svn commit: samba r14799 - in branches/SAMBA_4_0/source/lib/tdb:
common include
tridge at samba.org
tridge at samba.org
Thu Mar 30 04:52:39 GMT 2006
Author: tridge
Date: 2006-03-30 04:52:39 +0000 (Thu, 30 Mar 2006)
New Revision: 14799
WebSVN: http://websvn.samba.org/cgi-bin/viewcvs.cgi?view=rev&root=samba&rev=14799
Log:
added a tdb_get_seqnum() call, and the TDB_SEQNUM flag. This allows
for an extremely lightweight test to see if a tdb has possibly
changed.
Modified:
branches/SAMBA_4_0/source/lib/tdb/common/tdb.c
branches/SAMBA_4_0/source/lib/tdb/common/tdb_private.h
branches/SAMBA_4_0/source/lib/tdb/common/transaction.c
branches/SAMBA_4_0/source/lib/tdb/include/tdb.h
Changeset:
Modified: branches/SAMBA_4_0/source/lib/tdb/common/tdb.c
===================================================================
--- branches/SAMBA_4_0/source/lib/tdb/common/tdb.c 2006-03-30 04:39:37 UTC (rev 14798)
+++ branches/SAMBA_4_0/source/lib/tdb/common/tdb.c 2006-03-30 04:52:39 UTC (rev 14799)
@@ -30,6 +30,33 @@
TDB_DATA tdb_null;
+/*
+ increment the tdb sequence number if the tdb has been opened using
+ the TDB_SEQNUM flag
+*/
+static void tdb_increment_seqnum(struct tdb_context *tdb)
+{
+ tdb_off_t seqnum=0;
+
+ if (!(tdb->flags & TDB_SEQNUM)) {
+ return;
+ }
+
+ if (tdb_brlock(tdb, TDB_SEQNUM_OFS, F_WRLCK, F_SETLKW, 1) != 0) {
+ return;
+ }
+
+ /* we ignore errors from this, as we have no sane way of
+ dealing with them.
+ */
+ tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
+ seqnum++;
+ tdb_ofs_write(tdb, TDB_SEQNUM_OFS, &seqnum);
+
+ tdb_brlock(tdb, TDB_SEQNUM_OFS, F_UNLCK, F_SETLKW, 1);
+}
+
+
/* Returns 0 on fail. On success, return offset of record, and fills
in rec */
static tdb_off_t tdb_find(struct tdb_context *tdb, TDB_DATA key, u32 hash,
@@ -203,6 +230,11 @@
if (!(rec_ptr = tdb_find_lock_hash(tdb, key, hash, F_WRLCK, &rec)))
return -1;
ret = tdb_do_delete(tdb, rec_ptr, &rec);
+
+ if (ret == 0) {
+ tdb_increment_seqnum(tdb);
+ }
+
if (tdb_unlock(tdb, BUCKET(rec.full_hash), F_WRLCK) != 0)
TDB_LOG((tdb, 0, "tdb_delete: WARNING tdb_unlock failed!\n"));
return ret;
@@ -295,6 +327,9 @@
/* Need to tdb_unallocate() here */
goto fail;
}
+
+ tdb_increment_seqnum(tdb);
+
out:
SAFE_FREE(p);
tdb_unlock(tdb, BUCKET(hash), F_WRLCK);
@@ -369,3 +404,22 @@
{
return tdb->log_fn;
}
+
+
+/*
+ get the tdb sequence number. Only makes sense if the writers opened
+ with TDB_SEQNUM set. Note that this sequence number will wrap quite
+ quickly, so it should only be used for a 'has something changed'
+ test, not for code that relies on the count of the number of changes
+ made. If you want a counter then use a tdb record.
+
+ The aim of this sequence number is to allow for a very lightweight
+ test of a possible tdb change.
+*/
+int tdb_get_seqnum(struct tdb_context *tdb)
+{
+ tdb_off_t seqnum=0;
+
+ tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &seqnum);
+ return seqnum;
+}
Modified: branches/SAMBA_4_0/source/lib/tdb/common/tdb_private.h
===================================================================
--- branches/SAMBA_4_0/source/lib/tdb/common/tdb_private.h 2006-03-30 04:39:37 UTC (rev 14798)
+++ branches/SAMBA_4_0/source/lib/tdb/common/tdb_private.h 2006-03-30 04:52:39 UTC (rev 14799)
@@ -94,6 +94,7 @@
#define TDB_HASHTABLE_SIZE(tdb) ((tdb->header.hash_size+1)*sizeof(tdb_off_t))
#define TDB_DATA_START(hash_size) TDB_HASH_TOP(hash_size-1)
#define TDB_RECOVERY_HEAD offsetof(struct tdb_header, recovery_start)
+#define TDB_SEQNUM_OFS offsetof(struct tdb_header, sequence_number)
#define TDB_PAD_BYTE 0x42
#define TDB_PAD_U32 0x42424242
@@ -155,7 +156,8 @@
u32 hash_size; /* number of hash entries */
tdb_off_t rwlocks; /* obsolete - kept to detect old formats */
tdb_off_t recovery_start; /* offset of transaction recovery region */
- tdb_off_t reserved[30];
+ tdb_off_t sequence_number; /* used when TDB_SEQNUM is set */
+ tdb_off_t reserved[29];
};
struct tdb_lock_type {
Modified: branches/SAMBA_4_0/source/lib/tdb/common/transaction.c
===================================================================
--- branches/SAMBA_4_0/source/lib/tdb/common/transaction.c 2006-03-30 04:39:37 UTC (rev 14798)
+++ branches/SAMBA_4_0/source/lib/tdb/common/transaction.c 2006-03-30 04:52:39 UTC (rev 14799)
@@ -892,6 +892,12 @@
tdb_brlock_len(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
+ /*
+ TODO: maybe write to some dummy hdr field, or write to magic
+ offset without mmap, before the last sync, instead of the
+ utime() call
+ */
+
/* on some systems (like Linux 2.6.x) changes via mmap/msync
don't change the mtime of the file, this means the file may
not be backed up (as tdb rounding to block sizes means that
Modified: branches/SAMBA_4_0/source/lib/tdb/include/tdb.h
===================================================================
--- branches/SAMBA_4_0/source/lib/tdb/include/tdb.h 2006-03-30 04:39:37 UTC (rev 14798)
+++ branches/SAMBA_4_0/source/lib/tdb/include/tdb.h 2006-03-30 04:52:39 UTC (rev 14799)
@@ -46,6 +46,7 @@
#define TDB_CONVERT 16 /* convert endian (internal use) */
#define TDB_BIGENDIAN 32 /* header is big-endian (internal use) */
#define TDB_NOSYNC 64 /* don't use synchronous transactions */
+#define TDB_SEQNUM 128 /* maintain a sequence number */
#define TDB_ERRCODE(code, ret) ((tdb->ecode = (code)), ret)
@@ -109,6 +110,7 @@
int tdb_transaction_commit(struct tdb_context *tdb);
int tdb_transaction_cancel(struct tdb_context *tdb);
int tdb_transaction_recover(struct tdb_context *tdb);
+int tdb_get_seqnum(struct tdb_context *tdb);
/* Low level locking functions: use with care */
int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key);
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