Support single input file

madoop/__main__.py

@@ -56,7 +56,7 @@ def main():
     # Run MapReduce API
     try:
         mapreduce(
-            input_dir=args.input,
+            input_path=args.input,
             output_dir=args.output,
             map_exe=args.mapper,
             reduce_exe=args.reducer,

madoop/mapreduce.py

@@ -26,7 +26,7 @@
 LOGGER = logging.getLogger("madoop")
 
 
-def mapreduce(input_dir, output_dir, map_exe, reduce_exe):
+def mapreduce(input_path, output_dir, map_exe, reduce_exe):
     """Madoop API."""
     # Do not clobber existing output directory
     output_dir = pathlib.Path(output_dir)
@@ -54,8 +54,8 @@ def mapreduce(input_dir, output_dir, map_exe, reduce_exe):
         reduce_output_dir.mkdir()
 
         # Copy and rename input files: part-00000, part-00001, etc.
-        input_dir = pathlib.Path(input_dir)
-        prepare_input_files(input_dir, map_input_dir)
+        input_path = pathlib.Path(input_path)
+        prepare_input_files(input_path, map_input_dir)
 
         # Executables must be absolute paths
         map_exe = pathlib.Path(map_exe).resolve()
@@ -98,25 +98,23 @@ def mapreduce(input_dir, output_dir, map_exe, reduce_exe):
     LOGGER.info("Output directory: %s", output_dir)
 
 
-def prepare_input_files(input_dir, output_dir):
+def prepare_input_files(input_path, output_dir):
     """Copy and split input files.  Rename to part-00000, part-00001, etc.
 
-    If a file in input_dir is smaller than MAX_INPUT_SPLIT_SIZE, then copy it
-    to output_dir.  For larger files, split into blocks of MAX_INPUT_SPLIT_SIZE
-    bytes and write block to output_dir. Input files will never be combined.
+    The input_path can be a file or a directory of files.  If a file is smaller
+    than MAX_INPUT_SPLIT_SIZE, then copy it to output_dir.  For larger files,
+    split into blocks of MAX_INPUT_SPLIT_SIZE bytes and write block to
+    output_dir. Input files will never be combined.
 
     The number of files created will be the number of mappers since we will
     assume that the number of tasks per mapper is 1.  Apache Hadoop has a
     configurable number of tasks per mapper, however for both simplicity and
     because our use case has smaller inputs we use 1.
 
     """
-    assert input_dir.is_dir(), f"Can't find input_dir '{input_dir}'"
-
-    # Split and copy input files
     part_num = 0
     total_size = 0
-    for inpath in sorted(input_dir.glob('*')):
+    for inpath in normalize_input_paths(input_path):
         assert inpath.is_file()
 
         # Compute output filenames
@@ -148,6 +146,26 @@ def prepare_input_files(input_dir, output_dir):
     LOGGER.debug("total input size=%sB", total_size)
 
 
+def normalize_input_paths(input_path):
+    """Return a list of filtered input files.
+
+    If input_path is a file, then use it.  If input_path is a directory, then
+    grab all the *files* inside.  Ignore subdirectories.
+
+    """
+    input_paths = []
+    if input_path.is_dir():
+        for path in sorted(input_path.glob('*')):
+            if path.is_file():
+                input_paths.append(path)
+            else:
+                LOGGER.warning("Ignoring non-file: %s", path)
+    elif input_path.is_file():
+        input_paths.append(input_path)
+    assert input_paths, f"No input: {input_path}"
+    return input_paths
+
+
 def is_executable(exe):
     """Verify exe is executable and raise exception if it is not.
 

tests/test_api.py

@@ -9,7 +9,7 @@ def test_simple(tmpdir):
     """Run a simple MapReduce job and verify the output."""
     with tmpdir.as_cwd():
         madoop.mapreduce(
-            input_dir=TESTDATA_DIR/"word_count/input",
+            input_path=TESTDATA_DIR/"word_count/input",
             output_dir="output",
             map_exe=TESTDATA_DIR/"word_count/map.py",
             reduce_exe=TESTDATA_DIR/"word_count/reduce.py",
@@ -24,7 +24,7 @@ def test_bash_executable(tmpdir):
     """Run a MapReduce job written in Bash."""
     with tmpdir.as_cwd():
         madoop.mapreduce(
-            input_dir=TESTDATA_DIR/"word_count/input",
+            input_path=TESTDATA_DIR/"word_count/input",
             output_dir="output",
             map_exe=TESTDATA_DIR/"word_count/map.sh",
             reduce_exe=TESTDATA_DIR/"word_count/reduce.sh",
@@ -39,7 +39,7 @@ def test_bad_map_exe(tmpdir):
     """Map exe returns non-zero should produce an error message."""
     with tmpdir.as_cwd(), pytest.raises(madoop.MadoopError):
         madoop.mapreduce(
-            input_dir=TESTDATA_DIR/"word_count/input",
+            input_path=TESTDATA_DIR/"word_count/input",
             output_dir="output",
             map_exe=TESTDATA_DIR/"word_count/map_invalid.py",
             reduce_exe=TESTDATA_DIR/"word_count/reduce.py",
@@ -50,7 +50,7 @@ def test_missing_shebang(tmpdir):
     """Reduce exe with a bad shebag should produce an error message."""
     with tmpdir.as_cwd(), pytest.raises(madoop.MadoopError):
         madoop.mapreduce(
-            input_dir=TESTDATA_DIR/"word_count/input",
+            input_path=TESTDATA_DIR/"word_count/input",
             output_dir="output",
             map_exe=TESTDATA_DIR/"word_count/map.py",
             reduce_exe=TESTDATA_DIR/"word_count/reduce_invalid.py",
@@ -61,7 +61,39 @@ def test_empty_inputs(tmpdir):
     """Empty input files should not raise an error."""
     with tmpdir.as_cwd():
         madoop.mapreduce(
-            input_dir=TESTDATA_DIR/"word_count/input_empty",
+            input_path=TESTDATA_DIR/"word_count/input_empty",
+            output_dir="output",
+            map_exe=TESTDATA_DIR/"word_count/map.py",
+            reduce_exe=TESTDATA_DIR/"word_count/reduce.py",
+        )
+    utils.assert_dirs_eq(
+        TESTDATA_DIR/"word_count/correct/output",
+        tmpdir/"output",
+    )
+
+
+def test_single_input_file(tmpdir):
+    """Run a simple MapReduce job with an input file instead of dir."""
+    with tmpdir.as_cwd():
+        madoop.mapreduce(
+            input_path=TESTDATA_DIR/"word_count/input-single-file.txt",
+            output_dir="output",
+            map_exe=TESTDATA_DIR/"word_count/map.py",
+            reduce_exe=TESTDATA_DIR/"word_count/reduce.py",
+        )
+    utils.assert_dirs_eq(
+        TESTDATA_DIR/"word_count/correct/output",
+        tmpdir/"output",
+    )
+
+
+def test_ignores_subdirs(tmpdir):
+    """Run a simple MapReduce job with an input directory containing a
+    subdirectory. The subdirectory should be gracefully ignored.
+    """
+    with tmpdir.as_cwd():
+        madoop.mapreduce(
+            input_path=TESTDATA_DIR/"word_count/input_with_subdir",
             output_dir="output",
             map_exe=TESTDATA_DIR/"word_count/map.py",
             reduce_exe=TESTDATA_DIR/"word_count/reduce.py",

tests/testdata/word_count/input-single-file.txt

@@ -0,0 +1,4 @@
+Hello World
+Bye World
+Hello Hadoop
+Goodbye Hadoop

tests/testdata/word_count/input_with_subdir/input01.txt

@@ -0,0 +1,2 @@
+Hello World
+Bye World

tests/testdata/word_count/input_with_subdir/input02.txt

@@ -0,0 +1,2 @@
+Hello Hadoop
+Goodbye Hadoop