Re: [PATCH v2] Add string cache and use it in cooked index

[Simon Marchi <simark@simark.ca>]

On 3/10/25 3:38 PM, Tom Tromey wrote:
> The cooked index needs to allocate names in some cases -- when
> canonicalizing or when synthesizing Ada package names.  This process
> currently uses a vector of unique_ptrs to manage the memory.
> 
> Another series I'm writing adds another spot where this allocation
> must be done, and examining the result showed that certain names were
> allocated multiple times.
> 
> To clean this up, this patch introduces a string cache object and
> changes the cooked indexer to use it.  I considered using bcache here,
> but bcache doesn't work as nicely with string_view -- because bcache
> is fundamentally memory-based, a temporary copy of the contents must
> be made to ensure that bcache can see the trailing \0.  Furthermore,
> writing a custom class lets us avoid another copy when canonicalizing
> C++ names.

Thanks, LGTM.

Approved-By: Simon Marchi <simon.marchi@efficios.com>

I was thinking that maybe this woud actually be a good use case for an
obstack, since free'ing would probably be faster than freeing the
strings individually.  But we have cases where the caller passes a
unique_xmalloc_ptr, in two cases we'd need an extra copy into the
obstack.

Simon