linux下c++ 实现单例模式

最新推荐文章于 2025-05-23 19:33:43 发布

nanfenglei23

最新推荐文章于 2025-05-23 19:33:43 发布

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分类专栏： c++ 文章标签： linux c++实现单例模式

本文链接：https://blog.youkuaiyun.com/nanfenglei23/article/details/42458613

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本文详细介绍了如何在Linux系统中使用C++来实现单例模式，包括其重要性和常见实现方法，帮助读者理解并掌握在操作系统层面如何确保类只有一个实例。

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singleton.h，下面是源码

#include    <unistd.h>
#include    <pthread.h>
using namespace std;
class Lock  {
    private:
        pthread_mutex_t m_lock;
    public:
        Lock(pthread_mutex_t  cs) : m_lock(cs) {
            pthread_mutex_lock(&m_lock);
        }
        ~Lock() {
            pthread_mutex_unlock(&m_lock);
        }
};//锁类，实现多线程环境下高效工作

class Singleton {
    private:
        Singleton() {};
        Singleton(const Singleton &);
        Singleton& operator = (const Singleton &);

    public:
        static Singleton *Instantialize();
        static Singleton *pInstance;
        static pthread_mutex_t  mutex;
};
#endif

singleton.cc文件

<pre name="code" class="html">#include "singleton.h"
pthread_mutex_t  Singleton::mutex = PTHREAD_MUTEX_INITIALIZER;
Singleton* Singleton::pInstance = 0;

Singleton* Singleton::Instantialize()   {   
    if(pInstance == NULL)   {   
        //double check
        Lock lock(mutex);           //用lock实现线程安全，用资源管理类，实现异常安全
        //使用资源管理类，在抛出异常的时候，资源管理类对象会被析构，析构总是发生的无论是因为异常抛出还是语句块结束。
        if(pInstance == NULL)   {   
            pInstance = new Singleton();
        }   
    }   
    return pInstance;
}
~

tmain.cc

<pre name="code" class="html">#include    <iostream>
#include    <cassert>
#include    <unistd.h>
#include    <pthread.h>

#include    "singleton.h"

int main(int argc, char *argv[]) {
    Singleton *p = Singleton::Instantialize(); 
    Singleton *q = Singleton::Instantialize(); 
    assert(p != q); 
    return 0;
}

makefile

<pre name="code" class="html">#lizhiming
CC=gcc
CXX=g++
AR=ar
ARFLAGS=cru
CURRENT_DIR=$(shell echo `pwd`)
PARENT_DIRNAME=$(shell basename $(shell dirname $(CURRENT_DIR)))
SOURCE_DIR=$(CURRENT_DIR)/src
PREFIX=${CURRENT_DIR}
DEBUG :=
CFLAGS := $(DEBUG) -g -c -fPIC -Wshadow -Wcast-qual -Wcast-align  \
          -Wwrite-strings -Wsign-compare -Winvalid-pch -fms-extensions \
          -Wall \
          -I./include

CPPFLAGS=$(CFLAGS) -Woverloaded-virtual -Wsign-promo -fno-gnu-keywords

LDFLAGS=-L/usr/local/lib  \
        -lpthread\


DIRNAME=$(shell basename `pwd`)

SRCXXS := $(wildcard *.cc) \
          $(wildcard ./src/*.cc)

SRCS := $(SRCXXS)

CXXOBJS := $(patsubst %.cc, %.o, $(SRCXXS))
OBJS := ${CXXOBJS} \

DEPS := $(patsubst %.o, %.d, $(OBJS))

TARGET := lib$(PARENT_DIRNAME)_$(DIRNAME).so

ARFLAGS := -cvq

TARGET_A_LIB := lib$(PARENT_DIRNAME)_$(DIRNAME).a

all : $(TARGET) $(TARGET_A_LIB)
    
$(TARGET_A_LIB): $(OBJS)
    @ar $(ARFLAGS) $@ $^
    @ranlib $@ 

$(TARGET) : $(OBJS)
    $(CXX) $(OBJS) $(LDFLAGS) -o $@ -shared

-include $(DEPS)

%.o : %.cc
    $(CXX) $(CPPFLAGS) $< -o $@



t:
    @echo "DIRNAME:" $(DIRNAME)
 @echo "PARENT_DIRNAME:" $(PARENT_DIRNAME)
    @echo "SRCS:" $(SRCS)
    @echo "OBJS:" $(OBJS)
    @echo "CFLAGS:" $(CFLAGS)
    @echo "CPPFLAGS:" $(CPPFLAGS)
    @echo "ARFLAGS:" $(ARFLAGS)


clean:
    rm -rf *.o *.d *.a $(OBJS) $(DEPS) $(TARGET)