diff options
Diffstat (limited to 'pingora-cache/src')
| -rw-r--r-- | pingora-cache/src/lib.rs | 70 | ||||
| -rw-r--r-- | pingora-cache/src/predictor.rs | 2 |
2 files changed, 47 insertions, 25 deletions
diff --git a/pingora-cache/src/lib.rs b/pingora-cache/src/lib.rs index 6bebbd3..6ac49a5 100644 --- a/pingora-cache/src/lib.rs +++ b/pingora-cache/src/lib.rs @@ -125,8 +125,12 @@ pub enum NoCacheReason { /// /// This happens when the cache predictor predicted that this request is not cacheable, but /// the response turns out to be OK to cache. However, it might be too large to re-enable caching - /// for this request. + /// for this request Deferred, + /// Due to the proxy upstream filter declining the current request from going upstream + DeclinedToUpstream, + /// Due to the upstream being unreachable or otherwise erroring during proxying + UpstreamError, /// The writer of the cache lock sees that the request is not cacheable (Could be OriginNotCache) CacheLockGiveUp, /// This request waited too long for the writer of the cache lock to finish, so this request will @@ -147,6 +151,8 @@ impl NoCacheReason { StorageError => "StorageError", InternalError => "InternalError", Deferred => "Deferred", + DeclinedToUpstream => "DeclinedToUpstream", + UpstreamError => "UpstreamError", CacheLockGiveUp => "CacheLockGiveUp", CacheLockTimeout => "CacheLockTimeout", Custom(s) => s, @@ -299,9 +305,44 @@ impl HttpCache { .is_some() } + /// Release the cache lock if the current request is a cache writer. + /// + /// Generally callers should prefer using `disable` when a cache lock should be released + /// due to an error to clear all cache context. This function is for releasing the cache lock + /// while still keeping the cache around for reading, e.g. when serving stale. + pub fn release_write_lock(&mut self, reason: NoCacheReason) { + use NoCacheReason::*; + if let Some(inner) = self.inner.as_mut() { + let lock = inner.lock.take(); + if let Some(Locked::Write(_r)) = lock { + let lock_status = match reason { + // let the next request try to fetch it + InternalError | StorageError | Deferred | UpstreamError => { + LockStatus::TransientError + } + // depends on why the proxy upstream filter declined the request, + // for now still allow next request try to acquire to avoid thundering herd + DeclinedToUpstream => LockStatus::TransientError, + // no need for the lock anymore + OriginNotCache | ResponseTooLarge => LockStatus::GiveUp, + // not sure which LockStatus make sense, we treat it as GiveUp for now + Custom(_) => LockStatus::GiveUp, + // should never happen, NeverEnabled shouldn't hold a lock + NeverEnabled => panic!("NeverEnabled holds a write lock"), + CacheLockGiveUp | CacheLockTimeout => { + panic!("CacheLock* are for cache lock readers only") + } + }; + inner + .cache_lock + .unwrap() + .release(inner.key.as_ref().unwrap(), lock_status); + } + } + } + /// Disable caching pub fn disable(&mut self, reason: NoCacheReason) { - use NoCacheReason::*; match self.phase { CachePhase::Disabled(_) => { // replace reason @@ -309,28 +350,7 @@ impl HttpCache { } _ => { self.phase = CachePhase::Disabled(reason); - if let Some(inner) = self.inner.as_mut() { - let lock = inner.lock.take(); - if let Some(Locked::Write(_r)) = lock { - let lock_status = match reason { - // let the next request try to fetch it - InternalError | StorageError | Deferred => LockStatus::TransientError, - // no need for the lock anymore - OriginNotCache | ResponseTooLarge => LockStatus::GiveUp, - // not sure which LockStatus make sense, we treat it as GiveUp for now - Custom(_) => LockStatus::GiveUp, - // should never happen, NeverEnabled shouldn't hold a lock - NeverEnabled => panic!("NeverEnabled holds a write lock"), - CacheLockGiveUp | CacheLockTimeout => { - panic!("CacheLock* are for cache lock readers only") - } - }; - inner - .cache_lock - .unwrap() - .release(inner.key.as_ref().unwrap(), lock_status); - } - } + self.release_write_lock(reason); // log initial disable reason self.inner_mut() .traces @@ -824,6 +844,8 @@ impl HttpCache { CachePhase::Stale => { // replace cache meta header self.inner_mut().meta.as_mut().unwrap().0.header = header; + // upstream request done, release write lock + self.release_write_lock(reason); } _ => panic!("wrong phase {:?}", self.phase), } diff --git a/pingora-cache/src/predictor.rs b/pingora-cache/src/predictor.rs index df8f374..d131c20 100644 --- a/pingora-cache/src/predictor.rs +++ b/pingora-cache/src/predictor.rs @@ -120,7 +120,7 @@ where // CacheLockGiveUp: the writer will set OriginNotCache (if applicable) // readers don't need to do it NeverEnabled | StorageError | InternalError | Deferred | CacheLockGiveUp - | CacheLockTimeout => { + | CacheLockTimeout | DeclinedToUpstream | UpstreamError => { return None; } // Skip certain NoCacheReason::Custom according to user |