minimize save/restore allocations

master 800**2 harris for 10 timesteps

perf stat mpirun -n 8 python3 -Ou harris.py

t =  0.01000  -  3.09741sec  - total   3.097sec
t =  0.02000  -  4.06846sec  - total   7.166sec
t =  0.03000  -  3.59235sec  - total   10.76sec
t =  0.04000  -  3.61215sec  - total   14.37sec
t =  0.05000  -  3.54478sec  - total   17.92sec
t =  0.06000  -  3.65917sec  - total   21.57sec
t =  0.07000  -  3.52980sec  - total    25.1sec
t =  0.08000  -  3.47992sec  - total   28.58sec
t =  0.09000  -  3.50010sec  - total   32.08sec
t =  0.10000  -  3.49883sec  - total   35.58sec
mean advance time = 3.558296871185303
total advance time = 0:00:35.582969

 Performance counter stats for 'mpirun -n 8 python3 -Ou ../master/harris.py':

        306,346.10 msec task-clock                       #    7.727 CPUs utilized             
            16,856      context-switches                 #   55.023 /sec                      
             1,358      cpu-migrations                   #    4.433 /sec                      
        13,233,048      page-faults                      #   43.196 K/sec                     
   477,533,241,846      cycles                           #    1.559 GHz                       
    64,904,175,940      stalled-cycles-frontend          #   13.59% frontend cycles idle      
   947,676,761,783      instructions                     #    1.98  insn per cycle            
                                                  #    0.07  stalled cycles per insn   
    71,270,615,978      branches                         #  232.647 M/sec                     
     2,456,773,652      branch-misses                    #    3.45% of all branches           

      39.645463201 seconds time elapsed

     252.248087000 seconds user
      50.480167000 seconds sys

vs this PR

t =  0.01000  -  2.64360sec  - total   2.644sec
t =  0.02000  -  3.08067sec  - total   5.724sec
t =  0.03000  -  3.15369sec  - total   8.878sec
t =  0.04000  -  3.11711sec  - total    12.0sec
t =  0.05000  -  3.12012sec  - total   15.12sec
t =  0.06000  -  3.06334sec  - total   18.18sec
t =  0.07000  -  3.08013sec  - total   21.26sec
t =  0.08000  -  3.48485sec  - total   24.74sec
t =  0.09000  -  3.90359sec  - total   28.65sec
t =  0.10000  -  3.10904sec  - total   31.76sec
mean advance time = 3.17561354637146
total advance time = 0:00:31.756135

 Performance counter stats for 'mpirun -n 8 python3 -Ou harris.py':

        276,932.89 msec task-clock                       #    7.702 CPUs utilized             
            18,070      context-switches                 #   65.250 /sec                      
             1,410      cpu-migrations                   #    5.091 /sec                      
         4,189,838      page-faults                      #   15.129 K/sec                     
   403,919,758,323      cycles                           #    1.459 GHz                       
    33,425,036,082      stalled-cycles-frontend          #    8.28% frontend cycles idle      
   839,432,838,228      instructions                     #    2.08  insn per cycle            
                                                  #    0.04  stalled cycles per insn   
    50,362,453,610      branches                         #  181.858 M/sec                     
     1,155,931,187      branch-misses                    #    2.30% of all branches           

      35.956348966 seconds time elapsed

     258.903196000 seconds user
      14.351512000 seconds sys

Summary by CodeRabbit

New Features
- Introduced a new SaveState struct for improved state management of particles.
- Added default parameters to the ParticleArray constructor for easier instantiation.
- New functions isUsable and isSettable added for enhanced usability checks.
- Implemented optional parameters in the CellMap constructor.
- Introduced a MinimizingVector struct for efficient dynamic vector management.
Bug Fixes
- Updated method signatures for better const correctness.

📝 Walkthrough

## Walkthrough The pull request introduces several modifications across multiple files, primarily focusing on enhancing the `SolverPPC` and `ParticleArray` classes. Key changes include the addition of new structures and functions, updates to method signatures for improved const correctness, and the introduction of default parameters in constructors. Additionally, a new utility struct for managing vectors is added, along with new functions for usability checks in the `PHARE::core` namespace. ## Changes | File Path | Change Summary | |---------------------------------------------|----------------------------------------------------------------------------------------------------| | `src/amr/solvers/solver_ppc.hpp` | - Updated `saveState_` method signature to accept const references.
- Introduced `SaveState` struct.
- Refactored `saveState_` and `restoreState_` methods. | | `src/core/data/particles/particle_array.hpp` | - Updated `ParticleArray` constructor to have default parameters.
- Added `data()` methods for accessing particle data.
- Introduced overload for `replace_from` method. | | `src/core/def.hpp` | - Added `isUsable` and `isSettable` functions with `[[nodiscard]]` attribute. | | `src/core/utilities/cellmap.hpp` | - Updated `CellMap` constructor to have a default argument for `box`. | | `src/core/vector.hpp` | - Introduced `MinimizingVector` struct for managing dynamic vectors. | ## Possibly related PRs - **#897**: The changes in this PR involve modifications to the `SolverPPC` class, specifically updating the `saveState_` method, which is also a focus of the main PR. Both PRs are related through their alterations to the `saveState_` method and the management of particle states. ## Suggested reviewers - nicolasaunai - rochSmets

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PHAREHUB / PHARE

minimize save/restore allocations #909

Summary by CodeRabbit