Aggregate stats info emitted during analysis

Summary:
Run `InferStatsAggregator` at the end of the execution of `infer` top-level, and store
results on `infer-out/(frontend|backend|reporting)_stats/aggregated_stats.json`
Not ready yet for buck targets analyzed without the use of an `#infer*` flavor.

Reviewed By: jvillard

Differential Revision: D3365504

fbshipit-source-id: 98b2eb3

infer/lib/python/infer

@@ -19,6 +19,7 @@ from inferlib import analyze, config, utils
 from inferlib.capture import make
 
 CAPTURE_PACKAGE = 'capture'
+TOP_LEVEL_ENVVAR = 'TOP_LEVEL_INFER_INSTANCE_ALREADY_RUNNING'
 
 # token that identifies the end of the options for infer and the beginning
 # of the compilation command
@@ -99,6 +100,12 @@ def create_argparser(parents=[]):
 
 
 def main():
+    toplevel_envvar_value = os.environ.get(TOP_LEVEL_ENVVAR, None)
+    is_toplevel_instance = False
+    if toplevel_envvar_value is None:
+        os.environ[TOP_LEVEL_ENVVAR] = '1'
+        is_toplevel_instance = True
+
     to_parse, cmd = split_args_to_parse()
     # get the module name (if any), then load it
     capture_module_name = os.path.basename(cmd[0]) if len(cmd) > 0 else None
@@ -179,6 +186,18 @@ def main():
         analysis.analyze_and_report()
         analysis.save_stats()
 
+    if is_toplevel_instance is True:
+        buck_out_for_stats_aggregator = None
+        if (mod_name == 'buck' and
+            os.path.isfile(
+                os.path.join(args.infer_out,
+                             config.INFER_BUCK_DEPS_FILENAME))):
+            buck_out_for_stats_aggregator = 'buck-out'
+        logging.info('Aggregating stats')
+        output = utils.run_infer_stats_aggregator(
+            args.infer_out, buck_out_for_stats_aggregator)
+        logging.info(output)
+
     if args.fail_on_bug:
         bugs_filename = os.path.join(args.infer_out,
                                      config.JSON_REPORT_FILENAME)

infer/lib/python/inferlib/utils.py

@@ -129,6 +129,22 @@ def infer_key(analyzer):
     return os.pathsep.join([analyzer, infer_version()])
 
 
+def run_infer_stats_aggregator(infer_out, buck_out=None):
+    buck_out_args = []
+    if buck_out is not None:
+        buck_out_args = ['--buck-out', buck_out]
+    try:
+        cmd = get_cmd_in_bin_dir('InferStatsAggregator')
+        return subprocess.check_output(
+            [cmd, '--results-dir', infer_out] + buck_out_args,
+            stderr=subprocess.STDOUT)
+    except subprocess.CalledProcessError as exc:
+        output = 'Error while aggregating stats ({ec}): {output}'\
+            .format(ec=exc.returncode, output=exc.output)
+        stderr(output)
+        return output
+
+
 def vcs_branch(dir='.'):
     cwd = os.getcwd()
     devnull = open(os.devnull, 'w')