Generic bi-directional map, and related initialisation functions. At the moment

a single map is used to store mappings between sharing handles and disk blocks.
This is used to share pages which store data read of the same blocks on
(virtual) disk.
Note that the map is stored in a shared memory region, as it needs to be
accessed by multiple tapdisk processes. This complicates memory allocation
(malloc cannot be used), prevents poniters to be stored directly (as the shared
memory region might and is mapped at different base address) and finally pthread
locks need to be multi-process aware.

Signed-off-by: Grzegorz Milos <Grzegorz.Milos@citrix.com>

1 files changed, 113 insertions, 0 deletions

diff --git a/tools/memshr/bidir-hash.h b/tools/memshr/bidir-hash.h
new file mode 100644
index 0000000000..ed9ec58ff4
--- /dev/null
+++ b/tools/memshr/bidir-hash.h
@@ -0,0 +1,113 @@
+/******************************************************************************
+ *
+ * Copyright (c) 2009 Citrix (R&D) Inc. (Grzegorz Milos)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#ifndef __BIDIR_HASH_H__
+#define __BIDIR_HASH_H__
+
+#include <stdint.h>
+#include "memshr-priv.h"
+
+typedef struct vbdblk {
+    uint64_t sec;
+    uint16_t disk_id;
+} vbdblk_t;
+
+
+#if defined FINGERPRINT_MAP || BLOCK_MAP 
+#define DEFINE_SINGLE_MAP 
+#endif
+
+/*******************************************************/
+/* Fingerprint map                                     */
+/*******************************************************/
+#if defined FINGERPRINT_MAP || !defined DEFINE_SINGLE_MAP
+
+#undef BIDIR_NAME_PREFIX
+#undef BIDIR_KEY
+#undef BIDIR_VALUE
+#undef BIDIR_KEY_T
+#undef BIDIR_VALUE_T
+static uint32_t fgprtshr_fgprt_hash(uint32_t h)
+{
+    return h;
+}
+
+static uint32_t fgprtshr_mfn_hash(uint64_t m)
+{
+    return (uint32_t)m;
+}
+
+static int fgprtshr_fgprt_cmp(uint32_t h1, uint32_t h2)
+{
+    return (h1 == h2);
+}
+
+static int fgprtshr_mfn_cmp(uint32_t m1, uint32_t m2)
+{
+    return (m1 == m2);
+}
+#define BIDIR_NAME_PREFIX       fgprtshr 
+#define BIDIR_KEY               fgprt 
+#define BIDIR_VALUE             mfn 
+#define BIDIR_KEY_T             uint32_t
+#define BIDIR_VALUE_T           xen_mfn_t
+#include "bidir-namedefs.h"
+
+#endif /* FINGERPRINT_MAP */
+
+
+/*******************************************************/
+/* Block<->Memory sharing handles                      */
+/*******************************************************/
+#if defined BLOCK_MAP || !defined DEFINE_SINGLE_MAP
+
+#undef BIDIR_NAME_PREFIX
+#undef BIDIR_KEY
+#undef BIDIR_VALUE
+#undef BIDIR_KEY_T
+#undef BIDIR_VALUE_T
+/* TODO better hashes! */
+static inline uint32_t blockshr_block_hash(vbdblk_t block)
+{
+    return (uint32_t)(block.sec) ^ (uint32_t)(block.disk_id);
+}
+
+static inline uint32_t blockshr_shrhnd_hash(uint64_t shrhnd)
+{
+    return (uint32_t)shrhnd;
+}
+
+static inline int blockshr_block_cmp(vbdblk_t b1, vbdblk_t b2)
+{
+    return (b1.sec == b2.sec) && (b1.disk_id == b2.disk_id);
+}
+
+static inline int blockshr_shrhnd_cmp(uint64_t h1, uint64_t h2)
+{
+    return (h1 == h2);
+}
+#define BIDIR_NAME_PREFIX       blockshr
+#define BIDIR_KEY               block
+#define BIDIR_VALUE             shrhnd
+#define BIDIR_KEY_T             vbdblk_t
+#define BIDIR_VALUE_T           uint64_t
+#include "bidir-namedefs.h"
+
+#endif /* BLOCK_MAP */
+
+#endif /* __BIDIR_HASH_H__ */