/**
* antithread - Accelerated Native Technology Implementation of "threads"
*
- * Threads suck. Antithreads try not to. FIXME.
+ * On systems with multiple CPUs, it's often faster to split work across
+ * different execution units. Under Unix-like systems, the two methods of
+ * doing this are (POSIX) threads or processes.
*
- * Licence: LGPL (2 or any later version)
+ * Threads have the disadvantage that they share all of the address space:
+ * using software instead of hardware isolation (eg. for malloc) is
+ * inefficient and less secure. Various subtle errors can occur because
+ * programmers in one part of the code do not expect concurrency.
+ *
+ * Processes have the disadvantage that there is no common infrastructure
+ * for sharing memory: without this, programmers are faced with the unpalatable
+ * options of using slower options or creating their own infrastructure.
+ *
+ * The antithread module provides memory-sharing infrastructure: the programmer
+ * indicates the size of the memory to share, and then creates subprocesses
+ * which share the memory. Pipes are used to hand pointers between the
+ * main process and the children: usually pointers into the shared memory.
+ *
+ * Example:
+ * #include <ccan/antithread/antithread.h>
+ * #include <ccan/talloc/talloc.h>
+ * #include <ctype.h>
+ * #include <stdlib.h>
+ * #include <stdio.h>
+ * #include <string.h>
+ *
+ * // Silly example: child makes rot13 copy.
+ * static void *rot13(struct at_pool *pool, void *unused)
+ * {
+ * char *r, *p;
+ * while ((r = at_read_parent(pool)) != NULL) {
+ * unsigned int i;
+ * // r is inside pool, so talloc off it is also inside.
+ * p = talloc_array(r, char, strlen(r) + 1);
+ * for (i = 0; r[i]; i++) {
+ * if (!isalpha(r[i]))
+ * p[i] = r[i];
+ * else if (toupper(r[i]) < 'N')
+ * p[i] = r[i] + 13;
+ * else
+ * p[i] = r[i] - 13;
+ * }
+ * // Tell parent about our copy.
+ * at_tell_parent(pool, p);
+ * }
+ * return NULL;
+ * }
+ *
+ * #define NUM_CHILDREN 4
+ *
+ * int main(int argc, char *argv[])
+ * {
+ * struct at_pool *pool;
+ * struct athread *child[NUM_CHILDREN];
+ * unsigned int i;
+ *
+ * // Create pool and some children
+ * pool = at_pool(1024*1024);
+ * for (i = 0; i < NUM_CHILDREN; i++)
+ * child[i] = at_run(pool, rot13, NULL);
+ *
+ * // Pass out work to children.
+ * for (i = 1; i < argc; i++)
+ * at_tell(child[i % NUM_CHILDREN],
+ * talloc_strdup(at_pool_ctx(pool), argv[i]));
+ *
+ * // Read back results.
+ * for (i = 1; i < argc; i++)
+ * printf("%s ", (char *)at_read(child[i % NUM_CHILDREN]));
+ * printf("\n");
+ *
+ * // Freeing pool kills children, too.
+ * talloc_free(pool);
+ * return 0;
+ * }
+ *
+ * License: GPL (3 or any later version)
* Author: Rusty Russell <rusty@rustcorp.com.au>
*/
int main(int argc, char *argv[])
return 1;
if (strcmp(argv[1], "depends") == 0) {
- printf("ccan/talloc\n");
printf("ccan/alloc\n");
+ printf("ccan/list\n");
printf("ccan/noerr\n");
printf("ccan/read_write_all\n"); /* For tests */
+ printf("ccan/talloc\n");
return 0;
}