296 lines
9.5 KiB
C
296 lines
9.5 KiB
C
// Copyright 2015-2019 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/*
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* Log library implementation notes.
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*
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* Log library stores all tags provided to esp_log_level_set as a linked
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* list. See uncached_tag_entry_t structure.
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*
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* To avoid looking up log level for given tag each time message is
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* printed, this library caches pointers to tags. Because the suggested
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* way of creating tags uses one 'TAG' constant per file, this caching
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* should be effective. Cache is a binary min-heap of cached_tag_entry_t
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* items, ordering is done on 'generation' member. In this context,
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* generation is an integer which is incremented each time an operation
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* with cache is performed. When cache is full, new item is inserted in
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* place of an oldest item (that is, with smallest 'generation' value).
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* After that, bubble-down operation is performed to fix ordering in the
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* min-heap.
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*
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* The potential problem with wrap-around of cache generation counter is
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* ignored for now. This will happen if someone happens to output more
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* than 4 billion log entries, at which point wrap-around will not be
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* the biggest problem.
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*
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*/
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#include <stdbool.h>
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#include <stdarg.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <assert.h>
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#include "esp_log.h"
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#include "esp_log_private.h"
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#ifndef NDEBUG
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// Enable built-in checks in queue.h in debug builds
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#define INVARIANTS
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// Enable consistency checks and cache statistics in this file.
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#define LOG_BUILTIN_CHECKS
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#endif
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#include "sys/queue.h"
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// Number of tags to be cached. Must be 2**n - 1, n >= 2.
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#define TAG_CACHE_SIZE 31
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typedef struct {
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const char *tag;
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uint32_t level : 3;
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uint32_t generation : 29;
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} cached_tag_entry_t;
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typedef struct uncached_tag_entry_ {
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SLIST_ENTRY(uncached_tag_entry_) entries;
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uint8_t level; // esp_log_level_t as uint8_t
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char tag[0]; // beginning of a zero-terminated string
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} uncached_tag_entry_t;
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static esp_log_level_t s_log_default_level = ESP_LOG_VERBOSE;
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static SLIST_HEAD(log_tags_head, uncached_tag_entry_) s_log_tags = SLIST_HEAD_INITIALIZER(s_log_tags);
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static cached_tag_entry_t s_log_cache[TAG_CACHE_SIZE];
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static uint32_t s_log_cache_max_generation = 0;
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static uint32_t s_log_cache_entry_count = 0;
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static vprintf_like_t s_log_print_func = &vprintf;
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#ifdef LOG_BUILTIN_CHECKS
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static uint32_t s_log_cache_misses = 0;
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#endif
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static inline bool get_cached_log_level(const char *tag, esp_log_level_t *level);
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static inline bool get_uncached_log_level(const char *tag, esp_log_level_t *level);
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static inline void add_to_cache(const char *tag, esp_log_level_t level);
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static void heap_bubble_down(int index);
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static inline void heap_swap(int i, int j);
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static inline bool should_output(esp_log_level_t level_for_message, esp_log_level_t level_for_tag);
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static inline void clear_log_level_list(void);
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vprintf_like_t esp_log_set_vprintf(vprintf_like_t func)
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{
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esp_log_impl_lock();
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vprintf_like_t orig_func = s_log_print_func;
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s_log_print_func = func;
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esp_log_impl_unlock();
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return orig_func;
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}
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void esp_log_level_set(const char *tag, esp_log_level_t level)
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{
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esp_log_impl_lock();
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// for wildcard tag, remove all linked list items and clear the cache
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if (strcmp(tag, "*") == 0) {
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s_log_default_level = level;
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clear_log_level_list();
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esp_log_impl_unlock();
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return;
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}
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// search for existing tag
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uncached_tag_entry_t *it = NULL;
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SLIST_FOREACH(it, &s_log_tags, entries) {
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if (strcmp(it->tag, tag) == 0) {
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// one tag in the linked list matched, update the level
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it->level = level;
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// quit with it != NULL
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break;
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}
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}
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// no existing tag, append new one
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if (it == NULL) {
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// allocate new linked list entry and append it to the head of the list
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size_t tag_len = strlen(tag) + 1;
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size_t entry_size = offsetof(uncached_tag_entry_t, tag) + tag_len;
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uncached_tag_entry_t *new_entry = (uncached_tag_entry_t *) malloc(entry_size);
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if (!new_entry) {
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esp_log_impl_unlock();
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return;
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}
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new_entry->level = (uint8_t) level;
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strlcpy(new_entry->tag, tag, tag_len);
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SLIST_INSERT_HEAD(&s_log_tags, new_entry, entries);
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}
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// search in the cache and update the entry it if exists
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for (int i = 0; i < s_log_cache_entry_count; ++i) {
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#ifdef LOG_BUILTIN_CHECKS
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assert(i == 0 || s_log_cache[(i - 1) / 2].generation < s_log_cache[i].generation);
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#endif
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if (strcmp(s_log_cache[i].tag, tag) == 0) {
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s_log_cache[i].level = level;
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break;
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}
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}
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esp_log_impl_unlock();
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}
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void clear_log_level_list(void)
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{
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uncached_tag_entry_t *it;
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while ((it = SLIST_FIRST(&s_log_tags)) != NULL) {
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SLIST_REMOVE_HEAD(&s_log_tags, entries);
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free(it);
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}
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s_log_cache_entry_count = 0;
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s_log_cache_max_generation = 0;
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#ifdef LOG_BUILTIN_CHECKS
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s_log_cache_misses = 0;
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#endif
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}
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void esp_log_writev(esp_log_level_t level,
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const char *tag,
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const char *format,
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va_list args)
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{
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if (!esp_log_impl_lock_timeout()) {
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return;
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}
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esp_log_level_t level_for_tag;
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// Look for the tag in cache first, then in the linked list of all tags
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if (!get_cached_log_level(tag, &level_for_tag)) {
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if (!get_uncached_log_level(tag, &level_for_tag)) {
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level_for_tag = s_log_default_level;
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}
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add_to_cache(tag, level_for_tag);
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#ifdef LOG_BUILTIN_CHECKS
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++s_log_cache_misses;
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#endif
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}
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esp_log_impl_unlock();
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if (!should_output(level, level_for_tag)) {
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return;
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}
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(*s_log_print_func)(format, args);
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}
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void esp_log_write(esp_log_level_t level,
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const char *tag,
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const char *format, ...)
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{
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va_list list;
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va_start(list, format);
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esp_log_writev(level, tag, format, list);
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va_end(list);
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}
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static inline bool get_cached_log_level(const char *tag, esp_log_level_t *level)
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{
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// Look for `tag` in cache
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int i;
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for (i = 0; i < s_log_cache_entry_count; ++i) {
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#ifdef LOG_BUILTIN_CHECKS
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assert(i == 0 || s_log_cache[(i - 1) / 2].generation < s_log_cache[i].generation);
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#endif
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if (s_log_cache[i].tag == tag) {
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break;
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}
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}
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if (i == s_log_cache_entry_count) { // Not found in cache
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return false;
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}
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// Return level from cache
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*level = (esp_log_level_t) s_log_cache[i].level;
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// If cache has been filled, start taking ordering into account
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// (other options are: dynamically resize cache, add "dummy" entries
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// to the cache; this option was chosen because code is much simpler,
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// and the unfair behavior of cache will show it self at most once, when
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// it has just been filled)
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if (s_log_cache_entry_count == TAG_CACHE_SIZE) {
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// Update item generation
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s_log_cache[i].generation = s_log_cache_max_generation++;
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// Restore heap ordering
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heap_bubble_down(i);
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}
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return true;
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}
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static inline void add_to_cache(const char *tag, esp_log_level_t level)
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{
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uint32_t generation = s_log_cache_max_generation++;
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// First consider the case when cache is not filled yet.
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// In this case, just add new entry at the end.
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// This happens to satisfy binary min-heap ordering.
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if (s_log_cache_entry_count < TAG_CACHE_SIZE) {
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s_log_cache[s_log_cache_entry_count] = (cached_tag_entry_t) {
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.generation = generation,
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.level = level,
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.tag = tag
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};
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++s_log_cache_entry_count;
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return;
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}
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// Cache is full, so we replace the oldest entry (which is at index 0
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// because this is a min-heap) with the new one, and do bubble-down
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// operation to restore min-heap ordering.
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s_log_cache[0] = (cached_tag_entry_t) {
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.tag = tag,
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.level = level,
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.generation = generation
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};
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heap_bubble_down(0);
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}
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static inline bool get_uncached_log_level(const char *tag, esp_log_level_t *level)
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{
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// Walk the linked list of all tags and see if given tag is present in the list.
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// This is slow because tags are compared as strings.
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uncached_tag_entry_t *it;
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SLIST_FOREACH(it, &s_log_tags, entries) {
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if (strcmp(tag, it->tag) == 0) {
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*level = it->level;
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return true;
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}
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}
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return false;
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}
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static inline bool should_output(esp_log_level_t level_for_message, esp_log_level_t level_for_tag)
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{
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return level_for_message <= level_for_tag;
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}
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static void heap_bubble_down(int index)
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{
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while (index < TAG_CACHE_SIZE / 2) {
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int left_index = index * 2 + 1;
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int right_index = left_index + 1;
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int next = (s_log_cache[left_index].generation < s_log_cache[right_index].generation) ? left_index : right_index;
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heap_swap(index, next);
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index = next;
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}
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}
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static inline void heap_swap(int i, int j)
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{
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cached_tag_entry_t tmp = s_log_cache[i];
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s_log_cache[i] = s_log_cache[j];
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s_log_cache[j] = tmp;
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}
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