83 lines
2.2 KiB
Go
83 lines
2.2 KiB
Go
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// Copyright (c) 2013 Conformal Systems LLC.
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package main
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import (
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"fmt"
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"github.com/conformal/btcwire"
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"time"
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)
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// MruInventoryMap provides a map that is limited to a maximum number of items
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// with eviction for the oldest entry when the limit is exceeded.
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type MruInventoryMap struct {
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invMap map[btcwire.InvVect]int64 // Use int64 for time for less mem.
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limit uint
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}
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// String returns the map as a human-readable string.
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func (m MruInventoryMap) String() string {
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return fmt.Sprintf("<%d>%v", m.limit, m.invMap)
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}
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// Exists returns whether or not the passed inventory item is in the map.
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func (m *MruInventoryMap) Exists(iv *btcwire.InvVect) bool {
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if _, exists := m.invMap[*iv]; exists {
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return true
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}
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return false
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}
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// Add adds the passed inventory to the map and handles eviction of the oldest
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// item if adding the new item would exceed the max limit.
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func (m *MruInventoryMap) Add(iv *btcwire.InvVect) {
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// When the limit is zero, nothing can be added to the map, so just
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// return
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if m.limit == 0 {
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return
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}
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// When the entry already exists update its last seen time.
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if m.Exists(iv) {
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m.invMap[*iv] = time.Now().Unix()
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return
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}
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// Evict the oldest entry if the the new entry would exceed the size
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// limit for the map.
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if uint(len(m.invMap))+1 > m.limit {
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var oldestEntry btcwire.InvVect
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var oldestTime int64
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for iv, lastUpdated := range m.invMap {
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if oldestTime == 0 || lastUpdated < oldestTime {
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oldestEntry = iv
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oldestTime = lastUpdated
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}
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}
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m.Delete(&oldestEntry)
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}
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m.invMap[*iv] = time.Now().Unix()
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return
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}
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// Delete deletes the passed inventory item from the map (if it exists).
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func (m *MruInventoryMap) Delete(iv *btcwire.InvVect) {
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delete(m.invMap, *iv)
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}
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// NewMruInventoryMap returns a new inventory map that is limited to the number
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// of entries specified by limit. When the number of entries exceeds the limit,
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// the oldest (least recently used) entry will be removed to make room for the
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// new entry..
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func NewMruInventoryMap(limit uint) *MruInventoryMap {
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m := MruInventoryMap{
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invMap: make(map[btcwire.InvVect]int64),
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limit: limit,
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}
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return &m
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}
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