1 package user_lock is
2
3 -- DESCRIPTION
4 -- These routines allow the user to request, convert and release locks.
5 -- The locks are managed by the rdbms lock management services. All
6 -- lock ids are prepended with the 'UL' prefix so that they cannot
7 -- conflict with DBMS locks. A sleep procedure is also provided which
8 -- causes the caller to sleep for the given interval (expressed in
9 -- tens of milliseconds.
10 --
11 -- NOTES
12 -- It is up to the clients to agree on the use of these locks. The lock
13 -- identifier is a number in the range of 1 to approx. 2 billion.
14 -- Locks persist for the session and any outstanding locks are released
15 -- when the session terminates.
16
17 function request(id number, lockmode number, timeout number, global number)
18 return number;
19 -- Returns:
20 -- 0 success
21 -- 1 timeout
22 -- 2 deadlock
23 -- 3 parameter error
24
25 function convert(id number, lockmode number, timeout number) return number;
26 -- Returns:
27 -- 0 success
28 -- 1 timeout
29 -- 2 deadlock
30 -- 3 parameter error
31 -- 4 don't own lock 'id'
32
33 function release(id number) return number;
34 -- Returns:
35 -- 0 success
36 -- 4 don't own lock 'id'
37
38 procedure sleep(tens_of_millisecs number);
39
40 -- PARAMETERS:
41
42 -- lockid - this can be in the range of 0 to about 2 billion
43
44 -- lockmodes
45 nl_mode constant number := 1;
46 ss_mode constant number := 2;
47 sx_mode constant number := 3;
48 s_mode constant number := 4;
49 ssx_mode constant number := 5;
50 x_mode constant number := 6;
51
52 -- LOCK COMPATIBILITY RULES:
53 --
54 -- When another process holds "held", an attempt to get "get" does
55 -- the following:
56 --
57 -- held get-> NL SS SX S SSX X
58 -- NL SUCC SUCC SUCC SUCC SUCC SUCC
59 -- SS SUCC SUCC SUCC SUCC SUCC fail
60 -- SX SUCC SUCC SUCC fail fail fail
61 -- S SUCC SUCC fail SUCC fail fail
62 -- SSX SUCC SUCC fail fail fail fail
63 -- X SUCC fail fail fail fail fail
64
65 -- global means multi-instance (parallel server)
66 local constant number := 0;
67 global constant number := 1;
68
69 -- maxwait means wait forever
70 maxwait constant number := 32767;
71 end;
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