1 files changed, 216 insertions, 0 deletions
diff --git a/vendor/github.com/uber/jaeger-client-go/internal/throttler/remote/throttler.go b/vendor/github.com/uber/jaeger-client-go/internal/throttler/remote/throttler.go
new file mode 100644
index 000000000..20f434fe4
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-client-go/internal/throttler/remote/throttler.go
@@ -0,0 +1,216 @@
+// Copyright (c) 2018 The Jaeger Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package remote
+
+import (
+	"fmt"
+	"net/url"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/pkg/errors"
+
+	"github.com/uber/jaeger-client-go"
+	"github.com/uber/jaeger-client-go/utils"
+)
+
+const (
+	// minimumCredits is the minimum amount of credits necessary to not be throttled.
+	// i.e. if currentCredits > minimumCredits, then the operation will not be throttled.
+	minimumCredits = 1.0
+)
+
+var (
+	errorUUIDNotSet = errors.New("Throttler UUID must be set")
+)
+
+type operationBalance struct {
+	Operation string  `json:"operation"`
+	Balance   float64 `json:"balance"`
+}
+
+type creditResponse struct {
+	Balances []operationBalance `json:"balances"`
+}
+
+type httpCreditManagerProxy struct {
+	hostPort string
+}
+
+func newHTTPCreditManagerProxy(hostPort string) *httpCreditManagerProxy {
+	return &httpCreditManagerProxy{
+		hostPort: hostPort,
+	}
+}
+
+// N.B. Operations list must not be empty.
+func (m *httpCreditManagerProxy) FetchCredits(uuid, serviceName string, operations []string) (*creditResponse, error) {
+	params := url.Values{}
+	params.Set("service", serviceName)
+	params.Set("uuid", uuid)
+	for _, op := range operations {
+		params.Add("operations", op)
+	}
+	var resp creditResponse
+	if err := utils.GetJSON(fmt.Sprintf("http://%s/credits?%s", m.hostPort, params.Encode()), &resp); err != nil {
+		return nil, errors.Wrap(err, "Failed to receive credits from agent")
+	}
+	return &resp, nil
+}
+
+// Throttler retrieves credits from agent and uses it to throttle operations.
+type Throttler struct {
+	options
+
+	mux           sync.RWMutex
+	service       string
+	uuid          atomic.Value
+	creditManager *httpCreditManagerProxy
+	credits       map[string]float64 // map of operation->credits
+	close         chan struct{}
+	stopped       sync.WaitGroup
+}
+
+// NewThrottler returns a Throttler that polls agent for credits and uses them to throttle
+// the service.
+func NewThrottler(service string, options ...Option) *Throttler {
+	opts := applyOptions(options...)
+	creditManager := newHTTPCreditManagerProxy(opts.hostPort)
+	t := &Throttler{
+		options:       opts,
+		creditManager: creditManager,
+		service:       service,
+		credits:       make(map[string]float64),
+		close:         make(chan struct{}),
+	}
+	t.stopped.Add(1)
+	go t.pollManager()
+	return t
+}
+
+// IsAllowed implements Throttler#IsAllowed.
+func (t *Throttler) IsAllowed(operation string) bool {
+	t.mux.Lock()
+	defer t.mux.Unlock()
+	value, ok := t.credits[operation]
+	if !ok || value == 0 {
+		if !ok {
+			// NOTE: This appears to be a no-op at first glance, but it stores
+			// the operation key in the map. Necessary for functionality of
+			// Throttler#operations method.
+			t.credits[operation] = 0
+		}
+		if !t.synchronousInitialization {
+			t.metrics.ThrottledDebugSpans.Inc(1)
+			return false
+		}
+		// If it is the first time this operation is being checked, synchronously fetch
+		// the credits.
+		credits, err := t.fetchCredits([]string{operation})
+		if err != nil {
+			// Failed to receive credits from agent, try again next time
+			t.logger.Error("Failed to fetch credits: " + err.Error())
+			return false
+		}
+		if len(credits.Balances) == 0 {
+			// This shouldn't happen but just in case
+			return false
+		}
+		for _, opBalance := range credits.Balances {
+			t.credits[opBalance.Operation] += opBalance.Balance
+		}
+	}
+	return t.isAllowed(operation)
+}
+
+// Close stops the throttler from fetching credits from remote.
+func (t *Throttler) Close() error {
+	close(t.close)
+	t.stopped.Wait()
+	return nil
+}
+
+// SetProcess implements ProcessSetter#SetProcess. It's imperative that the UUID is set before any remote
+// requests are made.
+func (t *Throttler) SetProcess(process jaeger.Process) {
+	if process.UUID != "" {
+		t.uuid.Store(process.UUID)
+	}
+}
+
+// N.B. This function must be called with the Write Lock
+func (t *Throttler) isAllowed(operation string) bool {
+	credits := t.credits[operation]
+	if credits < minimumCredits {
+		t.metrics.ThrottledDebugSpans.Inc(1)
+		return false
+	}
+	t.credits[operation] = credits - minimumCredits
+	return true
+}
+
+func (t *Throttler) pollManager() {
+	defer t.stopped.Done()
+	ticker := time.NewTicker(t.refreshInterval)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ticker.C:
+			t.refreshCredits()
+		case <-t.close:
+			return
+		}
+	}
+}
+
+func (t *Throttler) operations() []string {
+	t.mux.RLock()
+	defer t.mux.RUnlock()
+	operations := make([]string, 0, len(t.credits))
+	for op := range t.credits {
+		operations = append(operations, op)
+	}
+	return operations
+}
+
+func (t *Throttler) refreshCredits() {
+	operations := t.operations()
+	if len(operations) == 0 {
+		return
+	}
+	newCredits, err := t.fetchCredits(operations)
+	if err != nil {
+		t.metrics.ThrottlerUpdateFailure.Inc(1)
+		t.logger.Error("Failed to fetch credits: " + err.Error())
+		return
+	}
+	t.metrics.ThrottlerUpdateSuccess.Inc(1)
+
+	t.mux.Lock()
+	defer t.mux.Unlock()
+	for _, opBalance := range newCredits.Balances {
+		t.credits[opBalance.Operation] += opBalance.Balance
+	}
+}
+
+func (t *Throttler) fetchCredits(operations []string) (*creditResponse, error) {
+	uuid := t.uuid.Load()
+	uuidStr, _ := uuid.(string)
+	if uuid == nil || uuidStr == "" {
+		return nil, errorUUIDNotSet
+	}
+	return t.creditManager.FetchCredits(uuidStr, t.service, operations)
+}