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path: root/vendor/github.com/uber/jaeger-client-go/rpcmetrics/endpoints.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 rpcmetrics

import "sync"

// normalizedEndpoints is a cache for endpointName -> safeName mappings.
type normalizedEndpoints struct {
    names       map[string]string
    maxSize     int
    defaultName string
    normalizer  NameNormalizer
    mux         sync.RWMutex
}

func newNormalizedEndpoints(maxSize int, normalizer NameNormalizer) *normalizedEndpoints {
    return &normalizedEndpoints{
        maxSize:    maxSize,
        normalizer: normalizer,
        names:      make(map[string]string, maxSize),
    }
}

// normalize looks up the name in the cache, if not found it uses normalizer
// to convert the name to a safe name. If called with more than maxSize unique
// names it returns "" for all other names beyond those already cached.
func (n *normalizedEndpoints) normalize(name string) string {
    n.mux.RLock()
    norm, ok := n.names[name]
    l := len(n.names)
    n.mux.RUnlock()
    if ok {
        return norm
    }
    if l >= n.maxSize {
        return ""
    }
    return n.normalizeWithLock(name)
}

func (n *normalizedEndpoints) normalizeWithLock(name string) string {
    norm := n.normalizer.Normalize(name)
    n.mux.Lock()
    defer n.mux.Unlock()
    // cache may have grown while we were not holding the lock
    if len(n.names) >= n.maxSize {
        return ""
    }
    n.names[name] = norm
    return norm
}