avoid precaching users if not worthwhile

If the user specifies individual projects and doesn't need to map email
addresses back to users, caching user <-> BZ email addresses is too much
of an overhead.

fixes: #22

Signed-off-by: Nils Philippsen <nils@redhat.com>

distgit_bugzilla_sync/script.py

@@ -112,7 +112,8 @@ def segment(iterable, chunk, fill=None):
 
 class BugzillaProxy:
 
-    def __init__(self, bz_server, username, password, config):
+    def __init__(self, bz_server, username, password, config,
+                 pre_cache_users=True):
         self.bz_xmlrpc_server = bz_server
         self.username = username
         self.password = password
@@ -123,6 +124,7 @@ class BugzillaProxy:
             password=self.password)
 
         self.product_cache = {}
+        self.user_cache = {}
         self.inverted_user_cache = {}
 
         # Connect to the fedora account system
@@ -133,6 +135,12 @@ class BugzillaProxy:
 
         self.config = config
 
+        if not pre_cache_users:
+            return
+
+        if config['verbose']:
+            print("Pre-caching FAS users and their Bugzilla email addresses.")
+
         try:
             self.user_cache = self.fas.people_by_key(
                 key='username',
@@ -140,7 +148,7 @@ class BugzillaProxy:
         except fedora.client.ServerError:
             # Sometimes, building the user cache up front fails with a timeout.
             # It's ok, we build the cache as-needed later in the script.
-            self.user_cache = {}
+            pass
         else:
             self.invert_user_cache()
 
@@ -743,13 +751,15 @@ class DistgitBugzillaSync:
             times["data structure end"] = time.time()
             delta = times["data structure end"] - times["start"]
             print("Ran for %s seconds -- ie: %.2f minutes" % (delta, delta/60.0))
-            print("Building FAS' cache")
 
         # Initialize the connection to bugzilla
-        bugzilla = BugzillaProxy(self.env['bugzilla']['url'],
-                                 self.env['bugzilla']['user'],
-                                 self.env['bugzilla']['password'],
-                                 self.env)
+        bugzilla = BugzillaProxy(
+            bz_server=self.env['bugzilla']['url'],
+            username=self.env['bugzilla']['user'],
+            password=self.env['bugzilla']['password'],
+            config=self.env,
+            pre_cache_users=not self.args.projects or self.args.print_fas_names,
+        )
 
         if self.env["verbose"]:
             times["FAS cache building end"] = time.time()