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path: root/vendor/github.com/uber/jaeger-client-go/internal/baggage/remote/restriction_manager.go
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// Copyright (c) 2017 Uber Technologies, Inc.
//
// 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"
    "time"

    "github.com/uber/jaeger-client-go/internal/baggage"
    thrift "github.com/uber/jaeger-client-go/thrift-gen/baggage"
    "github.com/uber/jaeger-client-go/utils"
)

type httpBaggageRestrictionManagerProxy struct {
    url string
}

func newHTTPBaggageRestrictionManagerProxy(hostPort, serviceName string) *httpBaggageRestrictionManagerProxy {
    v := url.Values{}
    v.Set("service", serviceName)
    return &httpBaggageRestrictionManagerProxy{
        url: fmt.Sprintf("http://%s/baggageRestrictions?%s", hostPort, v.Encode()),
    }
}

func (s *httpBaggageRestrictionManagerProxy) GetBaggageRestrictions(serviceName string) ([]*thrift.BaggageRestriction, error) {
    var out []*thrift.BaggageRestriction
    if err := utils.GetJSON(s.url, &out); err != nil {
        return nil, err
    }
    return out, nil
}

// RestrictionManager manages baggage restrictions by retrieving baggage restrictions from agent
type RestrictionManager struct {
    options

    mux                sync.RWMutex
    serviceName        string
    restrictions       map[string]*baggage.Restriction
    thriftProxy        thrift.BaggageRestrictionManager
    pollStopped        sync.WaitGroup
    stopPoll           chan struct{}
    invalidRestriction *baggage.Restriction
    validRestriction   *baggage.Restriction

    // Determines if the manager has successfully retrieved baggage restrictions from agent
    initialized bool
}

// NewRestrictionManager returns a BaggageRestrictionManager that polls the agent for the latest
// baggage restrictions.
func NewRestrictionManager(serviceName string, options ...Option) *RestrictionManager {
    // TODO there is a developing use case where a single tracer can generate traces on behalf of many services.
    // restrictionsMap will need to exist per service
    opts := applyOptions(options...)
    m := &RestrictionManager{
        serviceName:        serviceName,
        options:            opts,
        restrictions:       make(map[string]*baggage.Restriction),
        thriftProxy:        newHTTPBaggageRestrictionManagerProxy(opts.hostPort, serviceName),
        stopPoll:           make(chan struct{}),
        invalidRestriction: baggage.NewRestriction(false, 0),
        validRestriction:   baggage.NewRestriction(true, defaultMaxValueLength),
    }
    m.pollStopped.Add(1)
    go m.pollManager()
    return m
}

// isReady returns true if the manager has retrieved baggage restrictions from the remote source.
func (m *RestrictionManager) isReady() bool {
    m.mux.RLock()
    defer m.mux.RUnlock()
    return m.initialized
}

// GetRestriction implements RestrictionManager#GetRestriction.
func (m *RestrictionManager) GetRestriction(service, key string) *baggage.Restriction {
    m.mux.RLock()
    defer m.mux.RUnlock()
    if !m.initialized {
        if m.denyBaggageOnInitializationFailure {
            return m.invalidRestriction
        }
        return m.validRestriction
    }
    if restriction, ok := m.restrictions[key]; ok {
        return restriction
    }
    return m.invalidRestriction
}

// Close stops remote polling and closes the RemoteRestrictionManager.
func (m *RestrictionManager) Close() error {
    close(m.stopPoll)
    m.pollStopped.Wait()
    return nil
}

func (m *RestrictionManager) pollManager() {
    defer m.pollStopped.Done()
    // attempt to initialize baggage restrictions
    if err := m.updateRestrictions(); err != nil {
        m.logger.Error(fmt.Sprintf("Failed to initialize baggage restrictions: %s", err.Error()))
    }
    ticker := time.NewTicker(m.refreshInterval)
    defer ticker.Stop()

    for {
        select {
        case <-ticker.C:
            if err := m.updateRestrictions(); err != nil {
                m.logger.Error(fmt.Sprintf("Failed to update baggage restrictions: %s", err.Error()))
            }
        case <-m.stopPoll:
            return
        }
    }
}

func (m *RestrictionManager) updateRestrictions() error {
    restrictions, err := m.thriftProxy.GetBaggageRestrictions(m.serviceName)
    if err != nil {
        m.metrics.BaggageRestrictionsUpdateFailure.Inc(1)
        return err
    }
    newRestrictions := m.parseRestrictions(restrictions)
    m.metrics.BaggageRestrictionsUpdateSuccess.Inc(1)
    m.mux.Lock()
    defer m.mux.Unlock()
    m.initialized = true
    m.restrictions = newRestrictions
    return nil
}

func (m *RestrictionManager) parseRestrictions(restrictions []*thrift.BaggageRestriction) map[string]*baggage.Restriction {
    setters := make(map[string]*baggage.Restriction, len(restrictions))
    for _, restriction := range restrictions {
        setters[restriction.BaggageKey] = baggage.NewRestriction(true, int(restriction.MaxValueLength))
    }
    return setters
}