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之前对Thrift的理解有点不准确,使用之后发现Thrift比想象中的要简单得多。
Thrift做的事情就是跨语言的分布式RPC,通过编写.thrift文件声明接口类和方法,client调用定义的方法,Server端实现定义的接口。尽管的确RPC是须要网络请求,但不像Netty这样的NIO网络编程库(还要关注许多传输数据中的细节,比方数据怎样序列化、怎样在字节数组里建立结构、怎样在两端解析字节数组、怎样处理Handler里的事件状态、怎样把多个Handler按顺序串起来),Thrift掩盖了传输数据这件事情,开发人员使用的时候就是纯纯的RPC的使用感受。Thrift使用起来差点儿没有不论什么门槛,能够看这篇HelloWorld的文章,尽管有点老,可是看完之后基本使用起来没有不论什么障碍了。
官方给出的这个样例更加全面些,全面在.thrift文件中能够声明的东西列的更全些。
以下看看两个.thrift的定义:shared.thrift
/** * This Thrift file can be included by other Thrift files that want to share * these definitions. */ namespace java com.baidu.mordor.sink.service struct SharedStruct { 1: i32 key 2: string value } service SharedService { SharedStruct getStruct(1: i32 key) }
/** * The first thing to know about are types. The available types in Thrift are: * * bool Boolean, one byte * byte Signed byte * i16 Signed 16-bit integer * i32 Signed 32-bit integer * i64 Signed 64-bit integer * double 64-bit floating point value * string String * binary Blob (byte array) * map<t1,t2> Map from one type to another * list<t1> Ordered list of one type * set<t1> Set of unique elements of one type * * Did you also notice that Thrift supports C style comments? */ // Just in case you were wondering... yes. We support simple C comments too. /** * Thrift files can reference other Thrift files to include common struct * and service definitions. These are found using the current path, or by * searching relative to any paths specified with the -I compiler flag. * * Included objects are accessed using the name of the .thrift file as a * prefix. i.e. shared.SharedObject */ include "shared.thrift" /** * Thrift files can namespace, package, or prefix their output in various * target languages. */ namespace java com.baidu.mordor.sink.service /** * Thrift lets you do typedefs to get pretty names for your types. Standard * C style here. */ typedef i32 MyInteger /** * Thrift also lets you define constants for use across languages. Complex * types and structs are specified using JSON notation. */ const i32 INT32CONSTANT = 9853 const map<string,string> MAPCONSTANT = {‘hello‘:‘world‘, ‘goodnight‘:‘moon‘} /** * You can define enums, which are just 32 bit integers. Values are optional * and start at 1 if not supplied, C style again. */ enum Operation { ADD = 1, SUBTRACT = 2, MULTIPLY = 3, DIVIDE = 4 } /** * Structs are the basic complex data structures. They are comprised of fields * which each have an integer identifier, a type, a symbolic name, and an * optional default value. * * Fields can be declared "optional", which ensures they will not be included * in the serialized output if they aren‘t set. Note that this requires some * manual management in some languages. */ struct Work { 1: i32 num1 = 0, 2: i32 num2, 3: Operation op, 4: optional string comment, } /** * Structs can also be exceptions, if they are nasty. */ exception InvalidOperation { 1: i32 what, 2: string why } /** * Ahh, now onto the cool part, defining a service. Services just need a name * and can optionally inherit from another service using the extends keyword. */ service Calculator extends shared.SharedService { void ping(), i32 add(1:i32 num1, 2:i32 num2), i32 calculate(1:i32 logid, 2:Work w) throws (1:InvalidOperation ouch), /** * This method has a oneway modifier. That means the client only makes * a request and does not listen for any response at all. Oneway methods * must be void. */ oneway void zip() }
Thrift API里三个重要组成部分:Protocal,Transport,Server。
Protocal定义了消息怎样序列化。常见的是TBinaryProtocol,TJSONProtocol,TCompactProtocol。
Transport定义了消息在client和服务端怎样通信。常见的是TSocket,TFramedTransport,TNonblockingTransport等。
TSimpleServer在sever端仅仅有一个I/O堵塞的单线程,每次仅仅接受并服务一个client,适合測试使用,不能用于线上服务。
TNonblockingServer改动了TSimpleServer里堵塞的缺点,借助NIO里的Selector实现非堵塞I/O,同意多个client连接而且client能够使用select()选择。可是处理消息和select()的是同一个线程,当有大量client连接的时候,性能是不理想的。
THsHaServer(半同步半异步server)在以上基础上,使用一个单独线程来处理网络I/O,一个worker线程池来处理消息。优点是仅仅要有空暇worker线程,消息能够被及时、并行处理,吞吐量会大一些。
TThreadedSelectorServer,与THsHaServer的差别是处理网络I/O也是多线程了,它维护两个线程池,一个负责网络I/O,一个负责数据处理。优点是当网络I/O是瓶颈的情况下,性能比THsHaServer更好。
TThreadPoolServer有一个专用的线程来接收connections,连接被建立后,会从ThreadPoolExecutor里取一个工作线程来负责这次连接,直到连接断开后线程回到线程池里,且线程池大小可配。也就是说,并发性的大小可依据服务器设定,假设不介意开许多线程的话,TThreadPoolServer是个还不错的选择。
全文完 :)
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原文地址:http://www.cnblogs.com/gcczhongduan/p/4182949.html