Add parallel API calls via furrr/future

[maciekbanas]

Description

API calls across repos and orgs are currently sequential — each purrr::map loop waits for one HTTP response before starting the next. For setups with many repos/orgs, this is dominated by network latency.

This PR adds optional parallel execution using furrr/future. When a user enables parallelism via set_parallel(), API requests run concurrently across repos/orgs. When no parallel plan is set, behavior is identical to before (falls back to purrr::map).

Related Issue(s)

Fixes #736

Key changes

• gitstats_map(), gitstats_map2(), gitstats_map_chr() — drop-in wrappers in utils.R that check future::plan() and dispatch to either purrr::map (sequential) or furrr::future_map (parallel)
• set_parallel(workers) — exported convenience function to configure parallelism. Accepts TRUE (auto-detect cores), an integer, or FALSE/0 to disable
• ~35 API-bound loops replaced across GitHost.R, GitHostGitHub.R, GitHostGitLab.R, EngineGraphQL.R, EngineGraphQLGitHub.R, EngineGraphQLGitLab.R, EngineRestGitHub.R, EngineRestGitLab.R
• Data transformation loops and setup-time validation loops left as purrr::map (no benefit from parallelism)
• furrr and future added to Imports

Usage

library(GitStats)

# Enable parallel processing (4 workers)
set_parallel(4)

my_gitstats <- create_gitstats() |>
  set_github_host(
    token = Sys.getenv(\"GITHUB_PAT\"),
    orgs = c(\"r-world-devs\", \"openpharma\")
  )

# These now run API calls in parallel across repos
get_commits(my_gitstats, since = \"2024-01-01\")
get_repos(my_gitstats)

# Revert to sequential
set_parallel(FALSE)

Design decisions

• Opt-in parallelism: Default behavior unchanged. Users must call set_parallel() to enable.
• No <<- in parallel: Loops using <<- for side effects (e.g., get_orgs_from_orgs_and_repos in GitLab) are left sequential.
• seed = NULL: Passed to furrr_options since these are deterministic API calls, not stochastic computations.
• Dev mode support: get_furrr_options() detects whether GitStats is installed or loaded via devtools::load_all() and adjusts how internal functions are exported to workers.

How to test

1. Install with devtools::install() (requires furrr and future)
2. Run existing tests — all should pass unchanged (sequential by default)
3. Test parallel mode:

   set_parallel(2)
   # Run any get_* function and compare timing vs sequential
   set_parallel(FALSE)
   ```"

[codecov]

Codecov Report

❌ Patch coverage is 65.67164% with 23 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.37%. Comparing base (dea2177) to head (e6e7793).
⚠️ Report is 27 commits behind head on master.

Files with missing lines	Patch %	Lines
R/utils.R	33.33%	12 Missing ⚠️
R/gitstats_functions.R	0.00%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #734      +/-   ##
==========================================
- Coverage   91.82%   91.37%   -0.45%     
==========================================
  Files          26       26              
  Lines        4600     4628      +28     
==========================================
+ Hits         4224     4229       +5     
- Misses        376      399      +23     

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[maciekbanas]

Closing, as solution with mirai #737 was merged.