If this is your first Rust programming book, I warmly thank you for your enthusiasm, but encourage you to seek out a suitable introduction to the programming language. This book will hit the ground running, and it will likely not be appropriate if you've got questions about the basics. The Rust community has produced excellent documentation, including introductory texts. The Book (https://doc.rust-lang.org/book/first-edition/), first edition, is how many who are already in the community learned the language. The second edition of the book, still in progress at the time of writing, looks to be an improvement over the original text, and it is also recommended. There are many other excellent introductions widely available for purchase, as well.

The material that this book covers is very broad, and it attempts to go into that material at some depth. The material is written so that you can work straight through, but it's also expected that some readers will only be interested in a subset of the content.

Chapter 1, Preliminaries – Machine Architecture and Getting Started with Rust, discusses modern CPU architectures, focusing specifically on x86 and ARM. These two architectures will be the focus of the book. The reader is assumed to be familiar with Rust, but we will also discuss verifying that your installation works as expected.

Chapter 2, Sequential Rust Performance and Testing, introduces inspecting the performance of a Rust program. The details of the underlying computer hardware are especially important in this: cache interactions, memory layout, and exploiting the nature of the problem domain are key to writing fast programs. However, fast doesn't matter if the results are inaccurate. This chapter also focuses on testing in Rust.

Chapter 3, The Rust Memory Model – Ownership, References and Manipulation, discusses the memory model of Rust, focusing specifically on what makes Rust memory safe, how the language is constrained to achieve such safety and how these constraints influence the fundamental types' implementations. The reader will understand the borrow checker and its ways at the close of this chapter.

Chapter 4, Sync and Send – the Foundation of Rust Concurrency, is the first in which notions of concurrency make their appearance. The chapter discusses the Sync and Send traits, both why they exist and their implications. The chapter closes with a concrete demonstration of a multithreaded Rust program. Not the last, either.

Chapter 5, Locks – Mutex, Condvar, Barriers and RWLock, introduces the coarse synchronization methods available to the Rust programmer. Each is examined in turn and demonstrated in context of an industrial Rust project, hopper. The coarse synchronization methods are elaborated on in more detail in a series of smaller projects and data structures.

Chapter 6, Atomics – the Primitives of Synchronization, introduces fine synchronization in terms of atomic primitives available on all modern CPUs. This is an exceedingly difficult topic, and a deep investigation into atomic programming and its methods is carried out. The chapter lock-free, atomic data structures, and production-grade codebases. The reader will construct many of the coarse synchronization mechanisms seen in Chapter 5, Locks – Mutex, Condvar, Barriers and RWLock.

Chapter 7, Atomics – Safely Reclaiming Memory, discusses at length one of the key difficulties of atomic programming in any language—safely deallocating memory. The main three methods—reference counting, hazard pointers, epoch-based reclamation—are each discussed in great detail, and production-worthy codebases are investigated. Crossbeam, especially, is discussed in great detail.

Chapter 8, High-Level Parallelism – Threadpools, Parallel Iterators and Processes, motivates and explains the implementation of thread pooling. Having this knowledge in hand, the Rayon project is investigated and subsequently used in a complex project that benefits greatly from simple data parallelism.

Chapter 9, FFI and Embedding – Combining Rust and Other Languages, extends the final project of Chapter 8, High-Level Parallelism – Threadpools, Parallel Iterators, and Processes by embedding C code into it. The rlua project, a convenient library to extend Rust programs with lua programs, is discussed. The chapter closes by compiling Rust for embedding into C, Python, and Erlang projects.

Chapter 10, Futurism – Near-Term Rust, closes the book with a discussion of the near-term changes to the language that are apropos to parallel programmers, as well as a few miscellaneous remarks.

This book covers a deep topic in a relatively short space. Throughout the text, the reader is expected to be comfortable with the Rust programming language, have access to a Rust compiler and a computer on which to compile, and execute Rust programs. What additional software appears in this book is covered in Chapter 1, Preliminaries – Machine Architecture and Getting Started with Rust, and it is recommended for use but not mandatory. 

The basic premise of this book is as follows—parallel programming is difficult but not impossible. Parallel programming can be done, and done well, when attention is paid to the computing environment and care is put into the validation of the produced program. To that end, each chapter has been written with an eye toward imparting a solid foundation to the reader of the chapter's subject. Once a chapter is digested, the reader will, hopefully, have a solid path into the existing body of literature on that subject. In that, this is a book of beginnings, not ends. 

I strongly encourage the reader to take an active role in reading this book, download the source code, investigate the projects as you read through independent of the book's take, and probe the running programs with the tools available on your operating system. Like anything else, parallel programming ability is a skill that is acquired and honed by practice. 

One final note—allow the process of learning to proceed at its own pace. If one chapter's subject doesn't immediately settle in your mind, that's okay. For me, the process of writing the book was a confluence of flashes of insight and knowledge that unfolded slowly like a flower. I imagine that the process of reading the book will proceed analogously. 

fn main() {
    println!("Apollo is the name of a space program but also my dog.");
}

> cat hello.rs
fn main() {
 println!("Apollo is the name of a space program but also my dog.");
}
> rustc -C opt-level=2 hello.rs
> ./hello
Apollo is the name of a space program but also my dog.

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