From: Louie Lu <louie.lu@hopebaytech.com>
Date: Fri, 24 Feb 2017 03:59:49 +0000 (+0800)
Subject: bpo-29634: Reduce deque repeat execution when maxlen exist and size is not 1 (#255... 
X-Git-Tag: v3.7.0a1~1292
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=357bad7101df196d7f4ea3dc6ed9a6436afb022c;p=python

bpo-29634: Reduce deque repeat execution when maxlen exist and size is not 1 (#255) (#255)
---

diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 8615bf1d39..44e9e119ae 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -731,6 +731,10 @@ deque_inplace_repeat(dequeobject *deque, Py_ssize_t n)
     if (seq == NULL)
         return seq;
 
+    /* Reduce the number of repetitions when maxlen would be exceeded */
+    if (deque->maxlen >= 0 && n * size > deque->maxlen)
+        n = (deque->maxlen + size - 1) / size;
+
     for (i = 0 ; i < n-1 ; i++) {
         rv = deque_extend(deque, seq);
         if (rv == NULL) {