class Dialog(QDialog):
""" This class is a simple example of how to use QSharedMemory. It is a
simple dialog that presents a few buttons. Run the executable twice to
create two processes running the dialog. In one of the processes, press
the button to load an image into a shared memory segment, and then select
an image file to load. Once the first process has loaded and displayed the
image, in the second process, press the button to read the same image from
shared memory. The second process displays the same image loaded from its
new location in shared memory.
The class contains a data member sharedMemory, which is initialized with
the key "QSharedMemoryExample" to force all instances of Dialog to access
the same shared memory segment. The constructor also connects the
clicked() signal from each of the three dialog buttons to the slot function
appropriate for handling each button.
"""
def __init__(self, parent=None):
super(Dialog, self).__init__(parent)
self.sharedMemory = QSharedMemory('QSharedMemoryExample')
self.ui = Ui_Dialog()
self.ui.setupUi(self)
self.ui.loadFromFileButton.clicked.connect(self.loadFromFile)
self.ui.loadFromSharedMemoryButton.clicked.connect(self.loadFromMemory)
self.setWindowTitle("SharedMemory Example")
def loadFromFile(self):
""" This slot function is called when the "Load Image From File..."
button is pressed on the firs Dialog process. First, it tests whether
the process is already connected to a shared memory segment and, if so,
detaches from that segment. This ensures that we always start the
example from the beginning if we run it multiple times with the same
two Dialog processes. After detaching from an existing shared memory
segment, the user is prompted to select an image file. The selected
file is loaded into a QImage. The QImage is displayed in the Dialog
and streamed into a QBuffer with a QDataStream. Next, it gets a new
shared memory segment from the system big enough to hold the image data
in the QBuffer, and it locks the segment to prevent the second Dialog
process from accessing it. Then it copies the image from the QBuffer
into the shared memory segment. Finally, it unlocks the shared memory
segment so the second Dialog process can access it. After self
function runs, the user is expected to press the "Load Image from
Shared Memory" button on the second Dialog process.
"""
if self.sharedMemory.isAttached():
self.detach()
self.ui.label.setText("Select an image file")
fileName, _ = QFileDialog.getOpenFileName(
self, None, None, "Images (*.png *.xpm *.jpg)")
image = QImage()
if not image.load(fileName):
self.ui.label.setText(
"Selected file is not an image, please select another.")
return
self.ui.label.setPixmap(QPixmap.fromImage(image))
# Load into shared memory.
buf = QBuffer()
buf.open(QBuffer.ReadWrite)
out = QDataStream(buf)
out << image
size = buf.size()
if not self.sharedMemory.create(size):
self.ui.label.setText("Unable to create shared memory segment.")
return
size = min(self.sharedMemory.size(), size)
self.sharedMemory.lock()
# Copy image data from buf into shared memory area.
self.sharedMemory.data()[:] = buf.data().data()
self.sharedMemory.unlock()
def loadFromMemory(self):
""" This slot function is called in the second Dialog process, when the
user presses the "Load Image from Shared Memory" button. First, it
attaches the process to the shared memory segment created by the first
Dialog process. Then it locks the segment for exclusive access, copies
the image data from the segment into a QBuffer, and streams the QBuffer
into a QImage. Then it unlocks the shared memory segment, detaches
from it, and finally displays the QImage in the Dialog.
"""
if not self.sharedMemory.attach():
self.ui.label.setText(
"Unable to attach to shared memory segment.\nLoad an "
"image first.")
return
buf = QBuffer()
ins = QDataStream(buf)
image = QImage()
self.sharedMemory.lock()
buf.setData(self.sharedMemory.constData())
buf.open(QBuffer.ReadOnly)
ins >> image
self.sharedMemory.unlock()
self.sharedMemory.detach()
self.ui.label.setPixmap(QPixmap.fromImage(image))
def detach(self):
""" This private function is called by the destructor to detach the
process from its shared memory segment. When the last process detaches
from a shared memory segment, the system releases the shared memory.
"""
if not self.sharedMemory.detach():
self.ui.label.setText("Unable to detach from shared memory.")
def receiveMessage(self):
stream = QTextStream(self.conn)
if stream.atEnd():
return
data = stream.readAll()
for json_str in data.split("\n")[:-1]:
obj = json.loads(json_str)
msgType = obj["type"]
if msgType == self.TYPE_NOTIFICATION:
self.log("Notification Received. code: {0}".format(
obj["params"].get("code")))
if obj["params"].get("code") == self.N_DATA_RECEIVED:
memKey = obj["params"]["memoryKey"]
mem = self._mem[memKey]
if mem.isAttached():
mem.detach()
self.log(
"Shared memory detached: key={0}".format(memKey))
del self._mem[memKey]
else:
self.notified.emit(obj["params"])
elif msgType == self.TYPE_REQUEST:
self.log(
"Request Received. dataType: {0}, renderId: {1}".format(
obj["params"].get("dataType"),
obj["params"].get("renderId")))
self.requestReceived.emit(obj["params"])
elif msgType == self.TYPE_RESPONSE:
self.log(
"Response Received. dataType: {0}, renderId: {1}".format(
obj["meta"].get("dataType"),
obj["meta"].get("renderId")))
mem = QSharedMemory(obj["memoryKey"])
if not mem.attach(QSharedMemory.ReadOnly):
self.log(
"Cannot attach this process to the shared memory segment: {0}"
.format(mem.errorString()))
return
size = mem.size()
self.log("Size of memory segment is {0} bytes.".format(size))
mem.lock()
ba = QByteArray()
buffer = QBuffer(ba)
buffer.setData(mem.constData())
mem.unlock()
mem.detach()
data = ba.data()
lines = data.split(b"\n")
for line in lines[:5]:
self.log(line[:76])
if len(lines) > 5:
self.log("--Total {0} Lines Received--".format(len(lines)))
self.notify({
"code": self.N_DATA_RECEIVED,
"memoryKey": obj["memoryKey"]
})
self.responseReceived.emit(data, obj["meta"])
class Dialog(QDialog):
""" This class is a simple example of how to use QSharedMemory. It is a
simple dialog that presents a few buttons. Run the executable twice to
create two processes running the dialog. In one of the processes, press
the button to load an image into a shared memory segment, and then select
an image file to load. Once the first process has loaded and displayed the
image, in the second process, press the button to read the same image from
shared memory. The second process displays the same image loaded from its
new location in shared memory.
The class contains a data member sharedMemory, which is initialized with
the key "QSharedMemoryExample" to force all instances of Dialog to access
the same shared memory segment. The constructor also connects the
clicked() signal from each of the three dialog buttons to the slot function
appropriate for handling each button.
"""
def __init__(self, parent = None):
super(Dialog, self).__init__(parent)
self.sharedMemory = QSharedMemory('QSharedMemoryExample')
self.ui = Ui_Dialog()
self.ui.setupUi(self)
self.ui.loadFromFileButton.clicked.connect(self.loadFromFile)
self.ui.loadFromSharedMemoryButton.clicked.connect(self.loadFromMemory)
self.setWindowTitle("SharedMemory Example")
def loadFromFile(self):
""" This slot function is called when the "Load Image From File..."
button is pressed on the firs Dialog process. First, it tests whether
the process is already connected to a shared memory segment and, if so,
detaches from that segment. This ensures that we always start the
example from the beginning if we run it multiple times with the same
two Dialog processes. After detaching from an existing shared memory
segment, the user is prompted to select an image file. The selected
file is loaded into a QImage. The QImage is displayed in the Dialog
and streamed into a QBuffer with a QDataStream. Next, it gets a new
shared memory segment from the system big enough to hold the image data
in the QBuffer, and it locks the segment to prevent the second Dialog
process from accessing it. Then it copies the image from the QBuffer
into the shared memory segment. Finally, it unlocks the shared memory
segment so the second Dialog process can access it. After self
function runs, the user is expected to press the "Load Image from
Shared Memory" button on the second Dialog process.
"""
if self.sharedMemory.isAttached():
self.detach()
self.ui.label.setText("Select an image file")
fileName, _ = QFileDialog.getOpenFileName(self, None, None,
"Images (*.png *.xpm *.jpg)")
image = QImage()
if not image.load(fileName):
self.ui.label.setText(
"Selected file is not an image, please select another.")
return
self.ui.label.setPixmap(QPixmap.fromImage(image))
# Load into shared memory.
buf = QBuffer()
buf.open(QBuffer.ReadWrite)
out = QDataStream(buf)
out << image
size = buf.size()
if not self.sharedMemory.create(size):
self.ui.label.setText("Unable to create shared memory segment.")
return
size = min(self.sharedMemory.size(), size)
self.sharedMemory.lock()
# Copy image data from buf into shared memory area.
self.sharedMemory.data()[:] = buf.data().data()
self.sharedMemory.unlock()
def loadFromMemory(self):
""" This slot function is called in the second Dialog process, when the
user presses the "Load Image from Shared Memory" button. First, it
attaches the process to the shared memory segment created by the first
Dialog process. Then it locks the segment for exclusive access, copies
the image data from the segment into a QBuffer, and streams the QBuffer
into a QImage. Then it unlocks the shared memory segment, detaches
from it, and finally displays the QImage in the Dialog.
"""
if not self.sharedMemory.attach():
self.ui.label.setText(
"Unable to attach to shared memory segment.\nLoad an "
"image first.")
return
buf = QBuffer()
ins = QDataStream(buf)
image = QImage()
self.sharedMemory.lock()
buf.setData(self.sharedMemory.constData())
buf.open(QBuffer.ReadOnly)
ins >> image
self.sharedMemory.unlock()
self.sharedMemory.detach()
self.ui.label.setPixmap(QPixmap.fromImage(image))
def detach(self):
""" This private function is called by the destructor to detach the
process from its shared memory segment. When the last process detaches
from a shared memory segment, the system releases the shared memory.
"""
if not self.sharedMemory.detach():
self.ui.label.setText("Unable to detach from shared memory.")
# from tensorflow.keras.applications import ResNet50
# from tensorflow.keras.preprocessing import image
# from tensorflow.keras.applications.resnet50 import preprocess_input, decode_predictions
SIZE = 224
CHANNELS = 3
#model = ResNet50(weights="imagenet")
from PyQt5.QtCore import QSharedMemory,QBuffer
import numpy as np
from matplotlib import pyplot as plt
import cv2
mem = QSharedMemory("image4")
mem.attach()
while True:
mem.lock()
t = np.array(mem.constData().asarray())
n_t = t[0:SIZE*SIZE*CHANNELS]
plt.imshow(n_t.reshape((SIZE,SIZE,-1)))
cv2.imwrite("test123.png",n_t.reshape((SIZE,SIZE,-1)))
mem.unlock()
break
mem.unlock();
mem.detach();
#del model
class ProducerDialog(QDialog):
def __init__(self, parent=None):
super(ProducerDialog, self).__init__(parent)
self.ui = Ui_Dialog()
self.ui.setupUi(self)
# We only allow one image to be put into the shared memory (otherwise we would need to
# create a dedicated data structure within the SHARED memory and access it from Python and
# C++ appropriately). Also note that "Open" and "Create" have very different semantics (see
# docs) and we use "Create" to always create a "fresh" semaphore to not cause undesired
# blocking/stalls, see also https://doc.qt.io/qt-5/qsystemsemaphore.html
if CONSUMER == 0:
self.ui.loadFromFileButton.clicked.connect(self.load_from_file)
self.ui.loadFromSharedMemoryButton.setEnabled(False)
self.setWindowTitle("Shared Memory Producer: Python Example")
from prodcon_ipc.producer_ipc import ProducerIPC
self.producer_ipc = ProducerIPC(UNIQUE_SHARED_MEMORY_NAME,
SHARED_MEMORY_KEY_FILE)
else:
self.ui.loadFromSharedMemoryButton.clicked.connect(
self.load_from_memory)
self.ui.loadFromFileButton.setEnabled(False)
self.setWindowTitle("Shared Memory Consumer: Python Example")
from prodcon_ipc.consumer_ipc import ConsumerIPC
self.consumer_ipc = ConsumerIPC(UNIQUE_SHARED_MEMORY_NAME,
SHARED_MEMORY_KEY_FILE)
if SHARED_STRUCT == 1:
self.shmem_config = QSharedMemory('shared_struct_test')
if self.shmem_config.isAttached() or self.shmem_config.attach():
if self.shmem_config.lock():
counter, stop_flag, file_name = struct.unpack(
STRUCT_FORMAT, self.shmem_config.constData())
logzero.logger.debug(
"Shared memory struct read: counter=" + str(counter) +
", stop_flag=" + str(stop_flag) + ", file_name=" +
file_name)
self.shmem_config.unlock()
else:
logzero.logger.error("unable to lock " +
self.shmem_config.key())
# Note: if both processes detach from the memory, it gets deleted so that attach() fails. That's why we
# simply never detach (HERE). Depending on the app design, there may be a better solution.
#self.shmem_config.detach()
else:
logzero.logger.error("unable to attach " +
self.shmem_config.key())
def load_from_file(self): # producer slot
self.ui.label.setText("Select an image file")
file_name, t = QFileDialog.getOpenFileName(self, None, None,
"Images (*.png *.jpg)")
if not file_name:
return
image = QImage()
if not image.load(file_name):
self.ui.label.setText(
"Selected file is not an image, please select another.")
return
self.ui.label.setPixmap(QPixmap.fromImage(image))
# Get the image data:
buf = QBuffer()
buf.open(QBuffer.ReadWrite)
out = QDataStream(buf)
out << image
try:
from prodcon_ipc.producer_ipc import ScopedProducer
with ScopedProducer(self.producer_ipc, buf.size()) as sp:
# Copy image data from buf into shared memory area:
sp.data()[:sp.size()] = buf.data().data()[:sp.size()]
except Exception as err:
self.ui.label.setText(str(err))
if SHARED_STRUCT == 1:
# Read from shared memory, increase value and write it back:
if self.shmem_config.isAttached() or self.shmem_config.attach():
if self.shmem_config.lock():
counter, stop_flag, _ = struct.unpack(
STRUCT_FORMAT, self.shmem_config.constData())
data = struct.pack(STRUCT_FORMAT, counter + 1, stop_flag,
str(os.path.basename(file_name)[:30]))
size = min(struct.calcsize(STRUCT_FORMAT),
self.shmem_config.size())
self.shmem_config.data()[:size] = data[:size]
self.shmem_config.unlock()
if stop_flag: # stop producing?
logzero.logger.info(
"Consumer requested to stop the production.")
sys.exit(0)
else:
logzero.logger.error("unable to lock " +
self.shmem_config.key())
#self.shmem_config.detach()
else:
logzero.logger.error("unable to attach " +
self.shmem_config.key())
def load_from_memory(self): # consumer slot
buf = QBuffer()
ins = QDataStream(buf)
image = QImage()
if True: # first variant (much simpler / shorter, more robust)
try:
from prodcon_ipc.consumer_ipc import ScopedConsumer
with ScopedConsumer(self.consumer_ipc) as sc:
buf.setData(sc.data())
buf.open(QBuffer.ReadOnly)
ins >> image
except Exception as err:
self.ui.label.setText(str(err))
else: # second variant, using begin()...end() manually
try:
data = self.consumer_ipc.begin()
except RuntimeError as err:
self.ui.label.setText(str(err))
return
# Read from the shared memory:
try:
buf.setData(data)
buf.open(QBuffer.ReadOnly)
ins >> image
except Exception as err:
logzero.logger.error(str(err))
try:
self.consumer_ipc.end()
except RuntimeError as err:
self.ui.label.setText(str(err))
return
if not image.isNull():
self.ui.label.setPixmap(QPixmap.fromImage(image))
else:
logzero.logger.error("Image data was corrupted.")
