cbickel commented on a change in pull request #2338: Prepare cache to change it
by configuration
URL:
https://github.com/apache/incubator-openwhisk/pull/2338#discussion_r129039244
##########
File path:
common/scala/src/main/scala/whisk/core/database/MultipleReadersSingleWriterCache.scala
##########
@@ -146,138 +142,127 @@ trait MultipleReadersSingleWriterCache[W, Winfo] {
override def toString = s"tid ${transid.meta.id}, state ${state.get}"
}
- /**
- * This method posts a delete to the backing store, and either directly
invalidates the cache entry
- * or informs any outstanding transaction that it must invalidate the
cache on completion.
- */
- protected def cacheInvalidate[R](key: Any, invalidator: => Future[R])(
+ def cacheInvalidate[R](key: Any, invalidator: => Future[R])(
implicit ec: ExecutionContext, transid: TransactionId, logger:
Logging): Future[R] = {
- if (cacheEnabled) {
- logger.info(this, s"invalidating $key on delete")
-
- // try inserting our desired entry...
- val desiredEntry = Entry(transid, InvalidateInProgress, None)
- cache(key)(desiredEntry) flatMap { actualEntry =>
- // ... and see what we get back
- val currentState = actualEntry.state.get
-
- currentState match {
- case Cached =>
- // nobody owns the entry, forcefully grab ownership
- // note: if a new cache lookup is received while
- // the invalidator has not yet completed (and hence
the actual entry
- // removed from the cache), such lookup operations
will still be able
- // to return the value that is cached, and this is
acceptable (under
- // the eventual consistency model) as long as such
lookups do not
- // mutate the state of the cache to violate the
invalidation that is
- // about to occur (this is eventually consistent and
NOT sequentially
- // consistent since the cache lookup and the setting
of the
- // InvalidateInProgress bit are not atomic
+ logger.info(this, s"invalidating $key on delete")
+
+ // try inserting our desired entry...
+ val desiredEntry = Entry(transid, InvalidateInProgress, None)
+ cache(key)(desiredEntry) flatMap { actualEntry =>
+ // ... and see what we get back
+ val currentState = actualEntry.state.get
+
+ currentState match {
+ case Cached =>
+ // nobody owns the entry, forcefully grab ownership
+ // note: if a new cache lookup is received while
+ // the invalidator has not yet completed (and hence the
actual entry
+ // removed from the cache), such lookup operations will
still be able
+ // to return the value that is cached, and this is
acceptable (under
+ // the eventual consistency model) as long as such lookups
do not
+ // mutate the state of the cache to violate the
invalidation that is
+ // about to occur (this is eventually consistent and NOT
sequentially
+ // consistent since the cache lookup and the setting of the
+ // InvalidateInProgress bit are not atomic
+ invalidateEntryAfter(invalidator, key, actualEntry)
+
+ case ReadInProgress | WriteInProgress =>
+ if (actualEntry.trySet(currentState, InvalidateWhenDone)) {
+ // then the pre-existing owner will take care of the
invalidation
+ invalidator
+ } else {
+ // the pre-existing reader or writer finished and so
must
+ // explicitly invalidate here
invalidateEntryAfter(invalidator, key, actualEntry)
+ }
- case ReadInProgress | WriteInProgress =>
- if (actualEntry.trySet(currentState,
InvalidateWhenDone)) {
- // then the pre-existing owner will take care of
the invalidation
- invalidator
- } else {
- // the pre-existing reader or writer finished and
so must
- // explicitly invalidate here
- invalidateEntryAfter(invalidator, key, actualEntry)
- }
-
- case InvalidateInProgress =>
- if (actualEntry == desiredEntry) {
- // we own the entry, so we are responsible for
cleaning it up
- invalidateEntryAfter(invalidator, key, actualEntry)
- } else {
- // someone else requested an invalidation already
- invalidator
- }
-
- case InvalidateWhenDone =>
- // a pre-existing owner will take care of the
invalidation
+ case InvalidateInProgress =>
+ if (actualEntry == desiredEntry) {
+ // we own the entry, so we are responsible for
cleaning it up
+ invalidateEntryAfter(invalidator, key, actualEntry)
+ } else {
+ // someone else requested an invalidation already
invalidator
- }
+ }
+
+ case InvalidateWhenDone =>
+ // a pre-existing owner will take care of the invalidation
+ invalidator
}
- } else invalidator // not caching
+ }
}
- /**
- * This method may initiate a read from the backing store, and potentially
stores the result in the cache.
- */
- protected def cacheLookup[Wsuper >: W](key: Any, generator: => Future[W],
fromCache: Boolean = cacheEnabled)(
- implicit ec: ExecutionContext, transid: TransactionId, logger:
Logging): Future[W] = {
- if (fromCache) {
- val promise = Promise[W] // this promise completes with the
generator value
-
- // try inserting our desired entry...
- val desiredEntry = Entry(transid, ReadInProgress,
Some(promise.future))
- cache(key)(desiredEntry) flatMap { actualEntry =>
- // ... and see what we get back
-
- actualEntry.state.get match {
- case Cached =>
- logger.debug(this, "cached read")
- makeNoteOfCacheHit(key)
- actualEntry.unpack
-
- case ReadInProgress =>
- if (actualEntry == desiredEntry) {
- logger.debug(this, "read initiated");
- makeNoteOfCacheMiss(key)
- // updating the cache with the new value is done
in the listener
- // and will complete unless an invalidation
request or an intervening
- // write occur in the meantime
- listenForReadDone(key, actualEntry, generator,
promise)
- actualEntry.unpack
- } else {
- logger.debug(this, "coalesced read")
- makeNoteOfCacheHit(key)
- actualEntry.unpack
+ def cacheLookup[Wsub <: W](key: Any, generator: => Future[Wsub])(
+ implicit ec: ExecutionContext, transid: TransactionId, logger:
Logging, mw: Manifest[Wsub]): Future[Wsub] = {
+ val promise = Promise[W] // this promise completes with the generator
value
+
+ // try inserting our desired entry...
+ val desiredEntry = Entry(transid, ReadInProgress, Some(promise.future))
+ cache(key)(desiredEntry) flatMap { actualEntry =>
+ // ... and see what we get back
+
+ actualEntry.state.get match {
+ case Cached =>
+ logger.debug(this, "cached read")
+ makeNoteOfCacheHit(key)
+ actualEntry.unpack.map { entry =>
+ if (entry.getClass != mw.runtimeClass) {
+ throw DocumentTypeMismatchException(s"document
type ${entry.getClass} did not match expected type ${mw.runtimeClass}.")
}
+ entry.asInstanceOf[Wsub]
Review comment:
It's the same like getting the WhiskEntity out of the Datastore:
https://github.com/apache/incubator-openwhisk/blob/master/common/scala/src/main/scala/whisk/core/database/CouchDbRestStore.scala#L148
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