Optimize GEORADIUS command performance with pre-allocated buffer

[chzhoo]

Description

1. The GEORADIUS command stores searched map points in geoArray, which triggers at least two memory allocations: one for the geoArray creation and another for each geoPoint initialization.
2. We can reduce these two memory allocations:
   • converting geoArray from a heap-allocated variable to a stack-allocated one
   • embedding geoPoint directly within geoArray

Benchmark Run the benchmark command five times with the command below, and take the peak value as the final result.

for((x=0;x<5;x+=1)); do valkey-cli flushall; valkey-benchmark -r $POINTS_SIZE geoadd key 100 70 l__rand_int__; valkey-benchmark -P 2 -n 10000000 georadius key 100 70 300 km; done

$POINTS_SIZE	QPS before optimization	QPS after optimization	Performance Boost
1	430015.06	436585.88	1.5%
4	381766.81	386279.34	1.2%
16	264592.28	268391.53	1.4%
64	120035.05	120277.60	0.2%

CPU: AMD EPYC 9K65 192-Core Processor* 8 OS: Ubuntu Server 24.04 LTS 64bit Memory: 32GB VM: Tencent cloud SA9 | SA9.2XLARGE32

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 71.23%. Comparing base (1531b44) to head (b64df52). Report is 15 commits behind head on unstable.

Additional details and impacted files

@@             Coverage Diff              @@
##           unstable    #2116      +/-   ##
============================================
- Coverage     71.24%   71.23%   -0.02%     
============================================
  Files           122      122              
  Lines         66030    66049      +19     
============================================
+ Hits          47045    47051       +6     
- Misses        18985    18998      +13     

Files with missing lines	Coverage Δ
src/geo.c	93.62% <100.00%> (+0.04%)	:arrow_up:

... and 14 files with indirect coverage changes

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[zuiderkwast]

@KarthikSubbarao you know the geo code. PTAL.