dependency injection and lighter service Init methods.

1 files changed, 53 insertions, 26 deletions

diff --git a/service/container.go b/service/container.go
index 12c5a4a1..a003b7e3 100644
--- a/service/container.go
+++ b/service/container.go
@@ -7,20 +7,10 @@ import (
 	"sync"
 )
 
-// Config provides ability to slice configuration sections and unmarshal configuration data into
-// given structure.
-type Config interface {
-	// get nested config section (sub-map), returns nil if section not found.
-	Get(service string) Config
-
-	// Unmarshal unmarshal config data into given struct.
-	Unmarshal(out interface{}) error
-}
-
 // Container controls all internal RR services and provides plugin based system.
 type Container interface {
 	// Register add new service to the container under given name.
-	Register(name string, service Service)
+	Register(name string, service interface{})
 
 	// Reconfigure configures all underlying services with given configuration.
 	Init(cfg Config) error
@@ -30,7 +20,7 @@ type Container interface {
 
 	// get returns svc instance by it's name or nil if svc not found. Method returns current service status
 	// as second value.
-	Get(service string) (svc Service, status int)
+	Get(service string) (svc interface{}, status int)
 
 	// Serve all configured services. Non blocking.
 	Serve() error
@@ -39,6 +29,36 @@ type Container interface {
 	Stop()
 }
 
+// Service can serve. Service can provide Init method which must return (bool, error) signature and might accept
+// other services and/or configs as dependency. Container can be requested as well. Config can be requested in a form
+// of service.Config or pointer to service specific config struct (automatically unmarshalled), config argument must
+// implement service.HydrateConfig.
+type Service interface {
+	// Serve serves.
+	Serve() error
+
+	// Stop stops the service.
+	Stop()
+}
+
+// Config provides ability to slice configuration sections and unmarshal configuration data into
+// given structure.
+type Config interface {
+	// get nested config section (sub-map), returns nil if section not found.
+	Get(service string) Config
+
+	// Unmarshal unmarshal config data into given struct.
+	Unmarshal(out interface{}) error
+}
+
+// HydrateConfig provides ability to automatically hydrate config with values using
+// service.Config as the source.
+type HydrateConfig interface {
+	// Hydrate must populate config values using given config source.
+	// Must return error if config is not valid.
+	Hydrate(cfg Config) error
+}
+
 type container struct {
 	log      logrus.FieldLogger
 	mu       sync.Mutex
@@ -54,7 +74,7 @@ func NewContainer(log logrus.FieldLogger) Container {
 }
 
 // Register add new service to the container under given name.
-func (c *container) Register(name string, service Service) {
+func (c *container) Register(name string, service interface{}) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
@@ -82,7 +102,7 @@ func (c *container) Has(target string) bool {
 }
 
 // get returns svc instance by it's name or nil if svc not found.
-func (c *container) Get(target string) (svc Service, status int) {
+func (c *container) Get(target string) (svc interface{}, status int) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
@@ -98,27 +118,32 @@ func (c *container) Get(target string) (svc Service, status int) {
 // Init configures all underlying services with given configuration.
 func (c *container) Init(cfg Config) error {
 	for _, e := range c.services {
-		if e.getStatus() >= StatusConfigured {
+		if e.getStatus() >= StatusOK {
 			return fmt.Errorf("service [%s] has already been configured", e.name)
 		}
 
-		segment := cfg.Get(e.name)
-		if segment == nil {
-			c.log.Debugf("[%s]: no config has been provided", e.name)
-			continue
-		}
+		// inject service dependencies (todo: move to container)
+		if ok, err := initService(e.svc, cfg.Get(e.name), c); err != nil {
+			if err == noConfig {
+				c.log.Warningf("[%s]: no config has been provided", e.name)
+
+				// unable to meet dependency requirements, skippingF
+				continue
+			}
 
-		ok, err := e.svc.Init(segment, c)
-		if err != nil {
 			return errors.Wrap(err, fmt.Sprintf("[%s]", e.name))
 		} else if ok {
-			e.setStatus(StatusConfigured)
+			e.setStatus(StatusOK)
+			c.log.Debugf("[%s]: initiated", e.name)
+		} else {
+			c.log.Debugf("[%s]: disabled", e.name)
 		}
 	}
 
 	return nil
 }
 
+//todo: refactor ????
 // Serve all configured services. Non blocking.
 func (c *container) Serve() error {
 	var (
@@ -127,7 +152,7 @@ func (c *container) Serve() error {
 	)
 
 	for _, e := range c.services {
-		if e.hasStatus(StatusConfigured) {
+		if e.hasStatus(StatusOK) && e.canServe() {
 			numServing++
 		} else {
 			continue
@@ -138,7 +163,7 @@ func (c *container) Serve() error {
 			e.setStatus(StatusServing)
 			defer e.setStatus(StatusStopped)
 
-			if err := e.svc.Serve(); err != nil {
+			if err := e.svc.(Service).Serve(); err != nil {
 				c.log.Errorf("[%s]: %s", e.name, err)
 				done <- errors.Wrap(err, fmt.Sprintf("[%s]", e.name))
 			} else {
@@ -167,10 +192,12 @@ func (c *container) Serve() error {
 
 // Stop sends stop command to all running services.
 func (c *container) Stop() {
+	c.log.Debugf("received stop command")
 	for _, e := range c.services {
 		if e.hasStatus(StatusServing) {
-			e.svc.Stop()
+			e.svc.(Service).Stop()
 			e.setStatus(StatusStopped)
+
 			c.log.Debugf("[%s]: stopped", e.name)
 		}
 	}