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https://github.com/cloud-hypervisor/cloud-hypervisor.git
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c71da496c0
Add a 'rate_limiter/group' module that defines the RateLimiterGroup and a RateLimiterGroupHandle types. The RateLimiterGroupHandle can be used in place of a RateLimiter to limit the aggregate bandwidth and/or ops of multiple virtio-blk or virtio-net queues. Each RateLimiterGroup has an associated worker thread that broadcasts an event to each RateLimiterGroupHandle when a RateLimiter is unblocked. Signed-off-by: Thomas Barrett <tbarrett@crusoeenergy.com>
527 lines
19 KiB
Rust
527 lines
19 KiB
Rust
// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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// SPDX-License-Identifier: Apache-2.0
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//
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// Copyright 2023 Crusoe Energy Systems LLC
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// SPDX-License-Identifier: Apache-2.0
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use crate::{RateLimiter, TokenType};
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use core::panic::AssertUnwindSafe;
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use std::fs::File;
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use std::io;
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use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
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use std::result;
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use std::sync::{Arc, Mutex};
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use std::thread;
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use thiserror::Error;
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use vmm_sys_util::eventfd::EventFd;
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/// Errors associated with rate-limiter group.
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#[derive(Debug, Error)]
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pub enum Error {
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/// Cannot create thread
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#[error("Error spawning rate-limiter thread {0}")]
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ThreadSpawn(#[source] io::Error),
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/// Cannot create epoll context.
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#[error("Error creating epoll context: {0}")]
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Epoll(#[source] io::Error),
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/// Cannot create EventFd.
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#[error("Error creating EventFd: {0}")]
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EventFd(#[source] io::Error),
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/// Cannot create RateLimiter.
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#[error("Error creating RateLimiter: {0}")]
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RateLimiter(#[source] io::Error),
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/// Cannot read from EventFd.
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#[error("Error reading from EventFd: {0}")]
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EventFdRead(#[source] io::Error),
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/// Cannot write to EventFd.
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#[error("Error writing to EventFd: {0}")]
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EventFdWrite(#[source] io::Error),
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}
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/// The RateLimiterGroupHandle is a handle to a RateLimiterGroup that may be
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/// used in exactly the same way as the RateLimiter type. When the RateLimiter
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/// within a RateLimiterGroup is unblocked, each RateLimiterGroupHandle will
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/// be notified.
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pub struct RateLimiterGroupHandle {
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eventfd: Arc<EventFd>,
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inner: Arc<RateLimiterGroupInner>,
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}
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impl RateLimiterGroupHandle {
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fn new(inner: Arc<RateLimiterGroupInner>) -> result::Result<Self, Error> {
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let eventfd = Arc::new(EventFd::new(0).map_err(Error::EventFd)?);
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inner.handles.lock().unwrap().push(eventfd.clone());
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Ok(Self { eventfd, inner })
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}
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/// Attempts to consume tokens and returns whether that is possible.
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///
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/// If rate limiting is disabled on provided `token_type`, this function will always succeed.
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pub fn consume(&self, tokens: u64, token_type: TokenType) -> bool {
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self.inner.rate_limiter.consume(tokens, token_type)
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}
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/// Adds tokens of `token_type` to their respective bucket.
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///
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/// Can be used to *manually* add tokens to a bucket. Useful for reverting a
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/// `consume()` if needed.
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pub fn manual_replenish(&self, tokens: u64, token_type: TokenType) {
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self.inner.rate_limiter.manual_replenish(tokens, token_type)
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}
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/// This function needs to be called every time there is an event on the
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/// FD provided by this object's `AsRawFd` trait implementation.
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///
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/// # Errors
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///
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/// If the rate limiter is disabled or is not blocked, an error is returned.
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pub fn event_handler(&self) -> Result<(), Error> {
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self.eventfd.read().map_err(Error::EventFdRead).map(|_| ())
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}
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/// Returns whether this rate limiter is blocked.
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///
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/// The limiter 'blocks' when a `consume()` operation fails because there was not enough
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/// budget for it.
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/// An event will be generated on the exported FD when the limiter 'unblocks'.
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pub fn is_blocked(&self) -> bool {
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self.inner.rate_limiter.is_blocked()
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}
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}
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impl Clone for RateLimiterGroupHandle {
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fn clone(&self) -> Self {
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RateLimiterGroupHandle::new(self.inner.clone()).unwrap()
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}
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}
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impl AsRawFd for RateLimiterGroupHandle {
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fn as_raw_fd(&self) -> RawFd {
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self.eventfd.as_raw_fd()
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}
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}
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impl Drop for RateLimiterGroupHandle {
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fn drop(&mut self) {
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let mut handles = self.inner.handles.lock().unwrap();
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let index = handles
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.iter()
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.position(|handle| handle.as_raw_fd() == self.eventfd.as_raw_fd())
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.expect("RateLimiterGroupHandle must be subscribed to RateLimiterGroup");
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handles.remove(index);
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}
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}
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struct RateLimiterGroupInner {
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id: String,
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rate_limiter: RateLimiter,
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handles: Mutex<Vec<Arc<EventFd>>>,
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}
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/// A RateLimiterGroup is an extension of RateLimiter that enables rate-limiting
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/// the aggregate io consumption of multiple consumers.
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pub struct RateLimiterGroup {
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inner: Arc<RateLimiterGroupInner>,
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epoll_file: File,
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kill_evt: EventFd,
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epoll_thread: Option<thread::JoinHandle<()>>,
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[repr(u64)]
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enum EpollDispatch {
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Kill = 1,
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Unblocked = 2,
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Unknown,
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}
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impl From<u64> for EpollDispatch {
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fn from(v: u64) -> Self {
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use EpollDispatch::*;
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match v {
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1 => Kill,
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2 => Unblocked,
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_ => Unknown,
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}
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}
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}
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impl RateLimiterGroup {
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/// Create a new RateLimiterGroup.
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pub fn new(
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id: &str,
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bytes_total_capacity: u64,
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bytes_one_time_burst: u64,
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bytes_complete_refill_time_ms: u64,
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ops_total_capacity: u64,
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ops_one_time_burst: u64,
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ops_complete_refill_time_ms: u64,
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) -> result::Result<Self, Error> {
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let rate_limiter = RateLimiter::new(
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bytes_total_capacity,
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bytes_one_time_burst,
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bytes_complete_refill_time_ms,
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ops_total_capacity,
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ops_one_time_burst,
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ops_complete_refill_time_ms,
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)
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.map_err(Error::RateLimiter)?;
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let epoll_fd = epoll::create(true).map_err(Error::Epoll)?;
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let kill_evt = EventFd::new(0).map_err(Error::EventFd)?;
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epoll::ctl(
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epoll_fd,
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epoll::ControlOptions::EPOLL_CTL_ADD,
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kill_evt.as_raw_fd(),
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epoll::Event::new(epoll::Events::EPOLLIN, EpollDispatch::Kill as u64),
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)
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.map_err(Error::Epoll)?;
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epoll::ctl(
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epoll_fd,
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epoll::ControlOptions::EPOLL_CTL_ADD,
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rate_limiter.as_raw_fd(),
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epoll::Event::new(epoll::Events::EPOLLIN, EpollDispatch::Unblocked as u64),
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)
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.map_err(Error::Epoll)?;
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// Use 'File' to enforce closing on 'epoll_fd'
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// SAFETY: epoll_fd is valid
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let epoll_file = unsafe { File::from_raw_fd(epoll_fd) };
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Ok(Self {
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inner: Arc::new(RateLimiterGroupInner {
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id: id.to_string(),
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rate_limiter,
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handles: Mutex::new(Vec::new()),
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}),
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epoll_file,
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kill_evt,
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epoll_thread: None,
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})
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}
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/// Create a new RateLimiterGroupHandle.
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pub fn new_handle(&self) -> result::Result<RateLimiterGroupHandle, Error> {
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RateLimiterGroupHandle::new(self.inner.clone())
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}
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/// Start a worker thread to broadcast an event to each RateLimiterGroupHandle
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/// when the RateLimiter becomes unblocked.
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pub fn start_thread(&mut self, exit_evt: EventFd) -> result::Result<(), Error> {
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let inner = self.inner.clone();
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let epoll_fd = self.epoll_file.as_raw_fd();
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thread::Builder::new()
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.name(format!("rate-limit-group-{}", inner.id))
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.spawn(move || {
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let res = std::panic::catch_unwind(AssertUnwindSafe(move || {
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const EPOLL_EVENTS_LEN: usize = 2;
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let mut events =
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[epoll::Event::new(epoll::Events::empty(), 0); EPOLL_EVENTS_LEN];
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loop {
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let num_events = match epoll::wait(epoll_fd, -1, &mut events[..]) {
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Ok(res) => res,
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Err(e) => {
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if e.kind() == io::ErrorKind::Interrupted {
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continue;
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} else {
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return Err(Error::Epoll(e));
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}
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}
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};
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for event in events.iter().take(num_events) {
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let dispatch_event: EpollDispatch = event.data.into();
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match dispatch_event {
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EpollDispatch::Unknown => {
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let event = event.data;
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warn!("Unknown rate-limiter loop event: {}", event);
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}
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EpollDispatch::Unblocked => {
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inner.rate_limiter.event_handler().unwrap();
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let handles = inner.handles.lock().unwrap();
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for handle in handles.iter() {
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handle.write(1).map_err(Error::EventFdWrite)?
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}
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}
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EpollDispatch::Kill => {
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info!(
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"KILL_EVENT received, stopping rate-limit-group epoll loop"
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);
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return Ok(());
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}
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}
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}
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}
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}));
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match res {
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Ok(res) => {
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if let Err(e) = res {
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error!("Error running rate-limit-group worker: {:?}", e);
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exit_evt.write(1).unwrap();
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}
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}
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Err(_) => {
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error!("rate-limit-group worker panicked");
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exit_evt.write(1).unwrap();
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}
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};
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})
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.map(|thread| self.epoll_thread.insert(thread))
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.map_err(Error::ThreadSpawn)?;
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Ok(())
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}
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}
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impl Drop for RateLimiterGroup {
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fn drop(&mut self) {
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self.kill_evt.write(1).unwrap();
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if let Some(t) = self.epoll_thread.take() {
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if let Err(e) = t.join() {
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error!("Error joining thread: {:?}", e);
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}
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}
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}
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}
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#[cfg(test)]
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pub(crate) mod tests {
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use super::RateLimiterGroupHandle;
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use crate::{group::RateLimiterGroup, TokenBucket, TokenType, REFILL_TIMER_INTERVAL_MS};
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use std::{os::fd::AsRawFd, thread, time::Duration};
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use vmm_sys_util::eventfd::EventFd;
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impl RateLimiterGroupHandle {
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pub fn bandwidth(&self) -> Option<TokenBucket> {
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let guard = self.inner.rate_limiter.inner.lock().unwrap();
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guard.bandwidth.clone()
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}
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pub fn ops(&self) -> Option<TokenBucket> {
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let guard = self.inner.rate_limiter.inner.lock().unwrap();
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guard.ops.clone()
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}
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}
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#[test]
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fn test_rate_limiter_group_new() {
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let l = RateLimiterGroup::new("test", 1000, 1001, 1002, 1003, 1004, 1005).unwrap();
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let h = l.new_handle().unwrap();
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let bw = h.bandwidth().unwrap();
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assert_eq!(bw.capacity(), 1000);
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assert_eq!(bw.one_time_burst(), 1001);
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assert_eq!(bw.refill_time_ms(), 1002);
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assert_eq!(bw.budget(), 1000);
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let ops = h.ops().unwrap();
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assert_eq!(ops.capacity(), 1003);
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assert_eq!(ops.one_time_burst(), 1004);
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assert_eq!(ops.refill_time_ms(), 1005);
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assert_eq!(ops.budget(), 1003);
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}
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#[test]
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fn test_rate_limiter_group_manual_replenish() {
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// rate limiter with limit of 1000 bytes/s and 1000 ops/s
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let l = RateLimiterGroup::new("test", 1000, 0, 1000, 1000, 0, 1000).unwrap();
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let h = l.new_handle().unwrap();
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// consume 123 bytes
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assert!(h.consume(123, TokenType::Bytes));
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h.manual_replenish(23, TokenType::Bytes);
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{
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let bytes_tb = h.bandwidth().unwrap();
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assert_eq!(bytes_tb.budget(), 900);
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}
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// consume 123 ops
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assert!(h.consume(123, TokenType::Ops));
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h.manual_replenish(23, TokenType::Ops);
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{
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let bytes_tb = h.ops().unwrap();
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assert_eq!(bytes_tb.budget(), 900);
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}
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}
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#[test]
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fn test_rate_limiter_group_bandwidth() {
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// rate limiter with limit of 1000 bytes/s
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let mut l = RateLimiterGroup::new("test", 1000, 0, 1000, 0, 0, 0).unwrap();
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l.start_thread(EventFd::new(0).unwrap()).unwrap();
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let h = l.new_handle().unwrap();
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// limiter should not be blocked
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assert!(!h.is_blocked());
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// raw FD for this disabled should be valid
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assert!(h.as_raw_fd() > 0);
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// ops/s limiter should be disabled so consume(whatever) should work
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assert!(h.consume(u64::max_value(), TokenType::Ops));
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// do full 1000 bytes
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assert!(h.consume(1000, TokenType::Bytes));
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// try and fail on another 100
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assert!(!h.consume(100, TokenType::Bytes));
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// since consume failed, limiter should be blocked now
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assert!(h.is_blocked());
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// wait half the timer period
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thread::sleep(Duration::from_millis(REFILL_TIMER_INTERVAL_MS / 2));
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// limiter should still be blocked
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assert!(h.is_blocked());
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// wait the other half of the timer period
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thread::sleep(Duration::from_millis(REFILL_TIMER_INTERVAL_MS / 2));
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// the timer_fd should have an event on it by now
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assert!(h.event_handler().is_ok());
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// limiter should now be unblocked
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assert!(!h.is_blocked());
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// try and succeed on another 100 bytes this time
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assert!(h.consume(100, TokenType::Bytes));
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}
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#[test]
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fn test_rate_limiter_group_ops() {
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// rate limiter with limit of 1000 ops/s
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let mut l = RateLimiterGroup::new("test", 0, 0, 0, 1000, 0, 1000).unwrap();
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l.start_thread(EventFd::new(0).unwrap()).unwrap();
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let h = l.new_handle().unwrap();
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// limiter should not be blocked
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assert!(!h.is_blocked());
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// raw FD for this disabled should be valid
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assert!(h.as_raw_fd() > 0);
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// bytes/s limiter should be disabled so consume(whatever) should work
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assert!(h.consume(u64::max_value(), TokenType::Bytes));
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// do full 1000 ops
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assert!(h.consume(1000, TokenType::Ops));
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// try and fail on another 100
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assert!(!h.consume(100, TokenType::Ops));
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// since consume failed, limiter should be blocked now
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assert!(h.is_blocked());
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// wait half the timer period
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thread::sleep(Duration::from_millis(REFILL_TIMER_INTERVAL_MS / 2));
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// limiter should still be blocked
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assert!(h.is_blocked());
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// wait the other half of the timer period
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thread::sleep(Duration::from_millis(REFILL_TIMER_INTERVAL_MS / 2));
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// the timer_fd should have an event on it by now
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assert!(h.event_handler().is_ok());
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// limiter should now be unblocked
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assert!(!h.is_blocked());
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// try and succeed on another 100 ops this time
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assert!(h.consume(100, TokenType::Ops));
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}
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#[test]
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fn test_rate_limiter_group_full() {
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// rate limiter with limit of 1000 bytes/s and 1000 ops/s
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let mut l = RateLimiterGroup::new("test", 1000, 0, 1000, 1000, 0, 1000).unwrap();
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l.start_thread(EventFd::new(0).unwrap()).unwrap();
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let h = l.new_handle().unwrap();
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// limiter should not be blocked
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assert!(!h.is_blocked());
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// raw FD for this disabled should be valid
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assert!(h.as_raw_fd() > 0);
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// do full 1000 bytes
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assert!(h.consume(1000, TokenType::Ops));
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// do full 1000 bytes
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assert!(h.consume(1000, TokenType::Bytes));
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// try and fail on another 100 ops
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assert!(!h.consume(100, TokenType::Ops));
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// try and fail on another 100 bytes
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assert!(!h.consume(100, TokenType::Bytes));
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// since consume failed, limiter should be blocked now
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assert!(h.is_blocked());
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// wait half the timer period
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thread::sleep(Duration::from_millis(REFILL_TIMER_INTERVAL_MS / 2));
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// limiter should still be blocked
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assert!(h.is_blocked());
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// wait the other half of the timer period
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thread::sleep(Duration::from_millis(REFILL_TIMER_INTERVAL_MS / 2));
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// the timer_fd should have an event on it by now
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assert!(h.event_handler().is_ok());
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// limiter should now be unblocked
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assert!(!h.is_blocked());
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// try and succeed on another 100 ops this time
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assert!(h.consume(100, TokenType::Ops));
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// try and succeed on another 100 bytes this time
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assert!(h.consume(100, TokenType::Bytes));
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}
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#[test]
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fn test_rate_limiter_group_overconsumption() {
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// initialize the rate limiter
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let mut l = RateLimiterGroup::new("test", 1000, 0, 1000, 1000, 0, 1000).unwrap();
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l.start_thread(EventFd::new(0).unwrap()).unwrap();
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let h = l.new_handle().unwrap();
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// try to consume 2.5x the bucket size
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// we are "borrowing" 1.5x the bucket size in tokens since
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// the bucket is full
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assert!(h.consume(2500, TokenType::Bytes));
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// check that even after a whole second passes, the rate limiter
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// is still blocked
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|
thread::sleep(Duration::from_millis(1000));
|
|
assert!(h.is_blocked());
|
|
|
|
// after 1.5x the replenish time has passed, the rate limiter
|
|
// is available again
|
|
thread::sleep(Duration::from_millis(500));
|
|
assert!(h.event_handler().is_ok());
|
|
assert!(!h.is_blocked());
|
|
|
|
// reset the rate limiter
|
|
let mut l = RateLimiterGroup::new("test", 1000, 0, 1000, 1000, 0, 1000).unwrap();
|
|
l.start_thread(EventFd::new(0).unwrap()).unwrap();
|
|
|
|
let h = l.new_handle().unwrap();
|
|
// try to consume 1.5x the bucket size
|
|
// we are "borrowing" 1.5x the bucket size in tokens since
|
|
// the bucket is full, should arm the timer to 0.5x replenish
|
|
// time, which is 500 ms
|
|
assert!(h.consume(1500, TokenType::Bytes));
|
|
|
|
// check that after more than the minimum refill time,
|
|
// the rate limiter is still blocked
|
|
thread::sleep(Duration::from_millis(200));
|
|
assert!(h.is_blocked());
|
|
|
|
// try to consume some tokens, which should fail as the timer
|
|
// is still active
|
|
assert!(!h.consume(100, TokenType::Bytes));
|
|
assert!(h.is_blocked());
|
|
|
|
// check that after the minimum refill time, the timer was not
|
|
// overwritten and the rate limiter is still blocked from the
|
|
// borrowing we performed earlier
|
|
thread::sleep(Duration::from_millis(100));
|
|
assert!(h.is_blocked());
|
|
assert!(!h.consume(100, TokenType::Bytes));
|
|
|
|
// after waiting out the full duration, rate limiter should be
|
|
// available again
|
|
thread::sleep(Duration::from_millis(200));
|
|
assert!(h.event_handler().is_ok());
|
|
assert!(!h.is_blocked());
|
|
assert!(h.consume(100, TokenType::Bytes));
|
|
}
|
|
}
|