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feat: asynchronous, rate limited term session acquisition

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Xevion
2025-09-12 20:35:12 -05:00
parent 353c36bcf2
commit e9a0558535
4 changed files with 259 additions and 71 deletions
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110
Cargo.lock generated
View File

@@ -182,7 +182,9 @@ dependencies = [
"figment",
"fundu",
"futures",
"governor",
"http 1.3.1",
"once_cell",
"poise",
"rand 0.9.2",
"redis",
@@ -878,6 +880,12 @@ version = "0.3.31"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f90f7dce0722e95104fcb095585910c0977252f286e354b5e3bd38902cd99988"
[[package]]
name = "futures-timer"
version = "3.0.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f288b0a4f20f9a56b5d1da57e2227c661b7b16168e2f72365f57b63326e29b24"
[[package]]
name = "futures-util"
version = "0.3.31"
@@ -933,9 +941,11 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "26145e563e54f2cadc477553f1ec5ee650b00862f0a58bcd12cbdc5f0ea2d2f4"
dependencies = [
"cfg-if",
"js-sys",
"libc",
"r-efi",
"wasi 0.14.3+wasi-0.2.4",
"wasm-bindgen",
]
[[package]]
@@ -950,6 +960,29 @@ version = "0.3.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "0cc23270f6e1808e30a928bdc84dea0b9b4136a8bc82338574f23baf47bbd280"
[[package]]
name = "governor"
version = "0.10.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "444405bbb1a762387aa22dd569429533b54a1d8759d35d3b64cb39b0293eaa19"
dependencies = [
"cfg-if",
"dashmap 6.1.0",
"futures-sink",
"futures-timer",
"futures-util",
"getrandom 0.3.3",
"hashbrown 0.15.5",
"nonzero_ext",
"parking_lot",
"portable-atomic",
"quanta",
"rand 0.9.2",
"smallvec",
"spinning_top",
"web-time",
]
[[package]]
name = "h2"
version = "0.3.27"
@@ -1617,6 +1650,12 @@ dependencies = [
"tempfile",
]
[[package]]
name = "nonzero_ext"
version = "0.3.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "38bf9645c8b145698bb0b18a4637dcacbc421ea49bef2317e4fd8065a387cf21"
[[package]]
name = "nu-ansi-term"
version = "0.50.1"
@@ -1883,6 +1922,12 @@ dependencies = [
"syn 2.0.106",
]
[[package]]
name = "portable-atomic"
version = "1.11.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f84267b20a16ea918e43c6a88433c2d54fa145c92a811b5b047ccbe153674483"
[[package]]
name = "potential_utf"
version = "0.1.3"
@@ -1956,6 +2001,21 @@ dependencies = [
"unicase",
]
[[package]]
name = "quanta"
version = "0.12.6"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f3ab5a9d756f0d97bdc89019bd2e4ea098cf9cde50ee7564dde6b81ccc8f06c7"
dependencies = [
"crossbeam-utils",
"libc",
"once_cell",
"raw-cpuid",
"wasi 0.11.1+wasi-snapshot-preview1",
"web-sys",
"winapi",
]
[[package]]
name = "quote"
version = "1.0.40"
@@ -2041,6 +2101,15 @@ dependencies = [
"getrandom 0.3.3",
]
[[package]]
name = "raw-cpuid"
version = "11.6.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "498cd0dc59d73224351ee52a95fee0f1a617a2eae0e7d9d720cc622c73a54186"
dependencies = [
"bitflags 2.9.4",
]
[[package]]
name = "redis"
version = "0.32.5"
@@ -2682,6 +2751,15 @@ dependencies = [
"lock_api",
]
[[package]]
name = "spinning_top"
version = "0.3.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "d96d2d1d716fb500937168cc09353ffdc7a012be8475ac7308e1bdf0e3923300"
dependencies = [
"lock_api",
]
[[package]]
name = "spki"
version = "0.7.3"
@@ -3719,6 +3797,16 @@ dependencies = [
"wasm-bindgen",
]
[[package]]
name = "web-time"
version = "1.1.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "5a6580f308b1fad9207618087a65c04e7a10bc77e02c8e84e9b00dd4b12fa0bb"
dependencies = [
"js-sys",
"wasm-bindgen",
]
[[package]]
name = "webpki-roots"
version = "0.25.4"
@@ -3753,6 +3841,22 @@ dependencies = [
"wasite",
]
[[package]]
name = "winapi"
version = "0.3.9"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
dependencies = [
"winapi-i686-pc-windows-gnu",
"winapi-x86_64-pc-windows-gnu",
]
[[package]]
name = "winapi-i686-pc-windows-gnu"
version = "0.4.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
[[package]]
name = "winapi-util"
version = "0.1.10"
@@ -3762,6 +3866,12 @@ dependencies = [
"windows-sys 0.60.2",
]
[[package]]
name = "winapi-x86_64-pc-windows-gnu"
version = "0.4.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
[[package]]
name = "windows-core"
version = "0.61.2"

2
Cargo.toml
View File

@@ -41,5 +41,7 @@ tl = "0.7.8"
tracing = "0.1.41"
tracing-subscriber = { version = "0.3.20", features = ["env-filter", "json"] }
url = "2.5"
governor = "0.10.1"
once_cell = "1.21.3"
[dev-dependencies]

22
src/banner/api.rs
View File

@@ -279,7 +279,19 @@ impl BannerApi {
) -> Result<SearchResult, BannerApiError> {
// self.sessions.reset_data_form().await?;
let session = self.sessions.acquire(term.parse()?).await?;
let mut session = self.sessions.acquire(term.parse()?).await?;
if session.been_used() {
self.http
.post(&format!("{}/classSearch/resetDataForm", self.base_url))
.header("Cookie", session.cookie())
.send()
.await
.map_err(|e| BannerApiError::RequestFailed(e.into()))?;
}
session.touch();
let mut params = query.to_params();
// Add additional parameters
@@ -293,14 +305,6 @@ impl BannerApi {
params.insert("startDatepicker".to_string(), String::new());
params.insert("endDatepicker".to_string(), String::new());
if session.been_used() {
self.http
.post(&format!("{}/classSearch/resetDataForm", self.base_url))
.send()
.await
.map_err(|e| BannerApiError::RequestFailed(e.into()))?;
}
debug!(
term = term,
query = ?query,

196
src/banner/session.rs
View File

@@ -5,18 +5,28 @@ use crate::banner::models::Term;
use anyhow::{Context, Result};
use cookie::Cookie;
use dashmap::DashMap;
use governor::state::InMemoryState;
use governor::{Quota, RateLimiter};
use once_cell::sync::Lazy;
use rand::distr::{Alphanumeric, SampleString};
use reqwest::Client;
use reqwest_middleware::ClientWithMiddleware;
use std::collections::{HashMap, VecDeque};
use std::num::NonZeroU32;
use std::ops::{Deref, DerefMut};
use std::sync::{Arc, Mutex};
use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::sync::{Mutex, Notify};
use tracing::{debug, info};
use url::Url;
const SESSION_EXPIRY: Duration = Duration::from_secs(25 * 60); // 25 minutes
// A global rate limiter to ensure we only try to create one new session every 10 seconds,
// preventing us from overwhelming the server with session creation requests.
static SESSION_CREATION_RATE_LIMITER: Lazy<
RateLimiter<governor::state::direct::NotKeyed, InMemoryState, governor::clock::DefaultClock>,
> = Lazy::new(|| RateLimiter::direct(Quota::with_period(Duration::from_secs(10)).unwrap()));
/// Represents an active anonymous session within the Banner API.
/// Identified by multiple persistent cookies, as well as a client-generated "unique session ID".
#[derive(Debug, Clone)]
@@ -97,8 +107,8 @@ impl BannerSession {
/// A smart pointer that returns a BannerSession to the pool when dropped.
pub struct PooledSession {
session: Option<BannerSession>,
// This Arc points directly to the queue the session belongs to.
pool: Arc<Mutex<VecDeque<BannerSession>>>,
// This Arc points directly to the term-specific pool.
pool: Arc<TermPool>,
}
impl PooledSession {
@@ -125,33 +135,55 @@ impl DerefMut for PooledSession {
impl Drop for PooledSession {
fn drop(&mut self) {
if let Some(session) = self.session.take() {
// Don't return expired sessions to the pool.
if session.is_expired() {
debug!(
id = session.unique_session_id,
"Session is now expired, dropping."
);
return;
}
// This is a synchronous lock, so it's allowed in drop().
// It blocks the current thread briefly to return the session.
let mut queue = self.pool.lock().unwrap();
let id = session.unique_session_id.clone();
queue.push_back(session);
debug!(
id = id,
"Session returned to pool. Queue size is now {queue_size}.",
queue_size = queue.len(),
);
let pool = self.pool.clone();
// Since drop() cannot be async, we spawn a task to return the session.
tokio::spawn(async move {
pool.release(session).await;
});
}
}
}
pub struct TermPool {
sessions: Mutex<VecDeque<BannerSession>>,
notifier: Notify,
is_creating: Mutex<bool>,
}
impl TermPool {
fn new() -> Self {
Self {
sessions: Mutex::new(VecDeque::new()),
notifier: Notify::new(),
is_creating: Mutex::new(false),
}
}
async fn release(&self, session: BannerSession) {
let id = session.unique_session_id.clone();
if session.is_expired() {
debug!(id = id, "Session is now expired, dropping.");
// Wake up a waiter, as it might need to create a new session
// if this was the last one.
self.notifier.notify_one();
return;
}
let mut queue = self.sessions.lock().await;
queue.push_back(session);
let queue_size = queue.len();
drop(queue); // Release lock before notifying
debug!(
id = id,
"Session returned to pool. Queue size is now {queue_size}."
);
self.notifier.notify_one();
}
}
pub struct SessionPool {
sessions: DashMap<Term, Arc<Mutex<VecDeque<BannerSession>>>>,
sessions: DashMap<Term, Arc<TermPool>>,
http: ClientWithMiddleware,
base_url: String,
}
@@ -166,48 +198,88 @@ impl SessionPool {
}
/// Acquires a session from the pool.
/// If no sessions are available, a new one is created on demand.
/// If no sessions are available, a new one is created on demand,
/// respecting the global rate limit.
pub async fn acquire(&self, term: Term) -> Result<PooledSession> {
// Get the queue for the given term, or insert a new empty one.
let pool_entry = self
let term_pool = self
.sessions
.entry(term.clone())
.or_insert_with(|| Arc::new(Mutex::new(VecDeque::new())))
.or_insert_with(|| Arc::new(TermPool::new()))
.clone();
loop {
// Lock the specific queue for this term
let session_option = {
let mut queue = pool_entry.lock().unwrap();
queue.pop_front() // Try to get a session
};
if let Some(mut session) = session_option {
// We got a session, check if it's expired.
if !session.is_expired() {
debug!(id = session.unique_session_id, "Reusing session");
session.touch();
return Ok(PooledSession {
session: Some(session),
pool: pool_entry,
});
} else {
debug!(
id = session.unique_session_id,
"Popped an expired session, discarding.",
);
// The session is expired, so we loop again to try and get another one.
// Fast path: Try to get an existing, non-expired session.
{
let mut queue = term_pool.sessions.lock().await;
if let Some(session) = queue.pop_front() {
if !session.is_expired() {
debug!(id = session.unique_session_id, "Reusing session from pool");
return Ok(PooledSession {
session: Some(session),
pool: Arc::clone(&term_pool),
});
} else {
debug!(
id = session.unique_session_id,
"Popped an expired session, discarding."
);
}
}
} else {
// Queue was empty, so we create a new session.
let mut new_session = self.create_session(&term).await?;
new_session.touch();
} // MutexGuard is dropped, lock is released.
return Ok(PooledSession {
session: Some(new_session),
pool: pool_entry,
});
// Slow path: No sessions available. We must either wait or become the creator.
let mut is_creating_guard = term_pool.is_creating.lock().await;
if *is_creating_guard {
// Another task is already creating a session. Release the lock and wait.
drop(is_creating_guard);
debug!("Another task is creating a session, waiting for notification...");
term_pool.notifier.notified().await;
// Loop back to the top to try the fast path again.
continue;
}
// This task is now the designated creator.
*is_creating_guard = true;
drop(is_creating_guard);
// Race: wait for a session to be returned OR for the rate limiter to allow a new one.
debug!("Pool empty, racing notifier vs rate limiter...");
tokio::select! {
_ = term_pool.notifier.notified() => {
// A session was returned while we were waiting!
// We are no longer the creator. Reset the flag and loop to race for the new session.
debug!("Notified that a session was returned. Looping to retry.");
let mut guard = term_pool.is_creating.lock().await;
*guard = false;
drop(guard);
continue;
}
_ = SESSION_CREATION_RATE_LIMITER.until_ready() => {
// The rate limit has elapsed. It's our job to create the session.
debug!("Rate limiter ready. Proceeding to create a new session.");
let new_session_result = self.create_session(&term).await;
// After creation, we are no longer the creator. Reset the flag
// and notify all other waiting tasks.
let mut guard = term_pool.is_creating.lock().await;
*guard = false;
drop(guard);
term_pool.notifier.notify_waiters();
match new_session_result {
Ok(new_session) => {
debug!(id = new_session.unique_session_id, "Successfully created new session");
return Ok(PooledSession {
session: Some(new_session),
pool: term_pool,
});
}
Err(e) => {
// Propagate the error if session creation failed.
return Err(e.context("Failed to create new session in pool"));
}
}
}
}
}
}
@@ -269,7 +341,7 @@ impl SessionPool {
.context("Failed to get term selection page")?;
// TOOD: Validate success
/*let terms = self.get_terms("", 1, 10).await?;
let terms = self.get_terms("", 1, 10).await?;
if !terms.iter().any(|t| t.code == term.to_string()) {
return Err(anyhow::anyhow!("Failed to get term search response"));
}
@@ -280,7 +352,7 @@ impl SessionPool {
.any(|t| t.code == term.to_string())
{
return Err(anyhow::anyhow!("Failed to get term search response"));
}*/
}
let unique_session_id = generate_session_id();
self.select_term(&term.to_string(), &unique_session_id, &cookie_header)