sys.is_symlink: 100x speedup

Author: scivision

+stdlib/+sys/is_symlink.m

@@ -1,23 +1,14 @@
 function [ok, cmd] = is_symlink(file)
-arguments
-  file (1,1) string
-end
-
-ok = false;
 
 if ispc()
-  cmd = sprintf('pwsh -command "(Get-Item -Path ''%s'').Attributes"', file);
+  cmd = sprintf('fsutil reparsepoint query "%s"', file);
+  % cmd = sprintf('pwsh -command "(Get-Item -Path ''%s'').Attributes"', file);
+  % works (examine output for ReparsePoint) but is like 100x slower
 else
   cmd = sprintf('test -L "%s"', file);
 end
 
-if strlength(file)
-  [s, m] = system(cmd);
-  ok = s == 0;
-
-  if ispc()
-    ok = ok && contains(m, 'ReparsePoint');
-  end
-end
+[s, ~] = system(cmd);
+ok = s == 0;
 
 end

+stdlib/is_symlink.m

@@ -10,7 +10,7 @@
 function [ok, b] = is_symlink(file, backend)
 arguments
   file string
-  backend (1,:) string = ["native", "java", "dotnet", "python", "sys"]
+  backend (1,:) string = ["native", "java", "python", "dotnet", "sys"]
 end
 
 o = stdlib.Backend(mfilename(), backend);

example/BenchmarkIsSymlink.m

@@ -0,0 +1,59 @@
+classdef (SharedTestFixtures={ matlab.unittest.fixtures.PathFixture("..")}) ...
+    BenchmarkIsSymlink < matlab.perftest.TestCase
+
+properties
+link
+target
+not_exist = tempname()
+fun = @stdlib.is_symlink
+end
+
+properties(TestParameter)
+backend
+end
+
+methods (TestParameterDefinition, Static)
+function backend = setupBackend()
+  backend = init_backend('is_symlink');
+end
+end
+
+
+methods(TestClassSetup)
+function setup_symlink(tc)
+tc.applyFixture(matlab.unittest.fixtures.WorkingFolderFixture())
+
+tc.link = fullfile(pwd(), 'my.lnk');
+
+tc.target = [mfilename("fullpath") '.m'];
+
+tc.assertTrue(stdlib.create_symlink(tc.target, tc.link))
+end
+end
+
+
+methods (Test)
+
+function bench_exist(tc, backend)
+tc.startMeasuring()
+i = tc.fun(tc.link, backend);
+tc.stopMeasuring()
+
+tc.verifyClass(i, 'logical')
+tc.verifyTrue(i)
+end
+
+
+function bench_not_exist(tc, backend)
+tc.startMeasuring()
+i = tc.fun(tc.not_exist, backend);
+tc.stopMeasuring()
+
+tc.verifyClass(i, 'logical')
+tc.assertNotEmpty(i)
+tc.verifyFalse(i)
+end
+
+end
+
+end

example/BenchmarkIsSymlinkRun.m

@@ -0,0 +1,20 @@
+function [r, s] =  BenchmarkIsSymlinkRun()
+tname = "BenchmarkIsSymlink";
+
+%% Exist
+r.same = run_bench(tname + "/bench_exist");
+s.exist = sampleSummary(r.same);
+disp(sortrows(s.exist, "Median"))
+%% Not Exist
+r.not = run_bench(tname + "/bench_not_exist");
+s.not = sampleSummary(r.not);
+disp(sortrows(s.not, "Median"))
+
+end
+
+
+function result = run_bench(name)
+suite = testsuite(name);
+exp = matlab.perftest.TimeExperiment.limitingSamplingError(MaxSamples=20, RelativeMarginOfError=0.1);
+result = exp.run(suite);
+end