Re: [PATCH 3/6] gdbsupport: use dynamic partitioning in gdb::parallel_for_each

[Simon Marchi <simark@simark.ca>]

On 6/13/25 3:22 PM, Simon Marchi wrote:
> Another idea I had (but didn't try) was to make lambdas receive a
> "magic" range object, like athis:
> 
>   [&] (gdb::dynamic_range<dwarf2_per_cu *> range)
>     {
>       for (dwarf2_per_cu *cu : range)
>         process_unit (cu);
>     }
> 
> "range" would get work items from the work queue in batches, but yield
> one at a time.  It would reach its end when the work queue is empty.
> It will be a bit of work to implement, but it would have the advantage
> that any per-worker state could be right there in the lambda, like we
> have today.

Ah, I remembered why I didn't do this.  It wouldn't play well with how
minimal_symbol_reader::install() currently uses gdb::parallel_for_each.
Currently, it receives one contiguous range [start,end).  After having
computed the demangled names and hashes for the whole range, each worker
locks a mutex and installs the names in a shared hash table.

In my patch, it's similar, but each worker installs the names in the
share hash table at the end of each small range it receives.

With my "magic" iterator idea, it wouldn't be clear when and how to
install the names in the shared hash table.

Simon