transaction: Change id allocator method to be 'circular'
The idea is to find the highest used id and try to get the
next. This way when there are transactions back to back with
an overlap, we go 0 1 2 3 4 5 6 0 1 2 ...
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/openbsc/src/transaction.c b/openbsc/src/transaction.c
index e49f75b..c972037 100644
--- a/openbsc/src/transaction.c
+++ b/openbsc/src/transaction.c
@@ -119,7 +119,7 @@
struct gsm_network *net = subscr->net;
struct gsm_trans *trans;
unsigned int used_tid_bitmask = 0;
- int i;
+ int i, j, h;
if (ti_flag)
ti_flag = 0x8;
@@ -133,9 +133,14 @@
used_tid_bitmask |= (1 << trans->transaction_id);
}
+ /* find a new one, trying to go in a 'circular' pattern */
+ for (h = 6; h > 0; h--)
+ if (used_tid_bitmask & (1 << (h | ti_flag)))
+ break;
for (i = 0; i < 7; i++) {
- if ((used_tid_bitmask & (1 << (i | ti_flag))) == 0)
- return i | ti_flag;
+ j = ((h + i) % 7) | ti_flag;
+ if ((used_tid_bitmask & (1 << j)) == 0)
+ return j;
}
return -1;