xenapi: Make dom0 serialization consistent.

The dom0 plugin code had been using `pickle` for serializing input and
`json` for serializing output which was needlessly inconsistent. This
patch makes the code use `pickle`--chosen for its better handling of
`datetime` objects--for both sending and receiving data.

This patch also refactors the code so that neither the caller nor the
callee need to explicitly worry about serialization: the caller just
passes in args and kwargs, and the callee's function signature just
accepts the args and kwargs as usual.

Bonus: Removes unecessary imports

Change-Id: I3abb42eeebd8d37d67e6c26fa7bcae66d876b3ee

4 files changed, 34 insertions, 92 deletions

diff --git a/plugins/xenserver/xenapi/etc/xapi.d/plugins/glance b/plugins/xenserver/xenapi/etc/xapi.d/plugins/glance
index a574bb406..924bf10d7 100755
--- a/plugins/xenserver/xenapi/etc/xapi.d/plugins/glance
+++ b/plugins/xenserver/xenapi/etc/xapi.d/plugins/glance
@@ -20,18 +20,9 @@
 
 """Handle the uploading and downloading of images via Glance."""
 
-import cPickle as pickle
 import httplib
-try:
-    import json
-except ImportError:
-    import simplejson as json
 import md5
-import os
-import shutil
-
 import urllib2
-import XenAPIPlugin
 
 import utils
 
@@ -202,19 +193,11 @@ def _upload_tarball(staging_path, image_id, glance_host, glance_port,
     conn.close()
 
 
-def download_vhd(session, args):
+def download_vhd(session, image_id, glance_host, glance_port, glance_use_ssl,
+                 uuid_stack, sr_path, auth_token):
     """Download an image from Glance, unbundle it, and then deposit the VHDs
     into the storage repository
     """
-    params = pickle.loads(exists(args, 'params'))
-    image_id = params["image_id"]
-    glance_host = params["glance_host"]
-    glance_port = params["glance_port"]
-    glance_use_ssl = params["glance_use_ssl"]
-    uuid_stack = params["uuid_stack"]
-    sr_path = params["sr_path"]
-    auth_token = params["auth_token"]
-
     staging_path = utils.make_staging_area(sr_path)
     try:
         # Download tarball into staging area and extract it
@@ -223,28 +206,15 @@ def download_vhd(session, args):
             glance_use_ssl, auth_token)
 
         # Move the VHDs from the staging area into the storage repository
-        imported_vhds = utils.import_vhds(sr_path, staging_path, uuid_stack)
+        return utils.import_vhds(sr_path, staging_path, uuid_stack)
     finally:
         utils.cleanup_staging_area(staging_path)
 
-    # Right now, it's easier to return a single string via XenAPI,
-    # so we'll json encode the list of VHDs.
-    return json.dumps(imported_vhds)
-
 
-def upload_vhd(session, args):
+def upload_vhd(session, vdi_uuids, image_id, glance_host, glance_port,
+               glance_use_ssl, sr_path, auth_token, properties):
     """Bundle the VHDs comprising an image and then stream them into Glance.
     """
-    params = pickle.loads(exists(args, 'params'))
-    vdi_uuids = params["vdi_uuids"]
-    image_id = params["image_id"]
-    glance_host = params["glance_host"]
-    glance_port = params["glance_port"]
-    glance_use_ssl = params["glance_use_ssl"]
-    sr_path = params["sr_path"]
-    auth_token = params["auth_token"]
-    properties = params["properties"]
-
     staging_path = utils.make_staging_area(sr_path)
     try:
         utils.prepare_staging_area(sr_path, staging_path, vdi_uuids)
@@ -253,9 +223,6 @@ def upload_vhd(session, args):
     finally:
         utils.cleanup_staging_area(staging_path)
 
-    return ""  # Nothing useful to return on an upload
-
 
 if __name__ == '__main__':
-    XenAPIPlugin.dispatch({'upload_vhd': upload_vhd,
-                           'download_vhd': download_vhd})
+    utils.register_plugin_calls(download_vhd, upload_vhd)
diff --git a/plugins/xenserver/xenapi/etc/xapi.d/plugins/migration b/plugins/xenserver/xenapi/etc/xapi.d/plugins/migration
index 85ad0bdbc..35316a9b8 100755
--- a/plugins/xenserver/xenapi/etc/xapi.d/plugins/migration
+++ b/plugins/xenserver/xenapi/etc/xapi.d/plugins/migration
@@ -18,37 +18,18 @@
 """
 XenAPI Plugin for transfering data between host nodes
 """
-
-import cPickle as pickle
-try:
-    import json
-except ImportError:
-    import simplejson as json
-import os
-import os.path
-import shlex
-import shutil
-import subprocess
-
-import XenAPIPlugin
-
 import utils
 
 from pluginlib_nova import *
 configure_logging('migration')
 
 
-def move_vhds_into_sr(session, args):
+def move_vhds_into_sr(session, instance_uuid, sr_path, uuid_stack):
     """Moves the VHDs from their copied location to the SR"""
-    params = pickle.loads(exists(args, 'params'))
-    instance_uuid = params['instance_uuid']
-    sr_path = params['sr_path']
-    uuid_stack = params['uuid_stack']
-
     staging_path = "/images/instance%s" % instance_uuid
     imported_vhds = utils.import_vhds(sr_path, staging_path, uuid_stack)
     utils.cleanup_staging_area(staging_path)
-    return json.dumps(imported_vhds)
+    return imported_vhds
 
 
 def _rsync_vhds(instance_uuid, host, staging_path, user="root"):
@@ -65,15 +46,8 @@ def _rsync_vhds(instance_uuid, host, staging_path, user="root"):
     utils.finish_subprocess(rsync_proc, rsync_cmd)
 
 
-def transfer_vhd(session, args):
+def transfer_vhd(session, instance_uuid, host, vdi_uuid, sr_path, seq_num):
     """Rsyncs a VHD to an adjacent host"""
-    params = pickle.loads(exists(args, 'params'))
-    instance_uuid = params['instance_uuid']
-    host = params['host']
-    vdi_uuid = params['vdi_uuid']
-    sr_path = params['sr_path']
-    seq_num = params['seq_num']
-
     staging_path = utils.make_staging_area(sr_path)
     try:
         utils.prepare_staging_area(
@@ -82,9 +56,6 @@ def transfer_vhd(session, args):
     finally:
         utils.cleanup_staging_area(staging_path)
 
-    return ""
-
 
 if __name__ == '__main__':
-    XenAPIPlugin.dispatch({'transfer_vhd': transfer_vhd,
-                           'move_vhds_into_sr': move_vhds_into_sr})
+    utils.register_plugin_calls(move_vhds_into_sr, transfer_vhd)
diff --git a/plugins/xenserver/xenapi/etc/xapi.d/plugins/utils.py b/plugins/xenserver/xenapi/etc/xapi.d/plugins/utils.py
index 9eba58936..027d26a67 100644
--- a/plugins/xenserver/xenapi/etc/xapi.d/plugins/utils.py
+++ b/plugins/xenserver/xenapi/etc/xapi.d/plugins/utils.py
@@ -14,6 +14,7 @@
 
 """Various utilities used by XenServer plugins."""
 
+import cPickle as pickle
 import logging
 import os
 import shlex
@@ -21,6 +22,7 @@ import shutil
 import subprocess
 import tempfile
 
+import XenAPIPlugin
 
 CHUNK_SIZE = 8192
 
@@ -362,3 +364,21 @@ def extract_tarball(fileobj, path, callback=None):
         tar_proc.stdin.write(chunk)
 
     finish_subprocess(tar_proc, tar_cmd)
+
+
+def _handle_serialization(func):
+    def wrapped(session, params):
+        params = pickle.loads(params['params'])
+        rv = func(session, *params['args'], **params['kwargs'])
+        return pickle.dumps(rv)
+    return wrapped
+
+
+def register_plugin_calls(*funcs):
+    """Wrapper around XenAPIPlugin.dispatch which handles pickle
+    serialization.
+    """
+    wrapped_dict = {}
+    for func in funcs:
+        wrapped_dict[func.__name__] = _handle_serialization(func)
+    XenAPIPlugin.dispatch(wrapped_dict)
diff --git a/plugins/xenserver/xenapi/etc/xapi.d/plugins/workarounds b/plugins/xenserver/xenapi/etc/xapi.d/plugins/workarounds
index 771c27a0d..244939f00 100755
--- a/plugins/xenserver/xenapi/etc/xapi.d/plugins/workarounds
+++ b/plugins/xenserver/xenapi/etc/xapi.d/plugins/workarounds
@@ -17,21 +17,14 @@
 
 """Handle the uploading and downloading of images via Glance."""
 
-import cPickle as pickle
-try:
-    import json
-except ImportError:
-    import simplejson as json
 import os
 import shutil
 
-import XenAPIPlugin
-
 import utils
 
 #FIXME(sirp): should this use pluginlib from 5.6?
 from pluginlib_nova import *
-configure_logging('hacks')
+configure_logging('workarounds')
 
 
 def _copy_vdis(sr_path, staging_path, vdi_uuids):
@@ -43,23 +36,14 @@ def _copy_vdis(sr_path, staging_path, vdi_uuids):
         seq_num += 1
 
 
-def safe_copy_vdis(session, args):
-    params = pickle.loads(exists(args, 'params'))
-    sr_path = params["sr_path"]
-    vdi_uuids = params["vdi_uuids"]
-    uuid_stack = params["uuid_stack"]
-
+def safe_copy_vdis(session, sr_path, vdi_uuids, uuid_stack):
     staging_path = utils.make_staging_area(sr_path)
     try:
         _copy_vdis(sr_path, staging_path, vdi_uuids)
-        imported_vhds = utils.import_vhds(sr_path, staging_path, uuid_stack)
+        return utils.import_vhds(sr_path, staging_path, uuid_stack)
     finally:
         utils.cleanup_staging_area(staging_path)
 
-    # Right now, it's easier to return a single string via XenAPI,
-    # so we'll json encode the list of VHDs.
-    return json.dumps(imported_vhds)
-
 
 if __name__ == '__main__':
-    XenAPIPlugin.dispatch({'safe_copy_vdis': safe_copy_vdis})
+    utils.register_plugin_calls(safe_copy_vdis)