Add tests for get_chunks and change formula for get_chunks (#618)

* Add tests for get_chunks and change formula for get_chunks

* fix pep8

* Pass pool_size explicitly

* Fix year

* Use _check_get_chunks()

* Rename date with data

* Add parallel_chunks()

Author: PokhodenkoSA

sdc/tests/__init__.py

@@ -45,6 +45,7 @@
 from sdc.tests.test_hpat_jit import *
 
 from sdc.tests.test_sdc_numpy import *
+from sdc.tests.test_prange_utils import *
 
 # performance tests
 import sdc.tests.tests_perf

sdc/tests/test_prange_utils.py

@@ -0,0 +1,82 @@
+# *****************************************************************************
+# Copyright (c) 2020, Intel Corporation All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+#     Redistributions of source code must retain the above copyright notice,
+#     this list of conditions and the following disclaimer.
+#
+#     Redistributions in binary form must reproduce the above copyright notice,
+#     this list of conditions and the following disclaimer in the documentation
+#     and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+# OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+# OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+# *****************************************************************************
+
+from sdc.tests.test_base import TestCase
+
+from sdc.utilities.prange_utils import get_chunks, Chunk
+
+
+class ChunkTest(TestCase):
+
+    def _get_chunks_data(self):
+        yield (5, 5), [
+            Chunk(start=0, stop=1),
+            Chunk(start=1, stop=2),
+            Chunk(start=2, stop=3),
+            Chunk(start=3, stop=4),
+            Chunk(start=4, stop=5),
+        ]
+        yield (5, 6), [
+            Chunk(start=0, stop=1),
+            Chunk(start=1, stop=2),
+            Chunk(start=2, stop=3),
+            Chunk(start=3, stop=4),
+            Chunk(start=4, stop=5),
+        ]
+        yield (9, 5), [
+            Chunk(start=0, stop=2),
+            Chunk(start=2, stop=4),
+            Chunk(start=4, stop=6),
+            Chunk(start=6, stop=8),
+            Chunk(start=8, stop=9),
+        ]
+        yield (9, 4), [
+            Chunk(start=0, stop=3),
+            Chunk(start=3, stop=5),
+            Chunk(start=5, stop=7),
+            Chunk(start=7, stop=9),
+        ]
+        yield (9, 2), [
+            Chunk(start=0, stop=5),
+            Chunk(start=5, stop=9),
+        ]
+        yield (9, 3), [
+            Chunk(start=0, stop=3),
+            Chunk(start=3, stop=6),
+            Chunk(start=6, stop=9),
+        ]
+
+    def _check_get_chunks(self, args, expected_chunks):
+        pyfunc = get_chunks
+        cfunc = self.jit(pyfunc)
+
+        self.assertEqual(pyfunc(*args), expected_chunks)
+        self.assertEqual(cfunc(*args), expected_chunks)
+
+    def test_get_chunks(self):
+        for args, expected_chunks in self._get_chunks_data():
+            with self.subTest(args=args):
+                self._check_get_chunks(args, expected_chunks)

sdc/utilities/prange_utils.py

@@ -29,61 +29,37 @@
 import sdc
 
 from typing import NamedTuple
-from sdc.utilities.utils import sdc_overload
+from sdc.utilities.utils import sdc_overload, sdc_register_jitable
 
 
 class Chunk(NamedTuple):
     start: int
     stop: int
 
 
+@sdc_register_jitable
 def get_pool_size():
     if sdc.config.config_use_parallel_overloads:
         return numba.config.NUMBA_NUM_THREADS
 
     return 1
 
 
-@sdc_overload(get_pool_size)
-def get_pool_size_overload():
-    pool_size = get_pool_size()
-
-    def get_pool_size_impl():
-        return pool_size
-
-    return get_pool_size_impl
-
-
-def get_chunks(size, pool_size=0):
-    if pool_size == 0:
-        pool_size = get_pool_size()
-
-    chunk_size = (size - 1) // pool_size + 1
+@sdc_register_jitable
+def get_chunks(size, pool_size):
+    pool_size = min(pool_size, size)
+    chunk_size = size // pool_size
+    overload_size = size % pool_size
 
     chunks = []
     for i in range(pool_size):
-        start = min(i * chunk_size, size)
-        stop = min((i + 1) * chunk_size, size)
+        start = i * chunk_size + min(i, overload_size)
+        stop = (i + 1) * chunk_size + min(i + 1, overload_size)
         chunks.append(Chunk(start, stop))
 
     return chunks
 
 
-@sdc_overload(get_chunks)
-def get_chunks_overload(size, pool_size=0):
-    def get_chunks_impl(size, pool_size=0):
-        if pool_size == 0:
-            pool_size = get_pool_size()
-
-        chunk_size = (size - 1) // pool_size + 1
-
-        chunks = []
-        for i in range(pool_size):
-            start = min(i * chunk_size, size)
-            stop = min((i + 1) * chunk_size, size)
-            chunk = Chunk(start, stop)
-            chunks.append(chunk)
-
-        return chunks
-
-    return get_chunks_impl
+@sdc_register_jitable
+def parallel_chunks(size):
+    return get_chunks(size, get_pool_size())