From 5a7beb0db0cc0530e8808f1703e633852e7b2529 Mon Sep 17 00:00:00 2001
From: Ting-Yu Lin <tlin@mozilla.com>
Date: Fri, 8 Aug 2014 03:06:00 -0400
Subject: [PATCH] Bug 1049263 - Do not report ccache stats unless ccache was
 used. r=glandium

---
 python/mozbuild/mozbuild/controller/building.py   |  6 ++++++
 python/mozbuild/mozbuild/mach_commands.py         |  5 +++--
 .../mozbuild/test/controller/test_ccachestats.py  | 15 +++++++++++++++
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/python/mozbuild/mozbuild/controller/building.py b/python/mozbuild/mozbuild/controller/building.py
index 78ff61ec5f84..c3294e86f611 100644
--- a/python/mozbuild/mozbuild/controller/building.py
+++ b/python/mozbuild/mozbuild/controller/building.py
@@ -611,6 +611,12 @@ class CCacheStats(object):
 
         return '\n'.join(lines)
 
+    def __nonzero__(self):
+        relative_values = [v for k, v in self._values.items()
+                           if k not in self.ABSOLUTE_KEYS]
+        return (all(v >= 0 for v in relative_values) and
+                any(v > 0 for v in relative_values))
+
     @staticmethod
     def _format_value(v):
         if v > CCacheStats.GiB:
diff --git a/python/mozbuild/mozbuild/mach_commands.py b/python/mozbuild/mozbuild/mach_commands.py
index b43c4326b6e7..2a498ded8a3c 100644
--- a/python/mozbuild/mozbuild/mach_commands.py
+++ b/python/mozbuild/mozbuild/mach_commands.py
@@ -397,8 +397,9 @@ class Build(MachCommandBase):
 
         if ccache_start and ccache_end:
             ccache_diff = ccache_end - ccache_start
-            self.log(logging.INFO, 'ccache',
-                     {'msg': ccache_diff.hit_rate_message()}, "{msg}")
+            if ccache_diff:
+                self.log(logging.INFO, 'ccache',
+                         {'msg': ccache_diff.hit_rate_message()}, "{msg}")
 
         if monitor.elapsed > 300:
             # Display a notification when the build completes.
diff --git a/python/mozbuild/mozbuild/test/controller/test_ccachestats.py b/python/mozbuild/mozbuild/test/controller/test_ccachestats.py
index bb430d12dc75..6678977304f2 100644
--- a/python/mozbuild/mozbuild/test/controller/test_ccachestats.py
+++ b/python/mozbuild/mozbuild/test/controller/test_ccachestats.py
@@ -73,6 +73,21 @@ class TestCcacheStats(unittest.TestCase):
         stats_diff = stats2 - stats1
         self.assertEqual(stats_diff.hit_rates(), (0.9, 0.05, 0.05))
 
+    def test_stats_contains_data(self):
+        stats0 = CCacheStats(self.STAT0)
+        stats1 = CCacheStats(self.STAT1)
+        stats2 = CCacheStats(self.STAT2)
+        stats_diff_zero = stats1 - stats1
+        stats_diff_negative1 = stats0 - stats1
+        stats_diff_negative2 = stats1 - stats2
+
+        self.assertFalse(stats0)
+        self.assertTrue(stats1)
+        self.assertTrue(stats2)
+        self.assertFalse(stats_diff_zero)
+        self.assertFalse(stats_diff_negative1)
+        self.assertFalse(stats_diff_negative2)
+
 
 if __name__ == '__main__':
     main()