From 686d24f08f16f5dddba9792f001157402df8cb3a Mon Sep 17 00:00:00 2001
From: Michael Hanselmann <hansmi@google.com>
Date: Thu, 22 Nov 2012 18:37:15 +0100
Subject: [PATCH] Support opportunistic locks in mcpu/LUs
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Similar to β€œshare_locks”, a new dictionary containing booleans for each
locking level is added to β€œcmdlib.LogicalUnit”. Logical units wanting to
make use of opportunistic locks will be able to configure this
dictionary accordingly.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>
---
 lib/cmdlib.py |  7 ++++++-
 lib/mcpu.py   | 12 ++++++++----
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/lib/cmdlib.py b/lib/cmdlib.py
index b62732545..0d4b3df6e 100644
--- a/lib/cmdlib.py
+++ b/lib/cmdlib.py
@@ -138,13 +138,18 @@ class LogicalUnit(object):
     self.owned_locks = context.glm.list_owned
     self.context = context
     self.rpc = rpc_runner
-    # Dicts used to declare locking needs to mcpu
+
+    # Dictionaries used to declare locking needs to mcpu
     self.needed_locks = None
     self.share_locks = dict.fromkeys(locking.LEVELS, 0)
+    self.opportunistic_locks = dict.fromkeys(locking.LEVELS, False)
+
     self.add_locks = {}
     self.remove_locks = {}
+
     # Used to force good behavior when calling helper functions
     self.recalculate_locks = {}
+
     # logging
     self.Log = processor.Log # pylint: disable=C0103
     self.LogWarning = processor.LogWarning # pylint: disable=C0103
diff --git a/lib/mcpu.py b/lib/mcpu.py
index f737f7e14..8f4946932 100644
--- a/lib/mcpu.py
+++ b/lib/mcpu.py
@@ -275,7 +275,7 @@ class Processor(object):
     if not self._enable_locks:
       raise errors.ProgrammerError("Attempted to use disabled locks")
 
-  def _AcquireLocks(self, level, names, shared, timeout):
+  def _AcquireLocks(self, level, names, shared, opportunistic, timeout):
     """Acquires locks via the Ganeti lock manager.
 
     @type level: int
@@ -284,6 +284,8 @@ class Processor(object):
     @param names: Lock names
     @type shared: bool
     @param shared: Whether the locks should be acquired in shared mode
+    @type opportunistic: bool
+    @param opportunistic: Whether to acquire opportunistically
     @type timeout: None or float
     @param timeout: Timeout for acquiring the locks
     @raise LockAcquireTimeout: In case locks couldn't be acquired in specified
@@ -298,7 +300,8 @@ class Processor(object):
       priority = None
 
     acquired = self.context.glm.acquire(level, names, shared=shared,
-                                        timeout=timeout, priority=priority)
+                                        timeout=timeout, priority=priority,
+                                        opportunistic=opportunistic)
 
     if acquired is None:
       raise LockAcquireTimeout()
@@ -384,6 +387,7 @@ class Processor(object):
 
       lu.DeclareLocks(level)
       share = lu.share_locks[level]
+      opportunistic = lu.opportunistic_locks[level]
 
       try:
         assert adding_locks ^ acquiring_locks, \
@@ -393,7 +397,7 @@ class Processor(object):
           # Acquiring locks
           needed_locks = lu.needed_locks[level]
 
-          self._AcquireLocks(level, needed_locks, share,
+          self._AcquireLocks(level, needed_locks, share, opportunistic,
                              calc_timeout())
         else:
           # Adding locks
@@ -457,7 +461,7 @@ class Processor(object):
         # and in a shared fashion otherwise (to prevent concurrent run with
         # an exclusive LU.
         self._AcquireLocks(locking.LEVEL_CLUSTER, locking.BGL,
-                            not lu_class.REQ_BGL, calc_timeout())
+                            not lu_class.REQ_BGL, False, calc_timeout())
       elif lu_class.REQ_BGL:
         raise errors.ProgrammerError("Opcode '%s' requires BGL, but locks are"
                                      " disabled" % op.OP_ID)
-- 
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