From 43c8fea37f531dab10f392a03838a8af1b9dc376 Mon Sep 17 00:00:00 2001
From: Joel Collins <jtc9242@gmail.com>
Date: Fri, 27 Mar 2020 15:07:11 +0000
Subject: [PATCH] Use LabThings ClientEvent

---
 openflexure_microscope/camera/base.py | 55 +++------------------------
 1 file changed, 6 insertions(+), 49 deletions(-)

diff --git a/openflexure_microscope/camera/base.py b/openflexure_microscope/camera/base.py
index e203f44f..2d1e930a 100644
--- a/openflexure_microscope/camera/base.py
+++ b/openflexure_microscope/camera/base.py
@@ -3,16 +3,18 @@ import time
 import os
 import shutil
 import threading
-import gevent.event
 import datetime
 import logging
 
+import threading
+
 from abc import ABCMeta, abstractmethod
 from collections import OrderedDict
 
 from .capture import CaptureObject, build_captures_from_exif
 from openflexure_microscope.utilities import entry_by_uuid
 from labthings.core.lock import StrictLock
+from labthings.core.event import ClientEvent
 
 from openflexure_microscope.paths import data_file_path
 
@@ -45,51 +47,6 @@ def generate_numbered_basename(obj_list: list) -> str:
     return basename
 
 
-class CameraEvent(object):
-    """
-    A frame-signaller object used by any instances or subclasses of BaseCamera.
-
-    An event-like class that signals all active clients when a new frame is available.
-    """
-
-    def __init__(self):
-        self.events = {}
-
-    def wait(self, timeout: int = 5):
-        """Wait for the next frame (invoked from each client's thread)."""
-        ident = threading.get_ident()
-        if ident not in self.events:
-            # this is a new client
-            # add an entry for it in the self.events dict
-            # each entry has two elements, a threading.Event() and a timestamp
-            self.events[ident] = [gevent.event.Event(), time.time()]
-        return self.events[ident][0].wait(timeout)
-
-    def set(self):
-        """Signal that a new frame is available."""
-        now = time.time()
-        remove = None
-        for ident, event in self.events.items():
-            if not event[0].isSet():
-                # if this client's event is not set, then set it
-                # also update the last set timestamp to now
-                event[0].set()
-                event[1] = now
-            else:
-                # if the client's event is already set, it means the client
-                # did not process a previous frame
-                # if the event stays set for more than 5 seconds, then assume
-                # the client is gone and remove it
-                if now - event[1] > 5:
-                    remove = ident
-        if remove:
-            del self.events[remove]
-
-    def clear(self):
-        """Clear frame event, once processed."""
-        self.events[threading.get_ident()][0].clear()
-
-
 class BaseCamera(metaclass=ABCMeta):
     """
     Base implementation of StreamingCamera.
@@ -99,11 +56,11 @@ class BaseCamera(metaclass=ABCMeta):
         self.thread = None
         self.camera = None
 
-        self.lock = StrictLock(timeout=1)
+        self.lock = StrictLock(timeout=1, name="Camera")
 
         self.frame = None
         self.last_access = 0
-        self.event = CameraEvent()
+        self.event = ClientEvent()
         self.stop = False  # Used to indicate that the stream loop should break
 
         self.stream_timeout = 20
@@ -307,6 +264,7 @@ class BaseCamera(metaclass=ABCMeta):
         self.stop = False
 
         if not self.stream_active:
+            # Spawn a greenlet to handle stream
             # start background frame thread
             self.thread = threading.Thread(target=self._thread)
             self.thread.daemon = True
@@ -368,7 +326,6 @@ class BaseCamera(metaclass=ABCMeta):
         for frame in self.frames_iterator:
             self.frame = frame
             self.event.set()  # send signal to clients
-            time.sleep(0)
 
             # Handle timeout
             if (