code.grnet.gr Git - pithos-ms-client/blob - trunk/Pithos.Network/PithosClient.cs

   1 // -----------------------------------------------------------------------
   2 // <copyright file="PithosClient.cs" company="Microsoft">
   3 // TODO: Update copyright text.
   4 // </copyright>
   5 // -----------------------------------------------------------------------
   6
   7 using System.Collections.Specialized;
   8 using System.Diagnostics;
   9 using System.Diagnostics.Contracts;
  10 using System.Net;
  11 using System.Runtime.Serialization;
  12
  13 namespace Pithos.Network
  14 {
  15     using System;
  16     using System.Collections.Generic;
  17     using System.Linq;
  18     using System.Text;
  19
  20     /// <summary>
  21     /// TODO: Update summary.
  22     /// </summary>
  23     public class PithosClient:WebClient
  24     {
  25         public int Timeout { get; set; }
  26
  27         public bool TimedOut { get; set; }
  28
  29         public HttpStatusCode StatusCode { get; private set; }
  30
  31         public string StatusDescription { get; set; }
  32
  33
  34         public int Retries { get; set; }
  35
  36         private readonly Dictionary<string, string> _parameters=new Dictionary<string, string>();
  37         public Dictionary<string, string> Parameters
  38         {
  39             get { return _parameters; }
  40         }
  41
  42         public PithosClient():base()
  43         {
  44
  45         }
  46
  47
  48         public PithosClient(PithosClient other)
  49             : base()
  50         {
  51             CopyHeaders(other);
  52             Timeout = other.Timeout;
  53             Retries = other.Retries;
  54             BaseAddress = other.BaseAddress;
  55
  56
  57             foreach (var parameter in other.Parameters)
  58             {
  59                 Parameters.Add(parameter.Key,parameter.Value);
  60             }
  61
  62             this.Proxy = other.Proxy;
  63         }
  64
  65         protected override WebRequest GetWebRequest(Uri address)
  66         {
  67             TimedOut = false;
  68             HttpWebRequest request = base.GetWebRequest(address) as HttpWebRequest;
  69             request.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
  70             if(Timeout>0)
  71                 request.Timeout = Timeout;
  72             return request;
  73         }
  74
  75         protected override WebResponse GetWebResponse(WebRequest request, IAsyncResult result)
  76         {
  77             var response = (HttpWebResponse) base.GetWebResponse(request, result);
  78             StatusCode=response.StatusCode;
  79             StatusDescription=response.StatusDescription;
  80             return response;
  81         }
  82
  83
  84
  85         protected override WebResponse GetWebResponse(WebRequest request)
  86         {
  87             var response = (HttpWebResponse)base.GetWebResponse(request);
  88             StatusCode = response.StatusCode;
  89             StatusDescription = response.StatusDescription;
  90             return response;
  91         }
  92
  93         public string DownloadStringWithRetry(string address,int retries=0)
  94         {
  95             if (address == null)
  96                 throw new ArgumentNullException("address");
  97
  98             var actualAddress = GetActualAddress(address);
  99
 100             var actualRetries = (retries == 0) ? Retries : retries;
 101
 102
 103             var func = Retry(() =>
 104             {
 105                 var uriString = String.Join("/", BaseAddress, actualAddress);
 106                 var content = base.DownloadString(uriString);
 107
 108                 if (StatusCode == HttpStatusCode.NoContent)
 109                     return String.Empty;
 110                 return content;
 111
 112             }, actualRetries);
 113
 114             var result = func();
 115             return result;
 116         }
 117
 118         public void Head(string address,int retries=0)
 119         {
 120             RetryWithoutContent(address, retries, "HEAD");
 121         }
 122
 123         public void PutWithRetry(string address, int retries = 0)
 124         {
 125             RetryWithoutContent(address, retries, "PUT");
 126         }
 127
 128         public void DeleteWithRetry(string address,int retries=0)
 129         {
 130             RetryWithoutContent(address, retries, "DELETE");
 131         }
 132
 133         public string GetHeaderValue(string headerName)
 134         {
 135             var values=this.ResponseHeaders.GetValues(headerName);
 136             if (values == null)
 137                 throw new WebException(String.Format("The {0}  header is missing", headerName));
 138             else
 139                 return values[0];
 140         }
 141
 142         private void RetryWithoutContent(string address, int retries, string method)
 143         {
 144             if (address == null)
 145                 throw new ArgumentNullException("address");
 146
 147             var actualAddress = GetActualAddress(address);
 148
 149             var actualRetries = (retries == 0) ? Retries : retries;
 150             var func = Retry(() =>
 151             {
 152                 var uriString = String.Join("/",BaseAddress ,actualAddress);
 153                 var uri = new Uri(uriString);
 154                 var request =  GetWebRequest(uri);
 155                 request.Method = method;
 156                 if (ResponseHeaders!=null)
 157                     ResponseHeaders.Clear();
 158
 159                 var response = (HttpWebResponse)GetWebResponse(request);
 160                 StatusCode = response.StatusCode;
 161                 StatusDescription = response.StatusDescription;
 162
 163
 164                 return 0;
 165             }, actualRetries);
 166
 167             func();
 168         }
 169
 170         private string GetActualAddress(string address)
 171         {
 172             if (Parameters.Count == 0)
 173                 return address;
 174             var addressBuilder=new StringBuilder(address);
 175
 176             bool isFirst = true;
 177             foreach (var parameter in Parameters)
 178             {
 179                 if(isFirst)
 180                     addressBuilder.AppendFormat("?{0}={1}", parameter.Key, parameter.Value);
 181                 else
 182                     addressBuilder.AppendFormat("&{0}={1}", parameter.Key, parameter.Value);
 183                 isFirst = false;
 184             }
 185             return addressBuilder.ToString();
 186         }
 187
 188         public string DownloadStringWithRetry(Uri address,int retries=0)
 189         {
 190             if (address == null)
 191                 throw new ArgumentNullException("address");
 192
 193             var actualRetries = (retries == 0) ? Retries : retries;
 194             var func = Retry(() =>
 195             {
 196                 var content = base.DownloadString(address);
 197
 198                 if (StatusCode == HttpStatusCode.NoContent)
 199                     return String.Empty;
 200                 return content;
 201
 202             }, actualRetries);
 203
 204             var result = func();
 205             return result;
 206         }
 207
 208
 209         /// <summary>
 210         /// Copies headers from another PithosClient
 211         /// </summary>
 212         /// <param name="source">The PithosClient from which the headers are copied</param>
 213         public void CopyHeaders(PithosClient source)
 214         {
 215             Contract.Requires(source != null, "source can't be null");
 216             if (source == null)
 217                 throw new ArgumentNullException("source", "source can't be null");
 218             CopyHeaders(source.Headers,Headers);
 219         }
 220
 221         /// <summary>
 222         /// Copies headers from one header collection to another
 223         /// </summary>
 224         /// <param name="source">The source collection from which the headers are copied</param>
 225         /// <param name="target">The target collection to which the headers are copied</param>
 226         public static void CopyHeaders(WebHeaderCollection source,WebHeaderCollection target)
 227         {
 228             Contract.Requires(source != null, "source can't be null");
 229             Contract.Requires(target != null, "target can't be null");
 230             if (source == null)
 231                 throw new ArgumentNullException("source", "source can't be null");
 232             if (target == null)
 233                 throw new ArgumentNullException("target", "target can't be null");
 234             for (int i = 0; i < source.Count; i++)
 235             {
 236                 target.Add(source.GetKey(i), source[i]);
 237             }
 238         }
 239
 240         public void AssertStatusOK(string message)
 241         {
 242             if (StatusCode >= HttpStatusCode.BadRequest)
 243                 throw new WebException(String.Format("{0} with code {1} - {2}", message, StatusCode, StatusDescription));
 244         }
 245
 246         private Func<T> Retry<T>(Func< T> original, int retryCount)
 247         {
 248             return () =>
 249             {
 250                 while (true)
 251                 {
 252                     try
 253                     {
 254                         return original();
 255                     }
 256                     catch (WebException e)
 257                     {
 258                         var statusCode = ((HttpWebResponse)e.Response).StatusCode;
 259                         this.StatusCode = statusCode;
 260
 261                         switch (e.Status)
 262                         {
 263                             case WebExceptionStatus.Timeout:
 264
 265                                 TimedOut = true;
 266                                 if (retryCount == 0)
 267                                 {
 268                                     Trace.TraceError("[ERROR] Timed out too many times. {0}\n", e);
 269                                     throw new RetryException("Timed out too many times.", e);
 270                                 }
 271                                 retryCount--;
 272                                 Trace.TraceError(
 273                                     "[RETRY] Timed out after {0} ms. Will retry {1} more times\n{2}", Timeout,
 274                                     retryCount, e);
 275
 276                                 break;
 277                             case WebExceptionStatus.ProtocolError:
 278                                 switch (statusCode)
 279                                 {
 280                                     case HttpStatusCode.NotFound:
 281                                         {
 282                                             return default(T);
 283                                         }
 284                                     case HttpStatusCode.ServiceUnavailable:
 285                                         {
 286
 287                                             TimedOut = false;
 288                                             if (retryCount == 0)
 289                                             {
 290                                                 Trace.TraceError("[ERROR] Failed too many times. {0}\n", e);
 291                                                 throw new RetryException("Failed too many times.", e);
 292                                             }
 293                                             retryCount--;
 294                                             Trace.TraceError(
 295                                                 "[RETRY] Failed due to 503. Will retry {0} more times\n{1}", retryCount, e);
 296                                             break;
 297                                         }
 298                                     default:
 299                                         throw;
 300                                 }
 301                                 break;
 302                             default:
 303                                 throw;
 304                         }
 305                     }
 306                 }
 307             };
 308         }
 309
 310
 311     }
 312
 313     public class RetryException:Exception
 314     {
 315         public RetryException()
 316             :base()
 317         {
 318
 319         }
 320
 321         public RetryException(string message)
 322             :base(message)
 323         {
 324
 325         }
 326
 327         public RetryException(string message,Exception innerException)
 328             :base(message,innerException)
 329         {
 330
 331         }
 332
 333         public RetryException(SerializationInfo info,StreamingContext context)
 334             :base(info,context)
 335         {
 336
 337         }
 338     }
 339 }