DelayedClientTransport.PendingStream will override cancel(), which has a
clearer semantic.
Also permitting all status codes except OK in ClientStream.cancel(),
instead of just 4 codes.
Although the changes were determined automatically, they were manually
applied to the codebase.
ClientCalls actually has a bug fix, since the suggestion to add
interrupt() made it obvious that interrupted() was inappropriate.
Always return a completed future from `TransportSet`. If a (real) transport has not been created (e.g., in reconnect back-off), a `DelayedClientTransport` will be returned.
Eventually we will get rid of the transport futures everywhere, and have streams always __owned__ by some transports.
DelayedClientTransport
----------------------
After we get rid of the transport future, this is what `ClientCallImpl` and `LoadBalancer` get when a real transport has not been created yet. It buffers new streams and pings until `setTransport()` is called, after which point all buffered and future streams/pings are transferred to the real transport.
If a buffered stream is cancelled, `DelayedClientTransport` will remove it from the buffer list, thus #1342 will be resolved after the larger refactoring is complete.
This PR only makes `TransportSet` use `DelayedClientTransport`. Follow-up changes will be made to allow `LoadBalancer.pickTransport()` to return null, in which case `ManagedChannelImpl` will give `ClientCallImpl` a `DelayedClientTransport`.
Changes to ClientTransport shutdown semantics
---------------------------------------------
Previously when shutdown() is called, `ClientTransport` should not accept newStream(), and when all existing streams have been closed, `ClientTransport` is terminated. Only when a transport is terminated would a transport owner (e.g., `TransportSet`) remove the reference to it.
`DelayedClientTransport` brings about a new case: when `setTransport()` is called, we switch to the real transport and no longer need the delayed transport. This is achieved by calling `shutdown()` on the delayed transport and letting it terminate. However, as the delayed transport has already been handed out to users, we would like `newStream()` to keep working for them, even though the delayed transport is already shut down and terminated.
In order to make it easy to manage the life-cycle of `DelayedClientTransport`, we redefine the shutdown semantics of transport:
- A transport can own a stream. Typically the transport owns the streams
it creates, but there may be exceptions. `DelayedClientTransport` DOES
NOT OWN the streams it returns from `newStream()` after `setTransport()`
has been called. Instead, the ownership would be transferred to the
real transport.
- After `shutdown()` has been called, the transport stops owning new
streams, and `newStream()` may still succeed. With this idea,
`DelayedClientTransport`, even when terminated, will continue
passing `newStream()` to the real transport.
- When a transport is in shutdown state, and it doesn't own any stream,
it then can enter terminated state.
ManagedClientTransport / ClientTransport
----------------------------------------
Remove life-cycle interfaces from `ClientTransport`, and put them in its subclass - `ManagedClientTransport`, with the same idea that we have `Channel` and `ManagedChannel`. Only the one who creates the transport will get `ManagedClientTransport` thus is able to start and shutdown the transport. The users of transport, e.g., `LoadBalancer`, can only get `ClientTransport` thus are not alter its state. This change clarifies the responsibility of transport life-cycle management.
Fix TransportSet shutdown semantics
-----------------------------------
Currently, if `TransportSet.shutdown()` has been called, it no longer create new transports, which is wrong.
The correct semantics of `TransportSet.shutdown()` should be:
- Shutdown all transports, thus stop new streams being created on them
- Stop `obtainActiveTransport()` from returning transports
- Streams that already created, including those buffered in delayed transport, should continue. That means if delayed transport has buffered streams, we should let the existing reconnect task continue.
Having Handler implement ChannelInboundHandler is overspecifying and
unnecessary, as the code compiles fine just by changing "implements
ChannelInboundHandler" to "implements ChannelHandler".
PlaintextHandler was swapped to ChannelHandlerAdapter instead of
ChannelDuplexHandler because it just needs the ChannelHandler methods.
This just propagates the deprecated annotation from ChannelHandler. Note
that exceptionCaught is _not_ deprecated for ChannelInboundHandler and
ChannelDuplexHandler.
This provides more structured data into the application for it to do
special handling.
In general, we would hope most people don't need this functionality, but
it is a good escape hatch to allow users to workaround infrastructure
problems.
This reverts commit eca1f7c1d6.
We want to preserve the status message identical to what the server
sent. We'll need a better way to communicate debugging details.
We think this broke when the stream lifecycle listener was removed.
Observing the stream lifecycle would be the "proper" fix, but it had
notification ordering issues where streams would close before we were
notified of the event that caused the closure, which made it difficult
to provide useful error messages. The ordering of notifications was also
largely undefined.
The long term fix we look forward to is the HTTP/2 child channels, which
should have clearly defined ordering between error notification and
channel closure, and in the order that we need here.
Fixes#1251
NettyServer wasn't usable as public, since its constructor was
package-private. So although this reduces our API, it shouldn't actually
impact anyone.
Fixes#1047
This isn't expected to have much impact once the connection is
established because AbstractNettyHandler.exceptionCaught() wraps all
unknown exceptions with Http2Exception. Fixing that is future work.
Some cases we may now be unwrapping a StatusException, such as one
thrown by MessageDeframer. In general, that seems a Good Thing™, but it
is unclear exactly if it would be perceivable.
Fixes#1181
A few things to note:
- ByteString has gone away in favor of AsciiString.
- Http2Headers now uses CharSequence for all methods, so there are a few places that we have to explicitly check for AsciiString to get the optimizations.
- We now have to specify a graceful shutdown timeout for our Netty handlers. Using 5 seconds.
We've seen an NPE as a side-effect of a failure in protocol negotiation:
Oct 27, 2015 9:27:09 PM io.grpc.transport.netty.ProtocolNegotiators$AbstractBufferingHandler fail
SEVERE: Transport failed during protocol negotiation
java.lang.NullPointerException
at io.grpc.transport.netty.NettyClientHandler$2.visit(NettyClientHandler.java:218)
- Channel builders decide the default port based on whether TLS is used.
- Channel builders populate the default port via an Attributes object
passed to NameResolver.Factory#newNameResolver
- NameResolverRegistry contains all the official NameResolvers. Users
can also add custom NameResolvers to it. It looks up NameResolver by
try-and-fail. It is the default NameResolver.Factory for builders.
DnsNameResolver.
- Pass target as Strings instead of URIs from the channel builder to
ManagedChannelImpl. A target string is not necessarily a valid URI, in
which case ManagedChannelImpl will add "dns:///" to the beginning of
the target and use it as URI.
- DnsNameResolver will require scheme "dns" to be present. It no longer
allows scheme-absent URIs.
Kun Zhang
nmittler
Trask Stalnaker
Eric Anderson
Carl Mastrangelo
Louis Ryan
Jakob Buchgraber
Xudong Ma