feat(trace) Adds Suspend and Resume

internal/server/mock/trace/resume.go

@@ -0,0 +1,14 @@
+package trace
+
+import (
+	"context"
+
+	"github.com/skpr/api/pb"
+)
+
+// Resume tracing for a specific environment.
+func (s *Server) Resume(_ context.Context, req *pb.TraceResumeRequest) (*pb.TraceResumeResponse, error) {
+	s.SetSuspended(req.Environment, false)
+
+	return &pb.TraceResumeResponse{}, nil
+}

internal/server/mock/trace/server.go

@@ -1,10 +1,35 @@
 package trace
 
 import (
+	"sync"
+
 	"github.com/skpr/api/pb"
 )
 
 // Server implements the GRPC "trace" definition.
 type Server struct {
 	pb.UnimplementedTraceServer
+
+	lock      sync.Mutex
+	suspended map[string]bool
+}
+
+// SetSuspended marks tracing as suspended, or resumed, for an environment.
+func (s *Server) SetSuspended(environment string, suspended bool) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	if s.suspended == nil {
+		s.suspended = make(map[string]bool)
+	}
+
+	s.suspended[environment] = suspended
+}
+
+// IsSuspended determines if tracing has been suspended for an environment.
+func (s *Server) IsSuspended(environment string) bool {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	return s.suspended[environment]
 }

internal/server/mock/trace/stream_traces.go

@@ -6,15 +6,24 @@ import (
 	"time"
 
 	"github.com/brianvoe/gofakeit/v7"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 	"google.golang.org/protobuf/types/known/durationpb"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
 	"github.com/skpr/api/pb"
 )
 
 // StreamTraces streams traces from a specific environment.
-func (s *Server) StreamTraces(_ *pb.StreamTracesRequest, server pb.Trace_StreamTracesServer) error {
+func (s *Server) StreamTraces(req *pb.StreamTracesRequest, server pb.Trace_StreamTracesServer) error {
 	for {
+		// Tracing has been suspended for this environment, so there is nothing to
+		// send. Fail fast instead of holding open a stream which sends nothing,
+		// which the client cannot tell apart from an environment with no traffic.
+		if s.IsSuspended(req.Environment) {
+			return status.Errorf(codes.FailedPrecondition, "tracing is suspended for environment: %s", req.Environment)
+		}
+
 		now := time.Now()
 
 		// ~6ms realistic function execution time

internal/server/mock/trace/suspend.go

@@ -0,0 +1,14 @@
+package trace
+
+import (
+	"context"
+
+	"github.com/skpr/api/pb"
+)
+
+// Suspend tracing for a specific environment.
+func (s *Server) Suspend(_ context.Context, req *pb.TraceSuspendRequest) (*pb.TraceSuspendResponse, error) {
+	s.SetSuspended(req.Environment, true)
+
+	return &pb.TraceSuspendResponse{}, nil
+}