Add-on: check connection with Flamenco on URL change

Whenever the URL to Flamenco Manager is updated, check it and report.

This required moving the 'ping manager' code into a separate function, as
calling an operator from an RNA update callback is not a good idea.

addon/flamenco/comms.py

@@ -5,13 +5,18 @@
 import logging
 from typing import TYPE_CHECKING
 
+from urllib3.exceptions import HTTPError, MaxRetryError
+import bpy
+
 _flamenco_client = None
 _log = logging.getLogger(__name__)
 
 if TYPE_CHECKING:
     from flamenco.manager import ApiClient as _ApiClient
+    from .preferences import FlamencoPreferences as _FlamencoPreferences
 else:
     _ApiClient = object
+    _FlamencoPreferences = object
 
 
 def flamenco_api_client(manager_url: str) -> _ApiClient:
@@ -43,3 +48,47 @@ def discard_flamenco_data():
     _log.info("closing Flamenco client")
     _flamenco_client.close()
     _flamenco_client = None
+
+
+def ping_manager(context: bpy.types.Context, api_client: _ApiClient, prefs: _FlamencoPreferences) -> tuple[str, str]:
+    """Ping the Manager, update preferences, and return a report as string.
+
+    :returns: tuple (report, level). The report will be something like "<name>
+        version <version> found", or an error message. The level will be
+        'ERROR', 'WARNING', or 'INFO', suitable for reporting via
+        `Operator.report()`.
+    """
+
+    # Do a late import, so that the API is only imported when actually used.
+    from flamenco.manager import ApiException
+    from flamenco.manager.apis import MetaApi
+    from flamenco.manager.models import FlamencoVersion, ManagerConfiguration
+
+    context.window_manager.flamenco_status_ping = "..."
+
+    meta_api = MetaApi(api_client)
+    try:
+        version: FlamencoVersion = meta_api.get_version()
+        config: ManagerConfiguration = meta_api.get_configuration()
+    except ApiException as ex:
+        report = "Manager cannot be reached: %s" % ex
+        level = "ERROR"
+    except MaxRetryError as ex:
+        # This is the common error, when for example the port number is
+        # incorrect and nothing is listening.
+        report = "Manager cannot be reached"
+        level = "WARNING"
+    except HTTPError as ex:
+        report = "Manager cannot be reached: %s" % ex
+        level = "ERROR"
+    else:
+        report = "%s version %s found" % (version.name, version.version)
+        level = "INFO"
+
+        # Store whether this Manager supports the Shaman API.
+        prefs.is_shaman_enabled = config.shaman_enabled
+        prefs.job_storage = config.storage_location
+
+    context.window_manager.flamenco_status_ping = report
+
+    return report, level

addon/flamenco/operators.py

@@ -5,7 +5,7 @@ import datetime
 import logging
 from pathlib import Path, PurePosixPath
 from typing import Optional, TYPE_CHECKING
-from urllib3.exceptions import HTTPError, MaxRetryError
+from urllib3.exceptions import MaxRetryError
 
 import bpy
 
@@ -81,40 +81,14 @@ class FLAMENCO_OT_ping_manager(FlamencoOpMixin, bpy.types.Operator):
     bl_options = {"REGISTER"}  # No UNDO.
 
     def execute(self, context: bpy.types.Context) -> set[str]:
+        from . import comms, preferences
+
         api_client = self.get_api_client(context)
+        prefs = preferences.get(context)
 
-        from flamenco.manager import ApiException
-        from flamenco.manager.apis import MetaApi
-        from flamenco.manager.models import FlamencoVersion, ManagerConfiguration
-
-        context.window_manager.flamenco_status_ping = "..."
-
-        meta_api = MetaApi(api_client)
-        try:
-            version: FlamencoVersion = meta_api.get_version()
-            config: ManagerConfiguration = meta_api.get_configuration()
-        except ApiException as ex:
-            report = "Manager cannot be reached: %s" % ex
-            level = "ERROR"
-        except MaxRetryError as ex:
-            # This is the common error, when for example the port number is
-            # incorrect and nothing is listening.
-            report = "Manager cannot be reached"
-            level = "WARNING"
-        except HTTPError as ex:
-            report = "Manager cannot be reached: %s" % ex
-            level = "ERROR"
-        else:
-            report = "%s version %s found" % (version.name, version.version)
-            level = "INFO"
-
-            # Store whether this Manager supports the Shaman API.
-            prefs = preferences.get(context)
-            prefs.is_shaman_enabled = config.shaman_enabled
-            prefs.job_storage = config.storage_location
-
+        report, level = comms.ping_manager(context, api_client, prefs)
         self.report({level}, report)
-        context.window_manager.flamenco_status_ping = report
+
         return {"FINISHED"}
 
 

addon/flamenco/preferences.py

@@ -4,7 +4,7 @@
 import bpy
 
 
-def discard_flamenco_client(prefs, context):
+def discard_flamenco_client(context):
     """Discard any cached Flamenco client after the Manager URL changes."""
     from . import comms
 
@@ -22,6 +22,18 @@ def _refresh_the_planet(
                 region.tag_redraw()
 
 
+def _manager_url_updated(prefs, context):
+    discard_flamenco_client(context)
+
+    from . import comms
+
+    api_client = comms.flamenco_api_client(prefs.manager_url)
+
+    # Warning, be careful what of the context to access here. Accessing /
+    # changing too much can cause crashes, infinite loops, etc.
+    comms.ping_manager(context, api_client, prefs)
+
+
 class FlamencoPreferences(bpy.types.AddonPreferences):
     bl_idname = "flamenco"
 
@@ -29,7 +41,7 @@ class FlamencoPreferences(bpy.types.AddonPreferences):
         name="Manager URL",
         description="Location of the Manager",
         default="http://localhost:8080/",
-        update=discard_flamenco_client,
+        update=_manager_url_updated,
     )
 
     is_shaman_enabled: bpy.props.BoolProperty(  # type: ignore
@@ -68,16 +80,25 @@ class FlamencoPreferences(bpy.types.AddonPreferences):
 
         row = col.row(align=True)
         row.prop(self, "manager_url")
-        row.operator("flamenco.ping_manager", text="", icon="CHECKMARK")
-        if context.window_manager.flamenco_status_ping:
-            split = col.split(factor=0.4)
+        row.operator("flamenco.ping_manager", text="", icon="FILE_REFRESH")
+
+        def text_row(parent, label):
+            split = parent.split(factor=0.4)
             split.label(text="")
-            split.label(text=context.window_manager.flamenco_status_ping)
+            split.label(text=label)
+
+        if not self.job_storage:
+            text_row(col, "Press the refresh button before using Flamenco")
+
+        if context.window_manager.flamenco_status_ping:
+            text_row(col, context.window_manager.flamenco_status_ping)
+        else:
+            aligned = col.column(align=True)
+            text_row(aligned, "Press the refresh button to check the connection")
+            text_row(aligned, "and update the job storage location")
 
         if self.is_shaman_enabled:
-            split = col.split(factor=0.4)
-            split.label(text="")
-            split.label(text="Shaman enabled")
+            text_row(col, "Shaman enabled")
         col.prop(self, "job_storage_for_gui", text="Job Storage")