revlog: generate trivial deltas against null revision
To avoid extra memory usage and performance issues with large files,
generate a trivial delta header for deltas against the null revision
rather than calling the usual delta generator.
We append the delta header to meta rather than prepending it to data
to avoid a large allocate and copy.
#!/usr/bin/env python
import sys, os
from mercurial import revlog, transaction, node, util
f = sys.argv[1]
r1 = revlog.revlog(util.opener(os.getcwd(), audit=False), f + ".i", f + ".d")
r2 = revlog.revlog(util.opener(os.getcwd(), audit=False), f + ".i2", f + ".d2")
tr = transaction.transaction(sys.stderr.write, open, "journal")
for i in xrange(r1.count()):
n = r1.node(i)
p1, p2 = r1.parents(n)
l = r1.linkrev(n)
t = r1.revision(n)
n2 = r2.addrevision(t, tr, l, p1, p2)
tr.close()
os.rename(f + ".i", f + ".i.old")
os.rename(f + ".d", f + ".d.old")
os.rename(f + ".i2", f + ".i")
os.rename(f + ".d2", f + ".d")