What is proper use of Apache method apr_pool_create_ex in Delphi XE?
What is proper use of Apache method apr_pool_create_ex in Delphi XE?
I’ve created Apache modules before, but all were Handlers. Now I’m working on developing a Service provider. A skeleton module has been c开发者_Go百科reated and my child_init call back method is being called by Apache. In the child_init method I call ap_pool_create_ex* successfully (returns APR_SUCCESS), but after leaving the child_it call, I receive an access violation either during the (httpd.exe) spawning of the third or the fourth worker thread (third is showing in the event log).
procedure provider_child_init(pchild: Papr_pool_t; s: Pserver_rec); cdecl;
var
rv : apr_status_t;
mypool : Papr_pool_t;
begin
rv := -1;
rv := apr_pool_create_ex(@mypool,pchild,nil,nil);
end;
The AV message is:
“Project C:\Apache2.2\bin\http.exe raised too many consecutive exceptions: ‘access violation at 0x00000000: read of address 0x00000000’. Process Stopped. Use Step or Run to continues”
Event Log:
…
Thread Start: Thread ID: 5652. Process httpd.exe (4212)
Thread Start: Thread ID: 5132. Process httpd.exe (4212)
Thread Start: Thread ID: 5988. Process httpd.exe (4212)
NOTE: The AV occurs in Thread ID 5988 and 4212 is the Parent httpd.exe process.
- The windows “libapr-1.dll” does not include “apr_pool_create”, that is why I’m using the “_ex” version. Any idea why apr_pool_create is missing? I see apr_pool_create being used in other successful modules although they are written in ‘C’.
OS: Windows 7 Enterprise 64-bit
Apache: 2.2.17.0
IDE: Delphi XE
Is your translation of the function correct? Delphi XE Version Insight (Subversion plugin) declares it as follows:
type
PAprPool = ^TAprPool;
TAprPool = THandle;
PAprAllocator = ^TAprAllocator;
TAprAllocator = THandle;
TAprAbortFunc = function(retcode: Integer): Integer; stdcall;
var
apr_pool_create_ex: function(out newpool: PAprPool; parent: PAprPool; abort_fn: TAprAbortFunc;
allocator: PAprAllocator): TAprStatus; stdcall;
Also check if your provider_child_init
callback should really be declared as cdecl
and not stdcall
.
Also, some ideas since you get a null pointer access violation. According to the apr source code comment:
- if (as in your case) you pass it a nil allocator the allocator of the parent pool will be used. I assume that in case the parent pool is nil the allocator must not be nil.
abort_fn
will be called back if the pool cannot allocate memory. You're passing it nil; perhaps the pool is trying to call it because it cannot allocate memory?- I don't think you can access the same pool from different threads. You probably have to create a separate pool for each thread.
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