Refractored epd handler

main/display/transaction_guard.h

@@ -0,0 +1,33 @@
+#pragma once
+#include "freertos/FreeRTOS.h"
+#include "freertos/semphr.h"
+#include <esp_err.h>
+#include <type_traits>
+
+class WithTransaction {
+protected:
+  virtual esp_err_t end_transaction_() = 0;
+  virtual esp_err_t begin_transaction_(TickType_t timeout, uint32_t& out_id) = 0;
+
+  friend class TransactionGuard;
+};
+
+class TransactionGuard {
+public:
+  TransactionGuard(WithTransaction& handler, TickType_t timeout = portMAX_DELAY)
+    : handler_(handler) { }
+  ~TransactionGuard() { if (transaction_id_) handler_.end_transaction_(); }
+
+  esp_err_t begin(TickType_t timeout = portMAX_DELAY) {
+    esp_err_t err = handler_.begin_transaction_(timeout, transaction_id_);
+    return err;
+  }
+  uint32_t transaction_id() const { return transaction_id_; }
+  bool is_active() const { return transaction_id_ != 0; }
+private:
+  // delete copy constructor and assignment operator
+  TransactionGuard(const TransactionGuard&) = delete;
+  TransactionGuard& operator=(const TransactionGuard&) = delete;
+  WithTransaction& handler_;
+  uint32_t transaction_id_ = 0;
+};