put each radio type in its own module

in preparation for moving radio-specific radio code into these modules too

parsl/executors/base.py

@@ -5,7 +5,7 @@
 
 from typing_extensions import Literal, Self
 
-from parsl.monitoring.radios import MonitoringRadioSender
+from parsl.monitoring.radios.base import MonitoringRadioSender
 
 
 class ParslExecutor(metaclass=ABCMeta):

parsl/executors/high_throughput/interchange.py

@@ -19,7 +19,8 @@
 from parsl.executors.high_throughput.manager_record import ManagerRecord
 from parsl.executors.high_throughput.manager_selector import ManagerSelector
 from parsl.monitoring.message_type import MessageType
-from parsl.monitoring.radios import MonitoringRadioSender, ZMQRadioSender
+from parsl.monitoring.radios.base import MonitoringRadioSender
+from parsl.monitoring.radios.zmq import ZMQRadioSender
 from parsl.process_loggers import wrap_with_logs
 from parsl.serialize import serialize as serialize_object
 from parsl.utils import setproctitle

parsl/monitoring/monitoring.py

@@ -14,7 +14,7 @@
 
 from parsl.log_utils import set_file_logger
 from parsl.monitoring.errors import MonitoringHubStartError
-from parsl.monitoring.radios import MultiprocessingQueueRadioSender
+from parsl.monitoring.radios.multiprocessing import MultiprocessingQueueRadioSender
 from parsl.monitoring.router import router_starter
 from parsl.monitoring.types import TaggedMonitoringMessage
 from parsl.multiprocessing import ForkProcess, SizedQueue

parsl/monitoring/radios/base.py

@@ -0,0 +1,13 @@
+import logging
+from abc import ABCMeta, abstractmethod
+from typing import Optional
+
+_db_manager_excepts: Optional[Exception]
+
+logger = logging.getLogger(__name__)
+
+
+class MonitoringRadioSender(metaclass=ABCMeta):
+    @abstractmethod
+    def send(self, message: object) -> None:
+        pass

parsl/monitoring/radios/filesystem.py

@@ -0,0 +1,52 @@
+import logging
+import os
+import pickle
+import uuid
+
+from parsl.monitoring.radios.base import MonitoringRadioSender
+
+logger = logging.getLogger(__name__)
+
+
+class FilesystemRadioSender(MonitoringRadioSender):
+    """A MonitoringRadioSender that sends messages over a shared filesystem.
+
+    The messsage directory structure is based on maildir,
+    https://en.wikipedia.org/wiki/Maildir
+
+    The writer creates a message in tmp/ and then when it is fully
+    written, moves it atomically into new/
+
+    The reader ignores tmp/ and only reads and deletes messages from
+    new/
+
+    This avoids a race condition of reading partially written messages.
+
+    This radio is likely to give higher shared filesystem load compared to
+    the UDP radio, but should be much more reliable.
+    """
+
+    def __init__(self, *, monitoring_url: str, timeout: int = 10, run_dir: str):
+        logger.info("filesystem based monitoring channel initializing")
+        self.base_path = f"{run_dir}/monitor-fs-radio/"
+        self.tmp_path = f"{self.base_path}/tmp"
+        self.new_path = f"{self.base_path}/new"
+
+        os.makedirs(self.tmp_path, exist_ok=True)
+        os.makedirs(self.new_path, exist_ok=True)
+
+    def send(self, message: object) -> None:
+        logger.info("Sending a monitoring message via filesystem")
+
+        unique_id = str(uuid.uuid4())
+
+        tmp_filename = f"{self.tmp_path}/{unique_id}"
+        new_filename = f"{self.new_path}/{unique_id}"
+        buffer = message
+
+        # this will write the message out then atomically
+        # move it into new/, so that a partially written
+        # file will never be observed in new/
+        with open(tmp_filename, "wb") as f:
+            pickle.dump(buffer, f)
+        os.rename(tmp_filename, new_filename)

parsl/monitoring/radios/htex.py

@@ -0,0 +1,57 @@
+import logging
+import pickle
+
+from parsl.monitoring.radios.base import MonitoringRadioSender
+
+logger = logging.getLogger(__name__)
+
+
+class HTEXRadioSender(MonitoringRadioSender):
+
+    def __init__(self, monitoring_url: str, timeout: int = 10):
+        """
+        Parameters
+        ----------
+
+        monitoring_url : str
+            URL of the form <scheme>://<IP>:<PORT>
+        timeout : int
+            timeout, default=10s
+        """
+        logger.info("htex-based monitoring channel initialising")
+
+    def send(self, message: object) -> None:
+        """ Sends a message to the UDP receiver
+
+        Parameter
+        ---------
+
+        message: object
+            Arbitrary pickle-able object that is to be sent
+
+        Returns:
+            None
+        """
+
+        import parsl.executors.high_throughput.monitoring_info
+
+        result_queue = parsl.executors.high_throughput.monitoring_info.result_queue
+
+        # this message needs to go in the result queue tagged so that it is treated
+        # i) as a monitoring message by the interchange, and then further more treated
+        # as a RESOURCE_INFO message when received by monitoring (rather than a NODE_INFO
+        # which is the implicit default for messages from the interchange)
+
+        # for the interchange, the outer wrapper, this needs to be a dict:
+
+        interchange_msg = {
+            'type': 'monitoring',
+            'payload': message
+        }
+
+        if result_queue:
+            result_queue.put(pickle.dumps(interchange_msg))
+        else:
+            logger.error("result_queue is uninitialized - cannot put monitoring message")
+
+        return

parsl/monitoring/radios/multiprocessing.py

@@ -0,0 +1,17 @@
+from multiprocessing.queues import Queue
+
+from parsl.monitoring.radios.base import MonitoringRadioSender
+
+
+class MultiprocessingQueueRadioSender(MonitoringRadioSender):
+    """A monitoring radio which connects over a multiprocessing Queue.
+    This radio is intended to be used on the submit side, where components
+    in the submit process, or processes launched by multiprocessing, will have
+    access to a Queue shared with the monitoring database code (bypassing the
+    monitoring router).
+    """
+    def __init__(self, queue: Queue) -> None:
+        self.queue = queue
+
+    def send(self, message: object) -> None:
+        self.queue.put(message)