[core] Optimize fnv1_hash to avoid string allocations for static entities (#10529)

esphome/core/entity_base.cpp

@@ -45,10 +45,15 @@ void EntityBase::set_icon(const char *icon) {
 #endif
 }
 
+// Check if the object_id is dynamic (changes with MAC suffix)
+bool EntityBase::is_object_id_dynamic_() const {
+  return !this->flags_.has_own_name && App.is_name_add_mac_suffix_enabled();
+}
+
 // Entity Object ID
 std::string EntityBase::get_object_id() const {
   // Check if `App.get_friendly_name()` is constant or dynamic.
-  if (!this->flags_.has_own_name && App.is_name_add_mac_suffix_enabled()) {
+  if (this->is_object_id_dynamic_()) {
     // `App.get_friendly_name()` is dynamic.
     return str_sanitize(str_snake_case(App.get_friendly_name()));
   }
@@ -58,7 +63,7 @@ std::string EntityBase::get_object_id() const {
 StringRef EntityBase::get_object_id_ref_for_api_() const {
   static constexpr auto EMPTY_STRING = StringRef::from_lit("");
   // Return empty for dynamic case (MAC suffix)
-  if (!this->flags_.has_own_name && App.is_name_add_mac_suffix_enabled()) {
+  if (this->is_object_id_dynamic_()) {
     return EMPTY_STRING;
   }
   // For static case, return the string or empty if null
@@ -70,7 +75,10 @@ void EntityBase::set_object_id(const char *object_id) {
 }
 
 // Calculate Object ID Hash from Entity Name
-void EntityBase::calc_object_id_() { this->object_id_hash_ = fnv1_hash(this->get_object_id()); }
+void EntityBase::calc_object_id_() {
+  this->object_id_hash_ =
+      fnv1_hash(this->is_object_id_dynamic_() ? this->get_object_id().c_str() : this->object_id_c_str_);
+}
 
 uint32_t EntityBase::get_object_id_hash() { return this->object_id_hash_; }
 

esphome/core/entity_base.h

@@ -126,6 +126,9 @@ class EntityBase {
   virtual uint32_t hash_base() { return 0L; }
   void calc_object_id_();
 
+  /// Check if the object_id is dynamic (changes with MAC suffix)
+  bool is_object_id_dynamic_() const;
+
   StringRef name_;
   const char *object_id_c_str_{nullptr};
 #ifdef USE_ENTITY_ICON

esphome/core/helpers.cpp

@@ -142,11 +142,13 @@ uint16_t crc16be(const uint8_t *data, uint16_t len, uint16_t crc, uint16_t poly,
   return refout ? (crc ^ 0xffff) : crc;
 }
 
-uint32_t fnv1_hash(const std::string &str) {
+uint32_t fnv1_hash(const char *str) {
   uint32_t hash = 2166136261UL;
-  for (char c : str) {
-    hash *= 16777619UL;
-    hash ^= c;
+  if (str) {
+    while (*str) {
+      hash *= 16777619UL;
+      hash ^= *str++;
+    }
   }
   return hash;
 }

esphome/core/helpers.h

@@ -155,7 +155,8 @@ uint16_t crc16be(const uint8_t *data, uint16_t len, uint16_t crc = 0, uint16_t p
                  bool refout = false);
 
 /// Calculate a FNV-1 hash of \p str.
-uint32_t fnv1_hash(const std::string &str);
+uint32_t fnv1_hash(const char *str);
+inline uint32_t fnv1_hash(const std::string &str) { return fnv1_hash(str.c_str()); }
 
 /// Return a random 32-bit unsigned integer.
 uint32_t random_uint32();