refactor: Pass lifetimebound reference to SingleThreadedSchedulerClient #25040

1. 
   MarcoFalke commented at 7:21 am on April 30, 2022: member

   Currently a pointer is passed, which is confusing and requires run-time asserts to avoid nullptr dereference.

   All call sites can pass a reference, so do that. Also mark it LIFETIMEBOUND to avoid call sites passing a temporary. Also, unrelated cleanup in touched lines.

2. Pass lifetimebound reference to SingleThreadedSchedulerClient fa4652ce59
3. MarcoFalke added the label Refactoring on Apr 30, 2022
4. 
   pk-b2 commented at 1:33 am on May 2, 2022: none

   ACK https://github.com/bitcoin/bitcoin/pull/25040/commits/fa4652ce5995ace831b6a4d3125bfcac9563ff6f

   Built and debugged the changes locally.

5. 
   jonatack commented at 4:05 pm on May 3, 2022: member

   Code review ACK fa4652ce5995ace831b6a4d3125bfcac9563ff6f rebased to master, debug build, unit tests

   This commit:

   • passes the SingleThreadedSchedulerClient::scheduler param by reference instead of a pointer, which allows dropping a runtime non-nullptr assertion in SingleThreadedSchedulerClient::AddToProcessQueue() to avoid nullptr dereferencing (similar change in recently-merged #25016)
   • adds the clang LIFETIMEBOUND attribute to the SingleThreadedSchedulerClient and MainSignalsInstance constructors to avoid call sites passing a temporary
   • renames m_pscheduler to m_scheduler
   • adds missing header includes to scheduler.h
   • replaces a less-efficient std::bind with a lambda
   • replaces a reset(new) with preferred std::make_unique

   clang::lifetimebound is described in https://releases.llvm.org/12.0.0/tools/clang/docs/AttributeReference.html#lifetimebound:

   The lifetimebound attribute indicates that a resource owned by a function parameter or implicit object parameter is retained by the return value of the annotated function (or, for a parameter of a constructor, in the value of the constructed object).

6. vincenzopalazzo approved
7. 
   vincenzopalazzo commented at 8:30 pm on May 3, 2022: none

   ACK https://github.com/bitcoin/bitcoin/pull/25040/commits/fa4652ce5995ace831b6a4d3125bfcac9563ff6f
8. MarcoFalke merged this on May 4, 2022
9. MarcoFalke closed this on May 4, 2022

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10. MarcoFalke deleted the branch on May 4, 2022
11. MarcoFalke referenced this in commit d17bbc3c48 on May 4, 2022
12. sidhujag referenced this in commit 38f1a61086 on May 4, 2022
13. sidhujag referenced this in commit cedc09f1e9 on May 4, 2022
14. Fabcien referenced this in commit e10c411779 on Feb 15, 2023
15. DrahtBot locked this on May 4, 2023

Contributors
MarcoFalke pk-b2 jonatack vincenzopalazzo

Labels
Refactoring