From da8e07ab3ecd0abda03d7b8a7fbcfa706b02eebf Mon Sep 17 00:00:00 2001
From: Jan David Mol <mol@astron.nl>
Date: Wed, 22 Dec 2021 11:17:13 +0100
Subject: [PATCH] L2SS-497: Add measures management capabilities and expose
them in the Beam device (that will use the measures)
---
.../tangostationcontrol/common/measures.py | 120 ++++++++++++++++++
.../tangostationcontrol/devices/beam.py | 47 ++++++-
2 files changed, 163 insertions(+), 4 deletions(-)
create mode 100644 tangostationcontrol/tangostationcontrol/common/measures.py
diff --git a/tangostationcontrol/tangostationcontrol/common/measures.py b/tangostationcontrol/tangostationcontrol/common/measures.py
new file mode 100644
index 000000000..efba34a91
--- /dev/null
+++ b/tangostationcontrol/tangostationcontrol/common/measures.py
@@ -0,0 +1,120 @@
+# -*- coding: utf-8 -*-
+#
+# Distributed under the terms of the APACHE license.
+# See LICENSE.txt for more info.
+
+""" Utility functions for managing the casacore 'measures' tables.
+
+The 'measures' tables contain the ephemerides and geodetic calibrations
+as input for its time and space calculations. These tables are externally
+available (see MEASURES_URL).
+
+Casacore is expected to be configured to look in /opt/IERS/current for
+its 'measures' tables, through setting this in the ~/.casarc file as:
+
+ measures.directory: /opt/IERS/current
+
+Periodically new measures need to be installed, especially if a leap
+second is introduced. Measures are maintained in directories called
+/opt/IERS/IERS-YYYY-MM-DDTHH:MM:SS, and /opt/IERS/current is a symlink
+to the active set.
+
+Usage:
+
+The download_measures() function can be used to download new measures,
+which can then be activated using use_measures_directory(). If
+casacore.measures already accessed the measures, the python program
+needs to be restarted in order to clear the cache.
+
+"""
+
+import pathlib
+import urllib.request
+import tarfile
+import datetime
+import os
+import sys
+
+# Where to store the measures table sets
+IERS_ROOTDIR = "/opt/IERS"
+
+# Where to download files to
+TEMPDIR = "/tmp"
+
+# Where new measures can be downloaded
+MEASURES_URL = "ftp://ftp.astron.nl/outgoing/Measures/WSRT_Measures.ztar"
+
+def get_measures_directory():
+ """ Return the directory of the current measures table in use. """
+
+ return str(pathlib.Path(IERS_ROOTDIR, "current").resolve())
+
+def use_measures_directory(newdir):
+ """ Select a new set of measures tables to use.
+
+ NOTE: Python must be restarted if the 'casacore.measures' module
+ already loaded the measures table before this switch.
+
+ The 'restart_python()' function can be used for this purpose.
+ """
+
+ newdir = pathlib.Path(newdir)
+
+ # newdir must be one of the available measures
+ if str(newdir) not in get_available_measures_directories():
+ raise ValueError(f"Target is not an available measures directory: {newdir}")
+
+ # be sure newdir must point to a directory containing measures
+ for subdir in ['ephemerides', 'geodetic']:
+ subdir = pathlib.Path(newdir, subdir)
+
+ if not subdir.is_dir():
+ raise ValueError(f"Subdirectory {subdir} does not exist")
+
+ # switch to new directory
+ current_symlink = pathlib.Path(IERS_ROOTDIR, "current")
+ current_symlink.unlink()
+ current_symlink.symlink_to(newdir)
+
+def restart_python():
+ """ Force a restart this python program.
+
+ This function does not return. """
+
+ exe_path = pathlib.Path(sys.executable)
+ os.execv(exe_path, [exe_path.name] + sys.argv)
+
+ # NOTE: Python 3.4+ closes all file descriptors > 2 automatically, see https://www.python.org/dev/peps/pep-0446/
+
+def get_available_measures_directories() -> list:
+ """ Returns the set of installed measures tables. """
+ return [str(d) for d in pathlib.Path(IERS_ROOTDIR).glob("IERS-*") if d.is_dir() and not d.is_symlink()]
+
+def download_measures() -> str:
+ """ Download new measures and return the directory in which they were installed.
+ """
+
+ # create target directory for new measures
+ now = datetime.datetime.now()
+ iers_dir = pathlib.Path(now.strftime(f"{IERS_ROOTDIR}/IERS-%FT%T"))
+ iers_dir.mkdir()
+
+ try:
+ measures_filename = pathlib.Path(TEMPDIR, "WSRT_Measures.ztar")
+
+ # download measures
+ urllib.request.urlretrieve(MEASURES_URL, str(measures_filename))
+
+ # untar measures
+ tarball = tarfile.open(str(measures_filename))
+ tarball.extractall(path=str(iers_dir))
+
+ # remove download
+ measures_filename.unlink()
+ except Exception as e:
+ # don't linger our new directory if we could not install measures in it
+ iers_dir.rmdir()
+
+ raise
+
+ return str(iers_dir)
diff --git a/tangostationcontrol/tangostationcontrol/devices/beam.py b/tangostationcontrol/tangostationcontrol/devices/beam.py
index bbcea5f91..e271dcf04 100644
--- a/tangostationcontrol/tangostationcontrol/devices/beam.py
+++ b/tangostationcontrol/tangostationcontrol/devices/beam.py
@@ -8,10 +8,13 @@
"""
# PyTango imports
-from tango.server import attribute
-from tango import AttrWriteType
+from tango.server import attribute, command
+from tango import AttrWriteType, DebugIt
import numpy
import pathlib
+import urllib.request
+import tarfile
+import datetime
# Additional import
from tangostationcontrol.devices.device_decorators import *
@@ -19,6 +22,10 @@ from tangostationcontrol.common.entrypoint import entry
from tangostationcontrol.clients.attribute_wrapper import attribute_wrapper
from tangostationcontrol.devices.lofar_device import lofar_device
from tangostationcontrol.common.lofar_logging import device_logging_to_python, log_exceptions
+from tangostationcontrol.common.measures import get_measures_directory, use_measures_directory, download_measures, restart_python, get_available_measures_directories
+
+import logging
+logger = logging.getLogger()
__all__ = ["Beam", "main"]
@@ -34,8 +41,11 @@ class Beam(lofar_device):
# ----------
# Directory where the casacore measures that we use, reside. We configure ~/.casarc to
- # use /opt/IERS/current, but that is a symlink, so resolve it to get the actual location.
- measures_directory_R = attribute(dtype=str, access=AttrWriteType.READ, fget=lambda self: str(pathlib.Path("/opt/IERS/current").resolve()))
+ # use the symlink /opt/IERS/current, which we switch to the actual set of files to use.
+ measures_directory_R = attribute(dtype=str, access=AttrWriteType.READ, fget = lambda self: get_measures_directory())
+
+ # List of installed measures (the latest 64, anyway)
+ measures_directories_available_R = attribute(dtype=(str,), max_dim_x=64, access=AttrWriteType.READ, fget = lambda self: sorted(get_available_measures_directories())[-64:])
# --------
# overloaded functions
@@ -46,6 +56,35 @@ class Beam(lofar_device):
# Commands
# --------
+ @command(dtype_out=str, doc_out="Name of newly installed measures directory")
+ @DebugIt()
+ @log_exceptions()
+ def download_measures(self):
+ """ Download new measures into /opt/IERS.
+
+ NOTE: This may take a while to complete. """
+
+ return download_measures()
+
+ @command(dtype_in=str, doc_in="Measures directory to activate")
+ @DebugIt()
+ @log_exceptions()
+ def use_measures(self, newdir):
+ """ Activate a new measures directory.
+
+ NOTE: This will turn off and restart this device!! """
+
+ # switch to requested measures
+ use_measures_directory(newdir)
+ logger.info(f"Switched measures table to {newdir}")
+
+ # turn off our device, to prepare for a python restart
+ self.Off()
+
+ # restart this program to force casacore to adopt
+ # the new tables
+ logger.warning("Restarting device to activate new measures tables")
+ restart_python()
# ----------
# Run server
--
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