[logger] Conditionally compile runtime tag-specific log levels for performance

esphome/components/logger/__init__.py

@@ -95,6 +95,7 @@ DEFAULT = "DEFAULT"
 
 CONF_INITIAL_LEVEL = "initial_level"
 CONF_LOGGER_ID = "logger_id"
+CONF_RUNTIME_TAG_LEVELS = "runtime_tag_levels"
 CONF_TASK_LOG_BUFFER_SIZE = "task_log_buffer_size"
 
 UART_SELECTION_ESP32 = {
@@ -249,6 +250,7 @@ CONFIG_SCHEMA = cv.All(
                 }
             ),
             cv.Optional(CONF_INITIAL_LEVEL): is_log_level,
+            cv.Optional(CONF_RUNTIME_TAG_LEVELS, default=False): cv.boolean,
             cv.Optional(CONF_ON_MESSAGE): automation.validate_automation(
                 {
                     cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(LoggerMessageTrigger),
@@ -291,8 +293,12 @@ async def to_code(config):
         )
     cg.add(log.pre_setup())
 
-    for tag, log_level in config[CONF_LOGS].items():
-        cg.add(log.set_log_level(tag, LOG_LEVELS[log_level]))
+    # Enable runtime tag levels if logs are configured or explicitly enabled
+    logs_config = config[CONF_LOGS]
+    if logs_config or config[CONF_RUNTIME_TAG_LEVELS]:
+        cg.add_define("USE_LOGGER_RUNTIME_TAG_LEVELS")
+        for tag, log_level in logs_config.items():
+            cg.add(log.set_log_level(tag, LOG_LEVELS[log_level]))
 
     cg.add_define("USE_LOGGER")
     this_severity = LOG_LEVEL_SEVERITY.index(level)
@@ -443,6 +449,7 @@ async def logger_set_level_to_code(config, action_id, template_arg, args):
     level = LOG_LEVELS[config[CONF_LEVEL]]
     logger = await cg.get_variable(config[CONF_LOGGER_ID])
     if tag := config.get(CONF_TAG):
+        cg.add_define("USE_LOGGER_RUNTIME_TAG_LEVELS")
         text = str(cg.statement(logger.set_log_level(tag, level)))
     else:
         text = str(cg.statement(logger.set_log_level(level)))

esphome/components/logger/logger.cpp

@@ -148,9 +148,11 @@ void Logger::log_vprintf_(uint8_t level, const char *tag, int line, const __Flas
 #endif  // USE_STORE_LOG_STR_IN_FLASH
 
 inline uint8_t Logger::level_for(const char *tag) {
+#ifdef USE_LOGGER_RUNTIME_TAG_LEVELS
   auto it = this->log_levels_.find(tag);
   if (it != this->log_levels_.end())
     return it->second;
+#endif
   return this->current_level_;
 }
 
@@ -220,7 +222,9 @@ void Logger::process_messages_() {
 }
 
 void Logger::set_baud_rate(uint32_t baud_rate) { this->baud_rate_ = baud_rate; }
-void Logger::set_log_level(const std::string &tag, uint8_t log_level) { this->log_levels_[tag] = log_level; }
+#ifdef USE_LOGGER_RUNTIME_TAG_LEVELS
+void Logger::set_log_level(const char *tag, uint8_t log_level) { this->log_levels_[tag] = log_level; }
+#endif
 
 #if defined(USE_ESP32) || defined(USE_ESP8266) || defined(USE_RP2040) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
 UARTSelection Logger::get_uart() const { return this->uart_; }
@@ -271,9 +275,11 @@ void Logger::dump_config() {
   }
 #endif
 
+#ifdef USE_LOGGER_RUNTIME_TAG_LEVELS
   for (auto &it : this->log_levels_) {
-    ESP_LOGCONFIG(TAG, "  Level for '%s': %s", it.first.c_str(), LOG_STR_ARG(LOG_LEVELS[it.second]));
+    ESP_LOGCONFIG(TAG, "  Level for '%s': %s", it.first, LOG_STR_ARG(LOG_LEVELS[it.second]));
   }
+#endif
 }
 
 void Logger::set_log_level(uint8_t level) {

esphome/components/logger/logger.h

@@ -36,6 +36,13 @@ struct device;
 
 namespace esphome::logger {
 
+#ifdef USE_LOGGER_RUNTIME_TAG_LEVELS
+// Comparison function for const char* keys in log_levels_ map
+struct CStrCompare {
+  bool operator()(const char *a, const char *b) const { return strcmp(a, b) < 0; }
+};
+#endif
+
 // ANSI color code last digit (30-38 range, store only last digit to save RAM)
 static constexpr char LOG_LEVEL_COLOR_DIGIT[] = {
     '\0',  // NONE
@@ -133,8 +140,10 @@ class Logger : public Component {
 
   /// Set the default log level for this logger.
   void set_log_level(uint8_t level);
+#ifdef USE_LOGGER_RUNTIME_TAG_LEVELS
   /// Set the log level of the specified tag.
-  void set_log_level(const std::string &tag, uint8_t log_level);
+  void set_log_level(const char *tag, uint8_t log_level);
+#endif
   uint8_t get_log_level() { return this->current_level_; }
 
   // ========== INTERNAL METHODS ==========
@@ -242,7 +251,9 @@ class Logger : public Component {
 #endif
 
   // Large objects (internally aligned)
-  std::map<std::string, uint8_t> log_levels_{};
+#ifdef USE_LOGGER_RUNTIME_TAG_LEVELS
+  std::map<const char *, uint8_t, CStrCompare> log_levels_{};
+#endif
   CallbackManager<void(uint8_t, const char *, const char *, size_t)> log_callback_{};
   CallbackManager<void(uint8_t)> level_callback_{};
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER

esphome/core/defines.h

@@ -48,6 +48,7 @@
 #define USE_LIGHT
 #define USE_LOCK
 #define USE_LOGGER
+#define USE_LOGGER_RUNTIME_TAG_LEVELS
 #define USE_LVGL
 #define USE_LVGL_ANIMIMG
 #define USE_LVGL_ARC

tests/components/logger/common-default_uart.yaml

@@ -6,11 +6,16 @@ esphome:
           format: "Warning: Logger level is %d"
           args: [id(logger_id).get_log_level()]
       - logger.set_level: WARN
+      - logger.set_level:
+          level: ERROR
+          tag: mqtt.client
 
 logger:
   id: logger_id
   level: DEBUG
   initial_level: INFO
+  logs:
+    mqtt.component: WARN
 
 select:
   - platform: logger