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[core] Encapsulate entity preference creation to prepare for hash migration

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This commit is contained in:
J. Nick Koston
2026-01-23 22:00:48 -10:00
parent 139042acbe
commit dd98b6a3a7
1 changed files with 11 additions and 7 deletions
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18
esphome/core/entity_base.cpp
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@@ -93,14 +93,18 @@ StringRef EntityBase::get_object_id_to(std::span<char, OBJECT_ID_MAX_LEN> buf) c
uint32_t EntityBase::get_object_id_hash() { return this->object_id_hash_; }
ESPPreferenceObject EntityBase::make_entity_preference_(size_t size, uint32_t version) {
// This helper exists to centralize preference creation so we can fix hash collisions.
// This helper centralizes preference creation to enable fixing hash collisions.
// See: https://github.com/esphome/backlog/issues/85
//
// PROBLEM: get_preference_hash() uses fnv1_hash on the sanitized object_id, which can
// collide when different entity names sanitize to the same string (e.g., "Living Room"
// and "living_room" both become "living_room"). This causes entities to overwrite
// each other's stored preferences.
// COLLISION PROBLEM: get_preference_hash() uses fnv1_hash on sanitized object_id.
// Multiple entity names can sanitize to the same object_id:
// - "Living Room" and "living_room" both become "living_room"
// - UTF-8 names like "温度" and "湿度" both become "__" (underscores)
// This causes entities to overwrite each other's stored preferences.
//
// FUTURE MIGRATION: When implementing get_preference_hash_v2() that hashes
// the original entity name (not sanitized object_id), migration logic goes here:
//
// FUTURE MIGRATION (when implementing get_preference_hash_v2):
// uint32_t old_key = this->get_preference_hash() ^ version;
// uint32_t new_key = this->get_preference_hash_v2() ^ version;
// if (old_key != new_key) {
@@ -113,7 +117,7 @@ ESPPreferenceObject EntityBase::make_entity_preference_(size_t size, uint32_t ve
// }
// return global_preferences->make_preference(size, new_key);
//
// NOTE: Will need raw load/save methods on ESPPreferenceObject that take uint8_t* and size.
// This will require raw load/save methods on ESPPreferenceObject (uint8_t*, size).
//
uint32_t key = this->get_preference_hash() ^ version;
return global_preferences->make_preference(size, key);