| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |
Arguments: value place
push-atomic expands into code that acts like push with the same arguments except that the update to place is atomic with respect to all other processes looking at the same place. That is, any number of simultaneous push-atomic and pop-atomic operations on the same location will act as if they occured sequentially in some unspecified order.
If you just used push and
pop, on say the
list (1 2 3)
, then two simulaneous pop's could both
return 1 rather than one returning 1 and one returning 2. The list at
the end of a series of simultaneous push-atomic's or
simultaneous pop-atomic's
(but not both) will have the expected length and contents, although
for a series of
push-atomic's the order of
the elements is not specified. The result of a series of
combined push-atomic's
and pop-atomic's may have an
indeterminant number of elements if all the elements of the list were
popped before any new element were pushed.
Note on the place argument: not all places legal as the first argument of setf can be used as the place argument to this macro. The list of allowable places can be found in Atomic read-modify-write primitives in smp.htm.
See smp.htm and multiprocessing.htm for more information on this macro and on multiprocessing.
Copyright (c) 1998-2016, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.1 page.
Created 2010.1.21.
| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |