mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-11-29 23:22:45 +00:00
248 lines
8.8 KiB
Go
248 lines
8.8 KiB
Go
/*
|
|
*
|
|
* Copyright 2017 gRPC authors.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*
|
|
*/
|
|
|
|
package grpc
|
|
|
|
import (
|
|
"context"
|
|
"strings"
|
|
"sync"
|
|
|
|
"google.golang.org/grpc/balancer"
|
|
"google.golang.org/grpc/internal/channelz"
|
|
"google.golang.org/grpc/internal/grpcsync"
|
|
"google.golang.org/grpc/internal/pretty"
|
|
"google.golang.org/grpc/resolver"
|
|
"google.golang.org/grpc/serviceconfig"
|
|
)
|
|
|
|
// resolverStateUpdater wraps the single method used by ccResolverWrapper to
|
|
// report a state update from the actual resolver implementation.
|
|
type resolverStateUpdater interface {
|
|
updateResolverState(s resolver.State, err error) error
|
|
}
|
|
|
|
// ccResolverWrapper is a wrapper on top of cc for resolvers.
|
|
// It implements resolver.ClientConn interface.
|
|
type ccResolverWrapper struct {
|
|
// The following fields are initialized when the wrapper is created and are
|
|
// read-only afterwards, and therefore can be accessed without a mutex.
|
|
cc resolverStateUpdater
|
|
channelzID *channelz.Identifier
|
|
ignoreServiceConfig bool
|
|
opts ccResolverWrapperOpts
|
|
serializer *grpcsync.CallbackSerializer // To serialize all incoming calls.
|
|
serializerCancel context.CancelFunc // To close the serializer, accessed only from close().
|
|
|
|
// All incoming (resolver --> gRPC) calls are guaranteed to execute in a
|
|
// mutually exclusive manner as they are scheduled on the serializer.
|
|
// Fields accessed *only* in these serializer callbacks, can therefore be
|
|
// accessed without a mutex.
|
|
curState resolver.State
|
|
|
|
// mu guards access to the below fields.
|
|
mu sync.Mutex
|
|
closed bool
|
|
resolver resolver.Resolver // Accessed only from outgoing calls.
|
|
}
|
|
|
|
// ccResolverWrapperOpts wraps the arguments to be passed when creating a new
|
|
// ccResolverWrapper.
|
|
type ccResolverWrapperOpts struct {
|
|
target resolver.Target // User specified dial target to resolve.
|
|
builder resolver.Builder // Resolver builder to use.
|
|
bOpts resolver.BuildOptions // Resolver build options to use.
|
|
channelzID *channelz.Identifier // Channelz identifier for the channel.
|
|
}
|
|
|
|
// newCCResolverWrapper uses the resolver.Builder to build a Resolver and
|
|
// returns a ccResolverWrapper object which wraps the newly built resolver.
|
|
func newCCResolverWrapper(cc resolverStateUpdater, opts ccResolverWrapperOpts) (*ccResolverWrapper, error) {
|
|
ctx, cancel := context.WithCancel(context.Background())
|
|
ccr := &ccResolverWrapper{
|
|
cc: cc,
|
|
channelzID: opts.channelzID,
|
|
ignoreServiceConfig: opts.bOpts.DisableServiceConfig,
|
|
opts: opts,
|
|
serializer: grpcsync.NewCallbackSerializer(ctx),
|
|
serializerCancel: cancel,
|
|
}
|
|
|
|
// Cannot hold the lock at build time because the resolver can send an
|
|
// update or error inline and these incoming calls grab the lock to schedule
|
|
// a callback in the serializer.
|
|
r, err := opts.builder.Build(opts.target, ccr, opts.bOpts)
|
|
if err != nil {
|
|
cancel()
|
|
return nil, err
|
|
}
|
|
|
|
// Any error reported by the resolver at build time that leads to a
|
|
// re-resolution request from the balancer is dropped by grpc until we
|
|
// return from this function. So, we don't have to handle pending resolveNow
|
|
// requests here.
|
|
ccr.mu.Lock()
|
|
ccr.resolver = r
|
|
ccr.mu.Unlock()
|
|
|
|
return ccr, nil
|
|
}
|
|
|
|
func (ccr *ccResolverWrapper) resolveNow(o resolver.ResolveNowOptions) {
|
|
ccr.mu.Lock()
|
|
defer ccr.mu.Unlock()
|
|
|
|
// ccr.resolver field is set only after the call to Build() returns. But in
|
|
// the process of building, the resolver may send an error update which when
|
|
// propagated to the balancer may result in a re-resolution request.
|
|
if ccr.closed || ccr.resolver == nil {
|
|
return
|
|
}
|
|
ccr.resolver.ResolveNow(o)
|
|
}
|
|
|
|
func (ccr *ccResolverWrapper) close() {
|
|
ccr.mu.Lock()
|
|
if ccr.closed {
|
|
ccr.mu.Unlock()
|
|
return
|
|
}
|
|
|
|
channelz.Info(logger, ccr.channelzID, "Closing the name resolver")
|
|
|
|
// Close the serializer to ensure that no more calls from the resolver are
|
|
// handled, before actually closing the resolver.
|
|
ccr.serializerCancel()
|
|
ccr.closed = true
|
|
r := ccr.resolver
|
|
ccr.mu.Unlock()
|
|
|
|
// Give enqueued callbacks a chance to finish.
|
|
<-ccr.serializer.Done()
|
|
|
|
// Spawn a goroutine to close the resolver (since it may block trying to
|
|
// cleanup all allocated resources) and return early.
|
|
go r.Close()
|
|
}
|
|
|
|
// serializerScheduleLocked is a convenience method to schedule a function to be
|
|
// run on the serializer while holding ccr.mu.
|
|
func (ccr *ccResolverWrapper) serializerScheduleLocked(f func(context.Context)) {
|
|
ccr.mu.Lock()
|
|
ccr.serializer.Schedule(f)
|
|
ccr.mu.Unlock()
|
|
}
|
|
|
|
// UpdateState is called by resolver implementations to report new state to gRPC
|
|
// which includes addresses and service config.
|
|
func (ccr *ccResolverWrapper) UpdateState(s resolver.State) error {
|
|
errCh := make(chan error, 1)
|
|
if s.Endpoints == nil {
|
|
s.Endpoints = make([]resolver.Endpoint, 0, len(s.Addresses))
|
|
for _, a := range s.Addresses {
|
|
ep := resolver.Endpoint{Addresses: []resolver.Address{a}, Attributes: a.BalancerAttributes}
|
|
ep.Addresses[0].BalancerAttributes = nil
|
|
s.Endpoints = append(s.Endpoints, ep)
|
|
}
|
|
}
|
|
ok := ccr.serializer.Schedule(func(context.Context) {
|
|
ccr.addChannelzTraceEvent(s)
|
|
ccr.curState = s
|
|
if err := ccr.cc.updateResolverState(ccr.curState, nil); err == balancer.ErrBadResolverState {
|
|
errCh <- balancer.ErrBadResolverState
|
|
return
|
|
}
|
|
errCh <- nil
|
|
})
|
|
if !ok {
|
|
// The only time when Schedule() fail to add the callback to the
|
|
// serializer is when the serializer is closed, and this happens only
|
|
// when the resolver wrapper is closed.
|
|
return nil
|
|
}
|
|
return <-errCh
|
|
}
|
|
|
|
// ReportError is called by resolver implementations to report errors
|
|
// encountered during name resolution to gRPC.
|
|
func (ccr *ccResolverWrapper) ReportError(err error) {
|
|
ccr.serializerScheduleLocked(func(_ context.Context) {
|
|
channelz.Warningf(logger, ccr.channelzID, "ccResolverWrapper: reporting error to cc: %v", err)
|
|
ccr.cc.updateResolverState(resolver.State{}, err)
|
|
})
|
|
}
|
|
|
|
// NewAddress is called by the resolver implementation to send addresses to
|
|
// gRPC.
|
|
func (ccr *ccResolverWrapper) NewAddress(addrs []resolver.Address) {
|
|
ccr.serializerScheduleLocked(func(_ context.Context) {
|
|
ccr.addChannelzTraceEvent(resolver.State{Addresses: addrs, ServiceConfig: ccr.curState.ServiceConfig})
|
|
ccr.curState.Addresses = addrs
|
|
ccr.cc.updateResolverState(ccr.curState, nil)
|
|
})
|
|
}
|
|
|
|
// NewServiceConfig is called by the resolver implementation to send service
|
|
// configs to gRPC.
|
|
func (ccr *ccResolverWrapper) NewServiceConfig(sc string) {
|
|
ccr.serializerScheduleLocked(func(_ context.Context) {
|
|
channelz.Infof(logger, ccr.channelzID, "ccResolverWrapper: got new service config: %s", sc)
|
|
if ccr.ignoreServiceConfig {
|
|
channelz.Info(logger, ccr.channelzID, "Service config lookups disabled; ignoring config")
|
|
return
|
|
}
|
|
scpr := parseServiceConfig(sc)
|
|
if scpr.Err != nil {
|
|
channelz.Warningf(logger, ccr.channelzID, "ccResolverWrapper: error parsing service config: %v", scpr.Err)
|
|
return
|
|
}
|
|
ccr.addChannelzTraceEvent(resolver.State{Addresses: ccr.curState.Addresses, ServiceConfig: scpr})
|
|
ccr.curState.ServiceConfig = scpr
|
|
ccr.cc.updateResolverState(ccr.curState, nil)
|
|
})
|
|
}
|
|
|
|
// ParseServiceConfig is called by resolver implementations to parse a JSON
|
|
// representation of the service config.
|
|
func (ccr *ccResolverWrapper) ParseServiceConfig(scJSON string) *serviceconfig.ParseResult {
|
|
return parseServiceConfig(scJSON)
|
|
}
|
|
|
|
// addChannelzTraceEvent adds a channelz trace event containing the new
|
|
// state received from resolver implementations.
|
|
func (ccr *ccResolverWrapper) addChannelzTraceEvent(s resolver.State) {
|
|
var updates []string
|
|
var oldSC, newSC *ServiceConfig
|
|
var oldOK, newOK bool
|
|
if ccr.curState.ServiceConfig != nil {
|
|
oldSC, oldOK = ccr.curState.ServiceConfig.Config.(*ServiceConfig)
|
|
}
|
|
if s.ServiceConfig != nil {
|
|
newSC, newOK = s.ServiceConfig.Config.(*ServiceConfig)
|
|
}
|
|
if oldOK != newOK || (oldOK && newOK && oldSC.rawJSONString != newSC.rawJSONString) {
|
|
updates = append(updates, "service config updated")
|
|
}
|
|
if len(ccr.curState.Addresses) > 0 && len(s.Addresses) == 0 {
|
|
updates = append(updates, "resolver returned an empty address list")
|
|
} else if len(ccr.curState.Addresses) == 0 && len(s.Addresses) > 0 {
|
|
updates = append(updates, "resolver returned new addresses")
|
|
}
|
|
channelz.Infof(logger, ccr.channelzID, "Resolver state updated: %s (%v)", pretty.ToJSON(s), strings.Join(updates, "; "))
|
|
}
|