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http-cache: wait on pending stores

Browse source 
and various small improvements
This commit is contained in:
Gregory Terzian 2019-09-29 22:55:47 +08:00
parent e05f0b41ba
commit 4f3ba70704
4 changed files with 239 additions and 92 deletions
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179
components/net/http_loader.rs
View file

@ -12,7 +12,7 @@ use crate::fetch::methods::{
};
use crate::fetch::methods::{Data, DoneChannel, FetchContext, Target};
use crate::hsts::HstsList;
use crate::http_cache::HttpCache;
use crate::http_cache::{CacheKey, HttpCache};
use crate::resource_thread::AuthCache;
use crossbeam_channel::{unbounded, Sender};
use devtools_traits::{
@ -53,7 +53,7 @@ use std::iter::FromIterator;
use std::mem;
use std::ops::Deref;
use std::str::FromStr;
use std::sync::{Mutex, RwLock};
use std::sync::{Condvar, Mutex, RwLock};
use std::time::{Duration, SystemTime};
use time::{self, Tm};
use tokio::prelude::{future, Future, Stream};
@ -63,10 +63,25 @@ lazy_static! {
pub static ref HANDLE: Mutex<Runtime> = { Mutex::new(Runtime::new().unwrap()) };
}
/// The various states an entry of the HttpCache can be in.
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum HttpCacheEntryState {
/// The entry is fully up-to-date,
/// there are no pending concurrent stores,
/// and it is ready to construct cached responses.
ReadyToConstruct,
/// The entry is pending a number of concurrent stores.
PendingStore(usize),
}
pub struct HttpState {
pub hsts_list: RwLock<HstsList>,
pub cookie_jar: RwLock<CookieStorage>,
pub http_cache: RwLock<HttpCache>,
/// A map of cache key to entry state,
/// reflecting whether the cache entry is ready to read from,
/// or whether a concurrent pending store should be awaited.
pub http_cache_state: Mutex<HashMap<CacheKey, Arc<(Mutex<HttpCacheEntryState>, Condvar)>>>,
pub auth_cache: RwLock<AuthCache>,
pub history_states: RwLock<HashMap<HistoryStateId, Vec<u8>>>,
pub client: Client<Connector, Body>,
@ -80,6 +95,7 @@ impl HttpState {
auth_cache: RwLock::new(AuthCache::new()),
history_states: RwLock::new(HashMap::new()),
http_cache: RwLock::new(HttpCache::new()),
http_cache_state: Mutex::new(HashMap::new()),
client: create_http_client(ssl_connector_builder, HANDLE.lock().unwrap().executor()),
}
}
@ -1020,42 +1036,124 @@ fn http_network_or_cache_fetch(
// Step 5.18
// TODO If there’s a proxy-authentication entry, use it as appropriate.
// Step 5.19
if let Ok(http_cache) = context.state.http_cache.read() {
if let Some(response_from_cache) = http_cache.construct_response(&http_request, done_chan) {
let response_headers = response_from_cache.response.headers.clone();
// Substep 1, 2, 3, 4
let (cached_response, needs_revalidation) =
match (http_request.cache_mode, &http_request.mode) {
(CacheMode::ForceCache, _) => (Some(response_from_cache.response), false),
(CacheMode::OnlyIfCached, &RequestMode::SameOrigin) => {
(Some(response_from_cache.response), false)
},
(CacheMode::OnlyIfCached, _) |
(CacheMode::NoStore, _) |
(CacheMode::Reload, _) => (None, false),
(_, _) => (
Some(response_from_cache.response),
response_from_cache.needs_validation,
),
};
if needs_revalidation {
revalidating_flag = true;
// Substep 5
if let Some(http_date) = response_headers.typed_get::<LastModified>() {
let http_date: SystemTime = http_date.into();
http_request
.headers
.typed_insert(IfModifiedSince::from(http_date));
// If the cache is not ready to construct a response, wait.
//
// The cache is not ready if a previous fetch checked the cache, found nothing,
// and moved on to a network fetch, and hasn't updated the cache yet with a pending resource.
//
// Note that this is a different workflow from the one involving `wait_for_cached_response`.
// That one happens when a fetch gets a cache hit, and the resource is pending completion from the network.
{
let (lock, cvar) = {
let entry_key = CacheKey::new(&http_request);
let mut state_map = context.state.http_cache_state.lock().unwrap();
&*state_map
.entry(entry_key)
.or_insert_with(|| {
Arc::new((
Mutex::new(HttpCacheEntryState::ReadyToConstruct),
Condvar::new(),
))
})
.clone()
};
// Start of critical section on http-cache state.
let mut state = lock.lock().unwrap();
while let HttpCacheEntryState::PendingStore(_) = *state {
let (current_state, time_out) = cvar
.wait_timeout(state, Duration::from_millis(500))
.unwrap();
state = current_state;
if time_out.timed_out() {
// After a timeout, ignore the pending store.
break;
}
}
// Step 5.19
if let Ok(http_cache) = context.state.http_cache.read() {
if let Some(response_from_cache) =
http_cache.construct_response(&http_request, done_chan)
{
let response_headers = response_from_cache.response.headers.clone();
// Substep 1, 2, 3, 4
let (cached_response, needs_revalidation) =
match (http_request.cache_mode, &http_request.mode) {
(CacheMode::ForceCache, _) => (Some(response_from_cache.response), false),
(CacheMode::OnlyIfCached, &RequestMode::SameOrigin) => {
(Some(response_from_cache.response), false)
},
(CacheMode::OnlyIfCached, _) |
(CacheMode::NoStore, _) |
(CacheMode::Reload, _) => (None, false),
(_, _) => (
Some(response_from_cache.response),
response_from_cache.needs_validation,
),
};
if cached_response.is_none() {
// Ensure the done chan is not set if we're not using the cached response,
// as the cache might have set it to Some if it constructed a pending response.
*done_chan = None;
// Update the cache state, incrementing the pending store count,
// or starting the count.
if let HttpCacheEntryState::PendingStore(i) = *state {
let new = i + 1;
*state = HttpCacheEntryState::PendingStore(new);
} else {
*state = HttpCacheEntryState::PendingStore(1);
}
}
if let Some(entity_tag) = response_headers.get(header::ETAG) {
http_request
.headers
.insert(header::IF_NONE_MATCH, entity_tag.clone());
if needs_revalidation {
revalidating_flag = true;
// Substep 5
if let Some(http_date) = response_headers.typed_get::<LastModified>() {
let http_date: SystemTime = http_date.into();
http_request
.headers
.typed_insert(IfModifiedSince::from(http_date));
}
if let Some(entity_tag) = response_headers.get(header::ETAG) {
http_request
.headers
.insert(header::IF_NONE_MATCH, entity_tag.clone());
}
} else {
// Substep 6
response = cached_response;
}
}
}
// Notify the next thread waiting in line, if there is any.
if *state == HttpCacheEntryState::ReadyToConstruct {
cvar.notify_one();
}
// End of critical section on http-cache state.
}
// Decrement the number of pending stores,
// and set the state to ready to construct,
// if no stores are pending.
fn update_http_cache_state(context: &FetchContext, http_request: &Request) {
let (lock, cvar) = {
let entry_key = CacheKey::new(&http_request);
let mut state_map = context.state.http_cache_state.lock().unwrap();
&*state_map
.get_mut(&entry_key)
.expect("Entry in http-cache state to have been previously inserted")
.clone()
};
let mut state = lock.lock().unwrap();
if let HttpCacheEntryState::PendingStore(i) = *state {
let new = i - 1;
if new == 0 {
*state = HttpCacheEntryState::ReadyToConstruct;
// Notify the next thread waiting in line, if there is any.
cvar.notify_one();
} else {
// Substep 6
response = cached_response;
*state = HttpCacheEntryState::PendingStore(new);
}
}
}
@ -1065,6 +1163,7 @@ fn http_network_or_cache_fetch(
// The cache constructed a response with a body of ResponseBody::Receiving.
// We wait for the response in the cache to "finish",
// with a body of either Done or Cancelled.
assert!(response.is_some());
loop {
match ch
.1
@ -1095,6 +1194,9 @@ fn http_network_or_cache_fetch(
if response.is_none() {
// Substep 1
if http_request.cache_mode == CacheMode::OnlyIfCached {
// The cache will not be updated,
// set its state to ready to construct.
update_http_cache_state(context, &http_request);
return Response::network_error(NetworkError::Internal(
"Couldn't find response in cache".into(),
));
@ -1141,6 +1243,9 @@ fn http_network_or_cache_fetch(
let mut response = response.unwrap();
// The cache has been updated, set its state to ready to construct.
update_http_cache_state(context, &http_request);
// Step 8
// TODO: if necessary set response's range-requested flag
@ -1170,6 +1275,10 @@ fn http_network_or_cache_fetch(
return response;
}
// Make sure this is set to None,
// since we're about to start a new `http_network_or_cache_fetch`.
*done_chan = None;
// Substep 4
response = http_network_or_cache_fetch(
http_request,