From 0932de54bc0dbc6d29008b9e6087b88721ca8bb0 Mon Sep 17 00:00:00 2001
From: Nick Terrell <terrelln@fb.com>
Date: Mon, 26 Aug 2019 18:19:29 -0700
Subject: [PATCH] [dictBuilder] Fix deadlock in *COVER error case

The COVER and FASTCOVER dictionary builders can deadlock when
dictionary construction errors, likely because there are too few
samples, or too few distinct dmers. The deadlock only occurs when
there are errors.

Fixes #1746.
---
 lib/dictBuilder/cover.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/lib/dictBuilder/cover.c b/lib/dictBuilder/cover.c
index 62199675..4721205d 100644
--- a/lib/dictBuilder/cover.c
+++ b/lib/dictBuilder/cover.c
@@ -919,13 +919,12 @@ void COVER_best_finish(COVER_best_t *best, ZDICT_cover_params_t parameters,
         }
       }
       /* Save the dictionary, parameters, and size */
-      if (!dict) {
-        return;
+      if (dict) {
+        memcpy(best->dict, dict, dictSize);
+        best->dictSize = dictSize;
+        best->parameters = parameters;
+        best->compressedSize = compressedSize;
       }
-      memcpy(best->dict, dict, dictSize);
-      best->dictSize = dictSize;
-      best->parameters = parameters;
-      best->compressedSize = compressedSize;
     }
     if (liveJobs == 0) {
       ZSTD_pthread_cond_broadcast(&best->cond);