git.ozlabs.org Git - ccan/blob - ccan/lbalance/lbalance.h

   1 #ifndef CCAN_LBALANCE_H
   2 #define CCAN_LBALANCE_H
   3 #include "config.h"
   4
   5 struct lbalance;
   6 struct lbalance_task;
   7 struct timeval;
   8 struct rusage;
   9
  10 /**
  11  * lbalance_new - initialize a load balancing structure.
  12  */
  13 struct lbalance *lbalance_new(void);
  14
  15 /**
  16  * lbalance_task_new - mark the starting of a new task.
  17  * @lbalance: the load balancer from lbalance_new.
  18  */
  19 struct lbalance_task *lbalance_task_new(struct lbalance *lbalance);
  20
  21 /**
  22  * lbalance_task_free - mark the completion of a task.
  23  * @task: the lbalance_task from lbalance_task_new, which will be freed.
  24  * @usage: the resource usage for that task (or NULL).
  25  *
  26  * If @usage is NULL, you must have already wait()ed for the child so
  27  * that lbalance_task_free() can derive it from the difference in
  28  * getrusage() for the child processes.
  29  *
  30  * Otherwise, lbalance_task_free() is a noop, which is useful for failure
  31  * paths.
  32  */
  33 void lbalance_task_free(struct lbalance_task *task,
  34                         const struct rusage *usage);
  35
  36 /**
  37  * lbalance_target - how many tasks in parallel are recommended?
  38  * @lbalance: the load balancer from lbalance_new.
  39  *
  40  * Normally you keep creating tasks until this limit is reached.  It's
  41  * updated by stats from lbalance_task_free.
  42  */
  43 unsigned lbalance_target(struct lbalance *lbalance);
  44
  45 /**
  46  * lbalance_free - free a load balancing structure.
  47  * @lbalance: the load balancer from lbalance_new.
  48  *
  49  * Also frees any tasks still attached.
  50  */
  51 void lbalance_free(struct lbalance *lbalance);
  52 #endif /* CCAN_LBALANCE_H */