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https://github.com/anykeyh/await_async
Provide await and async methods to Crystal Lang
https://github.com/anykeyh/await_async
concurrency crystal-language
Last synced: about 1 month ago
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Provide await and async methods to Crystal Lang
- Host: GitHub
- URL: https://github.com/anykeyh/await_async
- Owner: anykeyh
- License: mit
- Created: 2018-07-04T09:55:29.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2023-09-02T18:32:58.000Z (over 1 year ago)
- Last Synced: 2024-10-25T01:26:01.960Z (about 2 months ago)
- Topics: concurrency, crystal-language
- Language: Crystal
- Homepage: https://github.com/anykeyh/await_async
- Size: 14.6 KB
- Stars: 84
- Watchers: 4
- Forks: 4
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-crystal - await_async - Add keywords await & async in Crystal Lang (Processes and Threads)
- awesome-crystal - await_async - Add keywords await & async in Crystal Lang (Processes and Threads)
- awesome-crystal - await_async - Add keywords await & async in Crystal Lang (Processes and Threads)
README
## Await / Async
[](https://travis-ci.org/anykeyh/await_async)
Add `await` and `async` keywords to Crystal.
## Installation
In your `shards.yml`:
```yaml
dependencies:
await_async:
github: anykeyh/await_async
branch: master
```
Then:
```crystal
require "await_async"
future = async fetch_something
do_some_computation_now
await future
```
## Usage
- Call `async` on any method or block to create a `MiniFuture`
- Call `await` on any `MiniFuture` to wait for/get the result
- Conveniently, you can call `await` on future's array.
Can improve drastically application which relay on blocking IO like web API
or file writing.
### await(timeout, future)
```crystal
future = async check_website
begin
await 5.seconds, future
rescue MiniFuture::TimeoutException
# rescue from timeout
end
```
### `async!` / `async`
By default, `async!` call the newly created fiber just after creation.
- You can use instead `async` so the fiber won't start now:
```crystal
future = async! { 1 + 2 }
# At this moment the result is already computed
# future.finished? == true
await future # => 3
# vs
future = async { 1 + 2 }
# Here the result is not computed
# future.finished? == false
await future # Compute now
```
Usually, use `async` if your block is computation intensive and current thread
has IO blocking operation. Use `async!` in other cases.
In case of errors, the exception will be raise at `await` moment, in the await
thread.
## `MiniFuture`
A minimalist version of future. Has `finished?` and `running?` methods.
I don't use Crystal's `Concurrent::Future` class because `:nodoc:`.
## Why?
Because crystal is great for building CLI tools. And CLI deals a lot with
files and sockets. And IO performed in main thread are slow.
Usage of `Channel` is recommended for complex software, as it offers more patterns.
`await/async` is useful to build fast and deliver fast.
## I don't want await/async to be exported in the global scope
1. require `await_async/helper` instead of `await_async`
2. In the class/module you want to use the methods, add `include AwaitAsync::Helper`.
You can also simply call `await/async` directly from `AwaitAsync::Helper`
## Example
```crystal
def fetch_websites_async
%w[
www.github.com
www.yahoo.com
www.facebook.com
www.twitter.com
crystal-lang.org
].map do |url|
async! do
HTTP::Client.get "https://#{url}"
end
end
end
# Process the websites concurrently. Start querying another website when the
# first one is waiting for response
await(5.seconds, fetch_websites_async).each do |response|
# ...
end
```
## License
MIT