Fail if the streams clock is too far apart

The current gate is set to 1 hour and it only checks the first event in
the stream. Added a test too.

src/emu/player.c

@@ -53,6 +53,42 @@ step_stream(struct player *player, struct stream *stream)
 	return 0;
 }
 
+static int
+check_clock_gate(struct trace *trace)
+{
+	/* 1 hour in nanoseconds */
+	int64_t maxgate = 3600LL * 1000LL * 1000LL * 1000LL;
+	int64_t t0 = 0LL;
+	int first = 1;
+	int ret = 0;
+
+	struct stream *stream;
+	DL_FOREACH(trace->streams, stream) {
+		struct ovni_ev *oev = stream_ev(stream);
+		int64_t sclock = stream_evclock(stream, oev);
+
+		if (first) {
+			first = 0;
+			t0 = sclock;
+		}
+
+		int64_t delta = llabs(t0 - sclock);
+		if (delta > maxgate) {
+			double hdelta = ((double) delta) / (3600.0 * 1e9);
+			err("stream %s has starting clock too far: delta=%.2f h",
+					stream->relpath, hdelta);
+			ret = -1;
+		}
+	}
+
+	if (ret != 0) {
+		err("detected large clock gate, run 'ovnisync' to set the offsets");
+		return -1;
+	}
+
+	return 0;
+}
+
 int
 player_init(struct player *player, struct trace *trace)
 {
@@ -76,6 +112,13 @@ player_init(struct player *player, struct trace *trace)
 		}
 	}
 
+	/* Ensure the first event sclocks are not too far apart. Otherwise an
+	 * offset table is mandatory. */
+	if (check_clock_gate(trace) != 0) {
+		err("check_clock_gate failed\n");
+		return -1;
+	}
+
 	return 0;
 }
 

src/emu/system.c

@@ -406,9 +406,6 @@ init_offsets(struct system *sys, struct trace *trace)
 	if (n == 0 && sys->nlooms > 1) {
 		err("warning: no clock offset file loaded with %ld looms",
 				sys->nlooms);
-
-		if (sys->args->linter_mode)
-			abort();
 	}
 
 	for (int i = 0; i < n; i++) {

test/emu/ovni/CMakeLists.txt

@@ -16,3 +16,4 @@ ovni_test(mp-simple.c MP)
 ovni_test(mp-rank.c MP)
 ovni_test(version-good.c)
 ovni_test(version-bad.c SHOULD_FAIL REGEX "version mismatch")
+ovni_test(clockgate.c MP SHOULD_FAIL REGEX "detected large clock gate")

test/emu/ovni/clockgate.c

@@ -0,0 +1,76 @@
+/* Copyright (c) 2021-2023 Barcelona Supercomputing Center (BSC)
+ * SPDX-License-Identifier: GPL-3.0-or-later */
+
+#define _POSIX_C_SOURCE 200112L
+#define _GNU_SOURCE
+
+#include <limits.h>
+#include <linux/limits.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "common.h"
+#include "compat.h"
+#include "ovni.h"
+
+int64_t delta = 0LL;
+
+static void
+thread_execute_delayed(int32_t cpu, int32_t creator_tid, uint64_t tag)
+{
+	struct ovni_ev ev = {0};
+	ovni_ev_set_mcv(&ev, "OHx");
+	ovni_ev_set_clock(&ev, ovni_clock_now() + delta);
+	ovni_payload_add(&ev, (uint8_t *) &cpu, sizeof(cpu));
+	ovni_payload_add(&ev, (uint8_t *) &creator_tid, sizeof(creator_tid));
+	ovni_payload_add(&ev, (uint8_t *) &tag, sizeof(tag));
+	ovni_ev_emit(&ev);
+}
+
+static inline void
+start_delayed(int rank, int nranks)
+{
+	char hostname[OVNI_MAX_HOSTNAME];
+	char rankname[OVNI_MAX_HOSTNAME + 64];
+
+	if (gethostname(hostname, HOST_NAME_MAX) != 0)
+		die("gethostname failed");
+
+	sprintf(rankname, "%s.%d", hostname, rank);
+
+	ovni_version_check();
+	ovni_proc_init(1, rankname, getpid());
+	ovni_proc_set_rank(rank, nranks);
+	ovni_thread_init(gettid());
+
+	/* All ranks inform CPUs */
+	for (int i = 0; i < nranks; i++)
+		ovni_add_cpu(i, i);
+
+	int curcpu = rank;
+
+	dbg("thread %d has cpu %d (ncpus=%d)\n",
+			gettid(), curcpu, nranks);
+
+	delta = ((int64_t) rank) * 2LL * 3600LL * 1000LL * 1000LL * 1000LL;
+	thread_execute_delayed(curcpu, -1, 0);
+}
+
+int
+main(void)
+{
+	int rank = atoi(getenv("OVNI_RANK"));
+	int nranks = atoi(getenv("OVNI_NRANKS"));
+
+	start_delayed(rank, nranks);
+
+	ovni_flush();
+	ovni_thread_free();
+	ovni_proc_fini();
+
+	return 0;
+}