# HG changeset patch
# User Eugene Baranov <eug.baranov@gmail.com>
# Date 1438214285 -3600
# Node ID 97a9f76020143e459b6cd8f0cb939f36d784e468
# Parent  9de443515f1dea6e5fdee375d82a2c1434a85995
convert: when getting file from Perforce concatenate data at the end

As it turned out, even when getting relatively small files, concatenating
string data every time when new chunk is received is very inefficient.
Maintaining a string list of data chunks and concatenating everything in one go
at the end seems much more efficient - in my testing it made getting 40 MB file
7 times faster, whilst converting of a particularly big changelist with some big
files went down from 20 hours to 3 hours.

diff -r 9de443515f1d -r 97a9f7602014 hgext/convert/p4.py
--- a/hgext/convert/p4.py	Sat Jul 18 17:10:28 2015 -0700
+++ b/hgext/convert/p4.py	Thu Jul 30 00:58:05 2015 +0100
@@ -216,7 +216,7 @@
             stdout = util.popen(cmd, mode='rb')
 
             mode = None
-            contents = ""
+            contents = []
             keywords = None
 
             for d in loaditer(stdout):
@@ -252,7 +252,7 @@
                             keywords = self.re_keywords
 
                 elif code == "text" or code == "binary":
-                    contents += data
+                    contents.append(data)
 
                 lasterror = None
 
@@ -262,6 +262,8 @@
         if mode is None:
             return None, None
 
+        contents = ''.join(contents)
+
         if keywords:
             contents = keywords.sub("$\\1$", contents)
         if mode == "l" and contents.endswith("\n"):