sync_struct: Notifier.{read -> raw_view}, factor out common dict update code [nfc]

artiq/master/databases.py

@@ -1,7 +1,7 @@
 import asyncio
 import tokenize
 
-from artiq.protocols.sync_struct import Notifier, process_mod
+from artiq.protocols.sync_struct import Notifier, process_mod, update_from_dict
 from artiq.protocols import pyon
 from artiq.tools import TaskObject
 
@@ -19,20 +19,14 @@ class DeviceDB:
         self.data = Notifier(device_db_from_file(self.backing_file))
 
     def scan(self):
-        new_data = device_db_from_file(self.backing_file)
+        update_from_dict(self.data,
-
+            device_db_from_file(self.backing_file))
-        for k in list(self.data.read.keys()):
-            if k not in new_data:
-                del self.data[k]
-        for k in new_data.keys():
-            if k not in self.data.read or self.data.read[k] != new_data[k]:
-                self.data[k] = new_data[k]
 
     def get_device_db(self):
-        return self.data.read
+        return self.data.raw_view
 
     def get(self, key):
-        return self.data.read[key]
+        return self.data.raw_view[key]
 
 
 class DatasetDB(TaskObject):
@@ -47,7 +41,7 @@ class DatasetDB(TaskObject):
         self.data = Notifier({k: (True, v) for k, v in file_data.items()})
 
     def save(self):
-        data = {k: v[1] for k, v in self.data.read.items() if v[0]}
+        data = {k: v[1] for k, v in self.data.raw_view.items() if v[0]}
         pyon.store_file(self.persist_file, data)
 
     async def _do(self):
@@ -59,7 +53,7 @@ class DatasetDB(TaskObject):
             self.save()
 
     def get(self, key):
-        return self.data.read[key][1]
+        return self.data.raw_view[key][1]
 
     def update(self, mod):
         process_mod(self.data, mod)
@@ -67,8 +61,8 @@ class DatasetDB(TaskObject):
     # convenience functions (update() can be used instead)
     def set(self, key, value, persist=None):
         if persist is None:
-            if key in self.data.read:
+            if key in self.data.raw_view:
-                persist = self.data.read[key][0]
+                persist = self.data.raw_view[key][0]
             else:
                 persist = False
         self.data[key] = (persist, value)

artiq/master/experiments.py

@@ -5,7 +5,7 @@ import shutil
 import time
 import logging
 
-from artiq.protocols.sync_struct import Notifier
+from artiq.protocols.sync_struct import Notifier, update_from_dict
 from artiq.master.worker import (Worker, WorkerInternalException,
                                  log_worker_exception)
 from artiq.tools import get_windows_drives, exc_to_warning
@@ -81,15 +81,6 @@ class _RepoScanner:
         return r
 
 
-def _sync_explist(target, source):
-    for k in list(target.read.keys()):
-        if k not in source:
-            del target[k]
-    for k in source.keys():
-        if k not in target.read or target.read[k] != source[k]:
-            target[k] = source[k]
-
-
 class ExperimentDB:
     def __init__(self, repo_backend, worker_handlers):
         self.repo_backend = repo_backend
@@ -125,7 +116,7 @@ class ExperimentDB:
             new_explist = await _RepoScanner(self.worker_handlers).scan(wd)
             logger.info("repository scan took %d seconds", time.monotonic()-t1)
 
-            _sync_explist(self.explist, new_explist)
+            update_from_dict(self.explist, new_explist)
         finally:
             self._scanning = False
             self.status["scanning"] = False

artiq/master/scheduler.py

@@ -442,8 +442,10 @@ class Scheduler:
 
     def get_status(self):
         """Returns a dictionary containing information about the runs currently
-        tracked by the scheduler."""
+        tracked by the scheduler.
-        return self.notifier.read
+
+        Must not be modified."""
+        return self.notifier.raw_view
 
     def check_pause(self, rid):
         """Returns ``True`` if there is a condition that could make ``pause``

artiq/master/worker_db.py

@@ -110,12 +110,12 @@ class DeviceManager:
 
 class DatasetManager:
     def __init__(self, ddb):
-        self.broadcast = Notifier(dict())
+        self._broadcaster = Notifier(dict())
         self.local = dict()
         self.archive = dict()
 
         self.ddb = ddb
-        self.broadcast.publish = ddb.update
+        self._broadcaster.publish = ddb.update
 
     def set(self, key, value, broadcast=False, persist=False, archive=True):
         if key in self.archive:
@@ -125,10 +125,12 @@ class DatasetManager:
 
         if persist:
             broadcast = True
+
         if broadcast:
-            self.broadcast[key] = persist, value
+            self._broadcaster[key] = persist, value
-        elif key in self.broadcast.read:
+        elif key in self._broadcaster.raw_view:
-            del self.broadcast[key]
+            del self._broadcaster[key]
+
         if archive:
             self.local[key] = value
         elif key in self.local:
@@ -138,10 +140,10 @@ class DatasetManager:
         target = None
         if key in self.local:
             target = self.local[key]
-        if key in self.broadcast.read:
+        if key in self._broadcaster.raw_view:
             if target is not None:
-                assert target is self.broadcast.read[key][1]
+                assert target is self._broadcaster.raw_view[key][1]
-            target = self.broadcast[key][1]
+            target = self._broadcaster[key][1]
         if target is None:
             raise KeyError("Cannot mutate non-existing dataset")
 
@@ -155,7 +157,7 @@ class DatasetManager:
     def get(self, key, archive=False):
         if key in self.local:
             return self.local[key]
-        else:
+        
         data = self.ddb.get(key)
         if archive:
             if key in self.archive:
@@ -168,6 +170,7 @@ class DatasetManager:
         datasets_group = f.create_group("datasets")
         for k, v in self.local.items():
             datasets_group[k] = v
+
         archive_group = f.create_group("archive")
         for k, v in self.archive.items():
             archive_group[k] = v

artiq/protocols/sync_struct.py

@@ -127,18 +127,19 @@ class Notifier:
     >>> n = Notifier([])
     >>> n.append([])
     >>> n[0].append(42)
-    >>> n.read
+    >>> n.raw_view
     [[42]]
 
     This class does not perform any network I/O and is meant to be used with
     e.g. the :class:`.Publisher` for this purpose. Only one publisher at most can be
     associated with a :class:`.Notifier`.
 
-    :param backing_struct: Structure to encapsulate. For convenience, it
+    :param backing_struct: Structure to encapsulate.
-        also becomes available as the ``read`` property of the :class:`.Notifier`.
     """
     def __init__(self, backing_struct, root=None, path=[]):
-        self.read = backing_struct
+        #: The raw data encapsulated (read-only!).
+        self.raw_view = backing_struct
+
         if root is None:
             self.root = self
             self.publish = None
@@ -197,6 +198,27 @@ class Notifier:
         return Notifier(item, self.root, self._path + [key])
 
 
+def update_from_dict(target, source):
+    """Updates notifier contents from given source dictionary.
+
+    Only the necessary changes are performed; unchanged fields are not written.
+    (Currently, modifications are only performed at the top level. That is,
+    whenever there is a change to a child array/struct the entire member is
+    updated instead of choosing a more optimal set of mods.)
+    """
+    curr = target.raw_view
+
+    # Delete removed keys.
+    for k in list(curr.keys()):
+        if k not in source:
+            del target[k]
+
+    # Insert/update changed data.
+    for k in source.keys():
+        if k not in curr or curr[k] != source[k]:
+            target[k] = source[k]
+
+
 class Publisher(AsyncioServer):
     """A network server that publish changes to structures encapsulated in
     a :class:`.Notifier`.
@@ -230,7 +252,7 @@ class Publisher(AsyncioServer):
             except KeyError:
                 return
 
-            obj = {"action": "init", "struct": notifier.read}
+            obj = {"action": "init", "struct": notifier.raw_view}
             line = pyon.encode(obj) + "\n"
             writer.write(line.encode())
 

artiq/test/test_sync_struct.py

@@ -63,7 +63,7 @@ class SyncStructCase(unittest.TestCase):
         await subscriber.close()
         await publisher.stop()
 
-        self.assertEqual(self.received_dict, test_dict.read)
+        self.assertEqual(self.received_dict, test_dict.raw_view)
 
     def test_recv(self):
         self.loop.run_until_complete(self._do_test_recv())