oeqa.buildperf: add method for measuring file disk usage

Add a new method to BuildPerfTest class for measuring the disk usage of
a file of directory.

(From OE-Core rev: 85cdc240e75d481e93238fbf75f8b8431da05f19)

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/buildperf/base.py

@@ -75,6 +75,7 @@ def time_cmd(cmd, **kwargs):
 class BuildPerfTest(object):
     """Base class for build performance tests"""
     SYSRES = 'sysres'
+    DISKUSAGE = 'diskusage'
 
     name = None
     description = None
@@ -153,6 +154,24 @@ class BuildPerfTest(object):
         with open(results_log, 'w') as fobj:
             fobj.write(timedata)
 
+    def measure_disk_usage(self, path, name, legend):
+        """Estimate disk usage of a file or directory"""
+        # TODO: 'ignore_status' could/should be removed when globalres.log is
+        # deprecated. The function would just raise an exception, instead
+        ret = runCmd(['du', '-s', path], ignore_status=True)
+        if ret.status:
+            log.error("du failed, disk usage will be reported as 0")
+            size = 0
+            self._failed = True
+        else:
+            size = int(ret.output.split()[0])
+            log.debug("Size of %s path is %s", path, size)
+        measurement = {'type': self.DISKUSAGE,
+                       'name': name,
+                       'legend': legend}
+        measurement['values'] = {'size': size}
+        self.results['measurements'].append(measurement)
+
     @staticmethod
     def force_rm(path):
         """Equivalent of 'rm -rf'"""