我正在尝试创建一个程序,其中各种进程可以访问存储在托管共享内存中的数据。我正在利用提升来完成任务。我有三个文件,shared_memory.h,shared_memory.cc和main.cc。
shared_memory.h
#ifndef __SHARED_ITN__
#define __SHARED_ITN__
#include <fst/fstlib.h>
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/allocators/allocator.hpp>
#include <boost/interprocess/containers/vector.hpp>
enum TokenType { SYMBOL = 1, BYTE = 2, UTF8 = 3 };
using namespace boost::interprocess;
typedef fst::VectorFst<fst::StdArc> Transducer;
typedef allocator<Transducer, managed_shared_memory::segment_manager> shmMyFstAllocator;
typedef boost::interprocess::vector<Transducer, shmMyFstAllocator> shmMyFst;
class SharedItn {
public:
SharedItn();
SharedItn(std::vector<string> model_path);
bool Read(std::vector<string> model_path, string input_str, string &output_str);
void Remove();
virtual ~SharedItn();
private:
static const string SHM_OBJ_IDENTIFIER;
static const int SHM_OBJ_SIZE;
shmMyFst* myFstPtr;
};
#endif
相应的c ++代码shared_memory.cc是:
shared_memory.cc
#include "shared_memory.h"
#include <cstdlib>
#include <cstring>
#include <vector>
using namespace fst;
typedef VectorFst<StdArc> Transducer;
typedef StringCompiler<StdArc> Compiler;
const string SharedItn::SHM_OBJ_IDENTIFIER = "SHARED_ITN_MODULES";
const int SharedItn::SHM_OBJ_SIZE = 104857600;
SharedItn::SharedItn() {
}
SharedItn::SharedItn(std::vector<string> model_path) {
try {
// Create managed shared memory object
shared_memory_object::remove(SHM_OBJ_IDENTIFIER.c_str());
managed_shared_memory segment(create_only, SHM_OBJ_IDENTIFIER.c_str(), SHM_OBJ_SIZE);
// Construct fst model within the shared memory object
shmMyFstAllocator alloc_inst(segment.get_segment_manager());
myFstPtr = segment.construct<shmMyFst>(model_path[0].c_str())(alloc_inst);
// Insert the loaded fst model into shared memory
Transducer* tmp_model_fst = Transducer::Read(model_path[0]);
myFstPtr->push_back(*tmp_model_fst);
} catch (interprocess_exception& e) {
std::cout << e.what() << std::endl;
}
}
SharedItn::~SharedItn() {}
bool SharedItn::Read(std::vector<string> model_path, string input_str, string& output_str) {
Transducer* transTmp;
shmMyFst* tmp;
try {
managed_shared_memory segment(open_only, SHM_OBJ_IDENTIFIER.c_str());
tmp = segment.find<shmMyFst>(model_path[0].c_str()).first;
for(int i = 0; i < tmp->size(); i++)
transTmp = tmp->at(i).Copy(true);
} catch (interprocess_exception& e) {
std::cout << e.what() << std::endl;
return false;
}
return true;
}
void SharedItn::Remove() {
try {
shared_memory_object::remove(SHM_OBJ_IDENTIFIER.c_str());
} catch(interprocess_exception& e) {
std::cout << e.what() << std::endl;
}
}
最后是main.cc文件,其中创建了服务器/客户端进程。
main.cc
#include "shared_memory.h"
int main(int argc, char* argv[]) {
if(argc != 2) {
std::cout << "Must provide either 'server' or 'client' as input." << std::endl;
return -1;
} else {
std::vector<string> file_path;
std::string file = "rule_PRE_PROC.fst";
file_path.push_back(file);
string input_str = "";
string result_str;
if(std::string(argv[1]) == "server") {
SharedItn loader(file_path);
while(1) {
std::cout << "Input test string: " << std::endl;
getline(std::cin, input_str);
if(input_str.compare("quit") == 0) {
loader.Remove();
std::cout << "Terminating." << std::endl;
break;
}
loader.Read(file_path, input_str, result_str);
std::cout << "RESULT: " << result_str << std::endl;
}
} else if(std::string(argv[1]) == "client") {
SharedItn loader;
while(1) {
std::cout << "Input test string: " << std::endl;
getline(std::cin, input_str);
if(input_str.compare("quit") == 0) {
loader.Remove();
std::cout << "Terminating." << std::endl;
break;
}
loader.Read(file_path, input_str, result_str);
std::cout << "RESULT: " << result_str << std::endl;
}
}
}
}
当我将程序作为服务器模式运行时,一切正常。但是,当我有一个正在运行的服务器进程并创建一个额外的客户端进程时,它会在尝试在共享内存中查找构造的对象时发生段错误。更具体地说,段错误发生在以下代码中:transTmp = tmp->at(i).Copy(true);
函数中的SharedItn::Read
。
我最好的猜测是客户端调用的find方法无法正常运行。但是,我无法弄清楚问题是什么。任何帮助将不胜感激。
答案 0 :(得分:1)
除非Transducer
是POD,否则这可能是您的问题。
如果fst::Vector<>
在共享内存段之外分配,它将在不同的进程中解决超出界限。