Azure的斑点：＆QUOT;采用HTTP条件标题（S）不满足＆QUOT指定的条件; [英] Azure Blob: "The condition specified using HTTP conditional header(s) is not met"

问题描述

当我运行我的应用程序我得到这个例外。这也恰好在现实的Azure Blob存储。

I got this exception when I run my application. It happens also in the real Azure blob storage.

我得了与小提琴手创建此问题要求：

I've caught with Fiddler the request that creates this problem:

GET http://127.0.0.1:10000/devstoreaccount1/ebb413ed-fdb5-49f2-a5ac-74faa7e2d3bf/8844c3ec-9e4b-43ec-88b2-58eddf65fc0a/perro?timeout=90 HTTP/1.1
x-ms-version: 2009-09-19
User-Agent: WA-Storage/6.0.6002.18006
x-ms-range: bytes=0-524304
If-Match: 0x8CDA190BD304DD0
x-ms-date: Wed, 23 Feb 2011 16:49:18 GMT
Authorization: SharedKey devstoreaccount1:5j3IScY9UJLN3o1ICWKwVEazO4/IDJG796sdZKqHlR4=
Host: 127.0.0.1:10000

这是响应：

HTTP/1.1 412 The condition specified using HTTP conditional header(s) is not met.
Content-Length: 252
Content-Type: application/xml
Server: Windows-Azure-Blob/1.0 Microsoft-HTTPAPI/2.0
x-ms-request-id: fbff9d15-65c8-4f21-9088-c95e4496c62c
x-ms-version: 2009-09-19
Date: Wed, 23 Feb 2011 16:49:18 GMT

<?xml version="1.0" encoding="utf-8"?><Error><Code>ConditionNotMet</Code><Message>The condition specified using HTTP conditional header(s) is not met.
RequestId:fbff9d15-65c8-4f21-9088-c95e4496c62c
Time:2011-02-23T16:49:18.8790478Z</Message></Error>

它发生时，我可以从该行检索到的流：

It happens when I use the Stream retrieved from this line:

blob.OpenRead();

为什么读操作的eTag头脑？我怎么可能避免这个问题？

Why the ETAG minds in a read operation? How may I avoid this problem?

这种事我每次推出几款并行任务的Blob存储做事的时间。

It happens every time I launch several parallel tasks doing things on the blob storage.

如果我使用：

blob.OpenRead(new BlobRequestOptions() { AccessCondition = AccessCondition.IfMatch("*") });

我得到这个意外没有内层（它与细节引发WebException前），无论是在提琴手故障行：

I got this exception with no inner one (before it had a WebException with the details), either a fail line in Fiddler :

Microsoft.WindowsAzure.StorageClient.StorageClientException was unhandled
  Message=The conditionals specified for this operation did not match server.
  Source=mscorlib
  StackTrace:
    Server stack trace: 
       at Microsoft.WindowsAzure.StorageClient.Tasks.Task`1.get_Result()
       at Microsoft.WindowsAzure.StorageClient.Tasks.Task`1.ExecuteAndWait()
       at Microsoft.WindowsAzure.StorageClient.TaskImplHelper.ExecuteImpl[T](Func`2 impl)
       at Microsoft.WindowsAzure.StorageClient.BlobReadStream.Read(Byte[] buffer, Int32 offset, Int32 count)
       at System.IO.BinaryReader.ReadBytes(Int32 count)
       at System.Runtime.Serialization.Formatters.Binary.SerializationHeaderRecord.Read(__BinaryParser input)
       at System.Runtime.Serialization.Formatters.Binary.__BinaryParser.ReadSerializationHeaderRecord()
       at System.Runtime.Serialization.Formatters.Binary.__BinaryParser.Run()
       at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
       at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
       ...........

先谢谢了。

推荐答案

Bufff ...谜解决了！

Bufff... mistery solved!

那么，当你做一个 CloudBlob.OpenRead（），客户端库正在做两个操作：

Well, when you do a CloudBlob.OpenRead(), the client library is doing two operations:

首先，让斑点块列表：

GET /devstoreaccount1/etagtest/test2.txt?comp=blocklist&blocklisttype=Committed&timeout=90 HTTP/1.1
x-ms-version: 2009-09-19
User-Agent: WA-Storage/6.0.6002.18006
x-ms-date: Wed, 23 Feb 2011 22:21:01 GMT
Authorization: SharedKey devstoreaccount1:SPOBe/IUrZJvoPXnAdD/Twnppvu37+qrUbHnaBHJY24=
Host: 127.0.0.1:10000

HTTP/1.1 200 OK
Transfer-Encoding: chunked
Content-Type: application/xml
Last-Modified: Wed, 23 Feb 2011 22:20:33 GMT
ETag: 0x8CDA1BF0593B660
Server: Windows-Azure-Blob/1.0 Microsoft-HTTPAPI/2.0
x-ms-request-id: ecffddf2-137f-403c-9595-c8fc2847c9d0
x-ms-version: 2009-09-19
x-ms-blob-content-length: 4
Date: Wed, 23 Feb 2011 22:21:02 GMT

注意在响应中的ETag。

Attention to the ETag in the response.

第二，我想这开始找回它，现在注意ETag的请求：

Second, I guess that start to retrieve it, and now attention to the ETag in the request:

GET /devstoreaccount1/etagtest/test2.txt?timeout=90 HTTP/1.1
x-ms-version: 2009-09-19
User-Agent: WA-Storage/6.0.6002.18006
x-ms-range: bytes=0-525311
If-Match: 0x8CDA1BF0593B660
x-ms-date: Wed, 23 Feb 2011 22:21:02 GMT
Authorization: SharedKey devstoreaccount1:WXzXRv5e9+p0SzlHUAd7iv7jRHXvf+27t9tO4nrhY5Q=
Host: 127.0.0.1:10000

HTTP/1.1 206 Partial Content
Content-Length: 4
Content-Type: text/plain
Content-Range: bytes 0-3/4
Last-Modified: Wed, 23 Feb 2011 22:20:33 GMT
ETag: 0x8CDA1BF0593B660
Server: Windows-Azure-Blob/1.0 Microsoft-HTTPAPI/2.0
x-ms-request-id: db1e221d-fc61-4837-a255-28b1547cb5d7
x-ms-version: 2009-09-19
x-ms-lease-status: unlocked
x-ms-blob-type: BlockBlob
Date: Wed, 23 Feb 2011 22:21:02 GMT

如果另一WebRole做呼叫之间的BLOB什么事发生？ 是一个竞争条件

What happen if another WebRole do something in the blob between call? YES a race condition.

解决方案：使用 CloudBlob.DownloadToStream（），该方法只发出一个电话：

Solution: Use CloudBlob.DownloadToStream(), that method only issues one call:

GET /devstoreaccount1/etagtestxx/test2.txt?timeout=90 HTTP/1.1
x-ms-version: 2009-09-19
User-Agent: WA-Storage/6.0.6002.18006
x-ms-date: Wed, 23 Feb 2011 22:34:02 GMT
Authorization: SharedKey devstoreaccount1:VjXIO2kbjCIP4UeiXPtxDxmFLeoYAKOqiRv4SV3bZno=
Host: 127.0.0.1:10000

HTTP/1.1 200 OK
Content-Length: 4
Content-Type: text/plain
Last-Modified: Wed, 23 Feb 2011 22:33:47 GMT
ETag: 0x8CDA1C0DEB562D0
Server: Windows-Azure-Blob/1.0 Microsoft-HTTPAPI/2.0
x-ms-request-id: 183a05bb-ea47-4811-8768-6a62195cdb64
x-ms-version: 2009-09-19
x-ms-lease-status: unlocked
x-ms-blob-type: BlockBlob
Date: Wed, 23 Feb 2011 22:34:02 GMT

我会在工作明天早上把这个实践，看看有什么情况发生。

I will put this on practice tomorrow morning at work and see what happen.

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