83bcfcb2ca
This commit improves the most-recently used inventory map human readable string to only show the inventory vectors. and adds tests for the entire structure to bring its coverage to 100%. In addition, removes the type assertion check in the Add function since the internal inventory list is only managed by the type itself and the tests would now catch any mistakes in the type of entries in the list.
109 lines
3 KiB
Go
109 lines
3 KiB
Go
// Copyright (c) 2013-2015 The btcsuite developers
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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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"bytes"
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"container/list"
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"fmt"
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"github.com/btcsuite/btcd/wire"
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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[wire.InvVect]*list.Element // nearly O(1) lookups
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invList *list.List // O(1) insert, update, delete
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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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lastEntryNum := len(m.invMap) - 1
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curEntry := 0
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buf := bytes.NewBufferString("[")
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for iv := range m.invMap {
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buf.WriteString(fmt.Sprintf("%v", iv))
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if curEntry < lastEntryNum {
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buf.WriteString(", ")
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}
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curEntry++
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}
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buf.WriteString("]")
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return fmt.Sprintf("<%d>%s", m.limit, buf.String())
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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 *wire.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. Adding an existing
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// item makes it the most recently used item.
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func (m *MruInventoryMap) Add(iv *wire.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 move it to the front of the list
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// thereby marking it most recently used.
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if node, exists := m.invMap[*iv]; exists {
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m.invList.MoveToFront(node)
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return
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}
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// Evict the least recently used entry (back of the list) if the the new
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// entry would exceed the size limit for the map. Also reuse the list
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// node so a new one doesn't have to be allocated.
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if uint(len(m.invMap))+1 > m.limit {
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node := m.invList.Back()
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lru := node.Value.(*wire.InvVect)
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// Evict least recently used item.
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delete(m.invMap, *lru)
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// Reuse the list node of the item that was just evicted for the
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// new item.
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node.Value = iv
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m.invList.MoveToFront(node)
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m.invMap[*iv] = node
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return
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}
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// The limit hasn't been reached yet, so just add the new item.
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node := m.invList.PushFront(iv)
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m.invMap[*iv] = node
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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 *wire.InvVect) {
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if node, exists := m.invMap[*iv]; exists {
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m.invList.Remove(node)
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delete(m.invMap, *iv)
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}
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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[wire.InvVect]*list.Element),
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invList: list.New(),
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limit: limit,
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}
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return &m
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}
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