From 13d0bd8b466231dace8a2eff910c2711df72f785 Mon Sep 17 00:00:00 2001
From: Andrew Gaul <andrew@gaul.org>
Date: Wed, 28 Mar 2018 15:06:05 -0700
Subject: [PATCH] Limit progress updates to avoid swamping the TTY

This makes the values more readable for large downloads on fast
connections.  200 ms value chosen from wget.
---
 news/5124.trivial             |  1 +
 src/pip/_internal/utils/ui.py | 10 ++++++++++
 2 files changed, 11 insertions(+)
 create mode 100644 news/5124.trivial

diff --git a/news/5124.trivial b/news/5124.trivial
new file mode 100644
index 000000000..bc0a19b87
--- /dev/null
+++ b/news/5124.trivial
@@ -0,0 +1 @@
+Limit progress bar update interval to 200 ms.
diff --git a/src/pip/_internal/utils/ui.py b/src/pip/_internal/utils/ui.py
index 8ade1e210..52302ac98 100644
--- a/src/pip/_internal/utils/ui.py
+++ b/src/pip/_internal/utils/ui.py
@@ -137,6 +137,7 @@ class DownloadProgressMixin(object):
     def __init__(self, *args, **kwargs):
         super(DownloadProgressMixin, self).__init__(*args, **kwargs)
         self.message = (" " * (get_indentation() + 2)) + self.message
+        self.last_update = 0.0
 
     @property
     def downloaded(self):
@@ -161,6 +162,15 @@ class DownloadProgressMixin(object):
             self.next(n)
         self.finish()
 
+    def update(self):
+        # limit updates to avoid swamping the TTY
+        now = time.time()
+        if now < self.last_update + 0.2:
+            return
+        self.last_update = now
+
+        super(DownloadProgressMixin, self).update()
+
 
 class WindowsMixin(object):