[pypy-commit] stmgc default: add another test that passes, not sure why

[Raemi]

Author: Remi Meier <remi.meier at gmail.com>
Branch: 
Changeset: r422:1e4740b610b6
Date: 2013-07-19 12:44 +0200
http://bitbucket.org/pypy/stmgc/changeset/1e4740b610b6/

Log:	add another test that passes, not sure why

diff --git a/c4/test/test_nursery.py b/c4/test/test_nursery.py
--- a/c4/test/test_nursery.py
+++ b/c4/test/test_nursery.py
@@ -235,6 +235,47 @@
     check_not_free(p2)
     assert classify(p2) == "private"
 
+def test_old_private_from_protected_to_young_private_3():
+    p0 = palloc_refs(1)
+    pw = lib.stm_write_barrier(p0)
+    lib.stm_commit_transaction()
+    lib.stm_begin_inevitable_transaction()
+    pr = lib.stm_read_barrier(p0)
+    assert classify(pr) == "protected"
+    assert lib.in_nursery(pr) # a young protected
+    #
+    minor_collect()
+    pr = lib.stm_read_barrier(p0)
+    pw = lib.stm_write_barrier(pr)
+    lib.setptr(pw, 0, ffi.NULL)
+    assert classify(pw) == "private_from_protected"
+    assert not lib.in_nursery(pw)
+    #
+    # Because it was protected young before, it has no WRITE_BARRIER
+    # flag. After transforming it to a PRIV_FROM_PROT, the following
+    # holds:
+    # its h_revision is a pointer to the backup copy, and not 
+    # stm_private_rev_num.  It means that the write barrier will
+    # always enter its slow path, even though the GCFLAG_WRITE_BARRIER 
+    # is not set.
+    assert pw.h_revision != lib.get_private_rev_num()
+    assert not (pw.h_tid & GCFLAG_WRITE_BARRIER)
+    # #
+    lib.stm_push_root(pw)
+    minor_collect()
+    p1 = nalloc(HDR)
+    pw = lib.stm_pop_root()
+    lib.setptr(pw, 0, p1)          # should trigger the write barrier again
+    assert classify(pr) == "private_from_protected"
+    minor_collect()
+    check_nursery_free(p1)
+    pr = lib.stm_read_barrier(p0)
+    assert classify(pr) == "private_from_protected"
+    p2 = lib.getptr(pr, 0)
+    assert not lib.in_nursery(p2)
+    check_not_free(p2)
+    assert classify(p2) == "private"
+
 def test_new_version():
     p1 = oalloc(HDR)
     assert lib.stm_write_barrier(p1) == p1