Merge pull request #151 from BishrutSubedi/biss/Uuid_builder

This PR adds UUID builder for uprotocol uuidv8

include/up-cpp/datamodel/builder/Uuid.h

@@ -100,7 +100,7 @@ struct UuidBuilder {
 	v1::UUID build();
 
 private:
-	UuidBuilder();
+	UuidBuilder(bool testing);
 
 	const bool testing_{false};
 	std::function<std::chrono::system_clock::time_point()> time_source_;

include/up-cpp/datamodel/constants/UuidConstants.h

@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2024 Contributors to the Eclipse Foundation
+//
+// See the NOTICE file(s) distributed with this work for additional
+// information regarding copyright ownership.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Apache License Version 2.0 which is available at
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// SPDX-License-Identifier: Apache-2.0
+
+#ifndef UP_CPP_DATAMODEL_UUID_CONSTANTS_H
+#define UP_CPP_DATAMODEL_UUID_CONSTANTS_H
+
+namespace uprotocol::datamodel {
+
+// Masks and shifts for various UUID fields
+constexpr uint64_t UUID_TIMESTAMP_MASK = 0xFFFFFFFFFFFF;
+constexpr uint64_t UUID_TIMESTAMP_SHIFT = 16;
+constexpr uint64_t UUID_VERSION_MASK = 0xF;
+constexpr uint64_t UUID_VERSION_SHIFT = 12;
+constexpr uint64_t UUID_VARIANT_MASK = 0x3;
+constexpr uint64_t UUID_VARIANT_SHIFT = 62;
+constexpr uint64_t UUID_COUNTER_MASK = 0xFFF;
+constexpr uint64_t UUID_RANDOM_MASK = 0x3FFFFFFFFFFFFFFF;
+
+// Constants for UUID version and variant
+constexpr uint8_t UUID_VERSION_8 = 8;
+constexpr uint8_t UUID_VARIANT_RFC4122 = 2;
+
+// Other constants
+constexpr uint32_t UUID_BYTE_SIZE = 16;
+constexpr uint32_t UUID_PART_SIZE = 4;
+constexpr uint32_t HEX_BASE = 16;
+constexpr uint64_t MASK_32_BITS = 0xFFFFFFFF;
+constexpr uint64_t MASK_16_BITS = 0xFFFF;
+constexpr uint64_t MASK_14_BITS = 0x3FFF;
+
+}  // namespace uprotocol::datamodel
+
+#endif  // UP_CPP_DATAMODEL_UUID_CONSTANTS_H

src/datamodel/builder/Uuid.cpp

@@ -10,3 +10,104 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #include "up-cpp/datamodel/builder/Uuid.h"
+
+#include <random>
+#include <stdexcept>
+
+#include "up-cpp/datamodel/constants/UuidConstants.h"
+
+namespace uprotocol::datamodel::builder {
+
+struct UuidBuilder::UuidSharedState {
+	std::mt19937_64 random_engine{std::random_device{}()};
+	uint16_t counter{0};
+	std::chrono::time_point<std::chrono::system_clock,
+	                        std::chrono::milliseconds>
+	    last_unix_ts_ms{};
+	uint64_t rand_b{0};
+	bool rand_b_initialized{false};
+};
+
+UuidBuilder UuidBuilder::getBuilder() { return UuidBuilder(false); }
+
+UuidBuilder UuidBuilder::getTestBuilder() { return UuidBuilder(true); }
+
+UuidBuilder& UuidBuilder::withTimeSource(
+    std::function<std::chrono::system_clock::time_point()>&& time_source) {
+	if (!testing_) {
+		throw std::domain_error(
+		    "Cannot set time source on non-test UuidBuilder");
+	}
+	time_source_ = std::move(time_source);
+	return *this;
+}
+
+UuidBuilder& UuidBuilder::withRandomSource(
+    std::function<uint64_t()>&& random_source) {
+	if (!testing_) {
+		throw std::domain_error(
+		    "Cannot set random source on non-test UuidBuilder");
+	}
+	random_source_ = std::move(random_source);
+	return *this;
+}
+
+UuidBuilder& UuidBuilder::withIndependentState() {
+	if (!testing_) {
+		throw std::domain_error(
+		    "Cannot set independent state on non-test UuidBuilder");
+	}
+	shared_state_ = std::make_shared<UuidSharedState>();
+	return *this;
+}
+
+v1::UUID UuidBuilder::build() {
+	v1::UUID uuid;
+	auto now = time_source_ ? time_source_() : std::chrono::system_clock::now();
+	auto unix_ts_ms =
+	    std::chrono::time_point_cast<std::chrono::milliseconds>(now);
+
+	if (unix_ts_ms != shared_state_->last_unix_ts_ms) {
+		// Reset the counter if the timestamp tick has changed
+		shared_state_->counter = 0;
+		shared_state_->last_unix_ts_ms = unix_ts_ms;
+	}
+
+	uint64_t msb = static_cast<uint64_t>(unix_ts_ms.time_since_epoch().count())
+	               << UUID_TIMESTAMP_SHIFT;
+	msb |= static_cast<uint64_t>(8)
+	       << UUID_VERSION_SHIFT;  // Set the version to 8
+
+	if (shared_state_->counter == 4095) {
+		// Counter has reached maximum value, freeze it
+		msb |= shared_state_->counter;
+	} else {
+		msb |= shared_state_->counter++;
+	}
+
+	uint64_t lsb;
+	if (!shared_state_->rand_b_initialized) {
+		shared_state_->rand_b = random_source_
+		                            ? random_source_()
+		                            : std::uniform_int_distribution<uint64_t>{}(
+		                                  shared_state_->random_engine) &
+		                                  UUID_RANDOM_MASK;
+		shared_state_->rand_b_initialized = true;
+	}
+	lsb = shared_state_->rand_b;
+
+	// set the Variant to 10b
+	lsb |= static_cast<uint64_t>(UUID_VARIANT_RFC4122) << UUID_VARIANT_SHIFT;
+
+	uuid.set_msb(msb);
+	uuid.set_lsb(lsb);
+	return uuid;
+}
+
+UuidBuilder::UuidBuilder(bool testing)
+    : testing_(testing),
+      time_source_(nullptr),
+      random_source_(nullptr),
+      shared_state_(std::make_shared<UuidSharedState>()) {}
+
+}  // namespace uprotocol::datamodel::builder