Crate slottle[−][src]
A throttle pool library designed for thread-based concurrency.
Concepts
This crate contain two primary types: ThrottlePool
and Throttle
.
Each Throttle
has it own concurrent and interval state for delaying.
On the other hand, ThrottlePool
can automatic create Throttle
when
corresponding id
first time be used. User can treat id
as some kind of
resource identity like hostname, IP address, etc.
Here is a running chart of a ThrottlePool
with concurrent
== 2
.
ThrottlePool
|
+-- Throttle (resource-1)
| |
| +-- Thread quota 1 ... run ...
| +-- Thread quota 2 ... run ...
|
+-- Throttle (resource-2)
| |
| +-- Thread quota 3 ... run ...
| +-- Thread quota 4 ... run ...
...
+-- Throttle (resource-N)
|
+-- Thread quota 2N-1 ... run ...
+-- Thread quota 2N ... run ...
If concurrent == 1
, thread quota usage may work like this:
f: assigned jobs, s: sleep function
thread 1: |f()----|s()----|f()--|s()------|f()----------------|f()-----|..........|f()--
| interval | interval | interval |...| interval |...|
^^^^^^^^^^^^^^^^^^^^^
job run longer than interval --^ ^^^^^^^^
so skip sleep() step /
/
If new job not inject into the -----------------------
"should wait interval", sleep() will not be triggered
time pass ----->
If concurrent == 2
, threads will work like this:
f: assigned jobs, s: sleep function
thread 1: |f()----|s()----|f()--|s()------|f()------------------------------|....|f()--
| interval | interval | 2x interval |......|
thread 2: ........|f()-|s()-------|f()-------|s()-|f()|s()|f()--|s|f()-|s-|f()---------
........| interval | interval | 1/2 | 1/2 | 1/2 |
^^^^^^^^^^^^^^^^^^^^^^^^^
max concurrent forced to 2 -------^
but expected value of maximux access speed is "concurrent per interval".
time pass ----->
Throttle
would not create threads, but only block current thread.
User should create threads by themself and sync throttle to all those
threads, to control access speed entirely.
User can just using Throttle
directly if not need the pool-related facility.
Examples
use rayon::prelude::*; use slottle::ThrottlePool; use std::time::{Duration, Instant}; // Make sure we have enough of threads can be blocked. // Here we use rayon as example but you can choice any thread implementation. rayon::ThreadPoolBuilder::new() .num_threads(8) .build_global() .unwrap(); // Create ThrottlePool. // // In here `id` is `bool` type for demonstration. // If you're writing a web spider, type of `id` might should be `url::Host`. let throttles: ThrottlePool<bool> = ThrottlePool::builder() .interval(Duration::from_millis(20)) // set interval to 20ms .concurrent(2) // set concurrent to 2 .build() .unwrap(); // HINT: according previous config, expected access speed is // 2 per 20ms = 1 per 10ms (in each throttle) let started_time = Instant::now(); let mut all_added_one: Vec<i32> = vec![1, 2, 3, 4, 5, 6] .into_par_iter() .map(|x| { throttles .get(x >= 5) // 5,6 in throttle `true` & 1,2,3,4 in throttle `false` .run(|| { // here is the operation we want to throttling let time_passed_ms = started_time.elapsed().as_secs_f64() * 1000.0; println!( "[throttle: {:>5}] allowed job {} to start at: {:.2}ms", x >= 5, x, time_passed_ms, ); // // you can add some long-running task to see how throttle work // std::thread::sleep(Duration::from_millis(40)); x + 1 }) }) .collect(); assert_eq!(all_added_one, vec![2, 3, 4, 5, 6, 7]);
Output:
[throttle: false] allowed job 1 to start at: 0.09ms
[throttle: true] allowed job 6 to start at: 0.10ms
[throttle: false] allowed job 4 to start at: 10.40ms
[throttle: true] allowed job 5 to start at: 10.42ms
[throttle: false] allowed job 3 to start at: 20.12ms
[throttle: false] allowed job 2 to start at: 30.12ms
Crate Naming
Crate name slottle
is the abbr of “slotted throttle”. Which is the original name of ThrottlePool
.
Structs
Interval | The interval configuration. |
Throttle | Limiting resource access speed by interval and concurrent. |
ThrottleBuilder | Use to build a |
ThrottleLog | Collect operation log of a |
ThrottlePool | A |
ThrottlePoolBuilder | Use to build a |
Enums
RetryableResult | The result type for |
Functions
fibonacci | Create fibonacci delay interval base on failure count. |