Question

我想在我的多线程项目中转换所有日志消息，以使用Apple System Log工具（或asl）。

根据以下asl手册 - https://developer.apple.com/library/ios/documentation/System/Conceptual/ManPages_iPhoneOS/man3/asl_get.3.html

从多个线程进行日志记录时，每个线程必须使用asl_open打开一个单独的客户端句柄。

出于这个原因，我已经为每个线程定义了asl客户端，以便在我的所有日志命令中使用。但是，在将asl客户端绑定到每个asl_log命令时面临一些主要困难。

1. what if some of my asl log commands reside in a code that is common for
   more than one thread - which asl client should i decide use on such message.

2. Even on thread unique code, one should be consistent in choosing the same
   asl_client on all log functions on a single thread code scope (this is
   not always easy to find in complex projects.).

有没有更简单的方法来采用我的项目日志消息来使用asl？

我考虑将asl客户端绑定到线程，

谢谢

Answer 1

好的，所以到目前为止我发现的最佳解决方案是创建一个特定于线程的全局变量asl客户端。

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <asl.h>
#define NUMTHREADS 4

pthread_key_t glob_var_key;

void print_func() //take global var and use it as the aslclient per thread
{ 
    asl_log(*((aslclient*) pthread_getspecific(glob_var_key)),NULL,ASL_LEVEL_NOTICE, "blablabla");
}

void* thread_func(void *arg)
{
    aslclient *p = malloc(sizeof(aslclient));
    // added tid to message format to distinguish between messages 
    uint64_t tid;
    pthread_threadid_np(NULL, &tid);
    char tid_str[20];
    sprintf(tid_str, "%llu", tid);

    *p = asl_open(tid_str,"Facility",ASL_OPT_STDERR);
    pthread_setspecific(glob_var_key, p);
    print_func();

    sleep(1); // enable ctx switch

    print_func();

    pthread_setspecific(glob_var_key, NULL);
    free(p);
    pthread_exit(NULL);
}


int main(void)
{
    pthread_t threads[NUMTHREADS];
    int i;

    pthread_key_create(&glob_var_key,NULL);
    for (i=0; i < NUMTHREADS; i++)
        pthread_create(&threads[i],NULL,thread_func,NULL);

    for (i=0; i < NUMTHREADS; i++)
        pthread_join(threads[i], NULL);
}

在mac OS-X多线程项目上使用asl布局进行日志记录

1 个答案: