Joe Orton wrote:
This stuff is a complete mess in APR. The name-based shmget method *does* use and create a real file, but it's redundant AFAICT; all it does is store the size of the segment, which shmctl will tell you anyway on.
An uncleanly shutdown httpd (kill -9 or pull the plug) will leave around both the shm segment *and* the file, and APR will give EEXIST when trying to create either, so you have this fun routine:
0. server reboots after power loss 1. start httpd: open(O_CREAT) => EEXIST 2. admin scratches head, removes file 3. start httpd: open(O_CREAT) => ok! shmget(IPC_CREAT) => EEXIST 4. admin scratches head, searches bugzilla, learns how to use ipcs/ipcrm 5. start httpd: open(O_CREAT) => EXIST 6. admin goes crazy
in the end using anonyous shm everywhere was easier than fixing all the FIXMEs in the shm code where it should have had real error handling, so I gave up with this stuff.
Ok - what I would like to do is put information on what needs to be done in the error message, so that when mod_ldap starts and the shared memory goes pear shaped, the admin is given exact instructions on what to do to fix it, this removing your step 4 above, and hopefully also step 6. [1]
Something like: "LDAP cache: shared memory segment could not be created due to problems with an unclean shutdown. Please run 'ipcrm -m XXXX' to fix this."
How would I get the XXXX part? Is this returned anywhere?
(This message would also be platform specific, a suitable message would need to be generated for Windows, or for other platforms that don't use ipc*).
[1] Remembers being such an admin referred to in step 6.
Regards, Graham --
