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Mostly corrections to conjugation.

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James Robb
2020-05-19 10:28:27 +00:00
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src/1_futures_in_rust.md
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@@ -18,7 +18,7 @@ future.
Async in Rust uses a `Poll` based approach, in which an asynchronous task will Async in Rust uses a `Poll` based approach, in which an asynchronous task will
have three phases. have three phases.
1. **The Poll phase.** A Future is polled which result in the task progressing until 1. **The Poll phase.** A Future is polled which results in the task progressing until
a point where it can no longer make progress. We often refer to the part of the a point where it can no longer make progress. We often refer to the part of the
runtime which polls a Future as an executor. runtime which polls a Future as an executor.
2. **The Wait phase.** An event source, most often referred to as a reactor, 2. **The Wait phase.** An event source, most often referred to as a reactor,
@@ -35,7 +35,7 @@ pretty different from one another.
### Leaf futures ### Leaf futures
Runtimes create _leaf futures_ which represents a resource like a socket. Runtimes create _leaf futures_ which represent a resource like a socket.
```rust, ignore, noplaypen ```rust, ignore, noplaypen
// stream is a **leaf-future** // stream is a **leaf-future**
@@ -54,7 +54,7 @@ completion alone as you'll understand by reading the next paragraph.
### Non-leaf-futures ### Non-leaf-futures
Non-leaf-futures is the kind of futures we as _users_ of a runtime write Non-leaf-futures are the kind of futures we as _users_ of a runtime write
ourselves using the `async` keyword to create a **task** which can be run on the ourselves using the `async` keyword to create a **task** which can be run on the
executor. executor.
@@ -76,30 +76,30 @@ let non_leaf = async {
The key to these tasks is that they're able to yield control to the runtime's The key to these tasks is that they're able to yield control to the runtime's
scheduler and then resume execution again where it left off at a later point. scheduler and then resume execution again where it left off at a later point.
In contrast to leaf futures, these kind of futures does not themselves represent In contrast to leaf futures, these kind of futures do not themselves represent
an I/O resource. When we poll these futures we either run some code or we yield an I/O resource. When we poll these futures we either run some code or we yield
to the scheduler while waiting for some resource to signal us that it's ready so to the scheduler while waiting for some resource to signal us that it's ready so
we can resume where we left off. we can resume where we left off.
## Runtimes ## Runtimes
Languages like C#, JavaScript, Java, GO and many others comes with a runtime Languages like C#, JavaScript, Java, GO, and many others comes with a runtime
for handling concurrency. So if you come from one of those languages this will for handling concurrency. So if you come from one of those languages this will
seem a bit strange to you. seem a bit strange to you.
Rust is different from these languages in the sense that Rust doesn't come with Rust is different from these languages in the sense that Rust doesn't come with
a runtime for handling concurrency, so you need to use a library which provide a runtime for handling concurrency, so you need to use a library which provides
this for you. this for you.
Quite a bit of complexity attributed to Futures is actually complexity rooted Quite a bit of complexity attributed to Futures is actually complexity rooted
in runtimes. Creating an efficient runtime is hard. in runtimes; creating an efficient runtime is hard.
Learning how to use one correctly requires quite a bit of effort as well, but Learning how to use one correctly requires quite a bit of effort as well, but
you'll see that there are several similarities between these kind of runtimes so you'll see that there are several similarities between these kind of runtimes, so
learning one makes learning the next much easier. learning one makes learning the next much easier.
The difference between Rust and other languages is that you have to make an The difference between Rust and other languages is that you have to make an
active choice when it comes to picking a runtime. Most often, in other languages active choice when it comes to picking a runtime. Most often in other languages,
you'll just use the one provided for you. you'll just use the one provided for you.
**An async runtime can be divided into two parts:** **An async runtime can be divided into two parts:**
@@ -125,10 +125,10 @@ The two most popular runtimes for Futures as of writing this is:
future through the `Future` trait. future through the `Future` trait.
2. An ergonomic way of creating tasks which can be suspended and resumed through 2. An ergonomic way of creating tasks which can be suspended and resumed through
the `async` and `await` keywords. the `async` and `await` keywords.
3. A defined interface wake up a suspended task through the `Waker` type. 3. A defined interface to wake up a suspended task through the `Waker` type.
That's really what Rusts standard library does. As you see there is no definition That's really what Rusts standard library does. As you see there is no definition
of non-blocking I/O, how these tasks are created or how they're run. of non-blocking I/O, how these tasks are created, or how they're run.
## I/O vs CPU intensive tasks ## I/O vs CPU intensive tasks
@@ -185,19 +185,19 @@ to the thread-pool most runtimes provide.
Most executors have a way to accomplish #1 using methods like `spawn_blocking`. Most executors have a way to accomplish #1 using methods like `spawn_blocking`.
These methods send the task to a thread-pool created by the runtime where you These methods send the task to a thread-pool created by the runtime where you
can either perform CPU-intensive tasks or "blocking" tasks which is not supported can either perform CPU-intensive tasks or "blocking" tasks which are not supported
by the runtime. by the runtime.
Now, armed with this knowledge you are already on a good way for understanding Now, armed with this knowledge you are already on a good way for understanding
Futures, but we're not gonna stop yet, there is lots of details to cover. Futures, but we're not gonna stop yet, there are lots of details to cover.
Take a break or a cup of coffe and get ready as we go for a deep dive in the next chapters. Take a break or a cup of coffee and get ready as we go for a deep dive in the next chapters.
## Bonus section ## Bonus section
If you find the concepts of concurrency and async programming confusing in If you find the concepts of concurrency and async programming confusing in
general, I know where you're coming from and I have written some resources to general, I know where you're coming from and I have written some resources to
try to give a high level overview that will make it easier to learn Rusts try to give a high-level overview that will make it easier to learn Rusts
Futures afterwards: Futures afterwards:
* [Async Basics - The difference between concurrency and parallelism](https://cfsamson.github.io/book-exploring-async-basics/1_concurrent_vs_parallel.html) * [Async Basics - The difference between concurrency and parallelism](https://cfsamson.github.io/book-exploring-async-basics/1_concurrent_vs_parallel.html)