Add a little filesystem watcher for those of us not building everything with eclipse

Author: timfel

mx.graalpython/mx_graalpython.py

@@ -31,6 +31,7 @@
 import shutil
 import sys
 import tempfile
+import time
 from argparse import ArgumentParser
 
 import mx
@@ -1019,12 +1020,52 @@ def python_coverage(args):
     mx.command_function("jacocoreport")(["--omit-excluded", "--format=html"])
 
 
+def python_build_watch(args):
+    """
+    Watch the suite and on any changes to .class, .jar, .h, or .c files rebuild.
+    By default, rebuilds only the archives and non-Java projects.
+    """
+    parser = ArgumentParser(prog='mx python-build-watch')
+    parser.add_argument('--full', action='store_true', help='Run a full mx build', required=False)
+    parser.add_argument('--graalvm', action='store_true', help='Build a graalvm', required=False)
+    parser.add_argument('--no-java', action='store_true', help='Build only archives and native projects [default]', required=False)
+    args = parser.parse_args(args)
+    if sum([args.full, args.graalvm, args.no_java]) > 1:
+        mx.abort("Only one of --full, --graalvm, --no-java can be specified")
+    while True:
+        out = mx.OutputCapture()
+        mx.run([
+            "inotifywait", "-q", "-e", "close_write,moved_to", "-r", "--format=%f",
+            "--exclude", ".*\\.py$",
+            "@%s" % os.path.join(SUITE.dir, ".git"),
+            SUITE.dir
+        ], out=out)
+        changed_file = out.data.strip()
+        mx.logv(changed_file)
+        suffixes = [".c", ".h", ".class", ".jar"]
+        if args.full:
+            suffixes.append(".java")
+        elif args.graalvm:
+            suffixes.extend([".java", ".py"])
+        if any(changed_file.endswith(ext) for ext in [".c", ".h", ".class", ".jar"]):
+            mx.log("Build needed ...")
+            time.sleep(2)
+            if args.full:
+                mx.command_function("build")()
+            elif args.graalvm:
+                mx.log(python_gvm())
+            else:
+                nativebuild([])
+            break
+
+
 # ----------------------------------------------------------------------------------------------------------------------
 #
 # register the suite commands (if any)
 #
 # ----------------------------------------------------------------------------------------------------------------------
 mx.update_commands(SUITE, {
+    'python-build-watch': [python_build_watch, ''],
     'python': [python, '[Python args|@VM options]'],
     'python3': [python, '[Python args|@VM options]'],
     'deploy-binary-if-master': [deploy_binary_if_master, ''],