WIP: withUndefinedBehavior block

Author: Prinzhorn

docs/api.md

@@ -15,6 +15,7 @@
 - [Database#aggregate()](#aggregatename-options---this)
 - [Database#loadExtension()](#loadextensionpath---this)
 - [Database#exec()](#execstring---this)
+- [Database#withUndefinedBehavior()](#withUndefinedBehaviorfunction---this)
 - [Database#close()](#close---this)
 - [Properties](#properties)
 
@@ -263,6 +264,18 @@ const migration = fs.readFileSync('migrate-schema.sql', 'utf8');
 db.exec(migration);
 ```
 
+### .withUndefinedBehavior(*function*) -> *this*
+
+Immediately synchronously executes the given function. Inside the function operations with potentially undefined behavior (as defined by the SQLite documentation) are allowed. This means certain sanity checks that better-sqlite3 performs are disabled. For example doing writes inside an iterator or executing statements inside the implementation of a user-defined function.
+
+Only use `withUndefinedBehavior` if you absolutely know what you are doing. Use it as low as possible in your call chain to only cover the absolute minimum number of operations you need to do.
+
+```js
+db.withUndefinedBehavior(() => {
+  // TODO: docs
+});
+```
+
 ### .close() -> *this*
 
 Closes the database connection. After invoking this method, no statements can be created or executed.

src/objects/database.lzz

@@ -55,6 +55,7 @@ public:
 		const bool safe_ints;
 		bool was_js_error;
 		unsigned short iterators;
+		unsigned short undefinedBehaviorBlocks;
 	};
 
 	inline State* GetState() {
@@ -98,6 +99,7 @@ private:
 		was_js_error(false),
 		has_logger(_logger->IsFunction()),
 		iterators(0),
+		undefinedBehaviorBlocks(0),
 		logger(isolate, _logger),
 		stmts(),
 		backups() {
@@ -118,6 +120,7 @@ private:
 		NODE_SET_PROTOTYPE_METHOD(t, "function", JS_function);
 		NODE_SET_PROTOTYPE_METHOD(t, "aggregate", JS_aggregate);
 		NODE_SET_PROTOTYPE_METHOD(t, "loadExtension", JS_loadExtension);
+		NODE_SET_PROTOTYPE_METHOD(t, "withUndefinedBehavior", JS_withUndefinedBehavior);
 		NODE_SET_PROTOTYPE_METHOD(t, "close", JS_close);
 		NODE_SET_PROTOTYPE_METHOD(t, "defaultSafeIntegers", JS_defaultSafeIntegers);
 		NODE_SET_PROTOTYPE_GETTER(t, "open", JS_open);
@@ -183,8 +186,8 @@ private:
 		Database* db = Unwrap<Database>(info.This());
 		REQUIRE_ARGUMENT_STRING(first, v8::Local<v8::String> source);
 		REQUIRE_DATABASE_OPEN(db);
-		REQUIRE_DATABASE_NOT_BUSY(db);
-		REQUIRE_DATABASE_NO_ITERATORS(db);
+		PREFER_DATABASE_NOT_BUSY(db);
+		PREFER_DATABASE_NO_ITERATORS(db);
 		db->busy = true;
 		UseIsolate;
 		if (db->Log(isolate, source)) {
@@ -318,6 +321,18 @@ private:
 		sqlite3_free(error);
 	}
 
+	NODE_METHOD(JS_withUndefinedBehavior) {
+		Database* db = Unwrap<Database>(info.This());
+		REQUIRE_ARGUMENT_FUNCTION(first, v8::Local<v8::Function> fn);
+		assert(db->undefinedBehaviorBlocks < USHRT_MAX);
+		db->undefinedBehaviorBlocks += 1;
+		UseIsolate;
+		v8::Local<v8::Function>::Cast(v8::Local<v8::Value>::New(isolate, fn))
+					->Call(OnlyContext, v8::Undefined(isolate), 0, NULL);
+		assert(db->undefinedBehaviorBlocks > 0);
+		db->undefinedBehaviorBlocks -= 1;
+	}
+
 	NODE_METHOD(JS_close) {
 		Database* db = Unwrap<Database>(info.This());
 		if (db->open) {
@@ -375,6 +390,7 @@ private:
 	bool was_js_error;
 	const bool has_logger;
 	unsigned short iterators;
+	unsigned short undefinedBehaviorBlocks;
 	const CopyablePersistent<v8::Value> logger;
 	std::set<Statement*, Database::CompareStatement> stmts;
 	std::set<Backup*, Database::CompareBackup> backups;

src/objects/statement-iterator.lzz

@@ -68,14 +68,14 @@ private:
 
 	NODE_METHOD(JS_next) {
 		StatementIterator* iter = Unwrap<StatementIterator>(info.This());
-		REQUIRE_DATABASE_NOT_BUSY(iter->db_state);
+		PREFER_DATABASE_NOT_BUSY(iter->db_state);
 		if (iter->alive) iter->Next(info);
 		else info.GetReturnValue().Set(DoneRecord(OnlyIsolate));
 	}
 
 	NODE_METHOD(JS_return) {
 		StatementIterator* iter = Unwrap<StatementIterator>(info.This());
-		REQUIRE_DATABASE_NOT_BUSY(iter->db_state);
+		PREFER_DATABASE_NOT_BUSY(iter->db_state);
 		if (iter->alive) iter->Return(info);
 		else info.GetReturnValue().Set(DoneRecord(OnlyIsolate));
 	}

src/util/macros.lzz

@@ -63,9 +63,15 @@ void ThrowRangeError(const char* message) { EasyIsolate; isolate->ThrowException
 #define REQUIRE_DATABASE_NOT_BUSY(db)                                          \
 	if (db->busy)                                                              \
 		return ThrowTypeError("This database connection is busy executing a query")
+#define PREFER_DATABASE_NOT_BUSY(db)                                          \
+	if (db->busy && !db->undefinedBehaviorBlocks)                              \
+		return ThrowTypeError("This database connection is busy executing a query")
 #define REQUIRE_DATABASE_NO_ITERATORS(db)                                      \
 	if (db->iterators)                                                         \
 		return ThrowTypeError("This database connection is busy executing a query")
+#define PREFER_DATABASE_NO_ITERATORS(db)                                      \
+	if (db->iterators && !db->undefinedBehaviorBlocks)                         \
+		return ThrowTypeError("This database connection is busy executing a query")
 #define REQUIRE_STATEMENT_NOT_LOCKED(stmt)                                     \
 	if (stmt->locked)                                                          \
 		return ThrowTypeError("This statement is busy executing a query")

src/util/query-macros.lzz

@@ -21,7 +21,7 @@
 	sqlite3_stmt* handle = stmt->handle;                                       \
 	Database* db = stmt->db;                                                   \
 	REQUIRE_DATABASE_OPEN(db->GetState());                                     \
-	REQUIRE_DATABASE_NOT_BUSY(db->GetState());                                 \
+	PREFER_DATABASE_NOT_BUSY(db->GetState());                                  \
 	MUTATE_CHECK();                                                            \
 	const bool bound = stmt->bound;                                            \
 	if (!bound) {                                                              \