From 6760259b6ddb21da67ff13939289fc87ae6697a2 Mon Sep 17 00:00:00 2001 From: wllenyj Date: Thu, 17 Mar 2022 15:59:07 +0800 Subject: [PATCH] dbs-utils: add rate limiter. Provides a rate limiter written in Rust useful for IO operations that need to be throttled. Signed-off-by: wllenyj --- crates/dbs-utils/Cargo.toml | 4 +- crates/dbs-utils/src/lib.rs | 1 + crates/dbs-utils/src/rate_limiter.rs | 880 +++++++++++++++++++++++++++ 3 files changed, 884 insertions(+), 1 deletion(-) create mode 100644 crates/dbs-utils/src/rate_limiter.rs diff --git a/crates/dbs-utils/Cargo.toml b/crates/dbs-utils/Cargo.toml index e276c8cff..adaa12d8c 100644 --- a/crates/dbs-utils/Cargo.toml +++ b/crates/dbs-utils/Cargo.toml @@ -11,8 +11,10 @@ readme = "README.md" [dependencies] anyhow = "1.0" -serde = { version = "1.0.27", features = ["derive", "rc"] } event-manager = { version = "0.2.1", features = [ "remote_endpoint" ] } +log = "0.4.14" +serde = { version = "1.0.27", features = ["derive", "rc"] } +timerfd = "1.0" vmm-sys-util = "0.9.0" [dev-dependencies] diff --git a/crates/dbs-utils/src/lib.rs b/crates/dbs-utils/src/lib.rs index 5e0844cf0..c58ad87c3 100644 --- a/crates/dbs-utils/src/lib.rs +++ b/crates/dbs-utils/src/lib.rs @@ -4,3 +4,4 @@ pub mod epoll_manager; pub mod metric; +pub mod rate_limiter; diff --git a/crates/dbs-utils/src/rate_limiter.rs b/crates/dbs-utils/src/rate_limiter.rs new file mode 100644 index 000000000..920267857 --- /dev/null +++ b/crates/dbs-utils/src/rate_limiter.rs @@ -0,0 +1,880 @@ +// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved. +// SPDX-License-Identifier: Apache-2.0 + +#![deny(missing_docs)] +//! # Rate Limiter +//! +//! Provides a rate limiter written in Rust useful for IO operations that need to +//! be throttled. +//! +//! ## Behavior +//! +//! The rate limiter starts off as 'unblocked' with two token buckets configured +//! with the values passed in the `RateLimiter::new()` constructor. +//! All subsequent accounting is done independently for each token bucket based +//! on the `TokenType` used. If any of the buckets runs out of budget, the limiter +//! goes in the 'blocked' state. At this point an internal timer is set up which +//! will later 'wake up' the user in order to retry sending data. The 'wake up' +//! notification will be dispatched as an event on the FD provided by the `AsRawFD` +//! trait implementation. +//! +//! The contract is that the user shall also call the `event_handler()` method on +//! receipt of such an event. +//! +//! The token buckets are replenished every time a `consume()` is called, before +//! actually trying to consume the requested amount of tokens. The amount of tokens +//! replenished is automatically calculated to respect the `complete_refill_time` +//! configuration parameter provided by the user. The token buckets will never +//! replenish above their respective `size`. +//! +//! Each token bucket can start off with a `one_time_burst` initial extra capacity +//! on top of their `size`. This initial extra credit does not replenish and +//! can be used for an initial burst of data. +//! +//! The granularity for 'wake up' events when the rate limiter is blocked is +//! currently hardcoded to `10 milliseconds`. +//! +//! ## Limitations +//! +//! This rate limiter implementation relies on the *Linux kernel's timerfd* so its +//! usage is limited to Linux systems. +//! +//! Another particularity of this implementation is that it is not self-driving. +//! It is meant to be used in an external event loop and thus implements the `AsRawFd` +//! trait and provides an *event-handler* as part of its API. This *event-handler* +//! needs to be called by the user on every event on the rate limiter's `AsRawFd` FD. + +use std::os::unix::io::{AsRawFd, RawFd}; +use std::time::{Duration, Instant}; +use std::{fmt, io}; + +use log::error; +use timerfd::{ClockId, SetTimeFlags, TimerFd, TimerState}; + +#[derive(Debug)] +/// Describes the errors that may occur while handling rate limiter events. +pub enum Error { + /// The event handler was called spuriously. + SpuriousRateLimiterEvent(&'static str), +} + +// Interval at which the refill timer will run when limiter is at capacity. +const REFILL_TIMER_INTERVAL_MS: u64 = 10; +const TIMER_REFILL_STATE: TimerState = + TimerState::Oneshot(Duration::from_millis(REFILL_TIMER_INTERVAL_MS)); + +const NANOSEC_IN_ONE_MILLISEC: u64 = 1_000_000; + +// Euclid's two-thousand-year-old algorithm for finding the greatest common divisor. +fn gcd(x: u64, y: u64) -> u64 { + let mut x = x; + let mut y = y; + while y != 0 { + let t = y; + y = x % y; + x = t; + } + x +} + +/// Enum describing the outcomes of a `reduce()` call on a `TokenBucket`. +#[derive(Clone, Debug, PartialEq)] +pub enum BucketReduction { + /// No enough tokens + Failure, + /// Part of the available tokens have been consumed. + Success, + /// A number of tokens `inner` times larger than the bucket size have been consumed. + OverConsumption(f64), +} + +/// TokenBucket provides a lower level interface to rate limiting with a +/// configurable capacity, refill-rate and initial burst. +#[derive(Clone, Debug, PartialEq)] +pub struct TokenBucket { + // Bucket defining traits. + size: u64, + // Initial burst size (number of free initial tokens, that can be consumed at no cost) + one_time_burst: u64, + // Complete refill time in milliseconds. + refill_time: u64, + + // Internal state descriptors. + budget: u64, + last_update: Instant, + + // Fields used for pre-processing optimizations. + processed_capacity: u64, + processed_refill_time: u64, +} + +impl TokenBucket { + /// Creates a TokenBucket of `size` total capacity that takes `complete_refill_time_ms` + /// milliseconds to go from zero tokens to total capacity. The `one_time_burst` is initial + /// extra credit on top of total capacity, that does not replenish and which can be used + /// for an initial burst of data. + pub fn new(size: u64, one_time_burst: u64, complete_refill_time_ms: u64) -> Self { + // Formula for computing current refill amount: + // refill_token_count = (delta_time * size) / (complete_refill_time_ms * 1_000_000) + // In order to avoid overflows, simplify the fractions by computing greatest common divisor. + + let complete_refill_time_ns = complete_refill_time_ms * NANOSEC_IN_ONE_MILLISEC; + // Get the greatest common factor between `size` and `complete_refill_time_ns`. + let common_factor = gcd(size, complete_refill_time_ns); + // The division will be exact since `common_factor` is a factor of `size`. + let processed_capacity: u64 = size / common_factor; + // The division will be exact since `common_factor` is a factor of `complete_refill_time_ns`. + let processed_refill_time: u64 = complete_refill_time_ns / common_factor; + + TokenBucket { + size, + one_time_burst, + refill_time: complete_refill_time_ms, + // Start off full. + budget: size, + // Last updated is now. + last_update: Instant::now(), + processed_capacity, + processed_refill_time, + } + } + + /// Attempts to consume `tokens` from the bucket and returns whether the action succeeded. + pub fn reduce(&mut self, mut tokens: u64) -> BucketReduction { + // First things first: consume the one-time-burst budget. + if self.one_time_burst > 0 { + // We still have burst budget for *all* tokens requests. + if self.one_time_burst >= tokens { + self.one_time_burst -= tokens; + self.last_update = Instant::now(); + // No need to continue to the refill process, we still have burst budget to consume from. + return BucketReduction::Success; + } else { + // We still have burst budget for *some* of the tokens requests. + // The tokens left unfulfilled will be consumed from current `self.budget`. + tokens -= self.one_time_burst; + self.one_time_burst = 0; + } + } + + // Compute time passed since last refill/update. + let time_delta = self.last_update.elapsed().as_nanos() as u64; + self.last_update = Instant::now(); + + // At each 'time_delta' nanoseconds the bucket should refill with: + // refill_amount = (time_delta * size) / (complete_refill_time_ms * 1_000_000) + // `processed_capacity` and `processed_refill_time` are the result of simplifying above + // fraction formula with their greatest-common-factor. + self.budget += (time_delta * self.processed_capacity) / self.processed_refill_time; + + if self.budget >= self.size { + self.budget = self.size; + } + + if tokens > self.budget { + // This operation requests a bandwidth higher than the bucket size + if tokens > self.size { + error!( + "Consumed {} tokens from bucket of size {}", + tokens, self.size + ); + // Empty the bucket and report an overconsumption of + // (remaining tokens / size) times larger than the bucket size + tokens -= self.budget; + self.budget = 0; + return BucketReduction::OverConsumption(tokens as f64 / self.size as f64); + } + // If not enough tokens consume() fails, return false. + return BucketReduction::Failure; + } + + self.budget -= tokens; + BucketReduction::Success + } + + /// "Manually" adds tokens to bucket. + pub fn replenish(&mut self, tokens: u64) { + // This means we are still during the burst interval. + // Of course there is a very small chance that the last reduce() also used up burst + // budget which should now be replenished, but for performance and code-complexity + // reasons we're just gonna let that slide since it's practically inconsequential. + if self.one_time_burst > 0 { + self.one_time_burst += tokens; + return; + } + self.budget = std::cmp::min(self.budget + tokens, self.size); + } + + /// Returns the capacity of the token bucket. + pub fn capacity(&self) -> u64 { + self.size + } + + /// Returns the remaining one time burst budget. + pub fn one_time_burst(&self) -> u64 { + self.one_time_burst + } + + /// Returns the time in milliseconds required to to completely fill the bucket. + pub fn refill_time_ms(&self) -> u64 { + self.refill_time + } + + /// Returns the current budget (one time burst allowance notwithstanding). + pub fn budget(&self) -> u64 { + self.budget + } +} + +/// Enum that describes the type of token used. +pub enum TokenType { + /// Token type used for bandwidth limiting. + Bytes, + /// Token type used for operations/second limiting. + Ops, +} + +/// Enum that describes the type of token bucket update. +#[derive(Clone, Debug)] +pub enum BucketUpdate { + /// No Update - same as before. + None, + /// Rate Limiting is disabled on this bucket. + Disabled, + /// Rate Limiting enabled with updated bucket. + Update(TokenBucket), +} + +/// Rate Limiter that works on both bandwidth and ops/s limiting. +/// +/// Bandwidth (bytes/s) and ops/s limiting can be used at the same time or individually. +/// +/// Implementation uses a single timer through TimerFd to refresh either or +/// both token buckets. +/// +/// Its internal buckets are 'passively' replenished as they're being used (as +/// part of `consume()` operations). +/// A timer is enabled and used to 'actively' replenish the token buckets when +/// limiting is in effect and `consume()` operations are disabled. +/// +/// RateLimiters will generate events on the FDs provided by their `AsRawFd` trait +/// implementation. These events are meant to be consumed by the user of this struct. +/// On each such event, the user must call the `event_handler()` method. +pub struct RateLimiter { + /// Bandwidth limit in bytes/s + bandwidth: Option, + /// Operate limit in ops/s + ops: Option, + /// Timer handle + timer_fd: TimerFd, + /// Internal flag that quickly determines timer state. + timer_active: bool, +} + +impl PartialEq for RateLimiter { + fn eq(&self, other: &RateLimiter) -> bool { + self.bandwidth == other.bandwidth && self.ops == other.ops + } +} + +impl fmt::Debug for RateLimiter { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + write!( + f, + "RateLimiter {{ bandwidth: {:?}, ops: {:?} }}", + self.bandwidth, self.ops + ) + } +} + +impl RateLimiter { + /// This function creates a `TokenBucket` wrapped in an `Option` with a given total capacity, + /// one time burst, and complete refill time (in miliseconds). If the total capacity or the + /// complete refill time are zero, then `None` is returned. + pub fn make_bucket( + total_capacity: u64, + one_time_burst: u64, + complete_refill_time_ms: u64, + ) -> Option { + // If either token bucket capacity or refill time is 0, disable limiting. + if total_capacity != 0 && complete_refill_time_ms != 0 { + Some(TokenBucket::new( + total_capacity, + one_time_burst, + complete_refill_time_ms, + )) + } else { + None + } + } + /// Creates a new Rate Limiter that can limit on both bytes/s and ops/s. + /// + /// # Arguments + /// + /// * `bytes_total_capacity` - the total capacity of the `TokenType::Bytes` token bucket. + /// * `bytes_one_time_burst` - initial extra credit on top of `bytes_total_capacity`, + /// that does not replenish and which can be used for an initial burst of data. + /// * `bytes_complete_refill_time_ms` - number of milliseconds for the `TokenType::Bytes` + /// token bucket to go from zero Bytes to `bytes_total_capacity` Bytes. + /// * `ops_total_capacity` - the total capacity of the `TokenType::Ops` token bucket. + /// * `ops_one_time_burst` - initial extra credit on top of `ops_total_capacity`, + /// that does not replenish and which can be used for an initial burst of data. + /// * `ops_complete_refill_time_ms` - number of milliseconds for the `TokenType::Ops` token + /// bucket to go from zero Ops to `ops_total_capacity` Ops. + /// + /// If either bytes/ops *size* or *refill_time* are **zero**, the limiter + /// is **disabled** for that respective token type. + /// + /// # Errors + /// + /// If the timerfd creation fails, an error is returned. + pub fn new( + bytes_total_capacity: u64, + bytes_one_time_burst: u64, + bytes_complete_refill_time_ms: u64, + ops_total_capacity: u64, + ops_one_time_burst: u64, + ops_complete_refill_time_ms: u64, + ) -> io::Result { + let bytes_token_bucket = Self::make_bucket( + bytes_total_capacity, + bytes_one_time_burst, + bytes_complete_refill_time_ms, + ); + + let ops_token_bucket = Self::make_bucket( + ops_total_capacity, + ops_one_time_burst, + ops_complete_refill_time_ms, + ); + + // We'll need a timer_fd, even if our current config effectively disables rate limiting, + // because `Self::update_buckets()` might re-enable it later, and we might be + // seccomp-blocked from creating the timer_fd at that time. + let timer_fd = TimerFd::new_custom(ClockId::Monotonic, true, true)?; + + Ok(RateLimiter { + bandwidth: bytes_token_bucket, + ops: ops_token_bucket, + timer_fd, + timer_active: false, + }) + } + + // Arm the timer of the rate limiter with the provided `TimerState`. + fn activate_timer(&mut self, timer_state: TimerState) { + // Register the timer; don't care about its previous state + self.timer_fd.set_state(timer_state, SetTimeFlags::Default); + self.timer_active = true; + } + + /// Attempts to consume tokens and returns whether that is possible. + /// + /// If rate limiting is disabled on provided `token_type`, this function will always succeed. + pub fn consume(&mut self, tokens: u64, token_type: TokenType) -> bool { + // If the timer is active, we can't consume tokens from any bucket and the function fails. + if self.timer_active { + return false; + } + + // Identify the required token bucket. + let token_bucket = match token_type { + TokenType::Bytes => self.bandwidth.as_mut(), + TokenType::Ops => self.ops.as_mut(), + }; + // Try to consume from the token bucket. + if let Some(bucket) = token_bucket { + let refill_time = bucket.refill_time_ms(); + match bucket.reduce(tokens) { + // When we report budget is over, there will be no further calls here, + // register a timer to replenish the bucket and resume processing; + // make sure there is only one running timer for this limiter. + BucketReduction::Failure => { + if !self.timer_active { + self.activate_timer(TIMER_REFILL_STATE); + } + false + } + // The operation succeeded and further calls can be made. + BucketReduction::Success => true, + // The operation succeeded as the tokens have been consumed + // but the timer still needs to be armed. + BucketReduction::OverConsumption(ratio) => { + // The operation "borrowed" a number of tokens `ratio` times + // greater than the size of the bucket, and since it takes + // `refill_time` milliseconds to fill an empty bucket, in + // order to enforce the bandwidth limit we need to prevent + // further calls to the rate limiter for + // `ratio * refill_time` milliseconds. + self.activate_timer(TimerState::Oneshot(Duration::from_millis( + (ratio * refill_time as f64) as u64, + ))); + true + } + } + } else { + // If bucket is not present rate limiting is disabled on token type, + // consume() will always succeed. + true + } + } + + /// Adds tokens of `token_type` to their respective bucket. + /// + /// Can be used to *manually* add tokens to a bucket. Useful for reverting a + /// `consume()` if needed. + pub fn manual_replenish(&mut self, tokens: u64, token_type: TokenType) { + // Identify the required token bucket. + let token_bucket = match token_type { + TokenType::Bytes => self.bandwidth.as_mut(), + TokenType::Ops => self.ops.as_mut(), + }; + // Add tokens to the token bucket. + if let Some(bucket) = token_bucket { + bucket.replenish(tokens); + } + } + + /// Returns whether this rate limiter is blocked. + /// + /// The limiter 'blocks' when a `consume()` operation fails because there was not enough + /// budget for it. + /// An event will be generated on the exported FD when the limiter 'unblocks'. + pub fn is_blocked(&self) -> bool { + self.timer_active + } + + /// This function needs to be called every time there is an event on the + /// FD provided by this object's `AsRawFd` trait implementation. + /// + /// # Errors + /// + /// If the rate limiter is disabled or is not blocked, an error is returned. + pub fn event_handler(&mut self) -> Result<(), Error> { + match self.timer_fd.read() { + 0 => Err(Error::SpuriousRateLimiterEvent( + "Rate limiter event handler called without a present timer", + )), + _ => { + self.timer_active = false; + Ok(()) + } + } + } + + /// Updates the parameters of the token buckets associated with this RateLimiter. + // TODO: Please note that, right now, the buckets become full after being updated. + pub fn update_buckets(&mut self, bytes: BucketUpdate, ops: BucketUpdate) { + match bytes { + BucketUpdate::Disabled => self.bandwidth = None, + BucketUpdate::Update(tb) => self.bandwidth = Some(tb), + BucketUpdate::None => (), + }; + match ops { + BucketUpdate::Disabled => self.ops = None, + BucketUpdate::Update(tb) => self.ops = Some(tb), + BucketUpdate::None => (), + }; + } + /// Returns an immutable view of the inner bandwidth token bucket. + pub fn bandwidth(&self) -> Option<&TokenBucket> { + self.bandwidth.as_ref() + } + + /// Returns an immutable view of the inner ops token bucket. + pub fn ops(&self) -> Option<&TokenBucket> { + self.ops.as_ref() + } +} + +impl AsRawFd for RateLimiter { + /// Provides a FD which needs to be monitored for POLLIN events. + /// + /// This object's `event_handler()` method must be called on such events. + /// + /// Will return a negative value if rate limiting is disabled on both + /// token types. + fn as_raw_fd(&self) -> RawFd { + self.timer_fd.as_raw_fd() + } +} + +impl Default for RateLimiter { + /// Default RateLimiter is a no-op limiter with infinite budget. + fn default() -> Self { + // Safe to unwrap since this will not attempt to create timer_fd. + RateLimiter::new(0, 0, 0, 0, 0, 0).expect("Failed to build default RateLimiter") + } +} + +#[cfg(test)] +mod tests { + use super::*; + use std::thread; + use std::time::Duration; + const TEST_REFILL_TIMER_INTERVAL_MS: u64 = 100; + impl TokenBucket { + // Resets the token bucket: budget set to max capacity and last-updated set to now. + fn reset(&mut self) { + self.budget = self.size; + self.last_update = Instant::now(); + } + + fn get_last_update(&self) -> &Instant { + &self.last_update + } + + fn get_processed_capacity(&self) -> u64 { + self.processed_capacity + } + + fn get_processed_refill_time(&self) -> u64 { + self.processed_refill_time + } + + // After a restore, we cannot be certain that the last_update field has the same value. + pub fn partial_eq(&self, other: &TokenBucket) -> bool { + (other.capacity() == self.capacity()) + && (other.one_time_burst() == self.one_time_burst()) + && (other.refill_time_ms() == self.refill_time_ms()) + && (other.budget() == self.budget()) + } + } + + impl RateLimiter { + fn get_token_bucket(&self, token_type: TokenType) -> Option<&TokenBucket> { + match token_type { + TokenType::Bytes => self.bandwidth.as_ref(), + TokenType::Ops => self.ops.as_ref(), + } + } + } + + #[test] + fn test_token_bucket_create() { + let before = Instant::now(); + let tb = TokenBucket::new(1000, 0, 1000); + assert_eq!(tb.capacity(), 1000); + assert_eq!(tb.budget(), 1000); + assert!(*tb.get_last_update() >= before); + let after = Instant::now(); + assert!(*tb.get_last_update() <= after); + assert_eq!(tb.get_processed_capacity(), 1); + assert_eq!(tb.get_processed_refill_time(), 1_000_000); + } + + #[test] + fn test_token_bucket_preprocess() { + let tb = TokenBucket::new(1000, 0, 1000); + assert_eq!(tb.get_processed_capacity(), 1); + assert_eq!(tb.get_processed_refill_time(), NANOSEC_IN_ONE_MILLISEC); + + let thousand = 1000; + let tb = TokenBucket::new(3 * 7 * 11 * 19 * thousand, 0, 7 * 11 * 13 * 17); + assert_eq!(tb.get_processed_capacity(), 3 * 19); + assert_eq!( + tb.get_processed_refill_time(), + 13 * 17 * (NANOSEC_IN_ONE_MILLISEC / thousand) + ); + } + + #[test] + fn test_token_bucket_reduce() { + // token bucket with capacity 1000 and refill time of 1000 milliseconds + // allowing rate of 1 token/ms. + let capacity = 1000; + let refill_ms = 1000; + let mut tb = TokenBucket::new(capacity, 0, refill_ms as u64); + + assert_eq!(tb.reduce(123), BucketReduction::Success); + assert_eq!(tb.budget(), capacity - 123); + + thread::sleep(Duration::from_millis(123)); + assert_eq!(tb.reduce(1), BucketReduction::Success); + assert_eq!(tb.budget(), capacity - 1); + assert_eq!(tb.reduce(100), BucketReduction::Success); + assert_eq!(tb.reduce(capacity), BucketReduction::Failure); + + // token bucket with capacity 1000 and refill time of 1000 milliseconds + let mut tb = TokenBucket::new(1000, 1100, 1000); + // safely assuming the thread can run these 3 commands in less than 500ms + assert_eq!(tb.reduce(1000), BucketReduction::Success); + assert_eq!(tb.one_time_burst(), 100); + assert_eq!(tb.reduce(500), BucketReduction::Success); + assert_eq!(tb.one_time_burst(), 0); + assert_eq!(tb.reduce(500), BucketReduction::Success); + assert_eq!(tb.reduce(500), BucketReduction::Failure); + thread::sleep(Duration::from_millis(500)); + assert_eq!(tb.reduce(500), BucketReduction::Success); + thread::sleep(Duration::from_millis(1000)); + assert_eq!(tb.reduce(2500), BucketReduction::OverConsumption(1.5)); + + let before = Instant::now(); + tb.reset(); + assert_eq!(tb.capacity(), 1000); + assert_eq!(tb.budget(), 1000); + assert!(*tb.get_last_update() >= before); + let after = Instant::now(); + assert!(*tb.get_last_update() <= after); + } + + #[test] + fn test_rate_limiter_default() { + let mut l = RateLimiter::default(); + + // limiter should not be blocked + assert!(!l.is_blocked()); + // limiter should be disabled so consume(whatever) should work + assert!(l.consume(u64::max_value(), TokenType::Ops)); + assert!(l.consume(u64::max_value(), TokenType::Bytes)); + // calling the handler without there having been an event should error + assert!(l.event_handler().is_err()); + assert_eq!( + format!("{:?}", l.event_handler().err().unwrap()), + "SpuriousRateLimiterEvent(\ + \"Rate limiter event handler called without a present timer\")" + ); + } + + #[test] + fn test_rate_limiter_new() { + let l = RateLimiter::new(1000, 1001, 1002, 1003, 1004, 1005).unwrap(); + + let bw = l.bandwidth.unwrap(); + assert_eq!(bw.capacity(), 1000); + assert_eq!(bw.one_time_burst(), 1001); + assert_eq!(bw.refill_time_ms(), 1002); + assert_eq!(bw.budget(), 1000); + + let ops = l.ops.unwrap(); + assert_eq!(ops.capacity(), 1003); + assert_eq!(ops.one_time_burst(), 1004); + assert_eq!(ops.refill_time_ms(), 1005); + assert_eq!(ops.budget(), 1003); + } + + #[test] + fn test_rate_limiter_manual_replenish() { + // rate limiter with limit of 1000 bytes/s and 1000 ops/s + let mut l = RateLimiter::new(1000, 0, 1000, 1000, 0, 1000).unwrap(); + + // consume 123 bytes + assert!(l.consume(123, TokenType::Bytes)); + l.manual_replenish(23, TokenType::Bytes); + { + let bytes_tb = l.get_token_bucket(TokenType::Bytes).unwrap(); + assert_eq!(bytes_tb.budget(), 900); + } + // consume 123 ops + assert!(l.consume(123, TokenType::Ops)); + l.manual_replenish(23, TokenType::Ops); + { + let bytes_tb = l.get_token_bucket(TokenType::Ops).unwrap(); + assert_eq!(bytes_tb.budget(), 900); + } + } + + #[test] + fn test_rate_limiter_bandwidth() { + // rate limiter with limit of 1000 bytes/s + let mut l = RateLimiter::new(1000, 0, 1000, 0, 0, 0).unwrap(); + + // limiter should not be blocked + assert!(!l.is_blocked()); + // raw FD for this disabled should be valid + assert!(l.as_raw_fd() > 0); + + // ops/s limiter should be disabled so consume(whatever) should work + assert!(l.consume(u64::max_value(), TokenType::Ops)); + + // do full 1000 bytes + assert!(l.consume(1000, TokenType::Bytes)); + // try and fail on another 100 + assert!(!l.consume(100, TokenType::Bytes)); + // since consume failed, limiter should be blocked now + assert!(l.is_blocked()); + // wait half the timer period + thread::sleep(Duration::from_millis(TEST_REFILL_TIMER_INTERVAL_MS / 2)); + // limiter should still be blocked + assert!(l.is_blocked()); + // wait the other half of the timer period + thread::sleep(Duration::from_millis(TEST_REFILL_TIMER_INTERVAL_MS / 2)); + // the timer_fd should have an event on it by now + assert!(l.event_handler().is_ok()); + // limiter should now be unblocked + assert!(!l.is_blocked()); + // try and succeed on another 100 bytes this time + assert!(l.consume(100, TokenType::Bytes)); + } + + #[test] + fn test_rate_limiter_ops() { + // rate limiter with limit of 1000 ops/s + let mut l = RateLimiter::new(0, 0, 0, 1000, 0, 1000).unwrap(); + + // limiter should not be blocked + assert!(!l.is_blocked()); + // raw FD for this disabled should be valid + assert!(l.as_raw_fd() > 0); + + // bytes/s limiter should be disabled so consume(whatever) should work + assert!(l.consume(u64::max_value(), TokenType::Bytes)); + + // do full 1000 ops + assert!(l.consume(1000, TokenType::Ops)); + // try and fail on another 100 + assert!(!l.consume(100, TokenType::Ops)); + // since consume failed, limiter should be blocked now + assert!(l.is_blocked()); + // wait half the timer period + thread::sleep(Duration::from_millis(TEST_REFILL_TIMER_INTERVAL_MS / 2)); + // limiter should still be blocked + assert!(l.is_blocked()); + // wait the other half of the timer period + thread::sleep(Duration::from_millis(TEST_REFILL_TIMER_INTERVAL_MS / 2)); + // the timer_fd should have an event on it by now + assert!(l.event_handler().is_ok()); + // limiter should now be unblocked + assert!(!l.is_blocked()); + // try and succeed on another 100 ops this time + assert!(l.consume(100, TokenType::Ops)); + } + + #[test] + fn test_rate_limiter_full() { + // rate limiter with limit of 1000 bytes/s and 1000 ops/s + let mut l = RateLimiter::new(1000, 0, 1000, 1000, 0, 1000).unwrap(); + + // limiter should not be blocked + assert!(!l.is_blocked()); + // raw FD for this disabled should be valid + assert!(l.as_raw_fd() > 0); + + // do full 1000 bytes + assert!(l.consume(1000, TokenType::Ops)); + // do full 1000 bytes + assert!(l.consume(1000, TokenType::Bytes)); + // try and fail on another 100 ops + assert!(!l.consume(100, TokenType::Ops)); + // try and fail on another 100 bytes + assert!(!l.consume(100, TokenType::Bytes)); + // since consume failed, limiter should be blocked now + assert!(l.is_blocked()); + // wait half the timer period + thread::sleep(Duration::from_millis(TEST_REFILL_TIMER_INTERVAL_MS / 2)); + // limiter should still be blocked + assert!(l.is_blocked()); + // wait the other half of the timer period + thread::sleep(Duration::from_millis(TEST_REFILL_TIMER_INTERVAL_MS / 2)); + // the timer_fd should have an event on it by now + assert!(l.event_handler().is_ok()); + // limiter should now be unblocked + assert!(!l.is_blocked()); + // try and succeed on another 100 ops this time + assert!(l.consume(100, TokenType::Ops)); + // try and succeed on another 100 bytes this time + assert!(l.consume(100, TokenType::Bytes)); + } + + #[test] + fn test_rate_limiter_overconsumption() { + // initialize the rate limiter + let mut l = RateLimiter::new(1000, 0, 1000, 1000, 0, 1000).unwrap(); + // try to consume 2.5x the bucket size + // we are "borrowing" 1.5x the bucket size in tokens since + // the bucket is full + assert!(l.consume(2500, TokenType::Bytes)); + + // check that even after a whole second passes, the rate limiter + // is still blocked + thread::sleep(Duration::from_millis(1000)); + assert!(l.event_handler().is_err()); + assert!(l.is_blocked()); + + // after 1.5x the replenish time has passed, the rate limiter + // is available again + thread::sleep(Duration::from_millis(500)); + assert!(l.event_handler().is_ok()); + assert!(!l.is_blocked()); + + // reset the rate limiter + let mut l = RateLimiter::new(1000, 0, 1000, 1000, 0, 1000).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!(l.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!(l.event_handler().is_err()); + assert!(l.is_blocked()); + + // try to consume some tokens, which should fail as the timer + // is still active + assert!(!l.consume(100, TokenType::Bytes)); + assert!(l.event_handler().is_err()); + assert!(l.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!(l.event_handler().is_err()); + assert!(l.is_blocked()); + assert!(!l.consume(100, TokenType::Bytes)); + + // after waiting out the full duration, rate limiter should be + // availale again + thread::sleep(Duration::from_millis(200)); + assert!(l.event_handler().is_ok()); + assert!(!l.is_blocked()); + assert!(l.consume(100, TokenType::Bytes)); + } + + #[test] + fn test_update_buckets() { + let mut x = RateLimiter::new(1000, 2000, 1000, 10, 20, 1000).unwrap(); + + let initial_bw = x.bandwidth.clone(); + let initial_ops = x.ops.clone(); + + x.update_buckets(BucketUpdate::None, BucketUpdate::None); + assert_eq!(x.bandwidth, initial_bw); + assert_eq!(x.ops, initial_ops); + + let new_bw = RateLimiter::make_bucket(123, 0, 57).unwrap(); + let new_ops = RateLimiter::make_bucket(321, 12346, 89).unwrap(); + x.update_buckets( + BucketUpdate::Update(new_bw.clone()), + BucketUpdate::Update(new_ops.clone()), + ); + + // We have manually adjust the last_update field, because it changes when update_buckets() + // constructs new buckets (and thus gets a different value for last_update). We do this so + // it makes sense to test the following assertions. + x.bandwidth.as_mut().unwrap().last_update = new_bw.last_update; + x.ops.as_mut().unwrap().last_update = new_ops.last_update; + + assert_eq!(x.bandwidth, Some(new_bw)); + assert_eq!(x.ops, Some(new_ops)); + + x.update_buckets(BucketUpdate::Disabled, BucketUpdate::Disabled); + assert_eq!(x.bandwidth, None); + assert_eq!(x.ops, None); + } + + #[test] + fn test_rate_limiter_debug() { + let l = RateLimiter::new(1, 2, 3, 4, 5, 6).unwrap(); + assert_eq!( + format!("{:?}", l), + format!( + "RateLimiter {{ bandwidth: {:?}, ops: {:?} }}", + l.bandwidth(), + l.ops() + ), + ); + } +}