This function was not used anymore after the atomic updates were implemented in 2.3, and it must not be used given that it does not yield and can easily make the process hang for tens of seconds on large acls/maps. Let's remove it before someone uses it as an example to implement something else!
Instead of being able to purge only values older than a specific value, let's support arbitrary ranges and make pat_ref_purge_older() just be one special case of this one.
Interestingly, all arrays used to declare patterns were read-write while only hard-coded. Let's mark them const so that they move from data to rodata and don't risk to experience false sharing.
Currently our atomic ops return a value but it's never known whether the fetch is done before or after the operation, which causes some confusion each time the value is desired. Let's create an explicit variant of these operations suffixed with _FETCH to explicitly mention that the fetch occurs after the operation, and make use of it at the few call places.
The functions needed to commit a pattern file generation number or increase it were still missing. Better not have the caller play with these.
It's about the third time I get confused by these functions, half of which manipulate the reference as a whole and those manipulating only an entry. For me "pat_ref_commit" means committing the pattern reference, not just an element, so let's rename it. A number of other ones should really be renamed before 2.4 gets released :-/
This is 13n iteration of typo fixes
This function will be usable to purge at most a specified number of old entries from a reference. Entries are declared old if their generation number is in the past compared to the one passed in argument. This will ease removal of early entries when new ones have been appended. We also call malloc_trim() when available, at the end of the series, because this is one place where there is a lot of memory to save. Reloads of 1M IP addresses used in an ACL made the process grow up to 1.7 GB RSS after 10 reloads and roughly stabilize there without this call, versus only 260 MB when the call is present. Sadly there is no direct equivalent for jemalloc, which stabilizes around 800MB-1GB.
pat_ref_load() basically combines pat_ref_append() and pat_ref_commit(). It's very similar to pat_ref_add() except that it also allows to set the generation ID and the line number. pat_ref_add() was modified to directly rely on it to avoid code duplication. Note that a previous declaration of pat_ref_load() was removed as it was just a leftover of an earlier incarnation of something possibly similar, so no existing functionality was changed here.