STATS命令
出于性能考虑，memcached没有提供遍历功能，不过我们可以通过以下两个stats命令得到所有的缓存对象。
1、stats items
显示各个slab中item的数目。
2、stats cachedump slab_id limit_num
显示某个slab中的前limit_num个key列表，显示格式：ITEM key_name [ value_length b; expire_time|access_time s]
基于此 我们就可以通过 扩展类的方式来实现其业务逻辑
public class MemcachedClient : Enyim.Caching.MemcachedClient
{
public MemcachedClient(string sectionName) : base(sectionName)
{
}
public IDictionary<IPEndPoint, List<string>> GetKeys()
{
var data = new Dictionary<IPEndPoint, List<string>>();
var result = StatsItems("items");
var itemsData = new Dictionary<IPEndPoint, Dictionary<string, string>>();
foreach (var item in result)
{
var ip = item.Key;
var items = new Dictionary<string, string>();
foreach (var info in item.Value)
{
var key = info.Key;
var strArry = key.Split(new string[] { ":" }, StringSplitOptions.RemoveEmptyEntries);
if (strArry.Length == 3 && strArry[2] == "number")
{
key = strArry[1].Trim();
var value = info.Value;
items.Add(key, value);
}
}
if (items.Any())
{
itemsData.Add(ip, items);
}
}
if (itemsData.Any())
{
foreach (var item in itemsData)
{
var ip = item.Key;
var list = new List<string>();
foreach (var info in item.Value)
{
var dump = StatsItems($"cachedump {info.Key} {info.Value}");
if (dump.TryGetValue(ip, out Dictionary<string, string> dics))
{
foreach (var dic in dics)
{
list.Add(dic.Key);
}
}
}
if (list.Any())
{
data.Add(ip, list);
}
}
}
return data;
}
private Dictionary<IPEndPoint, Dictionary<string, string>> StatsItems(string type)
{
var results = new Dictionary<IPEndPoint, Dictionary<string, string>>();
foreach (var node in this.Pool.GetWorkingNodes())
{
IStatsOperation cmd = new StatsItemsOperation(type);
node.Execute(cmd);
results[node.EndPoint] = cmd.Result;
}
return results;
}
}
public class StatsItemsOperation : Operation, IStatsOperation
{
private static Enyim.Caching.ILog log = Enyim.Caching.LogManager.GetLogger(typeof(StatsOperation));
private string type;
private Dictionary<string, string> result;
public StatsItemsOperation(string type)
{
this.type = type;
}
protected override IList<ArraySegment<byte>> GetBuffer()
{
var command = String.IsNullOrEmpty(this.type)
? "stats" + TextSocketHelper.CommandTerminator
: "stats " + this.type + TextSocketHelper.CommandTerminator;
return TextSocketHelper.GetCommandBuffer(command);
}
protected override IOperationResult ReadResponse(PooledSocket socket)
{
var serverData = new Dictionary<string, string>();
while (true)
{
string line = TextSocketHelper.ReadResponse(socket);
// stat values are terminated by END
if (String.Compare(line, "END", StringComparison.Ordinal) == 0)
break;
expected response is STAT item_name item_value
//if (line.Length < 6 || String.Compare(line, 0, "STAT ", 0, 5, StringComparison.Ordinal) != 0)
//{
// if (log.IsWarnEnabled)
// log.Warn("Unknow response: " + line);
// continue;
//}
// get the key&value
string[] parts = line.Remove(0, 5).Split(' ');
//if (parts.Length != 2)
//{
// if (log.IsWarnEnabled)
// log.Warn("Unknow response: " + line);
// continue;
//}
// store the stat item
serverData[parts[0]] = parts[1];
}
this.result = serverData;
return new TextOperationResult().Pass();
}
Dictionary<string, string> IStatsOperation.Result
{
get { return result; }
}
protected override bool ReadResponseAsync(PooledSocket socket, System.Action<bool> next)
{
throw new System.NotSupportedException();
}
}
internal static class TextSocketHelper
{
private const string GenericErrorResponse = "ERROR";
private const string ClientErrorResponse = "CLIENT_ERROR ";
private const string ServerErrorResponse = "SERVER_ERROR ";
private const int ErrorResponseLength = 13;
public const string CommandTerminator = "\r\n";
private static readonly Enyim.Caching.ILog log = Enyim.Caching.LogManager.GetLogger(typeof(TextSocketHelper));
/// <summary>
/// Reads the response of the server.
/// </summary>
/// <returns>The data sent by the memcached server.</returns>
/// <exception cref="T:System.InvalidOperationException">The server did not sent a response or an empty line was returned.</exception>
/// <exception cref="T:Enyim.Caching.Memcached.MemcachedException">The server did not specified any reason just returned the string ERROR. - or - The server returned a SERVER_ERROR, in this case the Message of the exception is the message returned by the server.</exception>
/// <exception cref="T:Enyim.Caching.Memcached.MemcachedClientException">The server did not recognize the request sent by the client. The Message of the exception is the message returned by the server.</exception>
public static string ReadResponse(PooledSocket socket)
{
string response = TextSocketHelper.ReadLine(socket);
if (log.IsDebugEnabled)
log.Debug("Received response: " + response);
if (String.IsNullOrEmpty(response))
throw new MemcachedClientException("Empty response received.");
if (String.Compare(response, GenericErrorResponse, StringComparison.Ordinal) == 0)
throw new NotSupportedException("Operation is not supported by the server or the request was malformed. If the latter please report the bug to the developers.");
if (response.Length >= ErrorResponseLength)
{
if (String.Compare(response, 0, ClientErrorResponse, 0, ErrorResponseLength, StringComparison.Ordinal) == 0)
{
throw new MemcachedClientException(response.Remove(0, ErrorResponseLength));
}
else if (String.Compare(response, 0, ServerErrorResponse, 0, ErrorResponseLength, StringComparison.Ordinal) == 0)
{
throw new MemcachedException(response.Remove(0, ErrorResponseLength));
}
}
return response;
}
/// <summary>
/// Reads a line from the socket. A line is terninated by \r\n.
/// </summary>
/// <returns></returns>
private static string ReadLine(PooledSocket socket)
{
MemoryStream ms = new MemoryStream(50);
bool gotR = false;
//byte[] buffer = new byte[1];
int data;
while (true)
{
data = socket.ReadByte();
if (data == 13)
{
gotR = true;
continue;
}
if (gotR)
{
if (data == 10)
break;
ms.WriteByte(13);
gotR = false;
}
ms.WriteByte((byte)data);
}
string retval = Encoding.ASCII.GetString(ms.GetBuffer(), 0, (int)ms.Length);
if (log.IsDebugEnabled)
log.Debug("ReadLine: " + retval);
return retval;
}
/// <summary>
/// Gets the bytes representing the specified command. returned buffer can be used to streamline multiple writes into one Write on the Socket
/// using the <see cref="M:Enyim.Caching.Memcached.PooledSocket.Write(IList<ArraySegment<byte>>)"/>
/// </summary>
/// <param name="value">The command to be converted.</param>
/// <returns>The buffer containing the bytes representing the command. The command must be terminated by \r\n.</returns>
/// <remarks>The Nagle algorithm is disabled on the socket to speed things up, so it's recommended to convert a command into a buffer
/// and use the <see cref="M:Enyim.Caching.Memcached.PooledSocket.Write(IList<ArraySegment<byte>>)"/> to send the command and the additional buffers in one transaction.</remarks>
public static IList<ArraySegment<byte>> GetCommandBuffer(string value)
{
var data = new ArraySegment<byte>(Encoding.ASCII.GetBytes(value));
return new ArraySegment<byte>[] { data };
}
}
使用方式;
2022年4月2日 最新的方案
/// <summary>
/// 获取全部key
/// </summary>
/// <returns></returns>
public List<string> GetKeys()
{
var data = new HashSet<string>();
var itemsData = StatsItems("items");
if (itemsData.Any())
{
foreach (var item in itemsData)
{
var ip = item.Key;
foreach (var info in item.Value)
{
var dump = StatsItems($"cachedump {info} 0", ip);
if (dump.TryGetValue(ip, out var dics))
{
foreach (var dic in dics)
{
data.Add(dic);
}
}
}
}
}
return data.ToList();
}
private Dictionary<IPEndPoint, List<string>> StatsItems(string type, IPEndPoint iPEndPoint = null)
{
var results = new Dictionary<IPEndPoint, List<string>>();
var servers = Pool.GetWorkingNodes();
if (iPEndPoint != null)
{
servers = servers.Where(t => t.EndPoint == iPEndPoint);
}
foreach (var node in servers)
{
IStatsOperation cmd = Pool.OperationFactory.Stats(type);
try
{
node.Execute(cmd);
results[node.EndPoint] = cmd.Result?.Keys.ToList();
}
catch (Exception e)
{
logger.Fatal($"服务发生了异常:{node.EndPoint},{e.Message}", e);
throw;
}
}
return results;
}
2022年4月6日 cachedump 会丢失一部分数据
目前采用 lru_crawler metadump all 才能获取全部数据 -1.4.33 ++版本，需要开启 memcached -o lru_crawle
