bee

Simple and clean coroutines in C

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Define BEE_MAIN before including bee.h in one (and only one of) the source files.

Reference

• beedef(bee_type,...) { ... ; beereturn ;} Defines a new type of bee. After the bee type name, there is a list of variables that will be preserved across yelding. This variables can be accessed as fields of the bee variable. The beereturn {...} instruction is mandatory and can't be used anywhere else than at the end of the bee definition. The code at the end is a cleanup code that will be executed when the bee returns (or is killed);

• beedef(bee_type) beename This form of beedef() can be used to declare bee varibles that will be defined later (forward declaration). Useful with beeyeldto().

• beestop Stops the execution of the bee. Next call to beefly() won't make it fly.

• void beeyeld Suspends the execution of the bee. The execution will resume from the next instruction.

• void beeyeldto(bee_t next) Suspends the execution of the current bee and resume the bee next.

• void beeyeldwhile(int expr) Suspends the execution of the bee for as long as the expr is true. If the bee is resumed and the expression is still true, it will yeld, otherwise the execution will resume from the next instruction.

• int beefly(void *bee) Starts or resume the execution of a bee. Returns 1 (BEE_READY) if the bee can be resumed, 0 (BEE_DONE) if the bee has completed its task, or 2 (BEE_SLEEP) if the bee will sleep for a certain amount of time.

• int beeready(void *bee) Checks if the bee has completed has completed its task (in which case will return 0) or can be resumed (regardless it is sleeping or not).

• void beekill(void *bee) Kills the bee so that next time beefly() is called, it won't resume.

• void beereset(void *bee) Reset the bee so that next time beefly() is called, it will start from the beginning.

• void *beenew(bee_type) Create a new bee of the specified type. Remember that bees are pointers.

• void *beefree(void *bee) Destroy the bee and free the associated memory. Returns NULL.

• void beesleep(int ms) Makes the bee unresponsive to fly for at least the next ms milliseconds. Note that due to the way bee sleeping is handled, max resolion is in hundreds of seconds (not milliseconds) and applications that use bees can't run for more than 8 months without being reset.

• void beewaitfor(void *bee) Suspend the process (with nanoleep()) to give enough time to the specified bee to awake.

Beehives

Beehives are simple scheduler for a group of bees. To use beehives, you have to include "beehive.h" instead of "bee.h"

• beehive_t beehivenew() Creates a new beehive.

• beehive_t beehivefree(beehive_t hive) Destrory the beehive and free the associated memory. Returns NULL.

• int32_t beehiveadd(beehive_t hive, void *bee) Adds a bee to the beehive. Returns the number of bees.

• clock_t beehivefly(beehive_t hive) Send all the bees in the beehive fyling once. If one of the bees complete its task (i.e. returns BEE_DONE) it is removed from the hive and freed. Returns BEEHIVE_DONE if all the bees have completed their task or the next wake time (0 if any of the bees is not sleeping).

• int beehiveswarm(beehive_t hive) Repeatedly send all the bees flying until all the bees have completed their task. Returns BEE_DONE.

example

#include "bee.h"

beedef(iter, int n;)
{
   for (bee->n = 0; bee->n < 10; bee->n++) {
     beeyeld();
   }
   beereturn;
}

int main(int argc, char *argv[])
{
    iter counter = beenew(iter);
    while (beefly(counter)) {
      printf("%d\n",counter->n); 
    }
    beefree(counter);
}

Look at fib.c, and prodcons.c for other examples.