lbcd/peer/mrunoncemap.go

130 lines
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peer: Refactor peer code into its own package. This commit introduces package peer which contains peer related features refactored from peer.go. The following is an overview of the features the package provides: - Provides a basic concurrent safe bitcoin peer for handling bitcoin communications via the peer-to-peer protocol - Full duplex reading and writing of bitcoin protocol messages - Automatic handling of the initial handshake process including protocol version negotiation - Automatic periodic keep-alive pinging and pong responses - Asynchronous message queueing of outbound messages with optional channel for notification when the message is actually sent - Inventory message batching and send trickling with known inventory detection and avoidance - Ability to wait for shutdown/disconnect - Flexible peer configuration - Caller is responsible for creating outgoing connections and listening for incoming connections so they have flexibility to establish connections as they see fit (proxies, etc.) - User agent name and version - Bitcoin network - Service support signalling (full nodes, bloom filters, etc.) - Maximum supported protocol version - Ability to register callbacks for handling bitcoin protocol messages - Proper handling of bloom filter related commands when the caller does not specify the related flag to signal support - Disconnects the peer when the protocol version is high enough - Does not invoke the related callbacks for older protocol versions - Snapshottable peer statistics such as the total number of bytes read and written, the remote address, user agent, and negotiated protocol version - Helper functions for pushing addresses, getblocks, getheaders, and reject messages - These could all be sent manually via the standard message output function, but the helpers provide additional nice functionality such as duplicate filtering and address randomization - Full documentation with example usage - Test coverage In addition to the addition of the new package, btcd has been refactored to make use of the new package by extending the basic peer it provides to work with the blockmanager and server to act as a full node. The following is a broad overview of the changes to integrate the package: - The server is responsible for all connection management including persistent peers and banning - Callbacks for all messages that are required to implement a full node are registered - Logic necessary to serve data and behave as a full node is now in the callback registered with the peer Finally, the following peer-related things have been improved as a part of this refactor: - Don't log or send reject message due to peer disconnects - Remove trace logs that aren't particularly helpful - Finish an old TODO to switch the queue WaitGroup over to a channel - Improve various comments and fix some code consistency cases - Improve a few logging bits - Implement a most-recently-used nonce tracking for detecting self connections and generate a unique nonce for each peer
2015-10-02 08:03:20 +02:00
// Copyright (c) 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"
)
// mruNonceMap 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 mruNonceMap struct {
mtx sync.Mutex
nonceMap map[uint64]*list.Element // nearly O(1) lookups
nonceList *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 *mruNonceMap) String() string {
m.mtx.Lock()
defer m.mtx.Unlock()
lastEntryNum := len(m.nonceMap) - 1
curEntry := 0
buf := bytes.NewBufferString("[")
for nonce := range m.nonceMap {
buf.WriteString(fmt.Sprintf("%d", nonce))
if curEntry < lastEntryNum {
buf.WriteString(", ")
}
curEntry++
}
buf.WriteString("]")
return fmt.Sprintf("<%d>%s", m.limit, buf.String())
}
// Exists returns whether or not the passed nonce is in the map.
//
// This function is safe for concurrent access.
func (m *mruNonceMap) Exists(nonce uint64) bool {
m.mtx.Lock()
defer m.mtx.Unlock()
if _, exists := m.nonceMap[nonce]; exists {
return true
}
return false
}
// Add adds the passed nonce 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 *mruNonceMap) Add(nonce uint64) {
m.mtx.Lock()
defer m.mtx.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.nonceMap[nonce]; exists {
m.nonceList.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.nonceMap))+1 > m.limit {
node := m.nonceList.Back()
lru := node.Value.(uint64)
// Evict least recently used item.
delete(m.nonceMap, lru)
// Reuse the list node of the item that was just evicted for the
// new item.
node.Value = nonce
m.nonceList.MoveToFront(node)
m.nonceMap[nonce] = node
return
}
// The limit hasn't been reached yet, so just add the new item.
node := m.nonceList.PushFront(nonce)
m.nonceMap[nonce] = node
return
}
// Delete deletes the passed nonce from the map (if it exists).
//
// This function is safe for concurrent access.
func (m *mruNonceMap) Delete(nonce uint64) {
m.mtx.Lock()
defer m.mtx.Unlock()
if node, exists := m.nonceMap[nonce]; exists {
m.nonceList.Remove(node)
delete(m.nonceMap, nonce)
}
}
// newMruNonceMap returns a new nonce 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 newMruNonceMap(limit uint) *mruNonceMap {
m := mruNonceMap{
nonceMap: make(map[uint64]*list.Element),
nonceList: list.New(),
limit: limit,
}
return &m
}