From c803a7566f25b6c636cab05214e04d85e2355485 Mon Sep 17 00:00:00 2001
From: Rodrigo Arias <rodrigo.arias@bsc.es>
Date: Thu, 20 Jun 2024 11:32:20 +0200
Subject: [PATCH] Prevent zero values in the mark API

These values cannot be differentiated from a null value, due to a
Paraver limitation.
---
 doc/user/runtime/mark.md     | 8 +++++++-
 src/emu/ovni/mark.c          | 5 +++++
 src/rt/ovni.c                | 9 +++++++++
 test/emu/ovni/libovni-mark.c | 8 +++-----
 4 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/doc/user/runtime/mark.md b/doc/user/runtime/mark.md
index e595864..8018acc 100644
--- a/doc/user/runtime/mark.md
+++ b/doc/user/runtime/mark.md
@@ -40,7 +40,13 @@ void ovni_mark_label(int32_t type, int64_t value, const char *label);
 ### Emit events
 
 All mark channels begin with the default value *null*, which is not shown in
-Paraver and will be displayed as the usual empty space.
+Paraver and will be displayed as the usual empty space. The value of the channel
+can be changed over time with the following functions.
+
+!!! warning
+
+    The value 0 is forbidden, as it is used by Paraver to represent the
+    "empty" state.
 
 If you have used a single channel (without `OVNI_MARK_STACK`), then you must use
 the following call to emit events at runtime:
diff --git a/src/emu/ovni/mark.c b/src/emu/ovni/mark.c
index 179f84a..e887ae5 100644
--- a/src/emu/ovni/mark.c
+++ b/src/emu/ovni/mark.c
@@ -624,6 +624,11 @@ mark_event(struct emu *emu)
 		return -1;
 	}
 
+	if (value == 0) {
+		err("mark value cannot be zero, type %ld", type);
+		return -1;
+	}
+
 	long index = mc->index;
 	struct ovni_thread *oth = EXT(emu->thread, 'O');
 	struct ovni_mark_thread *mth = &oth->mark;
diff --git a/src/rt/ovni.c b/src/rt/ovni.c
index d36c87f..0f43241 100644
--- a/src/rt/ovni.c
+++ b/src/rt/ovni.c
@@ -1136,6 +1136,9 @@ ovni_mark_label(int32_t type, int64_t value, const char *label)
 void
 ovni_mark_push(int32_t type, int64_t value)
 {
+	if (value == 0)
+		die("value cannot be 0, type %ld", (long) type);
+
 	struct ovni_ev ev = {0};
 	ovni_ev_set_clock(&ev, ovni_clock_now());
 	ovni_ev_set_mcv(&ev, "OM[");
@@ -1147,6 +1150,9 @@ ovni_mark_push(int32_t type, int64_t value)
 void
 ovni_mark_pop(int32_t type, int64_t value)
 {
+	if (value == 0)
+		die("value cannot be 0, type %ld", (long) type);
+
 	struct ovni_ev ev = {0};
 	ovni_ev_set_clock(&ev, ovni_clock_now());
 	ovni_ev_set_mcv(&ev, "OM]");
@@ -1158,6 +1164,9 @@ ovni_mark_pop(int32_t type, int64_t value)
 void
 ovni_mark_set(int32_t type, int64_t value)
 {
+	if (value == 0)
+		die("value cannot be 0, type %ld", (long) type);
+
 	struct ovni_ev ev = {0};
 	ovni_ev_set_clock(&ev, ovni_clock_now());
 	ovni_ev_set_mcv(&ev, "OM=");
diff --git a/test/emu/ovni/libovni-mark.c b/test/emu/ovni/libovni-mark.c
index 56af5a2..21a6694 100644
--- a/test/emu/ovni/libovni-mark.c
+++ b/test/emu/ovni/libovni-mark.c
@@ -46,9 +46,7 @@ main(void)
 	ovni_mark_label(MARK_COLORS, COL_GRAY, "Gray");
 	ovni_mark_label(MARK_COLORS, COL_RED,  "Red");
 
-	for (int i = 0; i < 100; i++) {
-		ovni_mark_set(MARK_PROGRESS, i);
-
+	for (int i = 1; i <= 100; i++) {
 		int which = 1 + (rand() % 3);
 
 		/* Simulate a thread goes to sleep */
@@ -61,9 +59,9 @@ main(void)
 
 		if (rank == 0 && i == 75)
 			instr_thread_resume();
-	}
 
-	ovni_mark_set(MARK_PROGRESS, 100);
+		ovni_mark_set(MARK_PROGRESS, i);
+	}
 
 	instr_end();