我正在尝试从CosmosDB创建到本地CouchBase Lite数据库的复制。为此，我使用了Microsoft.Azure.Documents.ChangeFeedProcessor
但由于某种原因，总是在IChangeFeedObserver ProcessChangesAsync结束后我在控制台上得到以下异常：
＆＃34;错误＆＃34;：＆＃34;未满足指定的前提条件之一＆＃34;]是什么意思？复制以其他方式成功结束，但这让我感到困扰。
使用system.diagnostics更新了
ChangeFeedEventHost Information: 53 : 09/25/2017 08:27:54: Host 'TESTIkiosk' starting to check for available leases.
ChangeFeedEventHost Information: 54 : 09/25/2017 08:27:54: Host 'TESTIkiosk' starting to check for available leases.
ChangeFeedEventHost Information: 55 : 09/25/2017 08:27:54: Host 'TESTIkiosk' 1 partitions, 1 hosts, 0 available leases, target = 1, min = 0, max = 0, mine = 1, will try to take 0 lease(s) for myself'.
ChangeFeedEventHost Information: 56 : 09/25/2017 08:27:54: Host 'TESTIkiosk' 1 partitions, 1 hosts, 0 available leases, target = 1, min = 0, max = 0, mine = 1, will try to take 0 lease(s) for myself'.
ChangeFeedEventHost Information: 57 : 09/25/2017 08:28:06: Host 'TESTIkiosk' starting renewal of Leases.
ChangeFeedEventHost Information: 58 : 09/25/2017 08:28:06: Host 'TESTIkiosk' renewing lease for PartitionId '0' with lease token '"0000fa04-0000-0000-0000-59c893d40000"'
ChangeFeedEventHost Information: 59 : 09/25/2017 08:28:06: Host 'TESTIkiosk' starting renewal of Leases.
ChangeFeedEventHost Information: 60 : 09/25/2017 08:28:06: Host 'TESTIkiosk' renewing lease for PartitionId '0' with lease token '"0000fb04-0000-0000-0000-59c893d40000"'
ChangeFeedEventHost Information: 61 : 09/25/2017 08:28:06: Host 'TESTIkiosk' attempted to renew lease for PartitionId '0' and lease token '"0000fa04-0000-0000-0000-59c893d40000"' with result: 'True'
ChangeFeedEventHost Information: 62 : 09/25/2017 08:28:06: Host 'TESTIkiosk' attempted to renew lease for PartitionId '0' and lease token '"0000fb04-0000-0000-0000-59c893d40000"' with result: 'True'
ChangeFeedEventHost Information: 63 : 09/25/2017 08:28:07: Host 'TESTIkiosk' starting to check for available leases.
ChangeFeedEventHost Information: 64 : 09/25/2017 08:28:07: Host 'TESTIkiosk' starting to check for available leases.
ChangeFeedEventHost Information: 65 : 09/25/2017 08:28:07: Host 'TESTIkiosk' 1 partitions, 1 hosts, 0 available leases, target = 1, min = 0, max = 0, mine = 1, will try to take 0 lease(s) for myself'.
ChangeFeedEventHost Information: 66 : 09/25/2017 08:28:07: Host 'TESTIkiosk' 1 partitions, 1 hosts, 0 available leases, target = 1, min = 0, max = 0, mine = 1, will try to take 0 lease(s) for myself'.
[08:28:15 INF] Change feed in Ingredients: total 1 doc(s)
[08:28:15 INF] Replicated 2614
ChangeFeedEventHost Information: 67 : 09/25/2017 08:28:15: Partition '0' update failed because the lease with token '"0000e804-0000-0000-0000-59c893b20000"' was updated by same/this host with token '"00000005-0000-0000-0000-59c893e50000"'. Will retry, 4 retry(s) left.
ChangeFeedEventHost Information: 68 : 09/25/2017 08:28:15: Checkpoint: partition 0, new continuation '"81"'
DocDBTrace Error: 0 : DocumentClientException with status code PreconditionFailed, message: Message: {"Errors":["One of the specified pre-condition is not met"]}, inner exception: null, and response headers: {
"x-ms-last-state-change-utc": "Sun, 24 Sep 2017 21:03:48.392 GMT",
"lsn": "954",
"x-ms-schemaversion": "1.3",
"x-ms-quorum-acked-lsn": "954",
"x-ms-current-write-quorum": "3",
"x-ms-current-replica-set-size": "4",
"x-ms-documentdb-partitionkeyrangeid": "0",
"x-ms-xp-role": "1",
"x-ms-request-charge": "1.24",
"x-ms-serviceversion": " version=1.17.52.1",
"x-ms-activity-id": "b9877abb-6203-4408-b1c3-92c9f52aad67",
}
DocDBTrace Error: 0 : Operation will NOT be retried. Current attempt 0, Exception: Microsoft.Azure.Documents.PreconditionFailedException: Message: {"Errors":["One of the specified pre-condition is not met"]}
ActivityId: b9877abb-6203-4408-b1c3-92c9f52aad67, Request URI: /apps/c9c8f510-0ca7-4702-aa6c-9c596d797367/services/75cca430-a307-47a0-89aa-82aabf32e065/partitions/53fb63ca-95ae-4d13-90be-d32f1a88843c/replicas/131504697049132845p/
at Microsoft.Azure.Documents.TransportClient.ThrowIfFailed(String resourceAddress, StoreResponse storeResponse, Uri physicalAddress, Guid activityId)
at Microsoft.Azure.Documents.RntbdTransportClient.<InvokeStoreAsync>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.ReplicatedResourceClient.<WriteAsync>d__1b.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.ReplicatedResourceClient.<InvokeAsync>d__b.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.ReplicatedResourceClient.<>c__DisplayClass1.<<InvokeAsync>b__0>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.BackoffRetryUtility`1.<>c__DisplayClassf`1.<<ExecuteAsync>b__d>d__11.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.BackoffRetryUtility`1.<ExecuteRetry>d__1b.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.Azure.Documents.BackoffRetryUtility`1.<ExecuteRetry>d__1b.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.BackoffRetryUtility`1.<ExecuteAsync>d__18`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.ReplicatedResourceClient.<InvokeAsync>d__7.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.StoreClient.<ProcessMessageAsync>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.Client.DocumentClient.<UpdateAsync>d__305.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.Client.DocumentClient.<ReplaceDocumentPrivateAsync>d__13d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.Client.DocumentClient.<ReplaceDocumentPrivateAsync>d__135.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.BackoffRetryUtility`1.<>c__DisplayClass2.<<ExecuteAsync>b__0>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Azure.Documents.BackoffRetryUtility`1.<ExecuteRetry>d__1b.MoveNext()
我的实施准则：
using Microsoft.Azure.Documents.ChangeFeedProcessor;
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
namespace Solteq.Pos.Repositories.Feeds
{
internal class MyHostFeed : IChangeFeedObserver
{
private int s_totalDocs = 0;
private Func<dynamic, bool> replicate;
private string name;
public Func<dynamic, bool> Replicate { get => replicate; set => replicate = value; }
public string Name { get => name; set => name = value; }
public Task OpenAsync(ChangeFeedObserverContext context)
{
Console.WriteLine("Worker opened for {0}, {1}", name, context.PartitionKeyRangeId);
return Task.CompletedTask; // Requires targeting .NET 4.6+.
}
public Task CloseAsync(ChangeFeedObserverContext context, ChangeFeedObserverCloseReason reason)
{
Console.WriteLine("Worker closed for {0}, {1}", name, context.PartitionKeyRangeId);
return Task.CompletedTask;
}
public Task ProcessChangesAsync(ChangeFeedObserverContext context, IReadOnlyList<Microsoft.Azure.Documents.Document> docs)
{
Console.WriteLine("Change feed in {0}: total {1} doc(s)", name, Interlocked.Add(ref s_totalDocs, docs.Count));
foreach (var one in docs)
{
Console.WriteLine("Replicated: " + one.Id);
Replicate(one);
}
return Task.CompletedTask;
}
}
}
Observer的初始化：
public async void StartReplication(string replicateFrom, string hostName, Func<dynamic, bool> replicate)
{
// Customizable change feed option and host options
ChangeFeedOptions feedOptions = new ChangeFeedOptions();
// ie customize StartFromBeginning so change feed reads from beginning
// can customize MaxItemCount, PartitonKeyRangeId, RequestContinuation, SessionToken and StartFromBeginning
// feedOptions.StartFromBeginning = true;
ChangeFeedHostOptions feedHostOptions = new ChangeFeedHostOptions();
// ie. customizing lease renewal interval to 15 seconds
// can customize LeaseRenewInterval, LeaseAcquireInterval, LeaseExpirationInterval, FeedPollDelay
//feedHostOptions.LeaseRenewInterval = TimeSpan.FromSeconds(15);
feedHostOptions.LeasePrefix = replicateFrom;
feedHostOptions.FeedPollDelay = TimeSpan.FromSeconds(60);
try
{
DocumentCollectionInfo documentCollectionLocation = new DocumentCollectionInfo
{
Uri = new Uri(_databaseServiceUri),
MasterKey = _databaseAuthKey,
DatabaseName = _databaseId,
CollectionName = replicateFrom
};
DocumentCollectionInfo leaseCollectionLocation = new DocumentCollectionInfo
{
Uri = new Uri(_databaseServiceUri),
MasterKey = _databaseAuthKey,
DatabaseName = _databaseId,
CollectionName = "leases"
};
DocumentFeedObserverFactory docObserverFactory = new DocumentFeedObserverFactory(replicate, replicateFrom);
ChangeFeedEventHost host = new ChangeFeedEventHost(hostName, documentCollectionLocation, leaseCollectionLocation, feedOptions, feedHostOptions);
await host.RegisterObserverFactoryAsync(docObserverFactory);
hosts.Add(host);
}
catch (Exception e)
{
Console.WriteLine("Replication process halted for (" + replicateFrom + ") reason: " + e.ToString());
//throw e;
}
}
答案 0 :(得分：2)
这是跟踪的一部分，而不是错误，它可以在Visual Studio中查看，因为跟踪已启用。
当ProcessChangesAsync完成时，处理器更新租约。但是有一个单独的线程也维护租约更新。很自然，两个线程都有可能尝试编写同一个文档并生成并发异常（前置条件消息），因此处理器会跟踪它并重试并继续前进。
这不是一个意外的错误，它是一个处理和预期的错误，库只是确保跟踪所有情况。