Refine request time propagation.

Request time is resolved at first call to `getLocalRateLimit()`, then is propagated across peer-to-peer for global behavior.

Makefile

@@ -13,7 +13,7 @@ $(GOLANGCI_LINT): ## Download Go linter
 
 .PHONY: lint
 lint: $(GOLANGCI_LINT) ## Run Go linter
-	$(GOLANGCI_LINT) run -v --fix -c .golangci.yml ./...
+	$(GOLANGCI_LINT) run -v -c .golangci.yml ./...
 
 .PHONY: test
 test: ## Run unit tests and measure code coverage

gubernator.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/mailgun/errors"
 	"github.com/mailgun/holster/v4/clock"
@@ -575,7 +576,13 @@ func (s *V1Instance) getLocalRateLimit(ctx context.Context, r *RateLimitReq) (_
 	defer func() { tracing.EndScope(ctx, err) }()
 	defer prometheus.NewTimer(metricFuncTimeDuration.WithLabelValues("V1Instance.getLocalRateLimit")).ObserveDuration()
 
-	requestTime := clock.Now()
+	var requestTime time.Time
+	if r.RequestTime != nil {
+		requestTime = time.UnixMilli(*r.RequestTime)
+	}
+	if requestTime.IsZero() {
+		requestTime = clock.Now()
+	}
 	resp, err := s.workerPool.GetRateLimit(ctx, r, requestTime)
 	if err != nil {
 		return nil, errors.Wrap(err, "during workerPool.GetRateLimit")

gubernator.proto

@@ -168,6 +168,11 @@ message RateLimitReq {
   // this to pass trace context to other peers. Might be useful for future clients to pass along
   // trace information to gubernator.
   map<string, string> metadata = 9;
+
+  // The exact time of request in Epoch milliseconds.
+  // The is intended to be used for peer-to-peer requests to preserve
+  // timestamps.
+  optional int64 request_time = 10;
 }
 
 enum Status {