Pb with module initialization

Vladimir Shebordaev vshebordaev at mail.ru
Fri Aug 17 14:00:04 UTC 2012

2012/8/17 Vladimir Shebordaev <vshebordaev at mail.ru>:
> 2012/8/17 MAGNIEN, Thierry <thierry.magnien at sfr.com>:
>>>>> A shared memory zone has a constructor, namely, init() method in
>>>>> ngx_shm_zone_t. This method is invoked by ngx_init_cycle() when the
>>>>> configuration is already processed and the shared memory zones are
>>>>> about to be (re)initialized, so I guess you can accees both your
>>>>> directives and the actual shm zone data from there. See file cache
>>>>> initialization routine ngx_http_file_cache_init() in
>>>>> src/http/ngx_http_file_cache.c for an example.
>>>> Well, I have such an init method but its arguments are only (ngx_shm_zone_t *shm_zone, void *data). I suppose I must use ngx_get_conf but what arguments should I give to it ?
> By the way, when the shm zone constructor is invoked by
> ngx_init_cycle() it gets the value of the data field of the shm zone
> descriptor from the old cycle as the second argument. NULL is passed
> there when the zone is initialized for the first time right after it
> is created anew.

Well, I rather mean that the shm zone is a global object
which live cicle is controlled by the server core, so the zone
contructor is the only proper place to manage the initialization. The
module init_process() and init_thread() methods are to solve other
tasks when the new worker process or thread is (re)spawned, those
events should not normally affect shared memory state, it is inherited
from the parent master process and is already mapped to the process
address space.

>>>You can access your module main configuration with
>>>ngx_http_cycle_get_module_main_conf()  through the global ngx_cycle
>>>that has the module contexts already set up by the shm initialization
>>>time. You can also access the configuration from the module
>>>init_process() method that is explicitly given the cycle. Either way,
>>>you can pass any parameters you need to the shm zone constructor
>>>through the zone data field that is to be installed right after the
>>>shm zone is added  at the module configuration time.
>> Just found out this, our messages crossed each other ;-)
>> Thanks for your help, however.

Thanks for your question :)

>> Regards,
>> Thierry

More information about the nginx-devel mailing list