wrapper/

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Version: v0.11.0 Latest Latest
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Published: Jun 5, 2018 License: Apache-2.0

README

Wrappers

Wrappers are a form of middleware that can be used with go-micro services. They can wrap both the Client and Server handlers.

Client Interface

// Wrapper wraps a client and returns a client
type Wrapper func(Client) Client

// StreamWrapper wraps a Stream and returns the equivalent
type StreamWrapper func(Streamer) Streamer

Handler Interface

// HandlerFunc represents a single method of a handler. It's used primarily
// for the wrappers. What's handed to the actual method is the concrete
// request and response types.
type HandlerFunc func(ctx context.Context, req Request, rsp interface{}) error

// SubscriberFunc represents a single method of a subscriber. It's used primarily
// for the wrappers. What's handed to the actual method is the concrete
// publication message.
type SubscriberFunc func(ctx context.Context, msg Publication) error

// HandlerWrapper wraps the HandlerFunc and returns the equivalent
type HandlerWrapper func(HandlerFunc) HandlerFunc

// SubscriberWrapper wraps the SubscriberFunc and returns the equivalent
type SubscriberWrapper func(SubscriberFunc) SubscriberFunc

// StreamerWrapper wraps a Streamer interface and returns the equivalent.
// Because streams exist for the lifetime of a method invocation this
// is a convenient way to wrap a Stream as its in use for trace, monitoring,
// metrics, etc.
type StreamerWrapper func(Streamer) Streamer

Client Wrapper Usage

Here's a basic log wrapper for the client

type logWrapper struct {
	client.Client
}

func (l *logWrapper) Call(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
	md, _ := metadata.FromContext(ctx)
	fmt.Printf("[Log Wrapper] ctx: %v service: %s method: %s\n", md, req.Service(), req.Method())
	return l.Client.Call(ctx, req, rsp)
}

func NewLogWrapper(c client.Client) client.Client {
	return &logWrapper{c}
}

Handler Wrapper Usage

Here's a basic log wrapper for the handler

func NewLogWrapper(fn server.HandlerFunc) server.HandlerFunc {
	return func(ctx context.Context, req server.Request, rsp interface{}) error {
		log.Printf("[Log Wrapper] Before serving request method: %v", req.Method())
		err := fn(ctx, req, rsp)
		log.Printf("[Log Wrapper] After serving request")
		return err
	}
}

Directories

Path Synopsis
breaker
Package endpoint provides a wrapper that executes other wrappers for specific methods
Package endpoint provides a wrapper that executes other wrappers for specific methods
ratelimiter
select
roundrobin
Package roundrobin implements a roundrobin call strategy
Package roundrobin implements a roundrobin call strategy
shard
Package shard implements the sharding call strategy
Package shard implements the sharding call strategy
Package wrapper injects a go-micro.Service into the context
Package wrapper injects a go-micro.Service into the context
trace
awsxray
Package awsxray is a wrapper for AWS X-Ray distributed tracing
Package awsxray is a wrapper for AWS X-Ray distributed tracing
opencensus
Package opencensus provides wrappers for OpenCensus tracing.
Package opencensus provides wrappers for OpenCensus tracing.
opentracing
Package opentracing provides wrappers for OpenTracing
Package opentracing provides wrappers for OpenTracing

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