[OE-core] [PATCH V2 1/2] sstate.bbclass: Only remove sstate file when task is existed

[Robert Yang]

This can improve the performance a lot for "bitbake <recipe-native/cross/crosssdk>
-ccleansstate" when there are a lot of sstate files.

For example:
* Before
  $ bitbake quilt-native -ccleansstate
  - Check log.do_cleansstate:
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package_qa.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package_write_rpm.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_packagedata.tgz*
  Removing /sstate-cache/*/sstate:quilt-native::0.65:r0::3:*_populate_lic.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_populate_sysroot.tgz*

  There are no package tasks for quilt-native, so the first 4 lines doesn't
  make any sense, but the glob pattern "sstate-cache/*/*" is very time
  consuming when there are no disk caches. E.g., I have more than 600,000
  sstate files:
  - Without disk caches
  # echo 3 >/proc/sys/vm/drop_caches
  $ time python3 -c 'import glob; glob.glob("/sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package.tgz*")'
    real    4m32.583s
    user    0m5.768s
    sys     0m12.892s

  - With disk caches (e.g., run it in the second time)
  $ time python3 -c 'import glob; glob.glob("/sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package.tgz*")'
    real    0m5.128s
    user    0m2.772s
    sys     0m2.308s

  So the 4 removing *package* commands cost more than 20s or 272s in theory.

* After
  $ bitbake quilt-native -ccleansstate
  - Check log.do_cleansstate:
  Removing /sstate-cache/*/sstate:quilt-native::0.65:r0::3:*_populate_lic.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_populate_sysroot.tgz*

  We can see that it saved 20s or 272s in theory.

Signed-off-by: Robert Yang <liezhi.yang at windriver.com>
---
 meta/classes/sstate.bbclass | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/meta/classes/sstate.bbclass b/meta/classes/sstate.bbclass
index efb0096..9f059a0 100644
--- a/meta/classes/sstate.bbclass
+++ b/meta/classes/sstate.bbclass
@@ -423,8 +423,9 @@ def sstate_clean_cachefile(ss, d):
     import oe.path
 
     sstatepkgfile = d.getVar('SSTATE_PATHSPEC') + "*_" + ss['task'] + ".tgz*"
-    bb.note("Removing %s" % sstatepkgfile)
-    oe.path.remove(sstatepkgfile)
+    if d.getVarFlag('do_%s' % ss['task'], 'task'):
+        bb.note("Removing %s" % sstatepkgfile)
+        oe.path.remove(sstatepkgfile)
 
 def sstate_clean_cachefiles(d):
     for task in (d.getVar('SSTATETASKS') or "").split():
-- 
2.7.4