This PR finishes the refactoring started by #1395. Resolves#1342.
Major changes:
- All interfaces that return `ListenableFuture<T>` now return `T`
- Stop passing `null` for transports after shut down. Pass
`FailingClientTransport` instead. This simplifies the interface
semantics of interfaces that return a transport, as well as their
callers because they no longer need to check for `null`.
- Add two methods to `TransportManager`:
- `createInterimTransport()` takes the place of `BlankFutureProvider`
in `LoadBalancer` implementations.
- `createFailingTransport()` takes the place of errors in the `Future`
when `LoadBalancer` implementations propagate errors to the caller.
- `createInterimTransport()` creates a `DelayedClientTransport` tracked
by `ManagedChannelImpl`, which will not terminate until all
`DelayedClientTransport`s, in addition to the `TransportSet`s, are
terminated.
- Removed the transport argument from the ready and shutdown callbacks,
because if `LoadBalancer` was given a delayed transport earlier, it
will get the real transport's shutdown event, thus won't be able to
match the two through identity comparison, which beats the purpose of
passing the transport.
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.
This reduces the number of classes defined, which reduces memory usage.
It also reduces the number of methods defined, which is important
because of the dex limit.
This should have virtually zero performance degradation because the
contiguous switch uses tableswitch bytecode.
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.
- Set knownAcceptEncodingRegistry in SingleTransportChannel
- Change the package name of load_balancer.proto to be consistent with
what is used internally.
Use LinkedHashSet in BlankFutureProvider so that it fulfills the futures
in the same order as they were created. This makes the behavior more
predictable, thus fixes the flakiness of GrpclbLoadBalancerTest and
simplifies BlankFutureProviderTest.
This LoadBalancer does round-robin on a address list received from a
separate "load-balancer service", via the protocol defined in
load_balancer.proto. Everything is put under a subproject `grpc-grpclb`,
because it has dependency to protobuf.
updateRetainedTransports() now accepts EquivalentAddressGroups. The
LoadBalancer merges the LB and normal server address groups when calling
it.
Carl Mastrangelo
Kun Zhang
Louis Ryan
Eric Anderson