    if self.query is not None:

     oprot.writeFieldBegin(‘query‘, TType.STRING, 1)

     oprot.writeString(self.query)

      oprot.writeFieldEnd()

    if self.compression is notNone:

     oprot.writeFieldBegin(‘compression‘, TType.I32, 2)

     oprot.writeI32(self.compression)

      oprot.writeFieldEnd()

    if self.consistency is notNone:

     oprot.writeFieldBegin(‘consistency‘, TType.I32, 3)

     oprot.writeI32(self.consistency)

      oprot.writeFieldEnd()

    oprot.writeFieldStop()

    oprot.writeStructEnd()

cassandra cqlsh代码分析

标签:cassandra   代码分析   集群   大数据   nosql   

原文地址:http://blog.csdn.net/u011291159/article/details/38844767

(0)
(0)
   
举报
评论 一句话评论(0
登录后才能评论!
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码!