[entropy.client] make possible to disable differential repository update feature

conf/repositories.conf.example

@@ -34,6 +34,17 @@ repository|sabayonlinux.org||ftp://mirror.aarnet.edu.au/pub/SabayonLinux/entropy
 repository|sabayonlinux.org||http://cross-lfs.sabayonlinux.org/entropy|
 repository|sabayonlinux.org||http://na.mirror.garr.it/mirrors/sabayonlinux/entropy|
 
+# syntax for differential-update
+# differential-update: This setting controls the way Entropy client updates
+#                      its repositories. If you're on a slow/unstable network
+#                      it is recommended to disable "differential-update"
+#                      in favour of a simple and more reliabile HTTP/FTP
+#                      connection. In fact, differential repository updates
+#                      are known to cause issues on some networks.
+# Valid parameters: disable, enable, true, false, disabled, enabled
+# Default is: enabled
+# differential-update: enabled
+
 # syntax for developer-repo
 #
 #  developer-repo: Enable this setting to fetch an extended repository database containing

libraries/entropy/client/interfaces/db.py

@@ -140,6 +140,8 @@ class AvailablePackagesRepositoryUpdater(object):
         )
         self._developer_repo = \
             self._settings['repositories']['developer_repo']
+        self._differential_update = \
+            self._settings['repositories']['differential_update']
         if self._developer_repo:
             const_debug_write(__name__,
                 "__init__: developer repo mode enabled")
@@ -295,6 +297,14 @@ class AvailablePackagesRepositoryUpdater(object):
             elif sqlite3_rc != 0:
                 repo_eapi = 1
 
+        # if differential update is disabled and FORCE_EAPI is not overriding
+        # we cannot use EAPI=3
+        if (eapi_env_clear is None) and (not self._differential_update) and \
+            (repo_eapi == 3):
+            const_debug_write(__name__,
+                "__get_repo_eapi: differential update is disabled !")
+            repo_eapi -= 1
+
         # check EAPI
         if eapi_env_clear is not None:
             repo_eapi = eapi_env_clear
@@ -303,7 +313,7 @@ class AvailablePackagesRepositoryUpdater(object):
             # developer_repo mode
             self._developer_repo = False
             const_debug_write(__name__,
-                "_setup_repo_eapi: developer repo mode disabled FORCE_EAPI")
+                "__get_repo_eapi: developer repo mode disabled FORCE_EAPI")
 
         elif repo_eapi > 1 and self._developer_repo:
             # enforce EAPI=1

libraries/entropy/core/settings/base.py

@@ -1150,6 +1150,7 @@ class SystemSettings(Singleton, EntropyPluginStore):
             'timeout': etpConst['default_download_timeout'],
             'security_advisories_url': etpConst['securityurl'],
             'developer_repo': False,
+            'differential_update': True,
         }
 
         repo_conf = etpConst['repositoriesconf']
@@ -1247,6 +1248,13 @@ class SystemSettings(Singleton, EntropyPluginStore):
                 if dev_repo in ("enable", "enabled", "true", "1", "yes",):
                     data['developer_repo'] = True
 
+            elif (line.find("differential-update|") != -1) and \
+                (not line.startswith("#")) and (split_line_len == 2):
+
+                dev_repo = split_line[1]
+                if dev_repo in ("disable", "disabled", "false", "0", "no",):
+                    data['differential_update'] = False
+
             elif (line.find("downloadspeedlimit|") != -1) and \
                 (not line.startswith("#")) and (split_line_len == 2):