From 50747839d489d40ff37735a513069bc05fd44e49 Mon Sep 17 00:00:00 2001
From: Andrew Belt <andrewpbelt@gmail.com>
Date: Thu, 10 Sep 2020 17:54:39 -0400
Subject: [PATCH] Use randomly-generated 53-bit IDs for Module and Cable.

---
 include/engine/Cable.hpp  |  6 +++++-
 include/engine/Module.hpp |  3 ++-
 src/engine/Engine.cpp     | 43 ++++++++-------------------------------
 3 files changed, 15 insertions(+), 37 deletions(-)

diff --git a/include/engine/Cable.hpp b/include/engine/Cable.hpp
index 43ccaded..1fe78a59 100644
--- a/include/engine/Cable.hpp
+++ b/include/engine/Cable.hpp
@@ -8,7 +8,11 @@ namespace engine {
 
 
 struct Cable {
-	int id = -1;
+	/** Unique ID for referring to the cable in the engine.
+	Between 0 and 2^53 since this is serialized with JSON.
+	Assigned when added to the engine.
+	*/
+	int64_t id = -1;
 	Module* inputModule = NULL;
 	int inputId;
 	Module* outputModule = NULL;
diff --git a/include/engine/Module.hpp b/include/engine/Module.hpp
index e1eff9ae..26952c8a 100644
--- a/include/engine/Module.hpp
+++ b/include/engine/Module.hpp
@@ -31,9 +31,10 @@ struct Module {
 
 	plugin::Model* model = NULL;
 	/** Unique ID for referring to the module in the engine.
+	Between 0 and 2^53 since this is serialized with JSON.
 	Assigned when added to the engine.
 	*/
-	int id = -1;
+	int64_t id = -1;
 
 	/** Arrays of components.
 	Initialized with config().
diff --git a/src/engine/Engine.cpp b/src/engine/Engine.cpp
index 66331756..6d368448 100644
--- a/src/engine/Engine.cpp
+++ b/src/engine/Engine.cpp
@@ -202,10 +202,6 @@ struct Engine::Internal {
 	int stepFrames = 0;
 	Module* primaryModule = NULL;
 
-	// For generating new IDs for added objects
-	int nextModuleId = 0;
-	int nextCableId = 0;
-
 	// Parameter smoothing
 	Module* smoothModule = NULL;
 	int smoothParamId = 0;
@@ -547,9 +543,6 @@ void Engine::clear() {
 		removeModule(module);
 		delete module;
 	}
-	// Reset engine state
-	internal->nextModuleId = 0;
-	internal->nextCableId = 0;
 }
 
 
@@ -693,20 +686,10 @@ void Engine::addModule(Module* module) {
 	// Check that the module is not already added
 	auto it = std::find(internal->modules.begin(), internal->modules.end(), module);
 	assert(it == internal->modules.end());
-	// Set ID
-	if (module->id < 0) {
-		// Automatically assign ID
-		module->id = internal->nextModuleId++;
-	}
-	else {
-		// Manual ID
-		// Check that the ID is not already taken
-		auto it = internal->modulesCache.find(module->id);
-		assert(it == internal->modulesCache.end());
-		// If ID is higher than engine's next assigned ID, enlarge it.
-		if (module->id >= internal->nextModuleId) {
-			internal->nextModuleId = module->id + 1;
-		}
+	// Set ID if unset or collides with an existing ID
+	while (module->id < 0 || internal->modulesCache.find(module->id) != internal->modulesCache.end()) {
+		// Randomly generate ID
+		module->id = random::u64() % (1ul << 53);
 	}
 	// Add module
 	internal->modules.push_back(module);
@@ -846,20 +829,10 @@ void Engine::addCable(Cable* cable) {
 		if (cable2->outputModule == cable->outputModule && cable2->outputId == cable->outputId)
 			outputWasConnected = true;
 	}
-	// Set ID
-	if (cable->id < 0) {
-		// Automatically assign ID
-		cable->id = internal->nextCableId++;
-	}
-	else {
-		// Manual ID
-		// Check that the ID is not already taken
-		for (Cable* w : internal->cables) {
-			assert(cable->id != w->id);
-		}
-		if (cable->id >= internal->nextCableId) {
-			internal->nextCableId = cable->id + 1;
-		}
+	// Set ID if unset or collides with an existing ID
+	while (cable->id < 0 || internal->cablesCache.find(cable->id) != internal->cablesCache.end()) {
+		// Randomly generate ID
+		cable->id = random::u64() % (1ul << 53);
 	}
 	// Add the cable
 	internal->cables.push_back(cable);