This is a more favorable approach than #3467. Doing the registration
in MethodDescriptor should allow us to deregister in case the
generated stub and its MethodDescriptors are garbage-collected
routinely, e.g., if they are loaded by a separate ClassLoader.
Two methods, outboundMessageSent() and inboundMessageRead() are added to StreamTracer in order to associate individual messages with sizes. Both types of sizes are optional, as allowed by Census tracing.
Both methods accept a sequence number as the type ID as required by Census. The original outboundMesage() and inboundMessage() are also replaced by overrides that take the sequence number, to better match the new methods. The deprecation of the old overrides are tracked by #3460
GrpclbLoadBalancer can work in non-GRPCLB (delegate) mode according to
name resolution results. Previously the policy selection, delegation
and GRPCLB logic are in the same file, which is not very readable. It
will get worse as we going to implement policy fallback logic soon.
This PR refactors the GRPCLB logic out, and makes GrpclbLoadBalancer
focus on the policy selection and delegation logic.
This bump changelist is applied a bit late with respect to the
1.6.0 branch cut. Look at the 1.6.0 to see the source of truth of
where it was cut. Do not assume it is the commit that precedes
this one.
Previously, the round-robin list that the client uses (effective
round-robin list, ERRL) was the received round-robin list (RRRL)
excluding non-READY backends. Drop and backend entries are in the
same list.
The problem with it is that when not all backends are READY, drop
entries take a larger proportion in ERRL than they do in the RRRL,
resulting a larger drop ratio than intended.
To fix this, we employ a two-list scheme:
- A "drop list" (DL) that is out of the RRRL, with the same size and
the same number of drop entries.
- A "backend list" (BL) that contains only the backend entries from
the RRRL, excluding non-READY ones.
For every pick, the client would round-robin on the DL to determine
whether the pick should be dropped. Only when it's not dropped,
round-robin on the BL to pick the actual backend.
This way, the drop ratio is always equal to the proportion they take
in the RRRL.
Previously only when all addresses returned by NameResolver are
balancers would GRPCLB be forced. This change is a follow-up of
https://github.com/grpc/grpc/pull/10258
The equivalent of the has* methods for oneofs is to check which Case()
is used. Reworked the code a bit because it seemed obvious that it
wasn't checking all the cases it should, and is probably more natural
now that the code uses Case().
This allows avoiding re-creating connections unnecessarily. For
NameResolvers that support notifications this avoids stampeding herds
when possible, since all clients may receive the notification at
approximately the same time.
Each time helper.updatePicker() is called, the Channel will re-process
all pending streams with the new picker. If the old picker is
equivalent to the old one, it's wasteful.
This is also needed to make our internal integration test easier.
Because the load-balancer may send address list that is identical to the
previous one, just to update the TTL. Without this change, new picker
replaces the old picker even if they carry the same list, which
effectively resets the round-robin pointer. This causes a little
imbalance between test backends, resulting in test failure.
Resolves#2716
- Add attributes to EquivalentAddressGroup
- Deprecate ResolvedServerInfoGroup by EquivalentAddressGroup
- Deprecate ResolvedServerInfo, because attributes for a single address
with an address group is not found to be useful.
- The changes on the NameResolver and LoadBalancer interfaces are backward-compatible
in the next release, with which implementors can switch to the new API smoothly.
As a related change, redefine the semantics of DnsNameResolver and
RoundRobinLoadBalancer:
- Before: DnsNameResolver returns all addresses in one address group.
RoundRobinLoadBalancer ignores the grouping of addresses and
round-robin on every single addresses. It doesn't work well with the
one-server-multiple-address setup, e.g., both IPv4 and IPv6 addresses
are returned for a single serve, even if they are put in the same
address group by the NameResolver.
- After: DnsNameResolver returns every address in its own
EAG. RoundRobinLoadBalancer takes an EAG as a whole, and only
round-robin on the list of EAGs. The new behavior is a better
interpretation of the EAGs, and really allows the case where one
server has more than one addresses (e.g., IPv4 and IPv6).
This change will affect users that use custom LoadBalancer with the
stock DnsNameResolver, and those who use custom NameResolver with the
stock RoundRobinLoadBalancer.
Users who use both the stock DnsNameResolver and RoundRobinLoadBalancer
or PickFirstBalancer will see no behavioral change. Because they will
still round-robin on individual addresses from DNS, or do pick-first on
all addresses from DNS (PickFirstBalancer flattens all addresses).
The result is a simpler API and reduction of boilderplates.
The balancer service attaches a token string for each Server entry it
sends to the client. The client has to set the token to the "lb-token"
header when assigning that Server entry to an RPC.
For convenience of testing, also implemented hashCode() and equals() for
PickResult.
Besides API changes, this implementation is also up-to-date with the
latest design:
1. Delegate to round-robin and pick-first policies if requested by
the naming system.
2. OOB channels to LoadBalancer always use the LB authority provided by
the naming system.
3. Never send application RPCs to balancer addresses, even if the
address returns UNIMPLEMENTED error.
Carl Mastrangelo
Kun Zhang
Lukasz Strzalkowski
Eric Anderson
zpencer
myPrecious
ZHANG Dapeng
Eric Gribkoff
Łukasz Strzałkowski
Kun Zhang