add -j -1 option to use all cores, closes #8

rio_color/scripts/cli.py

@@ -7,7 +7,7 @@
 
 @click.command('color')
 @click.option('--jobs', '-j', type=int, default=1,
-              help="Number of jobs to run simultaneously, default: 1")
+              help="Number of jobs to run simultaneously, Use -1 for all cores, default: 1")
 @click.option('--out-dtype', '-d', type=click.Choice(['uint8', 'uint16']),
               help="Integer data type for output data, default: same as input")
 @click.argument('src_path', type=click.Path(exists=True))
@@ -73,6 +73,12 @@ def color(ctx, jobs, out_dtype, src_path, dst_path, operations):
         'out_dtype': out_dtype
     }
 
+    if jobs == 0:
+        raise click.UsageError("Jobs must be >= 1 or == -1")
+    elif jobs < 0:
+        import multiprocessing
+        jobs = multiprocessing.cpu_count()
+
     if jobs > 1:
         with riomucho.RioMucho(
             [src_path],

tests/test_cli.py

@@ -98,3 +98,18 @@ def test_bad_op(tmpdir):
     assert result.exit_code == 2
     assert "foob is not a valid operation" in result.output
     assert not os.path.exists(output)
+
+
+def test_color_jobsn1(tmpdir):
+    output = str(tmpdir.join('colorj1.tif'))
+    runner = CliRunner()
+    result = runner.invoke(
+        color,
+        [
+            '-d', 'uint8',
+            '-j', '-1',
+            'tests/rgb8.tif',
+            output,
+            "gamma 1,2,3 1.85"])
+    assert result.exit_code == 0
+    assert os.path.exists(output)