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/* A surface that holds a snapshot until the server stops: a reader that
* never lets go, for run.py's held case (research/experiments/021-memory).
* It holds the first snapshot whose number view VIEW is at least AT (the
* first snapshot at all without them), and lets every other one go.
*
* pure-serve ... --surface hold-surface.so [-- VIEW AT] */
#include "surface.h"
#include <poll.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
int pure_surface_run(const PureSurface *s, int argc, char **argv) {
static PureApp reader;
int view = argc > 2 ? pure_module_view(s->module, argv[1]) : -1;
double at = argc > 2 ? atof(argv[2]) : 0, value = 0;
PureSnapshot *held = NULL;
while (!s->stopping(s->host)) {
struct pollfd wait = {s->changes, POLLIN, 0};
if (poll(&wait, 1, 20) > 0 && (wait.revents & POLLIN)) {
uint64_t saves;
if (read(s->changes, &saves, sizeof(saves)) < 0) { /* cleared already */ }
}
if (held) continue;
PureSnapshot *read_now = s->read(s->host, &reader);
if (!read_now) continue;
if (view < 0 || (pure_app_view(&reader, (uint32_t)view, &value) && value >= at)) held = read_now;
else s->release(s->host, read_now);
}
if (held) s->release(s->host, held);
return 0;
}
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