Opentracing support

vendor/github.com/opentracing/opentracing-go/ext/tags.go

@@ -0,0 +1,198 @@
+package ext
+
+import opentracing "github.com/opentracing/opentracing-go"
+
+// These constants define common tag names recommended for better portability across
+// tracing systems and languages/platforms.
+//
+// The tag names are defined as typed strings, so that in addition to the usual use
+//
+//     span.setTag(TagName, value)
+//
+// they also support value type validation via this additional syntax:
+//
+//    TagName.Set(span, value)
+//
+var (
+	//////////////////////////////////////////////////////////////////////
+	// SpanKind (client/server or producer/consumer)
+	//////////////////////////////////////////////////////////////////////
+
+	// SpanKind hints at relationship between spans, e.g. client/server
+	SpanKind = spanKindTagName("span.kind")
+
+	// SpanKindRPCClient marks a span representing the client-side of an RPC
+	// or other remote call
+	SpanKindRPCClientEnum = SpanKindEnum("client")
+	SpanKindRPCClient     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindRPCClientEnum}
+
+	// SpanKindRPCServer marks a span representing the server-side of an RPC
+	// or other remote call
+	SpanKindRPCServerEnum = SpanKindEnum("server")
+	SpanKindRPCServer     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindRPCServerEnum}
+
+	// SpanKindProducer marks a span representing the producer-side of a
+	// message bus
+	SpanKindProducerEnum = SpanKindEnum("producer")
+	SpanKindProducer     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindProducerEnum}
+
+	// SpanKindConsumer marks a span representing the consumer-side of a
+	// message bus
+	SpanKindConsumerEnum = SpanKindEnum("consumer")
+	SpanKindConsumer     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindConsumerEnum}
+
+	//////////////////////////////////////////////////////////////////////
+	// Component name
+	//////////////////////////////////////////////////////////////////////
+
+	// Component is a low-cardinality identifier of the module, library,
+	// or package that is generating a span.
+	Component = stringTagName("component")
+
+	//////////////////////////////////////////////////////////////////////
+	// Sampling hint
+	//////////////////////////////////////////////////////////////////////
+
+	// SamplingPriority determines the priority of sampling this Span.
+	SamplingPriority = uint16TagName("sampling.priority")
+
+	//////////////////////////////////////////////////////////////////////
+	// Peer tags. These tags can be emitted by either client-side of
+	// server-side to describe the other side/service in a peer-to-peer
+	// communications, like an RPC call.
+	//////////////////////////////////////////////////////////////////////
+
+	// PeerService records the service name of the peer.
+	PeerService = stringTagName("peer.service")
+
+	// PeerAddress records the address name of the peer. This may be a "ip:port",
+	// a bare "hostname", a FQDN or even a database DSN substring
+	// like "mysql://username@127.0.0.1:3306/dbname"
+	PeerAddress = stringTagName("peer.address")
+
+	// PeerHostname records the host name of the peer
+	PeerHostname = stringTagName("peer.hostname")
+
+	// PeerHostIPv4 records IP v4 host address of the peer
+	PeerHostIPv4 = uint32TagName("peer.ipv4")
+
+	// PeerHostIPv6 records IP v6 host address of the peer
+	PeerHostIPv6 = stringTagName("peer.ipv6")
+
+	// PeerPort records port number of the peer
+	PeerPort = uint16TagName("peer.port")
+
+	//////////////////////////////////////////////////////////////////////
+	// HTTP Tags
+	//////////////////////////////////////////////////////////////////////
+
+	// HTTPUrl should be the URL of the request being handled in this segment
+	// of the trace, in standard URI format. The protocol is optional.
+	HTTPUrl = stringTagName("http.url")
+
+	// HTTPMethod is the HTTP method of the request, and is case-insensitive.
+	HTTPMethod = stringTagName("http.method")
+
+	// HTTPStatusCode is the numeric HTTP status code (200, 404, etc) of the
+	// HTTP response.
+	HTTPStatusCode = uint16TagName("http.status_code")
+
+	//////////////////////////////////////////////////////////////////////
+	// DB Tags
+	//////////////////////////////////////////////////////////////////////
+
+	// DBInstance is database instance name.
+	DBInstance = stringTagName("db.instance")
+
+	// DBStatement is a database statement for the given database type.
+	// It can be a query or a prepared statement (i.e., before substitution).
+	DBStatement = stringTagName("db.statement")
+
+	// DBType is a database type. For any SQL database, "sql".
+	// For others, the lower-case database category, e.g. "redis"
+	DBType = stringTagName("db.type")
+
+	// DBUser is a username for accessing database.
+	DBUser = stringTagName("db.user")
+
+	//////////////////////////////////////////////////////////////////////
+	// Message Bus Tag
+	//////////////////////////////////////////////////////////////////////
+
+	// MessageBusDestination is an address at which messages can be exchanged
+	MessageBusDestination = stringTagName("message_bus.destination")
+
+	//////////////////////////////////////////////////////////////////////
+	// Error Tag
+	//////////////////////////////////////////////////////////////////////
+
+	// Error indicates that operation represented by the span resulted in an error.
+	Error = boolTagName("error")
+)
+
+// ---
+
+// SpanKindEnum represents common span types
+type SpanKindEnum string
+
+type spanKindTagName string
+
+// Set adds a string tag to the `span`
+func (tag spanKindTagName) Set(span opentracing.Span, value SpanKindEnum) {
+	span.SetTag(string(tag), value)
+}
+
+type rpcServerOption struct {
+	clientContext opentracing.SpanContext
+}
+
+func (r rpcServerOption) Apply(o *opentracing.StartSpanOptions) {
+	if r.clientContext != nil {
+		opentracing.ChildOf(r.clientContext).Apply(o)
+	}
+	SpanKindRPCServer.Apply(o)
+}
+
+// RPCServerOption returns a StartSpanOption appropriate for an RPC server span
+// with `client` representing the metadata for the remote peer Span if available.
+// In case client == nil, due to the client not being instrumented, this RPC
+// server span will be a root span.
+func RPCServerOption(client opentracing.SpanContext) opentracing.StartSpanOption {
+	return rpcServerOption{client}
+}
+
+// ---
+
+type stringTagName string
+
+// Set adds a string tag to the `span`
+func (tag stringTagName) Set(span opentracing.Span, value string) {
+	span.SetTag(string(tag), value)
+}
+
+// ---
+
+type uint32TagName string
+
+// Set adds a uint32 tag to the `span`
+func (tag uint32TagName) Set(span opentracing.Span, value uint32) {
+	span.SetTag(string(tag), value)
+}
+
+// ---
+
+type uint16TagName string
+
+// Set adds a uint16 tag to the `span`
+func (tag uint16TagName) Set(span opentracing.Span, value uint16) {
+	span.SetTag(string(tag), value)
+}
+
+// ---
+
+type boolTagName string
+
+// Add adds a bool tag to the `span`
+func (tag boolTagName) Set(span opentracing.Span, value bool) {
+	span.SetTag(string(tag), value)
+}