Implement hardware locks

openflexure_microscope/__init__.py

@@ -1,4 +1,4 @@
-__all__ = ['Microscope', 'config']
+__all__ = ['Microscope', 'config', 'task', 'lock']
 __version__ = "0.1.0"
 
 from .microscope import Microscope

openflexure_microscope/api/app.py

@@ -23,8 +23,9 @@ from flask_cors import CORS
 from openflexure_microscope.api.utilities import list_routes
 
 from openflexure_microscope import Microscope, config
+from openflexure_microscope.lock import LockError
 from openflexure_microscope.camera.pi import StreamingCamera
-from openflexure_stage import OpenFlexureStage
+from openflexure_microscope.stage.openflexure import Stage
 
 import atexit
 import logging, sys
@@ -66,6 +67,16 @@ def _handle_http_exception(e):
 for code in default_exceptions:
     app.errorhandler(code)(_handle_http_exception)
 
+def _handle_lock_exception(e):
+    return make_response(
+        jsonify({
+            'status_code': 423,
+            'error': e.code,
+            'details': e.message
+        }),
+        423)
+
+app.errorhandler(LockError)(_handle_lock_exception)
 
 # After app starts, but before first request, attach hardware to global microscope
 @app.before_first_request
@@ -77,7 +88,7 @@ def attach_microscope():
     logging.debug("Creating camera object...")
     api_camera = StreamingCamera(config=openflexurerc)
     logging.debug("Creating stage object...")
-    api_stage = OpenFlexureStage("/dev/ttyUSB0")
+    api_stage = Stage("/dev/ttyUSB0")
 
     logging.debug("Attaching devices to microscope...")
     api_microscope.attach(

openflexure_microscope/camera/base.py

@@ -19,6 +19,7 @@ except ImportError:
 from .capture import CaptureObject, capture_from_dict, BASE_CAPTURE_PATH
 from openflexure_microscope.config import USER_CONFIG_DIR
 from openflexure_microscope.utilities import entry_by_id
+from openflexure_microscope.lock import StrictLock
 
 
 def last_entry(object_list: list):
@@ -29,7 +30,6 @@ def last_entry(object_list: list):
         return None
 
 
-
 def generate_basename():
     """Return a default filename based on the capture datetime"""
     return datetime.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")
@@ -87,6 +87,8 @@ class BaseCamera(object):
         self.thread = None  #: Background thread reading frames from camera
         self.camera = None  #: Camera object
 
+        self.lock = StrictLock(timeout=1)  #: Strict lock controlling thread access to camera hardware
+
         self.frame = None  #: bytes: Current frame is stored here by background thread
         self.last_access = 0  #: time: Time of last client access to the camera
         self.event = CameraEvent()

openflexure_microscope/camera/pi.py

@@ -201,6 +201,8 @@ class StreamingCamera(BaseCamera):
 
         paused_stream = False
 
+        with self.lock:
+
             # Apply valid config params to Picamera object
             if not self.state['record_active']:  # If not recording a video
 
@@ -249,6 +251,7 @@ class StreamingCamera(BaseCamera):
         """
         Change the camera zoom, handling recentering and scaling.
         """
+        with self.lock:
             self.state['zoom_value'] = float(zoom_value)
             if self.state['zoom_value'] < 1:
                 self.state['zoom_value'] = 1
@@ -299,6 +302,7 @@ class StreamingCamera(BaseCamera):
             output_object (str/BytesIO): Target object.
 
         """
+        with self.lock:
             # Start recording method only if a current recording is not running
             if not self.state['record_active']:
 
@@ -334,6 +338,7 @@ class StreamingCamera(BaseCamera):
 
     def stop_recording(self) -> bool:
         """Stop the last started video recording on splitter port 2."""
+        with self.lock:
             # Stop the camera video recording on port 2
             logging.info("Stopping recording")
             self.camera.stop_recording(splitter_port=2)
@@ -378,7 +383,6 @@ class StreamingCamera(BaseCamera):
             splitter_port (int): Splitter port to start recording on
             resolution ((int, int)): Resolution to set the camera to, before starting recording. Defaults to `self.config['video_resolution']`.
         """
-
         # If no stream object exists
         if not hasattr(self, 'stream'):
             self.stream = io.BytesIO() # Create a stream object
@@ -421,6 +425,7 @@ class StreamingCamera(BaseCamera):
             resize ((int, int)): Resize the captured image.
         """
 
+        with self.lock:
             # If output is a StreamObject
             if isinstance(output, CaptureObject):
                 # Set target to capture stream
@@ -459,6 +464,7 @@ class StreamingCamera(BaseCamera):
             use_video_port (bool): Capture from the video port used for streaming. Lower resolution, faster.
             resize ((int, int)): Resize the captured image.
         """
+        with self.lock:
             if use_video_port:
                 resolution = self.config['video_resolution']
             else:
@@ -502,7 +508,7 @@ class StreamingCamera(BaseCamera):
             use_video_port (bool): Capture from the video port used for streaming. Lower resolution, faster.
             resize ((int, int)): Resize the captured image.
         """
-
+        with self.lock:
             if use_video_port:
                 resolution = self.config['video_resolution']
             else:

openflexure_microscope/lock.py

@@ -0,0 +1,65 @@
+from threading import RLock, ThreadError
+
+class LockError(ThreadError):
+    ERROR_CODES = {
+        'ACQUIRE_ERROR': "Unable to acquire. Lock in use by another thread.",
+        'IN_USE_ERROR': "Lock in use by another thread."
+    }
+
+    def __init__(self, code, lock):
+        self.code = code
+        if code in LockError.ERROR_CODES:
+            self.message = LockError.ERROR_CODES[code]
+        else:
+            self.message = "Unknown error."
+        print("{}: {}".format(self.code, self.message))
+
+        ThreadError.__init__(self)
+
+
+class StrictLock(object):
+    def __init__(self, timeout=1):
+        self._lock = RLock()
+        self.timeout = timeout
+
+    def acquire(self, blocking=True):
+        return self._lock.acquire(blocking, timeout=self.timeout)
+
+    def __enter__(self):
+        result = self._lock.acquire(blocking=True, timeout=self.timeout)
+        if result:
+            return result
+        else:
+            raise LockError('ACQUIRE_ERROR', self)
+
+    def __exit__(self, *args):
+        self._lock.release()
+
+    def release(self):
+        self._lock.release()
+
+
+class CompositeLock(object):
+    def __init__(self, locks, timeout=1):
+        self.locks = locks
+        self.timeout = timeout
+
+    def acquire(self, blocking=True):
+        return (lock.acquire(blocking=blocking, timeout=self.timeout) for lock in self.locks)
+
+    def __enter__(self):
+        result = (lock.acquire(blocking=True, timeout=self.timeout) for lock in self.locks)
+        if all(result):
+            return result
+        else:
+            msg = "Unable to acquire all locks {}.".format(self.locks)
+            logging.error(msg)
+            raise ThreadError(msg)
+
+    def __exit__(self, *args):
+        for lock in self.locks:
+            lock.release()
+
+    def release(self):
+        for lock in self.locks:
+            lock.release()

openflexure_microscope/plugins/example/api.py

@@ -67,6 +67,7 @@ class LongRunningAPI(MicroscopeViewPlugin):
         # Extract a values from the JSON payload.
         time_to_run = payload.param('time', default=10, convert=int)
 
+        # Attach the long-running method as a microscope task
         try:
             task = self.microscope.task.start(self.plugin.long_running, time_to_run)
             return jsonify(task.state), 202

openflexure_microscope/plugins/example/plugin.py

@@ -39,10 +39,12 @@ class Plugin(MicroscopePlugin):
         print("Starting a long-running task...")
         n_array = []
 
+        print("Acquiring camera lock...")
+        with self.microscope.camera.lock:
             for _ in range(t_run):
                 n_array.append(random.random())
                 time.sleep(1)
 
-        print("Long-running task finished!")
+            print("Long-running task finished! Releasing lock.")
 
         return n_array

openflexure_microscope/stage/__init__.py

@@ -0,0 +1 @@
+from . import openflexure

openflexure_microscope/stage/openflexure.py

@@ -0,0 +1,10 @@
+from openflexure_stage import OpenFlexureStage
+
+from openflexure_microscope.lock import StrictLock
+
+# TODO: Implement lock on movement
+class Stage(OpenFlexureStage):
+    def __init__(self, *args, **kwargs):
+        self.lock = StrictLock(timeout=2)  #: Strict lock controlling thread access to camera hardware
+
+        OpenFlexureStage.__init__(self, *args, **kwargs)

openflexure_microscope/task.py

@@ -57,10 +57,10 @@ class TaskOrchestrator:
     def start_condition(self, task_obj):
         """
         Method returning bool describing if a particular task is allowed to run.
-        In the future, this will depend on the state of hardware locks?
+        Currently always allows tasks to start, as locks determine access to hardware.
-        Currently just allows a single task at a time.
         """
-        return not any([task._running for task in self.tasks])
+        #return not any([task._running for task in self.tasks])
+        return True
 
 
 class Task: