[PATCH] add repository retrycount option

[lkcl]

>From 81205e3bb3bc04008b9473a71b90ec9a0612762c Mon Sep 17 00:00:00 2001
From: Luke Kenneth Casson Leighton <lkcl at lkcl.net>
Date: Mon, 19 Dec 2016 05:29:24 +0000
Subject: [PATCH] add repository retrycount option

Signed-off-by: Luke Kenneth Casson Leighton <lkcl at lkcl.net>
---
 offlineimap.conf            | 21 +++++++++++++++++++++
 offlineimap/folder/Gmail.py |  2 +-
 offlineimap/folder/IMAP.py  |  5 ++++-
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/offlineimap.conf b/offlineimap.conf
index 4df674b..2813061 100644
--- a/offlineimap.conf
+++ b/offlineimap.conf
@@ -1272,6 +1272,27 @@ remoteuser = username
 
 # This option stands in the [Repository RemoteExample] section.
 #
+# Operating under extreme network conditions (China) network connectivity
+# especially for SSL can be so bad and so slow that absolutely every
+# possible kind of connectivity error that can occur does occur.
+#
+# Rather than have offlineimap exit on errors it may be preferable
+# to have it simply retry connections dozens of times.  The alternative
+# is to restart offlineimap in a constant loop, which may involve using
+# significant CPU cycles (if the repository is large) to load up the
+# UID database again.
+#
+# This option is best utilised in combination with socktimeout, which
+# catches instances of interference by e.g. the GFW at the TCP layer,
+# as well as China ISPs simply not coping.
+#
+# Default value: retrycount = 2
+#
+#retrycount = 2
+
+
+# This option stands in the [Repository RemoteExample] section.
+#
 # If offlineiamp is having troubles to download some UIDS, it's possible to get
 # them ignored in a list. This only ignore the download.
 #
diff --git a/offlineimap/folder/Gmail.py b/offlineimap/folder/Gmail.py
index 31eaeb3..dc594d1 100644
--- a/offlineimap/folder/Gmail.py
+++ b/offlineimap/folder/Gmail.py
@@ -71,7 +71,7 @@ class GmailFolder(IMAPFolder):
                   (probably severity MESSAGE) if e.g. no message with
                   this UID could be found.
         """
-        data = self._fetch_from_imap(str(uid), 2)
+        data = self._fetch_from_imap(str(uid), self.retrycount)
 
         # data looks now e.g.
         #[('320 (X-GM-LABELS (...) UID 17061 BODY[] {2565}','msgbody....')]
diff --git a/offlineimap/folder/IMAP.py b/offlineimap/folder/IMAP.py
index f8fcf7b..6587b8a 100644
--- a/offlineimap/folder/IMAP.py
+++ b/offlineimap/folder/IMAP.py
@@ -55,6 +55,9 @@ class IMAPFolder(BaseFolder):
         # self.ui is set in BaseFolder.
         self.imap_query = ['BODY.PEEK[]']
 
+        # number of times to retry fetching messages
+        self.retrycount = int(self.repository.getconf('retry', '2'))
+
         fh_conf = self.repository.account.getconf('filterheaders', '')
         self.filterheaders = [h for h in re.split(r'\s*,\s*', fh_conf) if h]
 
@@ -305,7 +308,7 @@ class IMAPFolder(BaseFolder):
                   this UID could be found.
         """
 
-        data = self._fetch_from_imap(str(uid), 2)
+        data = self._fetch_from_imap(str(uid), self.retrycount)
 
         # Data looks now e.g.
         # [('320 (UID 17061 BODY[] {2565}','msgbody....')]
-- 
2.8.1