From 3977a4c14b93ea833d9e0e1efb9bf2bede70b576 Mon Sep 17 00:00:00 2001
From: Guido Trotter <ultrotter@google.com>
Date: Wed, 30 Jul 2008 11:30:10 +0000
Subject: [PATCH] Make sharing locks possible
LUs can declare which locks they need by populating the
self.needed_locks dictionary, but those locks are always acquired as
exclusive. Make it possible to acquire shared locks as well, by
declaring a particular level as shared in the self.share_locks
dictionary. By default this dictionary is populated so that all locks
are acquired exclusively.
Reviewed-by: iustinp
---
lib/cmdlib.py | 5 +++++
lib/mcpu.py | 5 ++++-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/lib/cmdlib.py b/lib/cmdlib.py
index 4d172eefc..a6d759f07 100644
--- a/lib/cmdlib.py
+++ b/lib/cmdlib.py
@@ -83,6 +83,7 @@ class LogicalUnit(object):
self.sstore = sstore
self.context = context
self.needed_locks = None
+ self.share_locks = dict(((i, 0) for i in locking.LEVELS))
self.__ssh = None
for attr_name in self._OP_REQP:
@@ -128,6 +129,10 @@ class LogicalUnit(object):
(this reflects what LockSet does, and will be replaced before
CheckPrereq with the full list of nodes that have been locked)
+ If you need to share locks (rather than acquire them exclusively) at one
+ level you can modify self.share_locks, setting a true value (usually 1) for
+ that level. By default locks are not shared.
+
Examples:
# Acquire all nodes and one instance
self.needed_locks = {
diff --git a/lib/mcpu.py b/lib/mcpu.py
index 66f657d48..93dfaea9f 100644
--- a/lib/mcpu.py
+++ b/lib/mcpu.py
@@ -134,10 +134,13 @@ class Processor(object):
# This gives a chance to LUs to make last-minute changes after acquiring
# locks at any preceding level.
lu.DeclareLocks(level)
+ needed_locks = lu.needed_locks[level]
+ share = lu.share_locks[level]
# This is always safe to do, as we can't acquire more/less locks than
# what was requested.
lu.needed_locks[level] = self.context.glm.acquire(level,
- lu.needed_locks[level])
+ needed_locks,
+ shared=share)
try:
result = self._LockAndExecLU(lu, level + 1)
finally:
--
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