exists: benchmark java.io.file vs java.nio.file

Author: scivision

+stdlib/canonical.m

@@ -31,7 +31,7 @@
   return
 end
 
-e = stdlib.exists(c);
+e = stdlib.exists(c, use_java);
 
 if ~stdlib.is_absolute(c)
   if e

+stdlib/create_symlink.m

@@ -19,7 +19,7 @@
 % ok = java.nio.file.Files.createSymbolicLink(java.io.File(link).toPath(), java.io.File(target).toPath());
 % the above should work, but Matlab Java doesn't recognize the optional argument omitted.
 
-if stdlib.exists(link)
+if stdlib.exists(link, stdlib.has_java())
   ok = false;
   return
 end

+stdlib/exists.m

@@ -5,18 +5,22 @@
 %%% Outputs
 % * ok: true if exists
 %
-% Ref: https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#exists()
 
 function ok = exists(p, use_java)
 arguments
   p (1,1) string
-  use_java (1,1) logical = false
+  use_java (1,1) logical = true
 end
 
 if use_java
-% Java takes 2x to 10x as long as intrinsic way worst case
-% the intrinsic way above is at least not slower
 
+% https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Files.html#exists(java.nio.file.Path,java.nio.file.LinkOption...)
+% this takes 2x longer than java.io.File.exists()
+% opt = java.nio.file.LinkOption.values;
+% ok = java.nio.file.Files.exists(java.io.File(p).toPath(), opt);
+
+% https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#exists()
+% about the same speed as native Matlab isfile || isfolder
   ok = java.io.File(p).exists();
 else
   ok = isfile(p) || isfolder(p);

+stdlib/samepath.m

@@ -17,7 +17,7 @@
 end
 
 issame = false;
-if ~stdlib.exists(path1) || ~stdlib.exists(path2)
+if ~stdlib.exists(path1, use_java) || ~stdlib.exists(path2, use_java)
   return
 end
 

example/bench_exists.m

@@ -0,0 +1,15 @@
+%% benchmark for exists()
+
+f = mfilename("fullpath");
+%f = tempname;
+
+fno = @() stdlib.exists(f, false);
+fjava = @() stdlib.exists(f, true);
+
+t_no = timeit(fno);
+t_java = timeit(fjava);
+
+disp("No Java: " + t_no + " s")
+disp("Java: " + t_java + " s")
+
+disp("Java is " + t_no/t_java + " times faster")

test/TestFileImpure.m

@@ -52,7 +52,7 @@ function setup_path(tc)
 methods (Test, ParameterCombination = 'sequential')
 
 function test_exists(tc, p_exists)
-tc.verifyEqual(stdlib.exists(p_exists{1}), p_exists{2})
+tc.verifyEqual(stdlib.exists(p_exists{1}, stdlib.has_java()), p_exists{2})
 end