Upgrade ArduinoJson to 6.18.5 and migrate code (#2844)

esphome/components/json/json_util.cpp

@@ -1,8 +1,10 @@
-#ifdef USE_ARDUINO
-
 #include "json_util.h"
 #include "esphome/core/log.h"
 
+#ifdef USE_ESP8266
+#include <Esp.h>
+#endif
+
 namespace esphome {
 namespace json {
 
@@ -10,110 +12,49 @@ static const char *const TAG = "json";
 
 static std::vector<char> global_json_build_buffer;  // NOLINT
 
-const char *build_json(const json_build_t &f, size_t *length) {
-  global_json_buffer.clear();
-  JsonObject &root = global_json_buffer.createObject();
+std::string build_json(const json_build_t &f) {
+  // Here we are allocating as much heap memory as available minus 2kb to be safe
+  // as we can not have a true dynamic sized document.
+  // The excess memory is freed below with `shrinkToFit()`
+#ifdef USE_ESP8266
+  const size_t free_heap = ESP.getMaxFreeBlockSize() - 2048;  // NOLINT(readability-static-accessed-through-instance)
+#elif defined(USE_ESP32)
+  const size_t free_heap = heap_caps_get_largest_free_block(MALLOC_CAP_DEFAULT) - 2048;
+#endif
 
+  DynamicJsonDocument json_document(free_heap);
+  JsonObject root = json_document.to<JsonObject>();
   f(root);
+  json_document.shrinkToFit();
 
-  // The Json buffer size gives us a good estimate for the required size.
-  // Usually, it's a bit larger than the actual required string size
-  //             | JSON Buffer Size | String Size |
-  // Discovery   | 388              | 351         |
-  // Discovery   | 372              | 356         |
-  // Discovery   | 336              | 311         |
-  // Discovery   | 408              | 393         |
-  global_json_build_buffer.reserve(global_json_buffer.size() + 1);
-  size_t bytes_written = root.printTo(global_json_build_buffer.data(), global_json_build_buffer.capacity());
-
-  if (bytes_written >= global_json_build_buffer.capacity() - 1) {
-    global_json_build_buffer.reserve(root.measureLength() + 1);
-    bytes_written = root.printTo(global_json_build_buffer.data(), global_json_build_buffer.capacity());
-  }
-
-  *length = bytes_written;
-  return global_json_build_buffer.data();
+  std::string output;
+  serializeJson(json_document, output);
+  return output;
 }
-void parse_json(const std::string &data, const json_parse_t &f) {
-  global_json_buffer.clear();
-  JsonObject &root = global_json_buffer.parseObject(data);
 
-  if (!root.success()) {
+void parse_json(const std::string &data, const json_parse_t &f) {
+  // Here we are allocating as much heap memory as available minus 2kb to be safe
+  // as we can not have a true dynamic sized document.
+  // The excess memory is freed below with `shrinkToFit()`
+#ifdef USE_ESP8266
+  const size_t free_heap = ESP.getMaxFreeBlockSize() - 2048;  // NOLINT(readability-static-accessed-through-instance)
+#elif defined(USE_ESP32)
+  const size_t free_heap = heap_caps_get_largest_free_block(MALLOC_CAP_DEFAULT) - 2048;
+#endif
+
+  DynamicJsonDocument json_document(free_heap);
+  DeserializationError err = deserializeJson(json_document, data);
+  json_document.shrinkToFit();
+
+  JsonObject root = json_document.as<JsonObject>();
+
+  if (err) {
     ESP_LOGW(TAG, "Parsing JSON failed.");
     return;
   }
 
   f(root);
 }
-std::string build_json(const json_build_t &f) {
-  size_t len;
-  const char *c_str = build_json(f, &len);
-  return std::string(c_str, len);
-}
-
-VectorJsonBuffer::String::String(VectorJsonBuffer *parent) : parent_(parent), start_(parent->size_) {}
-void VectorJsonBuffer::String::append(char c) const {
-  char *last = static_cast<char *>(this->parent_->do_alloc(1));
-  *last = c;
-}
-const char *VectorJsonBuffer::String::c_str() const {
-  this->append('\0');
-  return &this->parent_->buffer_[this->start_];
-}
-void VectorJsonBuffer::clear() {
-  for (char *block : this->free_blocks_)
-    free(block);  // NOLINT
-
-  this->size_ = 0;
-  this->free_blocks_.clear();
-}
-VectorJsonBuffer::String VectorJsonBuffer::startString() { return {this}; }  // NOLINT
-void *VectorJsonBuffer::alloc(size_t bytes) {
-  // Make sure memory addresses are aligned
-  uint32_t new_size = round_size_up(this->size_);
-  this->resize(new_size);
-  return this->do_alloc(bytes);
-}
-void *VectorJsonBuffer::do_alloc(size_t bytes) {  // NOLINT
-  const uint32_t begin = this->size_;
-  this->resize(begin + bytes);
-  return &this->buffer_[begin];
-}
-void VectorJsonBuffer::resize(size_t size) {  // NOLINT
-  if (size <= this->size_) {
-    this->size_ = size;
-    return;
-  }
-
-  this->reserve(size);
-  this->size_ = size;
-}
-void VectorJsonBuffer::reserve(size_t size) {  // NOLINT
-  if (size <= this->capacity_)
-    return;
-
-  uint32_t target_capacity = this->capacity_;
-  if (this->capacity_ == 0) {
-    // lazily initialize with a reasonable size
-    target_capacity = JSON_OBJECT_SIZE(16);
-  }
-  while (target_capacity < size)
-    target_capacity *= 2;
-
-  char *old_buffer = this->buffer_;
-  this->buffer_ = new char[target_capacity];  // NOLINT
-  if (old_buffer != nullptr && this->capacity_ != 0) {
-    this->free_blocks_.push_back(old_buffer);
-    memcpy(this->buffer_, old_buffer, this->capacity_);
-  }
-  this->capacity_ = target_capacity;
-}
-
-size_t VectorJsonBuffer::size() const { return this->size_; }
-
-VectorJsonBuffer global_json_buffer;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
 }  // namespace json
 }  // namespace esphome
-
-#endif  // USE_ARDUINO