Author: Armin Rigo <[email protected]>
Branch: extradoc
Changeset: r4702:b632d307e4c1
Date: 2012-08-18 21:16 +0200
http://bitbucket.org/pypy/extradoc/changeset/b632d307e4c1/
Log: Update to do something sensible with non-written local objects at
commit time.
diff --git a/talk/stm2012/stmimpl.rst b/talk/stm2012/stmimpl.rst
--- a/talk/stm2012/stmimpl.rst
+++ b/talk/stm2012/stmimpl.rst
@@ -439,8 +439,12 @@
def AcquireLocks(cur_time):
new_revision = cur_time + 1 # make an odd number
for (R, L) in global_to_local:
+ L->h_global = True
+ if not L->h_written:
+ #L->h_revision already points to R
+ L->h_possibly_outdated = True
+ continue
L->h_revision = new_revision
- L->h_global = True
L->h_written = False
assert L->h_possibly_outdated == False
v = R->h_revision
@@ -450,7 +454,11 @@
AbortTransaction() # already locked by someone else
if not CMPXCHG(&R->h_revision, v, -1):
AbortTransaction() # just changed by someone else
- locks_to_cancel.add(R, v)
+ locks_acquired.add(R, L, v)
+
+(Note that for non-written local objects, we skip this locking entirely;
+instead, we turn the object into a "global but outdated" object, keeping
+the same ``h_revision`` but with a different meaning.)
We use CMPXCHG to store the lock. This is required, because we must
not conflict with another CPU that would try to write the same lock
@@ -469,7 +477,7 @@
def AcquireLocksAgain(cur_time):
new_revision = cur_time + 1
- for (R, L) in global_to_local:
+ for (R, L, v) in locks_acquired:
L->h_revision = new_revision
@@ -478,7 +486,7 @@
fields::
def AbortTransaction():
- for R, v in locks_to_cancel:
+ for R, L, v in locks_acquired:
R->h_revision = v
# call longjmp(), which is the function from C
# going back to the transaction start
@@ -491,5 +499,5 @@
the chained list by one::
def UpdateChainHeads():
- for (R, L) in global_to_local:
+ for (R, L, v) in locks_acquired:
R->h_version = L
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