[PATCH] sstate: Remove master manifest usage

[Richard Purdie <richard.purdie@linuxfoundation.org>]

This was added to allow detection of duplicate files being installed by sstate.
There is a much simpler way, just check if the file already exists. This
effectively uses the kernel VFS as the cache which is much more efficient.

This resolves a significant performance bottleneck (lock contention on a
single file) when running builds that are just being generated from sstate
cache files.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---
diff --git a/meta/classes/sstate.bbclass b/meta/classes/sstate.bbclass
index 0037ce5..6878e1a 100644
--- a/meta/classes/sstate.bbclass
+++ b/meta/classes/sstate.bbclass
@@ -3,7 +3,6 @@ SSTATE_VERSION = "2"
 SSTATE_MANIFESTS ?= "${TMPDIR}/sstate-control"
 SSTATE_MANFILEBASE = "${SSTATE_MANIFESTS}/manifest-${SSTATE_MANMACH}-"
 SSTATE_MANFILEPREFIX = "${SSTATE_MANFILEBASE}${PN}"
-SSTATE_MASTERMANIFEST = "${SSTATE_MANIFESTS}/master.list"
 
 def generate_sstatefn(spec, hash, d):
     if not hash:
@@ -142,17 +141,11 @@ def sstate_install(ss, d):
                     dstdir = dstdir + "/"
                 shareddirs.append(dstdir)
 
-    # Check the file list for conflicts against the master manifest
-    mastermanifest = d.getVar("SSTATE_MASTERMANIFEST", True)
+    # Check the file list for conflicts against files which already exist
     whitelist = (d.getVar("SSTATE_DUPWHITELIST", True) or "").split()
-    lock = bb.utils.lockfile(mastermanifest + ".lock")
-    if not os.path.exists(mastermanifest):
-        open(mastermanifest, "w").close()
-    fileslist = [line.strip() for line in open(mastermanifest)]
-    bb.utils.unlockfile(lock)
     match = []
     for f in sharedfiles:
-        if f in fileslist:
+        if os.path.exists(f):
             realmatch = True
             for w in whitelist:
                 if f.startswith(w):
@@ -163,14 +156,10 @@ def sstate_install(ss, d):
     if match:
         bb.warn("The recipe is trying to install files into a shared area when those files already exist. Those files are:\n   %s" % "\n   ".join(match))
 
-    # Write out the manifest and add to the task's manifest file
-    lock = bb.utils.lockfile(mastermanifest + ".lock")
-    mf = open(mastermanifest, "a")
+    # Write out the manifest
     f = open(manifest, "w")
     for file in sharedfiles:
-        mf.write(file + "\n")
         f.write(file + "\n")
-    bb.utils.unlockfile(lock)
 
     # We want to ensure that directories appear at the end of the manifest
     # so that when we test to see if they should be deleted any contents
@@ -301,20 +290,6 @@ def sstate_clean_manifest(manifest, d):
         except OSError:
             pass
 
-    # Remove the entries from the master manifest
-    mastermanifest = d.getVar("SSTATE_MASTERMANIFEST", True)
-    lock = bb.utils.lockfile(mastermanifest + ".lock")
-    if not os.path.exists(mastermanifest):
-        open(mastermanifest, "w").close()
-    mf = open(mastermanifest + ".new", "w")
-    for line in open(mastermanifest, "r"):
-        if not line or line in entries:
-            continue
-        mf.write(line)
-    mf.close()
-    os.rename(mastermanifest + ".new", mastermanifest)
-    bb.utils.unlockfile(lock)
-
     oe.path.remove(manifest)
 
 def sstate_clean(ss, d):