person_detection/base_camera.py

import paho.mqtt.client as mqtt
import time
import threading
import logging as log
from multiprocessing import Process, Queue, Value, Lock

from roc import Roc
import config

try:
    from greenlet import getcurrent as get_ident
except ImportError:
    try:
        from thread import get_ident
    except ImportError:
        from _thread import get_ident


class CameraEvent(object):
    """An Event-like class that signals all active clients when a new frame is
    available.
    """
    def __init__(self):
        self.events = {}

    def wait(self):
        """Invoked from each client's thread to wait for the next frame."""
        ident = 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] = [threading.Event(), time.time()]
        return self.events[ident][0].wait(timeout=10.0)

    def set(self):
        """Invoked by the camera thread when 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 2 minutes, then assume
                # the client is gone and remove it
                if now - event[1] > 120:
                    remove = ident
        #if remove:
        #    del self.events[remove]

    def clear(self):
        """Invoked from each client's thread after a frame was processed."""
        self.events[get_ident()][0].clear()


class BaseCamera(object):
    frame = {}
    event = {}

    deviceQ = {}
    cameras = [0]*len(config.cameras)

    lock = Lock()
    activity_counter = Value('i', 0)

    def __init__(self, device, user, password, mbrlow, mbrhigh, devicegroup, noroc):
        self.mqttBroker = "localhost"
        self.device = device
        self.mbrlow = mbrlow
        self.mbrhigh = mbrhigh
        self.devicegroup = devicegroup
        self.noroc = noroc

        self.roc = Roc(config.url, user, password, config.enterprise, config.site)

        """Start the background camera process if it isn't running yet."""
        if BaseCamera.cameras[int(self.device)] == 0:
            BaseCamera.cameras[int(self.device)] = 1
            BaseCamera.event[self.device] = CameraEvent()
            self.last_detected = None
            self.timer = None
            self.detected = False
            BaseCamera.deviceQ[self.device] = Queue(100)
            self.set_resolution(self.device, "low")
            threading.Thread(target=self._thread).start()
            # start background frame process
            Process(target=self._process).start()
            # wait until frames are available
            _ = self.get_frame()
            log.info("Start camera {} feed to {}".format(self.device, self.client))

    def get_frame(self):
        """Return the current camera frame."""
        while not BaseCamera.event[self.device].wait():
            log.info("get_frame timeout device:{}, thread:{}".format(self.device, get_ident()))
        BaseCamera.event[self.device].clear()
        return BaseCamera.frame[self.device]

    def frames(self):
        """"Generator that returns frames from the camera."""
        raise NotImplementedError('Must be implemented by subclasses.')

    def _thread(self):
        while True:
            BaseCamera.frame[self.device] = BaseCamera.deviceQ[self.device].get(block=True)
            BaseCamera.event[self.device].set()  # send signal to clients
            time.sleep(0)

    def _process(self):
        """Camera background process."""
        frames_iterator = self.frames()
        for frame in frames_iterator:
            BaseCamera.deviceQ[self.device].put(frame, block=True)

    def person_detected(self, num):
        self.last_detected = time.time()
        if not self.detected:
            BaseCamera.lock.acquire()
            BaseCamera.activity_counter.value += 1
            BaseCamera.lock.release()
            self.set_resolution_high()
            if not self.noroc:
                self.roc.set_mbr(self.devicegroup, self.mbrhigh)
            self.detected = True
            self.start_timer()

    def no_person_detected(self):
        self.detected = False
        self.timer = None
        BaseCamera.lock.acquire()
        BaseCamera.activity_counter.value -= 1
        if BaseCamera.activity_counter.value <= 0:
            BaseCamera.activity_counter.value = 0
            self.set_resolution_low()
            if not self.noroc:
                self.roc.set_mbr(self.devicegroup, self.mbrlow)
        BaseCamera.lock.release()

    def start_timer(self):
        # log.info("Start timer for device {}".format(device))
        self.timer = threading.Timer(10.0, self.timer_expiry)
        self.timer.start()

    def set_resolution_high(self):
        for device in range(0, len(config.cameras)):
            self.set_resolution(str(device), "high")

    def set_resolution_low(self):
        for device in range(0, len(config.cameras)):
            self.set_resolution(str(device), "low")

    def set_resolution(self, device, level):
        log.info("Setting camera {} resolution to {}".format(device, level))
        client = mqtt.Client()
        client.connect(self.mqttBroker)
        client.publish("camera/" + str(5000 + int(device)), level)

    def timer_expiry(self):
        now = time.time()
        diff = now - self.last_detected
        log.debug("timer_expiry() - now:{}, last_detected:{}".format(now, self.last_detected))
        if diff > 5.0:
            self.no_person_detected()
        else:
            # Restart timer since person detected not too long back
            self.start_timer()