[PATCH] Add retry for unreliable network

[Mark Hamzy]

There are two particularly troublesome network calls that can fail
if the network has issues.  Therefore, add a retries option to allow
looping until the call succeeds or too many retries happen.

---
 mash/__init__.py | 32 +++++++++++++++++++++++++++-----
 mash/config.py   |  1 +
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/mash/__init__.py b/mash/__init__.py
index 566b8c1..9325794 100644
--- a/mash/__init__.py
+++ b/mash/__init__.py
@@ -31,6 +31,8 @@ import yum

import rpmUtils.arch

+import xml.parsers.expat
+
 def nevra(pkg):
     return '%s-%s:%s-%s.%s' % (pkg['name'],pkg['epoch'],pkg['version'],pkg['release'],pkg['arch'])

@@ -214,9 +216,17 @@ class Mash:
                           self.logger.error("ERROR: can't download %s from signed path %s" % (nevra(pkg), srcurl))
                           return 1
                       srcurl = os.path.join(koji.pathinfo.build(z), koji.pathinfo.rpm(pkg))
-                      try:
-                          result = urlgrabber.grabber.urlgrab(srcurl, cachepath)
-                      except:
+                      tries = 0
+                      downloaded = False
+                      while tries < self.config.retries and not downloaded:
+                          try:
+                              tries += 1
+                              result = urlgrabber.grabber.urlgrab(srcurl, cachepath)
+                              downloaded = True
+                          except:
+                              self.logger.warning("WARNING: can't download %s from %s, attempt #%d" % (nevra(pkg), srcurl, tries))
+                              os.remove(cachepath)
+                      if not downloaded:
                           self.logger.error("ERROR: can't download %s from %s" % (nevra(pkg), srcurl))
                           return 1

@@ -300,8 +310,20 @@ class Mash:
             os.makedirs(self.config.cachedir, 0755)
         # Get package list. This is an expensive operation.
         self.logger.info("Getting package lists for %s..." % (self.config.tag))
-        
-        (pkglist, buildlist) = self.session.listTaggedRPMS(self.config.tag, inherit = self.config.inherit, latest = self.config.latest, rpmsigs = True)
+
+        tries = 0
+        downloaded = False
+        while tries < self.config.retries and not downloaded:
+            try:
+                tries += 1
+                (pkglist, buildlist) = self.session.listTaggedRPMS(self.config.tag, inherit = self.config.inherit, latest = self.config.latest, rpmsigs = True)
+                downloaded = True
+            except xml.parsers.expat.ExpatError:
+                self.logger.warning("WARNING: can't listTaggedRPMS from koji, attempt #%d" % (tries))
+        if not downloaded:
+            self.logger.error("ERROR: can't listTaggedRPMS from koji")
+            sys.exit(1)
+
         # filter by key
         biglist = PackageList(self.config)
         for pkg in pkglist:
diff --git a/mash/config.py b/mash/config.py
index e4e9b95..3da98d1 100644
--- a/mash/config.py
+++ b/mash/config.py
@@ -100,6 +100,7 @@ class MashDistroConfig(config.BaseConfig):
     hash_packages = config.BoolOption(False)
     parent_repos = config.ListOption()
     previous = None
+    retries = config.Option(1)

def fixup(self, sect):
         if not self.name: