iothreads代码阅读笔记.doc

1.常见数据结构 1）io请求结构，对stub的简单封装，将stub组织成双向队列 struct iot_request { struct list_head list; /* 将io请求加入链表*/ call_stub_t *stub; }; 2）工作者结构，负责为请求服务 struct iot_worker { struct list_head rqlist; /* 分派给我的io请求链表*/ struct iot_conf *conf; int64_t q,dq; pthread_cond_t dq_cond; pthread_mutex_t qlock; int32_t queue_size; pthread_t thread; int state; /* 线程所处状态. */ int thread_idx; /* Threads index into the worker array. Since this will be thread local data,for ensuring that number of threads dont fall below a minimum, we just dont allow threads with specific indices to exit. Helps us in eliminating one place where otherwise a lock would have been required to update centralized state inside conf. */ }; struct iot_conf { int32_t thread_count; struct iot_worker **workers; xlator_t *this; /* Config state for ordered threads. */ pthread_mutex_t otlock; /* Used to sync any state that needs to be changed by the ordered threads. */ int max_o_threads; /* 已排序（ordered）线程的最大数目*/ int min_o_threads; /* 已排序线程的最小值，已排序线程的数目永远不低于这个数目*/ int o_idle_time; /*以秒为单位，某已排序线程退出后的空闲时间*/ gf_boolean_t o_scaling; /*如果用户不想动态增减线程数目，则设置为IOT_SCALING_OFF。此时，io-threads维护维护min_o