# HG changeset patch
# User Joerg Sonnenberger <joerg@bec.de>
# Date 2020-09-23 12:44:21
# Node ID 497271da24c9b5d5439a6c0289cbaec872a9e4fb
# Parent  2517df770648bf1229bab76859ee240b150c94d7

phases: fix performance regression with Python 2

Unlike Python 3, xrange doesn't support efficient "in" and uses a linear
time scan instead. Expand the condition to handle it fast.

Differential Revision: https://phab.mercurial-scm.org/D9072

diff --git a/mercurial/phases.py b/mercurial/phases.py
--- a/mercurial/phases.py
+++ b/mercurial/phases.py
@@ -282,26 +282,28 @@ def _trackphasechange(data, rev, old, ne
     while low < high:
         mid = (low + high) // 2
         revs = data[mid][0]
+        revs_low = revs[0]
+        revs_high = revs[-1]
 
-        if rev in revs:
+        if rev >= revs_low and rev <= revs_high:
             _sortedrange_split(data, mid, rev, t)
             return
 
-        if revs[0] == rev + 1:
+        if revs_low == rev + 1:
             if mid and data[mid - 1][0][-1] == rev:
                 _sortedrange_split(data, mid - 1, rev, t)
             else:
                 _sortedrange_insert(data, mid, rev, t)
             return
 
-        if revs[-1] == rev - 1:
+        if revs_high == rev - 1:
             if mid + 1 < len(data) and data[mid + 1][0][0] == rev:
                 _sortedrange_split(data, mid + 1, rev, t)
             else:
                 _sortedrange_insert(data, mid + 1, rev, t)
             return
 
-        if revs[0] > rev:
+        if revs_low > rev:
             high = mid
         else:
             low = mid + 1