[buildstream] 04/05: _platform/platform.py: Cache result from 'get_host_os'

[gi...@apache.org]

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github-bot pushed a commit to branch bschubert/optimize-element-init
in repository https://gitbox.apache.org/repos/asf/buildstream.git

commit 2f3a5033bfd124a2bf46ed6bc160e219742159c6
Author: Benjamin Schubert <co...@benschubert.me>
AuthorDate: Thu Oct 10 16:37:01 2019 +0100

    _platform/platform.py: Cache result from 'get_host_os'
    
    'get_host_os' is an expensive method and is called twice per element.
    Caching gives us some performance benefits.
---
 src/buildstream/_platform/platform.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/buildstream/_platform/platform.py b/src/buildstream/_platform/platform.py
index ca5fb75..02e8924 100644
--- a/src/buildstream/_platform/platform.py
+++ b/src/buildstream/_platform/platform.py
@@ -32,6 +32,7 @@ from .. import utils
 class Platform():
 
     _host_arch = None  # cache to not recompute the host arch every time
+    _host_os = None  # cache not to recompute the host os every time
 
     # Platform()
     #
@@ -122,9 +123,11 @@ class Platform():
         else:
             return min(cpu_count, cap)
 
-    @staticmethod
-    def get_host_os():
-        return platform.uname().system
+    @classmethod
+    def get_host_os(cls):
+        if cls._host_os is None:
+            cls._host_os = platform.uname().system
+        return cls._host_os
 
     # canonicalize_arch():
     #