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http-cache: improve handling of network errors and partial content

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gterzian committed Jun 1, 2019
1 parent d544c18 commit 4f41065dfbf6de00189d8713b3d6e716a5597e39
Showing with 40 additions and 9 deletions.
  1. +2 −4 components/net/fetch/methods.rs
  2. +38 −5 components/net/http_cache.rs
@@ -457,10 +457,8 @@ pub fn main_fetch(
// Step 24.
target.process_response_eof(&response);

if !response.is_network_error() {
if let Ok(mut http_cache) = context.state.http_cache.write() {
http_cache.update_awaiting_consumers(&request, &response);
}
if let Ok(mut http_cache) = context.state.http_cache.write() {
http_cache.update_awaiting_consumers(&request, &response);
}

// Steps 25-27.
@@ -638,9 +638,27 @@ impl HttpCache {
done_chan,
);
} else {
// Not a Range request.
if let Some(ref cached_resource) = candidates.first() {
// Returning the first response that can be constructed
while let Some(cached_resource) = candidates.pop() {
// Not a Range request.
// Do not allow 206 responses to be constructed.
//
// See https://tools.ietf.org/html/rfc7234#section-3.1
//
// A cache MUST NOT use an incomplete response to answer requests unless the
// response has been made complete or the request is partial and
// specifies a range that is wholly within the incomplete response.
//
// TODO: Combining partial content to fulfill a non-Range request
// see https://tools.ietf.org/html/rfc7234#section-3.3
match cached_resource.data.raw_status {
Some((ref code, _)) => {
if *code == 206 {
continue;
}
},
None => continue,
}
// Returning a response that can be constructed
// TODO: select the most appropriate one, using a known mechanism from a selecting header field,
// or using the Date header to return the most recent one.
let cached_headers = cached_resource.data.metadata.headers.lock().unwrap();
@@ -649,6 +667,7 @@ impl HttpCache {
return Some(cached_response);
}
}
// The cache wasn't able to construct anything.
None
}

@@ -657,10 +676,21 @@ impl HttpCache {
if let ResponseBody::Done(ref completed_body) = *response.body.lock().unwrap() {
let entry_key = CacheKey::new(request.clone());
if let Some(cached_resources) = self.entries.get(&entry_key) {
for cached_resource in cached_resources.iter() {
// Ensure we only wake-up consumers of relevant resources,
// ie we don't want to wake-up 200 awaiting consumers with a 206.
let relevant_cached_resources = cached_resources
.iter()
.filter(|resource| resource.data.raw_status == response.raw_status);
for cached_resource in relevant_cached_resources {
let mut awaiting_consumers = cached_resource.awaiting_body.lock().unwrap();
for done_sender in awaiting_consumers.drain(..) {
if cached_resource.aborted.load(Ordering::Relaxed) {
if cached_resource.aborted.load(Ordering::Relaxed) ||
response.is_network_error()
{
// In the case of an aborted fetch or a network errror,
// wake-up all awaiting consumers.
// Each will then start a new network request.
// TODO: Wake-up only one consumer, and make it the producer on which others wait.
let _ = done_sender.send(Data::Cancelled);
} else {
let _ = done_sender.send(Data::Payload(completed_body.clone()));
@@ -812,5 +842,8 @@ impl HttpCache {
};
let entry = self.entries.entry(entry_key).or_insert(vec![]);
entry.push(entry_resource);
// TODO: Complete incomplete responses, including 206 response, when stored here.
// See A cache MAY complete a stored incomplete response by making a subsequent range request
// https://tools.ietf.org/html/rfc7234#section-3.1
}
}

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