standalone-generate-dump-flight-runvars: memoise ap-fetch

This makes it _much_ faster.

Also you can say AP_FETCH_MEMO_KEEP=1 to make it reuse old
information, which is useful for making comparisons.

For a further speed improvement, one can use `eatmydata'.  This is not
the default because it risks corruption of `standalone.db' which is
used for other purposes too.  Add a comment about possibly improving
this.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/standalone-generate-dump-flight-runvars b/standalone-generate-dump-flight-runvars
index 440572044b947d508a15b8e7576086be31cb7af0..ed947925fcd5304c614d1a72c1b30b4971eb5e59 100755 (executable)
--- a/standalone-generate-dump-flight-runvars
+++ b/standalone-generate-dump-flight-runvars
@@ -36,6 +36,17 @@ if [ $# = 0 ]; then
    set `./mg-list-all-branches`
 fi
 
+if [ "x$AP_FETCH_MEMO_KEEP" = x ]; then
+       rm -rf tmp/apmemo
+       mkdir tmp/apmemo
+fi
+export AP_FETCH_PFX='./memoise tmp/apmemo'
+
+# In the future it might be nice for this script to arrange to use a
+# separate standalone.db, in tmp/ probably, for each different branch.
+# That would avoid a lot of needless write contention over the single
+# db, and make it possible to use `eatmydata' if it is installed.
+
 perbranch () {
     log=tmp/make-flight.$branch.log
     flight=check_${branch//[-._]/_}