From 0295aa38a2206f3229f60a4105767e15ebdca797 Mon Sep 17 00:00:00 2001
From: Yinan Zhang <zyn8950@gmail.com>
Date: Tue, 21 Apr 2020 13:29:07 -0700
Subject: [PATCH] Deduplicate entries in witness error message

---
 src/witness.c | 43 +++++++++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/src/witness.c b/src/witness.c
index f42b72ad..e9ddf596 100644
--- a/src/witness.c
+++ b/src/witness.c
@@ -14,15 +14,42 @@ witness_init(witness_t *witness, const char *name, witness_rank_t rank,
 	witness->opaque = opaque;
 }
 
+static void
+witness_print_witness(witness_t *w, unsigned n) {
+	assert(n > 0);
+	if (n == 1) {
+		malloc_printf(" %s(%u)", w->name, w->rank);
+	} else {
+		malloc_printf(" %s(%u)X%u", w->name, w->rank, n);
+	}
+}
+
+static void
+witness_print_witnesses(const witness_list_t *witnesses) {
+	witness_t *w, *last = NULL;
+	unsigned n = 0;
+	ql_foreach(w, witnesses, link) {
+		if (last != NULL && w->rank > last->rank) {
+			assert(w->name != last->name);
+			witness_print_witness(last, n);
+			n = 0;
+		} else if (last != NULL) {
+			assert(w->rank == last->rank);
+			assert(w->name == last->name);
+		}
+		last = w;
+		++n;
+	}
+	if (last != NULL) {
+		witness_print_witness(last, n);
+	}
+}
+
 static void
 witness_lock_error_impl(const witness_list_t *witnesses,
     const witness_t *witness) {
-	witness_t *w;
-
 	malloc_printf("<jemalloc>: Lock rank order reversal:");
-	ql_foreach(w, witnesses, link) {
-		malloc_printf(" %s(%u)", w->name, w->rank);
-	}
+	witness_print_witnesses(witnesses);
 	malloc_printf(" %s(%u)\n", witness->name, witness->rank);
 	abort();
 }
@@ -49,13 +76,9 @@ witness_not_owner_error_t *JET_MUTABLE witness_not_owner_error =
 static void
 witness_depth_error_impl(const witness_list_t *witnesses,
     witness_rank_t rank_inclusive, unsigned depth) {
-	witness_t *w;
-
 	malloc_printf("<jemalloc>: Should own %u lock%s of rank >= %u:", depth,
 	    (depth != 1) ?  "s" : "", rank_inclusive);
-	ql_foreach(w, witnesses, link) {
-		malloc_printf(" %s(%u)", w->name, w->rank);
-	}
+	witness_print_witnesses(witnesses);
 	malloc_printf("\n");
 	abort();
 }