/// <summary>
/// Read data entries and their corresponding eTags from the Azure table.
/// </summary>
/// <param name="filter">Filter string to use for querying the table and filtering the results.</param>
/// <returns>Enumeration of entries in the table which match the query condition.</returns>
public async Task <IEnumerable <Tuple <T, string> > > ReadTableEntriesAndEtagsAsync(string filter)
{
const string operation = "ReadTableEntriesAndEtags";
var startTime = DateTime.UtcNow;
try
{
TableQuery <T> cloudTableQuery = filter == null
? new TableQuery <T>()
: new TableQuery <T>().Where(filter);
try
{
Func <Task <List <T> > > executeQueryHandleContinuations = async() =>
{
TableQuerySegment <T> querySegment = null;
var list = new List <T>();
//ExecuteSegmentedAsync not supported in "WindowsAzure.Storage": "7.2.1" yet
while (querySegment == null || querySegment.ContinuationToken != null)
{
querySegment = await tableReference.ExecuteQuerySegmentedAsync(cloudTableQuery, querySegment?.ContinuationToken);
list.AddRange(querySegment);
}
return(list);
};
IBackoffProvider backoff = new FixedBackoff(AzureTableDefaultPolicies.PauseBetweenTableOperationRetries);
List <T> results = await AsyncExecutorWithRetries.ExecuteWithRetries(
counter => executeQueryHandleContinuations(),
AzureTableDefaultPolicies.MaxTableOperationRetries,
(exc, counter) => AzureStorageUtils.AnalyzeReadException(exc.GetBaseException(), counter, TableName, Logger),
AzureTableDefaultPolicies.TableOperationTimeout,
backoff);
// Data was read successfully if we got to here
return(results.Select(i => Tuple.Create(i, i.ETag)).ToList());
}
catch (Exception exc)
{
// Out of retries...
var errorMsg = $"Failed to read Azure storage table {TableName}: {exc.Message}";
if (!AzureStorageUtils.TableStorageDataNotFound(exc))
{
Logger.Warn(ErrorCode.AzureTable_09, errorMsg, exc);
}
throw new OrleansException(errorMsg, exc);
}
}
finally
{
CheckAlertSlowAccess(startTime, operation);
}
}
/// <summary>
/// Read data entries and their corresponding eTags from the Azure table.
/// </summary>
/// <param name="predicate">Predicate function to use for querying the table and filtering the results.</param>
/// <returns>Enumeration of entries in the table which match the query condition.</returns>
internal async Task <IEnumerable <Tuple <T, string> > > ReadTableEntriesAndEtagsAsync(Expression <Func <T, bool> > predicate)
{
const string operation = "ReadTableEntriesAndEtags";
var startTime = DateTime.UtcNow;
try
{
CloudTable tableReference = tableOperationsClient.GetTableReference(TableName);
TableQuery <T> cloudTableQuery = tableReference.CreateQuery <T>().Where(predicate).AsTableQuery();
try
{
Func <Task <List <T> > > executeQueryHandleContinuations = async() =>
{
TableQuerySegment <T> querySegment = null;
var list = new List <T>();
while (querySegment == null || querySegment.ContinuationToken != null)
{
querySegment = await cloudTableQuery.ExecuteSegmentedAsync(querySegment != null?querySegment.ContinuationToken : null);
list.AddRange(querySegment);
}
return(list);
};
IBackoffProvider backoff = new FixedBackoff(AzureTableDefaultPolicies.PauseBetweenTableOperationRetries);
List <T> results = await AsyncExecutorWithRetries.ExecuteWithRetries(
counter => executeQueryHandleContinuations(),
AzureTableDefaultPolicies.MaxTableOperationRetries,
(exc, counter) => AzureStorageUtils.AnalyzeReadException(exc.GetBaseException(), counter, TableName, Logger),
AzureTableDefaultPolicies.TableOperationTimeout,
backoff);
// Data was read successfully if we got to here
return(results.Select((T i) => Tuple.Create(i, i.ETag)).ToList());
}
catch (Exception exc)
{
// Out of retries...
var errorMsg = string.Format("Failed to read Azure storage table {0}: {1}", TableName, exc.Message);
if (!AzureStorageUtils.TableStorageDataNotFound(exc))
{
Logger.Warn(ErrorCode.AzureTable_09, errorMsg, exc);
}
throw new OrleansException(errorMsg, exc);
}
}
finally
{
CheckAlertSlowAccess(startTime, operation);
}
}
/// <summary>
/// Read data entries and their corresponding eTags from the Azure table.
/// </summary>
/// <param name="predicate">Predicate function to use for querying the table and filtering the results.</param>
/// <returns>Enumeration of entries in the table which match the query condition.</returns>
internal async Task <IEnumerable <Tuple <T, string> > > ReadTableEntriesAndEtagsAsync(Expression <Func <T, bool> > predicate)
{
const string operation = "ReadTableEntriesAndEtags";
var startTime = DateTime.UtcNow;
try
{
TableServiceContext svc = tableOperationsClient.GetDataServiceContext();
// Improve performance when table name differs from class name
// http://www.gtrifonov.com/2011/06/15/improving-performance-for-windows-azure-tables/
svc.ResolveType = ResolveEntityType;
//IQueryable<T> query = svc.CreateQuery<T>(TableName).Where(predicate);
CloudTableQuery <T> cloudTableQuery = svc.CreateQuery <T>(TableName).Where(predicate).AsTableServiceQuery(); // turn IQueryable into CloudTableQuery
try
{
Func <Task <List <T> > > executeQueryHandleContinuations = async() =>
{
// Read table with continuation token
// http://convective.wordpress.com/2013/11/03/queries-in-the-windows-azure-storage-client-library-v2-1/
// 1) First wrong sync way to read:
// List<T> queryResults = query.ToList(); // ToList will actually execute the query and add entities to svc. However, this will not handle continuation tokens.
// 2) Second correct sync way to read:
// http://convective.wordpress.com/2010/02/06/queries-in-azure-tables/
// CloudTableQuery.Execute will properly retrieve all the records from a table through the automatic handling of continuation tokens:
Task <ResultSegment <T> > firstSegmentPromise = Task <ResultSegment <T> > .Factory.FromAsync(
cloudTableQuery.BeginExecuteSegmented,
cloudTableQuery.EndExecuteSegmented,
null);
// 3) Third wrong async way to read:
// return firstSegmentPromise;
// 4) Forth correct async way to read - handles continuation tokens:
var list = new List <T>();
Task <ResultSegment <T> > nextSegmentAsync = firstSegmentPromise;
while (true)
{
ResultSegment <T> resultSegment = await nextSegmentAsync;
var capture = resultSegment.Results;
if (capture != null) // don't call Count or Any or anything else that can potentialy cause multiple evaluations of the IEnumerable
{
list.AddRange(capture);
}
if (!resultSegment.HasMoreResults)
{
// All data was read successfully if we got to here
break;
}
// ask to read the next segment
nextSegmentAsync = Task <ResultSegment <T> > .Factory.FromAsync(
resultSegment.BeginGetNext,
resultSegment.EndGetNext,
null);
}
return(list);
};
IBackoffProvider backoff = new FixedBackoff(AzureTableDefaultPolicies.PauseBetweenTableOperationRetries);
List <T> results = await AsyncExecutorWithRetries.ExecuteWithRetries(
counter => executeQueryHandleContinuations(),
AzureTableDefaultPolicies.MaxTableOperationRetries,
(exc, counter) => AzureStorageUtils.AnalyzeReadException(exc.GetBaseException(), counter, TableName, Logger),
AzureTableDefaultPolicies.TableOperationTimeout,
backoff);
// Data was read successfully if we got to here
return(PairEntitiesWithEtags(svc, results));
}
catch (Exception exc)
{
// Out of retries...
var errorMsg = string.Format("Failed to read Azure storage table {0}: {1}", TableName, exc.Message);
if (!AzureStorageUtils.TableStorageDataNotFound(exc))
{
Logger.Warn(ErrorCode.AzureTable_09, errorMsg, exc);
}
throw new OrleansException(errorMsg, exc);
}
}
finally
{
CheckAlertSlowAccess(startTime, operation);
}
}