Apache Thrift:返回列表/容器 [英] Apache Thrift: Returning a list/container
问题描述
我制作了一个简单的旧文件,如下所示:
I made a simple thrift file like this:
thrifttest.thrift
namespace cpp thrifttest
namespace d thrifttest
namespace java thrifttest
namespace php thrifttest
namespace perl thrifttest
service Test {
list<i64> ping();
}
并且在shell中运行了"thrift --gen cpp thrifttest.thrift"
and in shell ran "thrift --gen cpp thrifttest.thrift"
但是,当我查看gen-cpp/Test_server.skeleton.cpp时,它使i64列表成为参数,而不是返回类型:
However, when I looked at gen-cpp/Test_server.skeleton.cpp it made the i64 list a parameter, not a return type:
Test_server.skeleton.cpp(摘录)
void ping(std::vector<int64_t> & _return) {
// Your implementation goes here
printf("ping\n");
}
在我的server.cpp程序中,当我执行一个函数ping()并返回"std :: vector&"后,编译器抱怨
and in my server.cpp program, after I make a function ping() that returns an "std::vector &", the compiler complains that
错误:无法分配抽象类型为"TestHandler"的对象 server.cpp:30:7:注意:因为以下虚拟函数在"TestHandler"中是纯净的:
error: cannot allocate an object of abstract type ‘TestHandler’ server.cpp:30:7: note: because the following virtual functions are pure within ‘TestHandler’:
这是server.cpp的完整代码 server.cpp
this is the full code for server.cpp server.cpp
#include <thrift/concurrency/ThreadManager.h>
#include <thrift/concurrency/PosixThreadFactory.h>
#include <thrift/protocol/TBinaryProtocol.h>
#include <thrift/server/TSimpleServer.h>
#include <thrift/server/TThreadPoolServer.h>
#include <thrift/server/TThreadedServer.h>
#include <thrift/transport/TServerSocket.h>
#include <thrift/transport/TTransportUtils.h>
#include <iostream>
#include <stdexcept>
#include <sstream>
#include "gen-cpp/Test.h"
using namespace std;
using namespace apache::thrift;
using namespace apache::thrift::protocol;
using namespace apache::thrift::transport;
using namespace apache::thrift::server;
using boost::shared_ptr;
using namespace thrifttest;
using namespace boost;
unsigned long giant[100];
class TestHandler : virtual public TestIf {
public:
TestHandler() {
for (int i = 0; i < 100; i++) {
giant[i] = -1;
}
}
std::vector<int64_t> & ping() {
return (std::vector<int64_t> &)giant;
}
void ping(std::vector<int64_t> & bla) {}
};
int main(int argc, char **argv) {
shared_ptr<TestHandler> handler(new TestHandler());
shared_ptr<TProcessor> processor(new TestProcessor(handler));
shared_ptr<TServerTransport> serverTransport(new TServerSocket(port));
shared_ptr<TTransportFactory> transportFactory(new TBufferedTransportFactory());
shared_ptr<TProtocolFactory> protocolFactory(new TBinaryProtocolFactory());
TSimpleServer server(processor,
serverTransport,
transportFactory,
protocolFactory);
printf("Starting the server...\n");
server.serve();
printf("done.\n");
return 0;
}
推荐答案
我不小心碰到了一篇文章(价值模型"-Gupta .所以这是一个例子:
I accidentally came across an article (StackOverflow: Handling Apache Thrift List Map Return Types in C) that discussed this exact issue (though the answer didn't work in my case). Turns out, thrift uses a pass-by-reference syntax, even though "Thrift uses a pass by value model" - Gupta. So here's an example:
.thrift文件
service Test {
list<string> ping();
}
服务器端
void ping(std::vector<string> & _return) {
_return.push_back("hello"); //initialize the vector _return with values "hello","world"
_return.push_back("world");
}
客户端
std::vector<string> result; //create vector "result" for storing the values
client.ping(result);
printf("%s %s!\n", result[0].c_str(), result[1].c_str()); //c_str() turns the vector string into a C-style string
客户端输出(启动服务器后)
你好,世界!
hello world!
并感谢Thrift缺乏文档,我感到非常震惊! #4hoursgoogling& crying
and thank you Thrift for the lack of documentation, I had a blast! #4hoursgoogling&crying
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