我正在尝试异步获取表格中的所有条目，但无法弄清楚如何使用continuation token。我怀疑我需要采用我的匿名方法并将其转换为委托，然后使用延续令牌递归调用它。
如何获取以下代码并执行异步调用并获取新API中的所有条目？
Task<string[]> GetAllTableEntries(CloudTable tbl, string[] urls, string name, CancellationToken token)
{
TableRequestOptions reqOptions = new TableRequestOptions() { };
OperationContext ctx = new OperationContext() { ClientRequestID = "" };
object state = null;
// Register Cancelation Token
ICancellableAsyncResult result = null;
TableQuery qry = new TableQuery();
TableContinuationToken tok = null;
result = tbl.BeginExecuteQuerySegmented(qry, tok, reqOptions, ctx, (o) =>
{
var response = (o.AsyncState as CloudTable).EndExecuteQuerySegmented(o);
Console.WriteLine("Found " + response.Results.Count + " records");
// The following code was used in the previous version of the SDK
//
//26: // add first segment of data
//27: pageData.CompletedList.AddRange(
//28: from wu in response.Results
//29: select new CompletedWorkUnit(wu));
//30:
//31: // continue fetching segments to complete page
//32: while (response.HasMoreResults)
//33: {
//34: response = response.GetNext();
//35: pageData.CompletedList.AddRange(
//36: from wu in response.Results
//37: select new CompletedWorkUnit(wu));
//38: }
//39:
//40: // set continuation token for next page request
//41: pageData.ContinuationToken = response.ContinuationToken;
//42: evt.Set();
}, state);
// Add cancellation token according to guidance from Table Client 2.0 Breaking Changes blog entry
token.Register((o) => result.Cancel(), state);
答案 0 :(得分：3)
请试试这个：
static void ExecuteQuery()
{
TableContinuationToken token = null;
TableRequestOptions reqOptions = new TableRequestOptions() { };
OperationContext ctx = new OperationContext() { ClientRequestID = "" };
long totalEntitiesRetrieved = 0;
while (true)
{
CloudTable table = cloudTableClient.GetTableReference("MyTable");
TableQuery<TempEntity> query = (new TableQuery<TempEntity>()).Take(100);
System.Threading.ManualResetEvent evt = new System.Threading.ManualResetEvent(false);
var result = table.BeginExecuteQuerySegmented<TempEntity>(query, token, reqOptions, ctx, (o) =>
{
var response = (o.AsyncState as CloudTable).EndExecuteQuerySegmented<TempEntity>(o);
token = response.ContinuationToken;
int recordsRetrieved = response.Count();
totalEntitiesRetrieved += recordsRetrieved;
Console.WriteLine("Records retrieved in this attempt = " + recordsRetrieved + " | Total records retrieved = " + totalEntitiesRetrieved);
evt.Set();
}, table);
evt.WaitOne();
if (token == null)
{
break;
}
}
}
我注意到的一件事是，如果我执行一个返回动态表实体的查询，我将收到与DateTimeOffset相关的错误。这就是我最终创建一个临时实体的原因。
希望这有帮助。
答案 1 :(得分：2)
这是另一种选择，但这次是在TPL /任务并行库中。 Full source code is available here
/*
The following overloads of ExecuteQuerySegmentedAsync is executed like this)
*/
CloudTableClient client = acct.CreateCloudTableClient();
CloudTable tableSymmetricKeys = client.GetTableReference("SymmetricKeys5");
TableContinuationToken token = new TableContinuationToken() { };
TableRequestOptions opt = new TableRequestOptions() { };
OperationContext ctx = new OperationContext() { ClientRequestID = "ID" };
CancellationToken cancelToken = new CancellationToken();
List<Task> taskList = new List<Task>();
while (true)
{
Task<TableQuerySegment<DynamicTableEntity>> task3 = tableSymmetricKeys.ExecuteQuerySegmentedAsync(query, token, opt, ctx, cancelToken);
// Run the method
task3.Wait();
token = task3.Result.ContinuationToken;
Console.WriteLine("Records retrieved in this attempt = " + task3.Result.Count ());
if (token == null)
{
break;
}
else
{
// persist token
// token.WriteXml()
}
}
*/
// Overload #4
public static Task<TableQuerySegment<DynamicTableEntity>> ExecuteQuerySegmentedAsync(this CloudTable tbl, TableQuery query, TableContinuationToken continuationToken, TableRequestOptions opt, OperationContext ctx ,CancellationToken token )
{
ICancellableAsyncResult result = null;
if (opt == null && ctx == null)
result = tbl.BeginExecuteQuerySegmented(query, continuationToken, null, tbl);
else
result = tbl.BeginExecuteQuerySegmented(query, continuationToken, opt, ctx, null, tbl);
// Add cancellation token according to guidance from Table Client 2.0 Breaking Changes blog entry
var cancellationRegistration = token.Register(result.Cancel);
return Task.Factory.FromAsync(result, iAsyncResult =>
{
CloudTable currentTable = iAsyncResult.AsyncState as CloudTable;
//cancellationRegistration.Dispose();
return currentTable.EndExecuteQuerySegmented(result);
});
}
答案 2 :(得分：1)
这个人为ExecuteQueryAsync制作了一些包含分段方法的扩展方法
https://github.com/glueckkanja/tasync/blob/master/StorageExtensions.cs
答案 3 :(得分：0)
这是@Gaurav Mantri代码的替代实现。
public class AzureTableQueryState
{
public CloudTable CloudTable { get; set; }
public TableContinuationToken Token { get; set; }
public ManualResetEvent Evt { get; set; } //i'm guessing that's what this is
//any other variables you were using
public int TotalEntitiesRetrieved { get; set; }
}
// snip....
while (true)
{
// Initialize variables
TableQuery query = (new TableQuery()).Take(100);
AzureTableQueryState queryState = new AzureTableQueryState();
queryState.Evt = new System.Threading.ManualResetEvent(false);
queryState.TotalEntitiesRetrieved = 0;
AsyncCallback asyncCallback = (iAsyncResult) =>
{
AzureTableQueryState state = iAsyncResult.AsyncState as AzureTableQueryState;
var response = state.CloudTable.EndExecuteQuerySegmented(iAsyncResult);
token = response.ContinuationToken;
int recordsRetrieved = response.Results.Count;
state.TotalEntitiesRetrieved += recordsRetrieved;
Console.WriteLine("Records retrieved in this attempt = " + recordsRetrieved + " | Total records retrieved = " + state.TotalEntitiesRetrieved);
state.Evt.Set();
};
// Run the method
var result = tableSymmetricKeys.BeginExecuteQuerySegmented(query, token, opt, ctx, asyncCallback, tableSymmetricKeys);
// Add cancellation token according to guidance from Table Client 2.0 Breaking Changes blog entry
cancelToken.Register((o) => result.Cancel(), null);
queryState.Evt.WaitOne();
if (token == null)
{
break;
}
else
{
// persist token
// token.WriteXml()
}
}