add get_max_open_files

Author: scivision

+stdlib/+python/get_max_open_files.m

@@ -0,0 +1,22 @@
+%% python.get_max_open_files  Get process open-file soft limit via Python
+function omax = get_max_open_files()
+
+omax = [];
+
+if ispc()
+	omax = uint64(omax);
+	return
+end
+
+try
+	% RLIMIT_NOFILE soft limit is the active per-process descriptor cap.
+	lim = py.resource.getrlimit(py.resource.RLIMIT_NOFILE);
+	omax = lim(1);
+catch e
+	pythonException(e)
+	omax = [];
+end
+
+omax = uint64(omax);
+
+end

+stdlib/+sys/get_max_open_files.m

@@ -0,0 +1,22 @@
+%% sys.get_max_open_files  Get process open-file soft limit via shell
+function omax = get_max_open_files()
+
+omax = [];
+
+if ispc()
+  omax = uint64(omax);
+  return
+end
+
+[s, m] = system('ulimit -n');
+if s == 0
+  omax = str2double(strtrim(m));
+
+  if ~isfinite(omax) || omax <= 0
+    omax = [];
+  end
+end
+
+omax = uint64(omax);
+
+end

+stdlib/get_max_open_files.m

@@ -0,0 +1,39 @@
+%% GET_MAX_OPEN_FILES  Get process open-file soft limit
+% These limits can be important if using 
+% <https://www.mathworks.com/help/parallel-computing/recommended-system-limits-for-macintosh-and-linux.html Parallel Computing>
+
+function [omax, b] = get_max_open_files(backend)
+
+if nargin < 1
+  backend = {'python', 'sys'};
+else
+  backend = cellstr(backend);
+end
+
+omax = uint64([]);
+
+for j = 1:numel(backend)
+	b = backend{j};
+
+	switch b
+		case 'python'
+			if stdlib.has_python()
+				omax = stdlib.python.get_max_open_files();
+			end
+		case 'sys'
+			omax = stdlib.sys.get_max_open_files();
+		otherwise
+			error('stdlib:get_max_open_files:ValueError', 'Unknown backend: %s', b)
+	end
+
+	if ~isempty(omax)
+		return
+	end
+end
+
+end
+
+%!test
+%! n = stdlib.get_max_open_files();
+%! assert(isscalar(n));
+%! assert(n > 0);

test/TestDisk.m

@@ -59,6 +59,18 @@ function test_disk_capacity(tc, Ps, B_jdps)
 end
 
 
+function test_ulimit(tc, B_ps)
+[i, b] = stdlib.get_max_open_files(B_ps);
+tc.assertEqual(char(b), B_ps)
+tc.verifyClass(i, 'uint64')
+if ispc()
+  tc.verifyEmpty(i)
+else
+  tc.verifyGreaterThan(i, 0)
+end
+end
+
+
 function test_is_removable(tc, B_ps)
 [y, b] = stdlib.is_removable(pwd(), B_ps);
 tc.assertEqual(char(b), B_ps)