怎樣進(jìn)行基于linuxthreads2.0.1線程源碼分析attr.c

怎樣進(jìn)行基于linuxthreads2.0.1線程源碼分析attr.c，針對(duì)這個(gè)問題，這篇文章詳細(xì)介紹了相對(duì)應(yīng)的分析和解答，希望可以幫助更多想解決這個(gè)問題的小伙伴找到更簡(jiǎn)單易行的方法。

attr.c是線程屬性管理的實(shí)現(xiàn)。因?yàn)閘inuxthreads是通過創(chuàng)建一個(gè)進(jìn)程的方式實(shí)現(xiàn)線程的，所以屬性中支持設(shè)置調(diào)度的優(yōu)先級(jí)，調(diào)度策略等（參考操作系統(tǒng)的實(shí)現(xiàn)）。該文件沒有太多內(nèi)容。具體作用在分析其他文件的時(shí)候再作分析。

 
    

#include <unistd.h>
#include "pthread.h"
#include "internals.h"
// 初始化線程屬性結(jié)構(gòu)體
int pthread_attr_init(pthread_attr_t *attr)
{
  attr->detachstate = PTHREAD_CREATE_JOINABLE;
  attr->schedpolicy = SCHED_OTHER;
  attr->schedparam.sched_priority = 0;
  attr->inheritsched = PTHREAD_EXPLICIT_SCHED;
  attr->scope = PTHREAD_SCOPE_SYSTEM;
  return 0;
}

int pthread_attr_destroy(pthread_attr_t *attr)
{
  return 0;
}
// 設(shè)置detach狀態(tài)
int pthread_attr_setdetachstate(pthread_attr_t *attr, int detachstate)
{
  if (detachstate < PTHREAD_CREATE_JOINABLE ||
      detachstate > PTHREAD_CREATE_DETACHED)
    return EINVAL;
  attr->detachstate = detachstate;
  return 0;
}

int pthread_attr_getdetachstate(const pthread_attr_t *attr, int *detachstate)
{
  *detachstate = attr->detachstate;
  return 0;
}
// 設(shè)置調(diào)度優(yōu)先級(jí)的屬性
int pthread_attr_setschedparam(pthread_attr_t *attr,
                               const struct sched_param *param)
{
  // 由系統(tǒng)提供的最大和最小優(yōu)先級(jí)
  int max_prio = sched_get_priority_max(attr->schedpolicy);
  int min_prio = sched_get_priority_min(attr->schedpolicy);

  if (param->sched_priority < min_prio || param->sched_priority > max_prio)
    return EINVAL;
  attr->schedparam = *param;
  return 0;
}

int pthread_attr_getschedparam(const pthread_attr_t *attr,
                               struct sched_param *param)
{
  *param = attr->schedparam;
  return 0;
}

int pthread_attr_setschedpolicy(pthread_attr_t *attr, int policy)
{
  if (policy != SCHED_OTHER && policy != SCHED_FIFO && policy != SCHED_RR)
    return EINVAL;
  // SCHED_OTHER是分時(shí)調(diào)度，設(shè)置成非分時(shí)調(diào)度需要是超級(jí)用戶
  if (policy != SCHED_OTHER && geteuid() != 0)
    return ENOTSUP;
  attr->schedpolicy = policy;
  return 0;
}

int pthread_attr_getschedpolicy(const pthread_attr_t *attr, int *policy)
{
  *policy = attr->schedpolicy;
  return 0;
}
// 調(diào)度策略來源于繼承還是顯示設(shè)置的
int pthread_attr_setinheritsched(pthread_attr_t *attr, int inherit)
{
  if (inherit != PTHREAD_INHERIT_SCHED && inherit != PTHREAD_EXPLICIT_SCHED)
    return EINVAL;
  attr->inheritsched = inherit;
  return 0;
}

int pthread_attr_getinheritsched(const pthread_attr_t *attr, int *inherit)
{
  *inherit = attr->inheritsched;
  return 0;
}
// 優(yōu)先級(jí)的有效范圍，PTHREAD_SCOPE_SYSTEM是和系統(tǒng)所有線程競(jìng)爭(zhēng)，否則是和本進(jìn)程內(nèi)的其他線程競(jìng)爭(zhēng)
int pthread_attr_setscope(pthread_attr_t *attr, int scope)
{
  switch (scope) {
  case PTHREAD_SCOPE_SYSTEM:
    attr->scope = scope;
    return 0;
  case PTHREAD_SCOPE_PROCESS:
    return ENOTSUP;
  default:
    return EINVAL;
  }
}

int pthread_attr_getscope(const pthread_attr_t *attr, int *scope)
{
  *scope = attr->scope;
  return 0;
}
   

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