From 5a00790518773385e681e6430a4f85245fae957d Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Wed, 18 Mar 2015 12:25:26 +0100
Subject: ipc: replace reverse hash table with a radix tree

Currently, there is a hash table mapping (space, object) tuples to
`ipc_entry' objects.  This hash table is intertwined with the IPC
tables.  There is one hash table per IPC space, but it is only for the
entries in the IPC table.  This hash table is called `local' in the
source.  All IPC entries being spilled into the splay tree are instead
mapped by a global hash table.

Replace the local (i.e. per IPC space) reverse hash table with a radix
tree.

* ipc/ipc_entry.c (ipc_entry_grow_table): Adjust accordingly.
* ipc/ipc_entry.h (struct ipc_entry): Adjust comment.
* ipc/ipc_hash.c: Adjust comment explaining the local lookup table.
(IPC_LOCAL_HASH_INVARIANT): New macro.
(ipc_hash_local_lookup): Use the new `ipc_reverse_lookup' function.
(ipc_hash_local_insert): Use the new `ipc_reverse_insert' function.
(ipc_hash_local_delete): Use the new `ipc_reverse_remove' function.
* ipc/ipc_space.c (ipc_space_create): Initialize radix tree.
(ipc_space_destroy): Free radix tree.
* ipc/ipc_space.h (struct ipc_space): Add radix tree.
(ipc_reverse_insert): New function.
(ipc_reverse_remove): Likewise.
(ipc_reverse_remove_all): Likewise.
(ipc_reverse_lookup): Likewise.
* ipc/ipc_right.c (ipc_right_clean): Update comment.
---
 ipc/ipc_right.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'ipc/ipc_right.c')

diff --git a/ipc/ipc_right.c b/ipc/ipc_right.c
index 503eb1fc..35061c9a 100644
--- a/ipc/ipc_right.c
+++ b/ipc/ipc_right.c
@@ -423,7 +423,7 @@ ipc_right_check(
  *	Purpose:
  *		Cleans up an entry in a dead space.
  *		The entry isn't deallocated or removed
- *		from reverse hash tables.
+ *		from the reverse mappings.
  *	Conditions:
  *		The space is dead and unlocked.
  */
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