Bug 1605879 - for clang-tidy based static-analysis pass the files for analysis in chuncks. r=sylvestre

Since we have a limit of the number of arguments length that the shell can support we have to
pass the files for the analysis to `run-clang-tidy.py` in chuncks, calculated in proportion
to the number or logical cpu cores.

Differential Revision: https://phabricator.services.mozilla.com/D58971

--HG--
extra : moz-landing-system : lando

python/mozbuild/mozbuild/code-analysis/mach_commands.py

@@ -273,16 +273,28 @@ class StaticAnalysis(MachCommandBase):
         self._compilation_commands_path = self.topobjdir
         if self._clang_tidy_config is None:
             self._clang_tidy_config = self._get_clang_tidy_config()
-        args = self._get_clang_tidy_command(
-            checks=checks, header_filter=header_filter, sources=source, jobs=jobs, fix=fix)
 
         monitor = StaticAnalysisMonitor(
             self.topsrcdir, self.topobjdir, self._clang_tidy_config, total)
 
         footer = StaticAnalysisFooter(self.log_manager.terminal, monitor)
+
         with StaticAnalysisOutputManager(self.log_manager, monitor, footer) as output_manager:
-            rc = self.run_process(args=args, ensure_exit_code=False,
-                                  line_handler=output_manager.on_line, cwd=cwd)
+            import math
+            import multiprocessing
+            batch_size = int(math.ceil(float(len(source)) / multiprocessing.cpu_count()))
+            for i in range(0, len(source), batch_size):
+                args = self._get_clang_tidy_command(
+                    checks=checks,
+                    header_filter=header_filter,
+                    sources=source[i:(i + batch_size)],
+                    jobs=jobs,
+                    fix=fix)
+                rc = self.run_process(
+                    args=args,
+                    ensure_exit_code=False,
+                    line_handler=output_manager.on_line,
+                    cwd=cwd)
 
             self.log(logging.WARNING, 'warning_summary',
                      {'count': len(monitor.warnings_db)},