Ferricstore.Application (ferricstore v0.3.4)

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OTP Application for the FerricStore core engine.

Starts the core supervision tree: shards, Raft, ETS tables, merge schedulers, PubSub, and MemoryGuard. Network-facing children (Ranch TCP/TLS listener, HTTP health endpoint) are started by the separate :ferricstore_server application.

Supervision tree (:one_for_one)

Ferricstore.Supervisor
├── Ferricstore.Stats                   (global counters & run metadata)
├── Ferricstore.SlowLog                 (slow command log)
├── Ferricstore.AuditLog                (audit trail)
├── Ferricstore.Config                  (runtime config)
├── Ferricstore.NamespaceConfig         (per-namespace overrides)
├── (ACL moved to ferricstore_server)
├── Ferricstore.HLC                     (Hybrid Logical Clock)
├── Ferricstore.Raft.Batcher (x N)     (group-commit batchers)
├── Ferricstore.Store.BitcaskWriter (x N) (background Bitcask flushers)
├── Ferricstore.Store.RmwCoordinator (x N) (async RMW contention fallback)
├── Ferricstore.Store.ShardSupervisor   (one_for_one over N Shard GenServers)
├── Ferricstore.Merge.Supervisor        (Semaphore + N Scheduler GenServers)
├── Ferricstore.PubSub
├── Ferricstore.FetchOrCompute
└── Ferricstore.MemoryGuard

Stats starts first so counters are available before any connection arrives. The ShardSupervisor must start before the Ranch listener (in the server app) so that the key-value store is ready before any client connection arrives.

Configuration (application env)

  • :data_dir - Bitcask data directory (default: "data")
  • :shard_count - Number of shards (default: System.schedulers_online())
  • :max_memory_bytes - Memory budget for eviction (default: 1 GiB)

Summary

Functions

scan_large_values(shard_count, threshold_bytes \\ nil)

Scans all shard ETS tables for values exceeding the configured threshold.

Functions

scan_large_values(shard_count, threshold_bytes \\ nil)

@spec scan_large_values(non_neg_integer(), non_neg_integer()) ::
  {non_neg_integer(), binary() | nil, non_neg_integer()}

Scans all shard ETS tables for values exceeding the configured threshold.

Returns {count, largest_key, largest_size} where count is the number of entries whose value exceeds threshold_bytes, largest_key is the key with the largest value, and largest_size is its size in bytes.

Returns {0, nil, 0} when no large values are found.

This is a pure RAM scan -- ETS already holds the full value per entry, so no disk reads are needed.

Parameters

  • shard_count -- number of shards to scan
  • threshold_bytes -- values larger than this are flagged (default: Application.get_env(:ferricstore, :embedded_large_value_warning_bytes, 512 * 1024))