0d39c5ca00
* Rename "serialize" and "deserialize" functions to "read" and "update" to reflect API in StatefulService * Move new definitions to StatefulService.h so it is obvious it is not general purpose * Update README
99 lines
2.9 KiB
C++
99 lines
2.9 KiB
C++
#ifndef FSPersistence_h
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#define FSPersistence_h
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#include <StatefulService.h>
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#include <FS.h>
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template <class T>
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class FSPersistence {
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public:
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FSPersistence(JsonStateReader<T> stateReader,
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JsonStateUpdater<T> stateUpdater,
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StatefulService<T>* statefulService,
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FS* fs,
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char const* filePath,
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size_t bufferSize = DEFAULT_BUFFER_SIZE) :
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_stateReader(stateReader),
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_stateUpdater(stateUpdater),
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_statefulService(statefulService),
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_fs(fs),
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_filePath(filePath),
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_bufferSize(bufferSize),
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_updateHandlerId(0) {
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enableUpdateHandler();
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}
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void readFromFS() {
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File settingsFile = _fs->open(_filePath, "r");
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if (settingsFile) {
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DynamicJsonDocument jsonDocument = DynamicJsonDocument(_bufferSize);
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DeserializationError error = deserializeJson(jsonDocument, settingsFile);
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if (error == DeserializationError::Ok && jsonDocument.is<JsonObject>()) {
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JsonObject jsonObject = jsonDocument.as<JsonObject>();
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_statefulService->updateWithoutPropagation(jsonObject, _stateUpdater);
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settingsFile.close();
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return;
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}
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settingsFile.close();
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}
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// If we reach here we have not been successful in loading the config,
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// hard-coded emergency defaults are now applied.
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applyDefaults();
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}
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bool writeToFS() {
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// create and populate a new json object
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DynamicJsonDocument jsonDocument = DynamicJsonDocument(_bufferSize);
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JsonObject jsonObject = jsonDocument.to<JsonObject>();
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_statefulService->read(jsonObject, _stateReader);
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// serialize it to filesystem
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File settingsFile = _fs->open(_filePath, "w");
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// failed to open file, return false
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if (!settingsFile) {
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return false;
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}
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// serialize the data to the file
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serializeJson(jsonDocument, settingsFile);
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settingsFile.close();
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return true;
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}
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void disableUpdateHandler() {
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if (_updateHandlerId) {
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_statefulService->removeUpdateHandler(_updateHandlerId);
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_updateHandlerId = 0;
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}
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}
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void enableUpdateHandler() {
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if (!_updateHandlerId) {
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_updateHandlerId = _statefulService->addUpdateHandler([&](const String& originId) { writeToFS(); });
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}
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}
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private:
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JsonStateReader<T> _stateReader;
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JsonStateUpdater<T> _stateUpdater;
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StatefulService<T>* _statefulService;
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FS* _fs;
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char const* _filePath;
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size_t _bufferSize;
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update_handler_id_t _updateHandlerId;
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protected:
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// We assume the updater supplies sensible defaults if an empty object
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// is supplied, this virtual function allows that to be changed.
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virtual void applyDefaults() {
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DynamicJsonDocument jsonDocument = DynamicJsonDocument(_bufferSize);
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JsonObject jsonObject = jsonDocument.as<JsonObject>();
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_statefulService->updateWithoutPropagation(jsonObject, _stateUpdater);
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}
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};
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#endif // end FSPersistence
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