Cache Issue Tracker connections per base_url. Fixes #290

in this way we create object to connect to the remote end only
once, which should improve speed of work when working often with
bugs directly from Kiwi TCMS. This also makes it possible to
still have multiple IT integrations in the same instance b/c they
will have unique base URLs.

tcms/issuetracker/types.py

@@ -35,6 +35,7 @@ class IssueTrackerType:
         This is a common interface for all issue trackers that Kiwi TCMS
         supports!
     """
+    rpc_cache = {}
 
     def __init__(self, bug_system):
         """
@@ -64,7 +65,7 @@ def bug_id_from_url(cls, url):
         """
         return int(RE_ENDS_IN_INT.search(url.strip()).group(0))
 
-    def details(self, url):
+    def details(self, url):  # pylint: disable=no-self-use
         """
             Returns bug details to be used later. By default this method
             returns OpenGraph metadata (dict) which is shown in the UI as tooltips.
@@ -137,6 +138,31 @@ def is_adding_testcase_to_issue_disabled(self):  # pylint: disable=invalid-name,
                     and self.bug_system.api_username
                     and self.bug_system.api_password)
 
+    def _rpc_connection(self):
+        """
+            Returns an object which is used to communicate to the external system.
+            This method is meant to be overriden by inherited classes.
+        """
+        raise NotImplementedError()
+
+    @property
+    def rpc(self):
+        """
+            Returns an object which is used to communicate to the external system.
+            This proerty is meant to be used by the rest of the integration code
+            and provides caching b/c connecting to a remote system may be a slow
+            operation.
+        """
+        # b/c jira.JIRA tries to connect when object is created
+        # see https://github.com/kiwitcms/Kiwi/issues/100
+        if not self.is_adding_testcase_to_issue_disabled():
+            return None
+
+        if self.bug_system.base_url not in self.rpc_cache:
+            self.rpc_cache[self.bug_system.base_url] = self._rpc_connection()
+
+        return self.rpc_cache[self.bug_system.base_url]
+
 
 class Bugzilla(IssueTrackerType):
     """
@@ -161,22 +187,18 @@ def __init__(self, bug_system):
             "BUGZILLA_AUTH_CACHE_DIR",
             tempfile.mkdtemp(prefix='.bugzilla-')
         )
+
+    def _rpc_connection(self):
         if not os.path.exists(self._bugzilla_cache_dir):
             os.makedirs(self._bugzilla_cache_dir, 0o700)
 
-        self._rpc = None
-
-    @property
-    def rpc(self):
-        if self._rpc is None:
-            self._rpc = bugzilla.Bugzilla(
-                self.bug_system.api_url,
-                user=self.bug_system.api_username,
-                password=self.bug_system.api_password,
-                cookiefile=self._bugzilla_cache_dir + 'cookie',
-                tokenfile=self._bugzilla_cache_dir + 'token',
-            )
-        return self._rpc
+        return bugzilla.Bugzilla(
+            self.bug_system.api_url,
+            user=self.bug_system.api_username,
+            password=self.bug_system.api_password,
+            cookiefile=self._bugzilla_cache_dir + 'cookie',
+            tokenfile=self._bugzilla_cache_dir + 'token',
+        )
 
     def add_testexecution_to_issue(self, executions, issue_url):
         bug_id = self.bug_id_from_url(issue_url)
@@ -217,22 +239,17 @@ class JIRA(IssueTrackerType):
         the code uses ``jira.JIRA.DEFAULT_OPTIONS`` from the ``jira`` Python module!
     """
 
-    def __init__(self, bug_system):
-        super().__init__(bug_system)
-
+    def _rpc_connection(self):
         if hasattr(settings, 'JIRA_OPTIONS'):
             options = settings.JIRA_OPTIONS
         else:
             options = None
 
-        # b/c jira.JIRA tries to connect when object is created
-        # see https://github.com/kiwitcms/Kiwi/issues/100
-        if not self.is_adding_testcase_to_issue_disabled():
-            self.rpc = jira.JIRA(
-                bug_system.api_url,
-                basic_auth=(self.bug_system.api_username, self.bug_system.api_password),
-                options=options,
-            )
+        return jira.JIRA(
+            self.bug_system.api_url,
+            basic_auth=(self.bug_system.api_username, self.bug_system.api_password),
+            options=options,
+        )
 
     @classmethod
     def bug_id_from_url(cls, url):
@@ -300,11 +317,9 @@ class GitHub(IssueTrackerType):
             the integration code doesn't use them!
     """
 
-    def __init__(self, bug_system):
-        super().__init__(bug_system)
-
+    def _rpc_connection(self):
         # NOTE: we use an access token so only the password field is required
-        self.rpc = github.Github(self.bug_system.api_password)
+        return github.Github(self.bug_system.api_password)
 
     def add_testexecution_to_issue(self, executions, issue_url):
         bug_id = self.bug_id_from_url(issue_url)
@@ -344,20 +359,18 @@ class Gitlab(IssueTrackerType):
             the integration code doesn't use it!
     """
 
-    def __init__(self, bug_system):
-        super().__init__(bug_system)
-
+    def _rpc_connection(self):
         # we use an access token so only the password field is required
-        self.rpc = gitlab.Gitlab(self.bug_system.api_url,
-                                 private_token=self.bug_system.api_password)
+        return gitlab.Gitlab(self.bug_system.api_url,
+                             private_token=self.bug_system.api_password)
 
     def add_testexecution_to_issue(self, executions, issue_url):
         bug_id = self.bug_id_from_url(issue_url)
         for execution in executions:
             gitlab_integration.GitlabThread(self.rpc, self.bug_system, execution, bug_id).start()
 
     def is_adding_testcase_to_issue_disabled(self):
-        return not (self.bug_system.base_url and self.bug_system.api_password)
+        return not (self.bug_system.api_url and self.bug_system.api_password)
 
     def report_issue_from_testexecution(self, execution):
         args = {
@@ -381,15 +394,12 @@ class Redmine(IssueTrackerType):
         :api_password: - the password for this username
     """
 
-    def __init__(self, bug_system):
-        super().__init__(bug_system)
-
-        if not self.is_adding_testcase_to_issue_disabled():
-            self.rpc = redminelib.Redmine(
-                self.bug_system.api_url,
-                username=self.bug_system.api_username,
-                password=self.bug_system.api_password
-            )
+    def _rpc_connection(self):
+        return redminelib.Redmine(
+            self.bug_system.api_url,
+            username=self.bug_system.api_username,
+            password=self.bug_system.api_password
+        )
 
     def add_testexecution_to_issue(self, executions, issue_url):
         bug_id = self.bug_id_from_url(issue_url)