Linux线程私有数据

最近做的一个项目中，有这么个需求，系统中使用多线程技术，每个线程访问redis，希望每个线程来保存对redis的一份长链接，而不是每个请求建立一次链接。如果在线程启动之前建立好链接，然后传到线程的私有数据中，可以实现。可是系统的框架封装的实现，无法传入数据，这时可以采用线程的私有数据技术进行储存和获取。

其中，有三个关键的系统API可供调用，分别是：

1、pthread_key_create ，创建一个key，各个线程可以用这个key去读数据和写数据。

2、存储数据，采用pthread_setspecific

3、获取数据，采用pthread_getspecific

这里转载一个网友给出来的示例：http://blog.csdn.net/lmh12506/article/details/8452700

#include <malloc.h>

#include <pthread.h>

#include <stdio.h>

/* The key used to associate a log file pointer with each thread. */

static pthread_key_t thread_log_key;

/* Write MESSAGE to the log file for the current thread. */

void write_to_thread_log (const char* message)

{
FILE* thread_log = (FILE*) pthread_getspecific (thread_log_key);

fprintf (thread_log, “%s\n”, message);
}

/* Close the log file pointer THREAD_LOG. */

void close_thread_log (void* thread_log)

{
fclose ((FILE*) thread_log);
}

void* thread_function (void* args)

{
char thread_log_filename[20];

FILE* thread_log;

/* Generate the filename for this thread’s log file. */

sprintf (thread_log_filename, “thread%d.log”, (int) pthread_self ());

/* Open the log file. */

thread_log = fopen (thread_log_filename, “w”);

/* Store the file pointer in thread-specific data under thread_log_key. */

pthread_setspecific (thread_log_key, thread_log);

write_to_thread_log (“Thread starting.”);

/* Do work here... */

return NULL;
}

int main ()

{

int i;

pthread_t threads[5];

/* Create a key to associate thread log file pointers in

thread-specific data. Use close_thread_log to clean up the file

pointers. */

pthread_key_create (&thread_log_key, close_thread_log);

/* Create threads to do the work. */

for (i = 0; i < 5; ++i)

pthread_create (&(threads[i]), NULL, thread_function, NULL);

/* Wait for all threads to finish. */

for (i = 0; i < 5; ++i)

pthread_join (threads[i], NULL);

return 0;

}