mirror of
https://github.com/btcsuite/btcd.git
synced 2024-11-19 18:00:11 +01:00
98 lines
2.7 KiB
Go
98 lines
2.7 KiB
Go
// Copyright (c) 2013-2014 Conformal Systems LLC.
|
|
// Use of this source code is governed by an ISC
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package main
|
|
|
|
import (
|
|
"container/list"
|
|
"fmt"
|
|
|
|
"github.com/conformal/btcwire"
|
|
)
|
|
|
|
// MruInventoryMap provides a map that is limited to a maximum number of items
|
|
// with eviction for the oldest entry when the limit is exceeded.
|
|
type MruInventoryMap struct {
|
|
invMap map[btcwire.InvVect]*list.Element // nearly O(1) lookups
|
|
invList *list.List // O(1) insert, update, delete
|
|
limit uint
|
|
}
|
|
|
|
// String returns the map as a human-readable string.
|
|
func (m MruInventoryMap) String() string {
|
|
return fmt.Sprintf("<%d>%v", m.limit, m.invMap)
|
|
}
|
|
|
|
// Exists returns whether or not the passed inventory item is in the map.
|
|
func (m *MruInventoryMap) Exists(iv *btcwire.InvVect) bool {
|
|
if _, exists := m.invMap[*iv]; exists {
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
// Add adds the passed inventory to the map and handles eviction of the oldest
|
|
// item if adding the new item would exceed the max limit.
|
|
func (m *MruInventoryMap) Add(iv *btcwire.InvVect) {
|
|
// When the limit is zero, nothing can be added to the map, so just
|
|
// return.
|
|
if m.limit == 0 {
|
|
return
|
|
}
|
|
|
|
// When the entry already exists move it to the front of the list
|
|
// thereby marking it most recently used.
|
|
if node, exists := m.invMap[*iv]; exists {
|
|
m.invList.MoveToFront(node)
|
|
return
|
|
}
|
|
|
|
// Evict the least recently used entry (back of the list) if the the new
|
|
// entry would exceed the size limit for the map. Also reuse the list
|
|
// node so a new one doesn't have to be allocated.
|
|
if uint(len(m.invMap))+1 > m.limit {
|
|
node := m.invList.Back()
|
|
lru, ok := node.Value.(*btcwire.InvVect)
|
|
if !ok {
|
|
return
|
|
}
|
|
|
|
// Evict least recently used item.
|
|
delete(m.invMap, *lru)
|
|
|
|
// Reuse the list node of the item that was just evicted for the
|
|
// new item.
|
|
node.Value = iv
|
|
m.invList.MoveToFront(node)
|
|
m.invMap[*iv] = node
|
|
return
|
|
}
|
|
|
|
// The limit hasn't been reached yet, so just add the new item.
|
|
node := m.invList.PushFront(iv)
|
|
m.invMap[*iv] = node
|
|
return
|
|
}
|
|
|
|
// Delete deletes the passed inventory item from the map (if it exists).
|
|
func (m *MruInventoryMap) Delete(iv *btcwire.InvVect) {
|
|
if node, exists := m.invMap[*iv]; exists {
|
|
m.invList.Remove(node)
|
|
delete(m.invMap, *iv)
|
|
}
|
|
}
|
|
|
|
// NewMruInventoryMap returns a new inventory map that is limited to the number
|
|
// of entries specified by limit. When the number of entries exceeds the limit,
|
|
// the oldest (least recently used) entry will be removed to make room for the
|
|
// new entry.
|
|
func NewMruInventoryMap(limit uint) *MruInventoryMap {
|
|
m := MruInventoryMap{
|
|
invMap: make(map[btcwire.InvVect]*list.Element),
|
|
invList: list.New(),
|
|
limit: limit,
|
|
}
|
|
return &m
|
|
}
|