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GO_MEM(3)		   libdill Library Functions		     GO_MEM(3)

NAME
       go_mem -	launches a coroutine

SYNOPSIS
	      #include <libdill.h>

	      int go_mem(
		  expression,
		  void*	mem,
		  size_t memlen);

DESCRIPTION
       This  construct	launches  a  coroutine	on a user-supplied stack.  The
       stack has no guard page and stack overflow will result  in  overwriting
       memory.

       expression: Expression to evaluate as a coroutine.

       mem:  Buffer to hold the	coroutine's stack.  The	buffer doesn't have to
       be aligned.  The	function will take care	of properly aligning the stack
       itself.

       memlen: Size of the mem buffer.

       The coroutine is	executed concurrently, and its lifetime	may exceed the
       lifetime	of the caller coroutine.  The return value of  the  coroutine,
       if any, is discarded and	cannot be retrieved by the caller.

       Any  function  to  be  invoked as a coroutine must be declared with the
       coroutine specifier.

       Use hclose to cancel the	coroutine.  When the coroutine is canceled all
       the blocking calls within the coroutine will start failing  with	 ECAN-
       CELED error.

       WARNING:	 Coroutines  will  most	likely work even without the coroutine
       specifier.  However, they may fail in  random  non-deterministic	 ways,
       depending  on  the  code	 in question and the particular	combination of
       compiler	and optimization level.	 Additionally, arguments to  a	corou-
       tine  must  not	be  function calls.  If	they are, the program may fail
       non-deterministically.  If you need to pass a result of	a  computation
       to  a  coroutine, do the	computation first, and then pass the result as
       an argument.  Instead of:

	      go(bar(foo(a)));

       Do this:

	      int a = foo();
	      go(bar(a));

RETURN VALUE
       In case of success the function returns handle of a  bundle  containing
       the  new	 coroutine.   In case of error it returns -1 and sets errno to
       one of the values below.

       For details on coroutine	bundles	see bundle function.

ERRORS
       • ECANCELED: Current coroutine was canceled.

       • EMFILE: The maximum number of file descriptors	in the process are al-
	 ready open.

       • ENFILE: The maximum number of file descriptors	in the system are  al-
	 ready open.

       • ENOMEM: Not enough memory.

EXAMPLE
	      coroutine	void add(int a,	int b) {
		  printf("%d+%d=%d\n", a, b, a + b);
	      }

	      ...
	      char mem[16384];
	      int h = go_mem(add(1, 2),	mem, sizeof(mem));

SEE ALSO
       bundle(3)  bundle_go(3)	bundle_go_mem(3)  bundle_mem(3)	bundle_wait(3)
       go(3) hclose(3) yield(3)

libdill								     GO_MEM(3)

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