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agent/service_manager: remove 'defaults' field from serviceConfigWatch 

This field was always read by the same function that populated the field,
so it does not need to be a field. Passing the value as an argument to
functions makes it more obvious where the value comes from, and also reduces
the scope of the variable significantly.
This commit is contained in:
Daniel Nephin 2020-04-17 16:50:25 -04:00
parent 93235da253
commit 26291a8482
1 changed files with 29 additions and 34 deletions
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63
agent/service_manager.go
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@ -27,10 +27,11 @@ type ServiceManager struct {
// services tracks all active watches for registered services // services tracks all active watches for registered services
services map[structs.ServiceID]*serviceConfigWatch services map[structs.ServiceID]*serviceConfigWatch
// registerCh is a channel for processing service registrations in the // registerCh is a channel for receiving service registration requests from
// background when watches are notified of changes. All sends and receives // from serviceConfigWatchers.
// must also obey the ctx.Done() channel to avoid a deadlock during // The registrations are handled in the background when watches are notified of
// shutdown. // changes. All sends and receives must also obey the ctx.Done() channel to
// avoid a deadlock during shutdown.
registerCh chan *asyncRegisterRequest registerCh chan *asyncRegisterRequest
// ctx is the shared context for all goroutines launched // ctx is the shared context for all goroutines launched
@ -220,7 +221,6 @@ type serviceRegistration struct {
// service/proxy defaults. // service/proxy defaults.
type serviceConfigWatch struct { type serviceConfigWatch struct {
registration *serviceRegistration registration *serviceRegistration
defaults *structs.ServiceConfigResponse
agent *Agent agent *Agent
registerCh chan<- *asyncRegisterRequest registerCh chan<- *asyncRegisterRequest
@ -239,7 +239,7 @@ type serviceConfigWatch struct {
// NOTE: this is called while holding the Agent.stateLock // NOTE: this is called while holding the Agent.stateLock
func (w *serviceConfigWatch) RegisterAndStart( func (w *serviceConfigWatch) RegisterAndStart(
ctx context.Context, ctx context.Context,
previousDefaults *structs.ServiceConfigResponse, serviceDefaults *structs.ServiceConfigResponse,
waitForCentralConfig bool, waitForCentralConfig bool,
persistServiceConfig bool, persistServiceConfig bool,
wg *sync.WaitGroup, wg *sync.WaitGroup,
@ -251,16 +251,16 @@ func (w *serviceConfigWatch) RegisterAndStart(
// operation. Either way the watcher will end up with something flagged // operation. Either way the watcher will end up with something flagged
// as defaults even if they don't actually reflect actual defaults. // as defaults even if they don't actually reflect actual defaults.
if waitForCentralConfig { if waitForCentralConfig {
if err := w.fetchDefaults(ctx); err != nil { var err error
serviceDefaults, err = w.fetchDefaults(ctx)
if err != nil {
return fmt.Errorf("could not retrieve initial service_defaults config for service %q: %v", service.ID, err) return fmt.Errorf("could not retrieve initial service_defaults config for service %q: %v", service.ID, err)
} }
} else {
w.defaults = previousDefaults
} }
// Merge the local registration with the central defaults and update this service // Merge the local registration with the central defaults and update this service
// in the local state. // in the local state.
merged, err := w.mergeServiceConfig() merged, err := mergeServiceConfig(serviceDefaults, w.registration.service)
if err != nil { if err != nil {
return err return err
} }
@ -272,7 +272,7 @@ func (w *serviceConfigWatch) RegisterAndStart(
service: merged, service: merged,
chkTypes: w.registration.chkTypes, chkTypes: w.registration.chkTypes,
persistService: w.registration.service, persistService: w.registration.service,
persistDefaults: w.defaults, persistDefaults: serviceDefaults,
persist: w.registration.persist, persist: w.registration.persist,
persistServiceConfig: persistServiceConfig, persistServiceConfig: persistServiceConfig,
token: w.registration.token, token: w.registration.token,
@ -289,22 +289,20 @@ func (w *serviceConfigWatch) RegisterAndStart(
} }
// NOTE: this is called while holding the Agent.stateLock // NOTE: this is called while holding the Agent.stateLock
func (w *serviceConfigWatch) fetchDefaults(ctx context.Context) error { func (w *serviceConfigWatch) fetchDefaults(ctx context.Context) (*structs.ServiceConfigResponse, error) {
req := makeConfigRequest(w.agent, w.registration) req := makeConfigRequest(w.agent, w.registration)
raw, _, err := w.agent.cache.Get(ctx, cachetype.ResolvedServiceConfigName, req) raw, _, err := w.agent.cache.Get(ctx, cachetype.ResolvedServiceConfigName, req)
if err != nil { if err != nil {
return err return nil, err
} }
reply, ok := raw.(*structs.ServiceConfigResponse) serviceConfig, ok := raw.(*structs.ServiceConfigResponse)
if !ok { if !ok {
// This should never happen, but we want to protect against panics // This should never happen, but we want to protect against panics
return fmt.Errorf("internal error: response type not correct") return nil, fmt.Errorf("internal error: response type not correct")
} }
return serviceConfig, nil
w.defaults = reply
return nil
} }
// Start starts the config watch and a goroutine to handle updates over the // Start starts the config watch and a goroutine to handle updates over the
@ -381,7 +379,7 @@ func (w *serviceConfigWatch) handleUpdate(ctx context.Context, event cache.Updat
return fmt.Errorf("error watching service config: %v", event.Err) return fmt.Errorf("error watching service config: %v", event.Err)
} }
res, ok := event.Result.(*structs.ServiceConfigResponse) serviceDefaults, ok := event.Result.(*structs.ServiceConfigResponse)
if !ok { if !ok {
return fmt.Errorf("unknown update event type: %T", event) return fmt.Errorf("unknown update event type: %T", event)
} }
@ -393,11 +391,10 @@ func (w *serviceConfigWatch) handleUpdate(ctx context.Context, event cache.Updat
// delivered) the correct config so just ignore this old message. // delivered) the correct config so just ignore this old message.
return nil return nil
} }
w.defaults = res
// Merge the local registration with the central defaults and update this service // Merge the local registration with the central defaults and update this service
// in the local state. // in the local state.
merged, err := w.mergeServiceConfig() merged, err := mergeServiceConfig(serviceDefaults, w.registration.service)
if err != nil { if err != nil {
return err return err
} }
@ -415,7 +412,7 @@ func (w *serviceConfigWatch) handleUpdate(ctx context.Context, event cache.Updat
service: merged, service: merged,
chkTypes: w.registration.chkTypes, chkTypes: w.registration.chkTypes,
persistService: w.registration.service, persistService: w.registration.service,
persistDefaults: w.defaults, persistDefaults: serviceDefaults,
persist: w.registration.persist, persist: w.registration.persist,
persistServiceConfig: true, persistServiceConfig: true,
token: w.registration.token, token: w.registration.token,
@ -484,19 +481,17 @@ func makeConfigRequest(agent *Agent, registration *serviceRegistration) *structs
return req return req
} }
// mergeServiceConfig returns the final effective config for the watched service, // mergeServiceConfig from service into defaults to produce the final effective
// including the latest known global defaults from the servers. // config for the watched service.
// func mergeServiceConfig(defaults *structs.ServiceConfigResponse, service *structs.NodeService) (*structs.NodeService, error) {
// NOTE: this is called while holding the Agent.stateLock if defaults == nil {
func (w *serviceConfigWatch) mergeServiceConfig() (*structs.NodeService, error) { return service, nil
if w.defaults == nil {
return w.registration.service, nil
} }
// We don't want to change s.registration in place since it is our source of // We don't want to change s.registration in place since it is our source of
// truth about what was actually registered before defaults applied. So copy // truth about what was actually registered before defaults applied. So copy
// it first. // it first.
nsRaw, err := copystructure.Copy(w.registration.service) nsRaw, err := copystructure.Copy(service)
if err != nil { if err != nil {
return nil, err return nil, err
} }
@ -504,16 +499,16 @@ func (w *serviceConfigWatch) mergeServiceConfig() (*structs.NodeService, error)
// Merge proxy defaults // Merge proxy defaults
ns := nsRaw.(*structs.NodeService) ns := nsRaw.(*structs.NodeService)
if err := mergo.Merge(&ns.Proxy.Config, w.defaults.ProxyConfig); err != nil { if err := mergo.Merge(&ns.Proxy.Config, defaults.ProxyConfig); err != nil {
return nil, err return nil, err
} }
if err := mergo.Merge(&ns.Proxy.Expose, w.defaults.Expose); err != nil { if err := mergo.Merge(&ns.Proxy.Expose, defaults.Expose); err != nil {
return nil, err return nil, err
} }
if ns.Proxy.MeshGateway.Mode == structs.MeshGatewayModeDefault { if ns.Proxy.MeshGateway.Mode == structs.MeshGatewayModeDefault {
ns.Proxy.MeshGateway.Mode = w.defaults.MeshGateway.Mode ns.Proxy.MeshGateway.Mode = defaults.MeshGateway.Mode
} }
// Merge upstream defaults if there were any returned // Merge upstream defaults if there were any returned
@ -529,7 +524,7 @@ func (w *serviceConfigWatch) mergeServiceConfig() (*structs.NodeService, error)
us.MeshGateway.Mode = ns.Proxy.MeshGateway.Mode us.MeshGateway.Mode = ns.Proxy.MeshGateway.Mode
} }
usCfg, ok := w.defaults.UpstreamIDConfigs.GetUpstreamConfig(us.DestinationID()) usCfg, ok := defaults.UpstreamIDConfigs.GetUpstreamConfig(us.DestinationID())
if !ok { if !ok {
// No config defaults to merge // No config defaults to merge
continue continue