+++ /dev/null
-// Copyright (c) 2013-2015 The btcsuite developers
-// Use of this source code is governed by an ISC
-// license that can be found in the LICENSE file.
-
-package peer
-
-import (
- "bytes"
- "container/list"
- "fmt"
- "sync"
-
- "github.com/btcsuite/btcd/wire"
-)
-
-// mruInventoryMap provides a concurrency safe map that is limited to a maximum
-// number of items with eviction for the oldest entry when the limit is
-// exceeded.
-type mruInventoryMap struct {
- invMtx sync.Mutex
- invMap map[wire.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.
-//
-// This function is safe for concurrent access.
-func (m *mruInventoryMap) String() string {
- m.invMtx.Lock()
- defer m.invMtx.Unlock()
-
- lastEntryNum := len(m.invMap) - 1
- curEntry := 0
- buf := bytes.NewBufferString("[")
- for iv := range m.invMap {
- buf.WriteString(fmt.Sprintf("%v", iv))
- if curEntry < lastEntryNum {
- buf.WriteString(", ")
- }
- curEntry++
- }
- buf.WriteString("]")
-
- return fmt.Sprintf("<%d>%s", m.limit, buf.String())
-}
-
-// Exists returns whether or not the passed inventory item is in the map.
-//
-// This function is safe for concurrent access.
-func (m *mruInventoryMap) Exists(iv *wire.InvVect) bool {
- m.invMtx.Lock()
- _, exists := m.invMap[*iv]
- m.invMtx.Unlock()
-
- return exists
-}
-
-// 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. Adding an existing
-// item makes it the most recently used item.
-//
-// This function is safe for concurrent access.
-func (m *mruInventoryMap) Add(iv *wire.InvVect) {
- m.invMtx.Lock()
- defer m.invMtx.Unlock()
-
- // 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 := node.Value.(*wire.InvVect)
-
- // 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
-}
-
-// Delete deletes the passed inventory item from the map (if it exists).
-//
-// This function is safe for concurrent access.
-func (m *mruInventoryMap) Delete(iv *wire.InvVect) {
- m.invMtx.Lock()
- if node, exists := m.invMap[*iv]; exists {
- m.invList.Remove(node)
- delete(m.invMap, *iv)
- }
- m.invMtx.Unlock()
-}
-
-// 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[wire.InvVect]*list.Element),
- invList: list.New(),
- limit: limit,
- }
- return &m
-}
OSDN Git Service
