19.8.1 Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 20 Smart Pointers 122 20.1 Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 30.2 Dereferencing Raw Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 30.3 Mutable Static Variables . . . 20 minutes, including breaks) Segment Duration Welcome 3 minutes Memory Management 1 hour Smart Pointers 55 minutes • Day 3 Afternoon (1 hour and 55 minutes, including breaks) Segment Duration Borrowing

19.8.1 Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 20 Smart Pointers 118 20.1 Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 30.2 Dereferencing Raw Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 30.3 Mutable Static Variables . . . 20 minutes, including breaks) Segment Duration Welcome 3 minutes Memory Management 1 hour Smart Pointers 55 minutes • Day 3 Afternoon (1 hour and 55 minutes, including breaks) Segment Duration Borrowing

. . . . . 383 2.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384 3 Smart Pointers 385 3.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386 3.2 . . . . . . . time. When our code calls a function, the values passed into the function (including, potentially, pointers to data on the heap) and the function’s local variables get pushed onto the stack. When the function the drop function and cleans up the heap memory for that variable. But Figure 4-4 shows both data pointers pointing to the same location. This is a problem: when s2 and s1 go out of scope, they will both

(e.g. for add_3) and Clone (e.g. multiply_sum), depending on what the closure captures. Function pointers (references to fn items) implement Copy and Fn . � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � vector � � heap � � � � � . � � � � � � vector � � � � � � � � � � � � � ) fat pointers ( � � � � � : – � � � � � � � � � � ) fat pointer ( � � � � � � � � � � � � � � � � � � � � � � and they are not accessed either through the references or / / concurrently through any other pointers . unsafe } println!("r1 � � � � � � � � : } { " , * r1 ( ; * r1 = String::from ) " � � � � "

the annotations are checked for validity by the compiler. Note that this is not the case for raw pointers (unsafe), and this is a common source of errors with unsafe Rust. Students may ask when to use block, and they are not accessed either through the references or // concurrently through any other pointers. unsafe { println!("r1 is: {}", *r1); *r1 = String::from("uhoh"); println!("r2 is: {}", *r2); count: {}", count_chars(unsafe { emojis.get_unchecked(0..7) })); // SAFETY: `abs` doesn't deal with pointers and doesn't have any safety // requirements. unsafe { println!("Absolute value of -3 according

file_operations. Contains pointer to non-constant instance of struct module. Language Const support: pointers to non-const from const Minimal example: static mut MODULE: u32 = 10; const PTR: *mut u32 = unsafe tables: ToUse /// Represents which fields of [`struct file_operations`] should be populated with pointers. pub struct ToUse { /// The `read` field of [`struct file_operations`]. pub read: bool, } This is defined by the declare_file_operations macro. It is used to define which function pointers to initialise in operations table. Language Ergonomics of implementing traits: "implement members"

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 20 Ponteiros Inteligentes (Smart Pointers) 122 20.1 Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Segment Duration Bem-vindos 3 minutes Gerenciamento de Memória 1 hour Ponteiros Inteligentes (Smart Pointers) 55 minutes • Dia 3 Tarde (1 hora and 55 minutos, incluindo intervalos) Segment Duration Empréstimo empréstimo (borrow checker): como o Rust garante a segurança da memória. • Ponteiros inteligentes (smart pointers): tipos de ponteiros da biblioteca padrão. Agenda Including 10 minute breaks, this session should

block, and they are not accessed either through the // references or concurrently through any other pointers. unsafe { println!("r1 is: {}", *r1); *r1 = String::from("uhoh"); println!("r2 is: {}", *r2); of the unsafe operations it is doing. In the case of pointer dereferences, this means that the pointers must be valid, i.e.: • The pointer must be non-null. • The pointer must be dereferenceable (within 如果您的函式必須滿足特定條件才能避免未定義的行為，您可以將其標示為 unsafe。 /// Swaps the values pointed to by the given pointers. /// /// # Safety /// /// The pointers must be valid and properly aligned. unsafe fn swap(a: *mut u8, b: *mut u8) {

block, and they are not accessed either through the // references or concurrently through any other pointers. unsafe { println!("r1 is: {}", *r1); *r1 = String::from("uhoh"); println!("r2 is: {}", *r2); of the unsafe operations it is doing. In the case of pointer dereferences, this means that the pointers must be valid, i.e.: • The pointer must be non-null. • The pointer must be dereferenceable (within 如果您的函式必須滿足特定條件才能避免未定義的行為，您可以將其標示為 unsafe。 /// Swaps the values pointed to by the given pointers. /// /// # Safety /// /// The pointers must be valid and properly aligned. unsafe fn swap(a: *mut u8, b: *mut u8) {

stealing Software Queue Issues Producer Enqueue Software Dequeue Software Head and Tail pointers Dequeue Software Dequeue Software Enqueue Software Producer Consumer Consumer Consumer Memory/Cache latency • CPU cycles latency DLB ： Dynamic Load Balance DLB Enqueue Logic Head and Tail pointers Dequeue Logic & Load Balancer Producer Producer Consumer Consumer Consumer • No Synchronization