CRE Programmer's Guide

CRE Service Functions
Common Run-Time Environment (CRE) Programmer’s Guide—528146-004
6-34
CRE_Receive_Open_Close_
Specifying Maximum^requesters:
•
Maximum^requesters specifies the maximum number of opens from other
processes that your process can manage at any point in time. The CRE returns
error 12, “file in use,” if it receives an open request that would exceed the number
you specify in the
Maximum^requesters field.
Specifying
Maximum^syncdepth:
•
Maximum^syncdepth specifies the maximum number of replies that the CRE
holds for each requester in case the requester’s backup process becomes the
primary process and begins executing the instructions that appear immediately
after the previous CHECKPOINT. The value you specify for
Maximum^syncdepth
is application dependent. In general,
Maximum^syncdepth specifies the
maximum number of messages that any requester can send to your process
before the requester calls a checkpoint system procedure such as CHECKPOINT,
Figure 6-4. Structure Allocation to Support Requesters Running as Process
Pairs
loop: ...
WRITE to server
...
WRITE to server
...
WRITE to server
...
WRITE to server
CHECKPOINT
GO TO loop
loop: ...
WRITE to server
...
WRITE to server
...
WRITE to server
...
WRITE to server
CHECKPOINT
GO TO loop
loop: ...
WRITE to server
...
WRITE to server
...
WRITE to server
...
WRITE to server
CHECKPOINT
GO TO loop
Requesters
Requester A Requester B Requester C
Server
Maximum^reply = 24
Receive^depth = 8
Maximum^syncdepth = 4
Maximum requesters = 3
Maximum
requesters
= 3
Reply 1 Reply 1 Reply 1
Reply 2 Reply 2 Reply 2
Reply 3 Reply 3 Reply 3
Reply 4 Reply 4 Reply 4
1
2
3
4
24
bytes
24
bytes
24
bytes
(Maximum^reply)
Requester 1
Replies
(Maximum^reply)
Requester 2
Replies
(Maximum^reply)
Requester 3
Replies
Receive
depth
= 8
Received Message 1
Received Message 2
Received Message 3
Received Message 4
Received Message 5
Received Message 6
Received Message 7
Received Message 8
1
2
3
4
5
6
7
8
Received Message Table
604VST .VSD