# (feat): BitVector Pooling Support

[mgyoo86]

Summary

This PR introduces comprehensive support for pooling BitArrays (specifically BitVector and its multidimensional views), enabling significant memory savings for boolean arrays compared to standard Vector{Bool}.

Key Changes

1. New Bit Sentinel Type

Introduced Bit as a sentinel type to distinguish between bit-packed arrays and standard boolean arrays:

• acquire!(pool, Bit, n): Returns a pooled BitVector (1 bit per element).
• acquire!(pool, Bool, n): Returns a pooled Vector{Bool} (1 byte per element).

2. BitTypedPool Implementation

• Added specialized BitTypedPool to AdaptiveArrayPool (accessible via .bits).
• Allocates and manages a simplified pool of BitVectors.
• Returns SubArray{Bool, 1, BitVector} for 1D requests.
• Returns ReshapedArray{Bool, N, ...} wrapper for N-D requests, maintaining zero-allocation usage where possible.

3. API Integrations

• falses! (or zeros!) / trues! (or ones!) Support:

  # Allocates BitVector filled with false (reused if available)
  mask = falses!(pool, 1000) # or zeros!(pool, Bit, 1000)
  
  # Allocates BitVector filled with true
  flags = trues!(pool, 1000) # or ones!(pool, Bit, 1000)

• Sentinel Methods: Defined zero(Bit) === false and one(Bit) === true to support generic fill operations.

4. Memory Efficiency

• ~8x reduction in memory usage for boolean arrays.
• Ideal for large masks, flags, and binary datasets where Vector{Bool} overhead is significant.

Usage Example

using AdaptiveArrayPools

pool = AdaptiveArrayPool()

# 1. Standard Bool Vector (1000 bytes)
v_bool = acquire!(pool, Bool, 1000) 

# 2. BitVector (1000 bits ≈ 125 bytes)
v_bit = acquire!(pool, Bit, 1000)

# 3. Multidimensional BitArray
# Returns a ReshapedArray viewing the pooled BitVector
matrix_bit = trues!(pool, 100, 100)

Testing

• Added test/test_bitarray.jl covering:
  • Sentinel type behavior.
  • Pool structure verification.
  • 1D and N-D acquisition and reuse.
  • zeros! and ones! convenience functions.
  • Resizing behaviors (via pool release/re-acquire).

[codecov]

Codecov Report

❌ Patch coverage is 97.14286% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.45%. Comparing base (e7553b4) to head (020317d).
⚠️ Report is 16 commits behind head on master.

Files with missing lines	Patch %	Lines
src/macros.jl	80.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #14      +/-   ##
==========================================
+ Coverage   96.41%   96.45%   +0.04%     
==========================================
  Files           8        8              
  Lines        1004     1072      +68     
==========================================
+ Hits          968     1034      +66     
- Misses         36       38       +2     

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[Copilot]

Pull request overview

This PR introduces comprehensive BitVector pooling support to AdaptiveArrayPools, enabling significant memory savings (approximately 8x) for boolean arrays by using bit-packed storage instead of byte-per-element storage.

Changes:

• Introduced Bit sentinel type to distinguish bit-packed arrays from standard boolean arrays
• Added BitTypedPool specialized pool for managing BitVector instances with 1D caching
• Integrated Bit type support into existing APIs (acquire!, zeros!, ones!) with proper error handling for unsupported unsafe_acquire!

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/types.jl	Defines Bit sentinel type, BitTypedPool structure, and adds bits field to AdaptiveArrayPool; includes dispatch for get_typed_pool!
src/acquire.jl	Implements allocation dispatch for BitTypedPool, defines zero/one for Bit, adds clear error handling for unsupported unsafe_acquire!, and provides DisabledPool fallbacks
src/convenience.jl	Adds zeros!/ones! support for DisabledPool with Bit type using falses/trues
src/AdaptiveArrayPools.jl	Exports the Bit type for public use
test/test_bitarray.jl	Comprehensive test suite covering all aspects of BitArray pooling including acquisition, state management, error handling, and memory efficiency
test/test_fixed_slots.jl	Updates fixed slot infrastructure tests to include BitTypedPool and use AbstractTypedPool type checks
test/test_coverage.jl	Adds tests for pooling_enabled dispatch covering both AbstractArrayPool and DisabledPool
test/runtests.jl	Includes new BitArray test file in the test suite

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