[OE-core] [PATCH 3/6] sstate: Ensure a given machine only removes things which it created

[Richard Purdie]

Currently if you build qemux86 and then generic86, the latter will
remove all of the former from deploy and workdir. This is because
qemux86 is i586, genericx86 is i686 and the architctures are compatible
therefore the sstate 'cleaup' code kicks in.

There was a valid reason for this to ensure i586 packages didn't get into
an i686 rootfs for example. With the rootfs creation being filtered now, this
is no longer necessary.

Instead, save out a list of stamps which a give machine has ever seen in
a given build and only clean up these things if they're no longer
"reachable".

In particular this means the autobuilder should no longer spend a load of time
deleting files when switching MACHINE, improving build times.

Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
---
 meta/classes/sstate.bbclass | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/meta/classes/sstate.bbclass b/meta/classes/sstate.bbclass
index 9927c76596e..a091c6e843e 100644
--- a/meta/classes/sstate.bbclass
+++ b/meta/classes/sstate.bbclass
@@ -1045,6 +1045,15 @@ python sstate_eventhandler2() {
         with open(preservestampfile, 'r') as f:
             preservestamps = f.readlines()
     seen = []
+
+    # The machine index contains all the stamps this machine has ever seen in this build directory.
+    # We should only remove things which this machine once accessed but no longer does.
+    machineindex = set()
+    mi = d.expand("${SSTATE_MANIFESTS}/index-machine-${MACHINE}")
+    if os.path.exists(mi):
+        with open(mi, "r") as f:
+            machineindex = set(f.readlines())
+
     for a in sorted(list(set(d.getVar("SSTATE_ARCHS").split()))):
         toremove = []
         i = d.expand("${SSTATE_MANIFESTS}/index-" + a)
@@ -1054,7 +1063,7 @@ python sstate_eventhandler2() {
             lines = f.readlines()
             for l in lines:
                 (stamp, manifest, workdir) = l.split()
-                if stamp not in stamps and stamp not in preservestamps:
+                if stamp not in stamps and stamp not in preservestamps and stamp in machineindex:
                     toremove.append(l)
                     if stamp not in seen:
                         bb.debug(2, "Stamp %s is not reachable, removing related manifests" % stamp)
@@ -1083,6 +1092,11 @@ python sstate_eventhandler2() {
         with open(i, "w") as f:
             for l in lines:
                 f.write(l)
+    machineindex |= set(stamps)
+    with open(mi, "w") as f:
+        for l in machineindex:
+            f.write(l + "\n")
+
     if preservestamps:
         os.remove(preservestampfile)
 }
-- 
2.17.1