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#### Why do we need this new feature?
There are cases when a NIF needs to send a message, using `enif_send()`, to a long-lived process with a registered name.
A common use-case is logging, where asynchronous fire-and-forget messages are the norm.
There can also be cases where a yielding or dirty NIF or background thread may request a callback from a service with additional information it needs to complete its operation, yielding or waiting (with suitable timeouts, etc) until its state has been updated through the NIF module's API.
NIFs can only send messages to pids, and the lack of name resolution leaves a complicated dance between separate monitoring processes and the NIF as the only way to keep a NIF informed of the whereabouts of such long-lived processes.
Providing a reliable, built-in facility for NIFs to resolve process (or port) names simplifies these use cases considerably.
#### Risks or uncertain artifacts?
Testing has not exposed any significant risk.
The implementation behaves as expected on regular and dirty scheduler threads as well as non-scheduler threads.
By constraining the `enif_whereis_...()` functions to their minimal scopes and using patterns consistent with related functions, the implementation, testing, and maintenance burden is low.
The API and behavior of existing functions is unchanged.
#### How did you solve it?
While extending `enif_send()` to operate on a pid or an atom (as `erlang:send/2` does) was attractive, it would have entailed changing the type of its `to_pid` parameter and thereby breaking backward compatibility.
The same consideration applies to `enif_port_command()`.
That leaves a choice between 1, 2, or 3 new functions:
1. `enif_whereis()`
2. `enif_whereis_pid()` and `enif_whereis_port()`
3. All of the above.
While option (1), directly mimicking the behavior of `erlang:whereis/1`, is appealing, it poses potential problems if `pid()` or `port()` are subsequently implemented as non-integral types that must be bound to an owning `ErlNifEnv` instance.
Therefore, option (2) has been chosen to use `ErlNifPid`/`ErlNifPort` structures in the API to maintain proper term ownership semantics.
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* maint:
Update copyright-year
Conflicts:
lib/dialyzer/src/dialyzer.hrl
lib/dialyzer/src/dialyzer_options.erl
lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer.hrl
lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer_races.erl
lib/hipe/icode/hipe_icode.erl
lib/hipe/main/hipe.erl
lib/hipe/main/hipe.hrl.src
lib/hipe/main/hipe_main.erl
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Anywhere but the beam sources we shouldn't #include "erl_nif.h", because
what "erl_nif.h" does is: (1) fail to find it outside of -I dirs, (2)
then treat it as if it was written like <erl_nif.h>. Using <erl_nif.h>
skips (1).
More information can be found in 6.10.2 of the C standard.
Because the examples use "erl_nif.h", NIF projects in the Erlang
ecosystem copy this verbatim and make the same mistake.
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* rickard/dirty_nif_SUITE-win-fix:
Fix windows
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Dirty schedulers only execute NIFs, so having them execute the full
process_main function isn't necessary. Add dirty_process_main for
dirty schedulers to execute instead.
Add erts_pre_dirty_nif(), called when preparing to execute a dirty
nif.
Add more dirty NIF tests to verify that activities requiring the
process main lock can succeed when the process is executing a dirty
NIF.
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