Architecture: Magic numbers in configuration defaults

[drmingdrmer]

Summary

Configuration defaults use magic numbers with inconsistent formatting and no named constants.

Location

crates/raft-store/src/config.rs:182-216

impl Default for RaftConfig {
    fn default() -> Self {
        Self {
            log_cache_max_items: 1_000_000,
            log_cache_capacity: 1024 * 1024 * 1024,         // 1GB - expression
            log_wal_chunk_max_records: 100_000,
            log_wal_chunk_max_size: 256 * 1024 * 1024,      // 256MB - expression
            snapshot_chunk_size: 4194304,                    // 4MB - raw number
            snapshot_db_block_cache_size: 1073741824,        // 1GB - raw number
            // ...
        }
    }
}

Problem

1. Inconsistent formats: some use 1024 * 1024 * 1024, others use 1073741824
2. Some have comments explaining units, others do not
3. No named constants - hard to understand intent
4. Difficult to tune or document configuration options

Suggested Fix

Define named constants:

// In a constants module
const KB: u64 = 1024;
const MB: u64 = 1024 * KB;
const GB: u64 = 1024 * MB;

const DEFAULT_LOG_CACHE_MAX_ITEMS: u64 = 1_000_000;
const DEFAULT_LOG_CACHE_CAPACITY: u64 = 1 * GB;
const DEFAULT_WAL_CHUNK_MAX_RECORDS: u64 = 100_000;
const DEFAULT_WAL_CHUNK_MAX_SIZE: u64 = 256 * MB;
const DEFAULT_SNAPSHOT_CHUNK_SIZE: u64 = 4 * MB;
const DEFAULT_BLOCK_CACHE_SIZE: u64 = 1 * GB;

impl Default for RaftConfig {
    fn default() -> Self {
        Self {
            log_cache_max_items: DEFAULT_LOG_CACHE_MAX_ITEMS,
            log_cache_capacity: DEFAULT_LOG_CACHE_CAPACITY,
            // ...
        }
    }
}

Priority

P2 - Code maintainability