⚙️ Aeon::CacheManager – 4 + 1 Architecture

Keeps time’s memory close, coherent, and fast.

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1️⃣ Logical View

Purpose:
Aeon::CacheManager is Aeon’s unified caching interface.
It reads and writes serialized occurrences to Redis, with optional in-process memoization.

Responsibilities - fetch → read or compute and store. - write / delete / clear_expired. - Enforce TTL and size limits. - Support tag-based invalidation (topic: prefix).

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2️⃣ Process View

1. Timekeeper requests occurrences for a period.
2. CacheManager computes key via CacheWindow.key_for.
3. If found → deserialize and return.
4. If missing → execute block, store serialized JSON, set TTL.
5. Refresher periodically rehydrates near-expiring keys.

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3️⃣ Development View

File: app/services/aeon/cache_manager.rb

class Aeon::CacheManager
  TTL_DEFAULT = 6.hours

  def self.fetch(key, ttl: TTL_DEFAULT)
    cached = Redis.current.get(key)
    return deserialize(cached) if cached
    value = yield
    Redis.current.set(key, serialize(value), ex: ttl.to_i)
    value
  end

  def self.delete(key) = Redis.current.del(key)
  def self.clear_expired; end # handled by Redis TTL
  def self.serialize(v)   = JSON.dump(v)
  def self.deserialize(v) = JSON.parse(v, symbolize_names: true)
end

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4️⃣ Physical View

Attribute	Description
Store	Redis 6+
TTL	Configurable (6 h default)
Index	key prefix aeon:cache:
Observability	Argus metrics aeon_cache_hits_total

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➕ 1 Scenario View

Scenario A: Cache Hit

CacheManager.fetch("aeon:cache:task:abc") { slow_query }
# => returns cached payload

Scenario B: Cache Miss

Computes from source and stores new entry.

Scenario C: Expiry

After TTL passes, Refresher detects and rebuilds.

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