private static void RetryNImpl(Action action, int numberOfRetries, TimeSpan minBackoff, TimeSpan maxBackoff, TimeSpan deltaBackoff)
{
int totalNumberOfRetries = numberOfRetries;
int backoff;
if (minBackoff > maxBackoff)
{
throw new ArgumentException("The minimum backoff must not be larger than the maximum backoff period.");
}
if (minBackoff.TotalMilliseconds < 0)
{
throw new ArgumentException("The minimum backoff period must not be negative.");
}
do
{
try
{
action();
break;
}
catch (InvalidOperationException e)
{
HttpStatusCode status;
// precondition failed is the status code returned by the server to indicate that the etag is wrong
if (TableStorageHelpers.EvaluateException(e, out status))
{
if (status == HttpStatusCode.PreconditionFailed)
{
if (numberOfRetries == 0)
{
throw;
}
backoff = CalculateCurrentBackoff(minBackoff, maxBackoff, deltaBackoff, totalNumberOfRetries - numberOfRetries);
Debug.Assert(backoff >= minBackoff.TotalMilliseconds);
Debug.Assert(backoff <= maxBackoff.TotalMilliseconds);
if (backoff > 0)
{
Thread.Sleep(backoff);
}
}
else
{
throw;
}
}
else
{
throw;
}
}
}while (numberOfRetries-- > 0);
}
// remember that there is no is no rollback functionality for the table storage service right now
// be cautious when using this function
// if a role does not exist, we stop deleting roles, if a user in a role does not exist, we continue deleting
// in case of error conditions, the behavior of this function is different than the SQL role provider
public override void RemoveUsersFromRoles(string[] usernames, string[] roleNames)
{
SecUtility.CheckArrayParameter(ref roleNames, true, true, true, MaxTableRoleNameLength, "roleNames");
SecUtility.CheckArrayParameter(ref usernames, true, true, true, Constants.MaxTableUsernameLength, "usernames");
RoleRow row;
try
{
TableStorageDataServiceContext svc = CreateDataServiceContext();
foreach (string role in roleNames)
{
if (!RoleExists(role))
{
throw new ProviderException(string.Format(CultureInfo.InstalledUICulture, "The role {0} does not exist!", role));
}
foreach (string user in usernames)
{
row = GetUserInRole(svc, role, user);
if (row == null)
{
Log.Write(EventKind.Warning, string.Format(CultureInfo.InstalledUICulture, "The user {0} does not exist in the role {1}.", user, role));
continue;
}
try
{
svc.DeleteObject(row);
svc.SaveChangesWithRetries();
}
catch (Exception e)
{
HttpStatusCode status;
if (TableStorageHelpers.EvaluateException(e, out status) && (status == HttpStatusCode.NoContent || status == HttpStatusCode.NotFound))
{
Log.Write(EventKind.Warning, string.Format(CultureInfo.InstalledUICulture, "The user {0} does not exist in the role {1}.", user, role));
svc.Detach(row);
}
else
{
throw new ProviderException(string.Format(CultureInfo.InstalledUICulture, "Error deleting user {0} from role {1}.", user, role));
}
}
}
}
}
catch (InvalidOperationException e)
{
throw new ProviderException("Error while accessing the data store.", e);
}
}
// Because of limited transactional support in the table storage offering, this function gives limited guarantees
// for inserting all users into all roles.
// We do not recommend using this function because of missing transactional support.
public override void AddUsersToRoles(string[] usernames, string[] roleNames)
{
SecUtility.CheckArrayParameter(ref roleNames, true, true, true, MaxTableRoleNameLength, "roleNames");
SecUtility.CheckArrayParameter(ref usernames, true, true, true, Constants.MaxTableUsernameLength, "usernames");
RoleRow row;
try
{
TableStorageDataServiceContext svc = CreateDataServiceContext();
foreach (string role in roleNames)
{
if (!RoleExists(role))
{
throw new ProviderException(string.Format(CultureInfo.InstalledUICulture, "The role {0} does not exist!", role));
}
foreach (string user in usernames)
{
row = new RoleRow(_applicationName, role, user);
try
{
svc.AddObject(_tableName, row);
svc.SaveChangesWithRetries();
}
catch (InvalidOperationException e)
{
HttpStatusCode status;
if (TableStorageHelpers.EvaluateException(e, out status) && status == HttpStatusCode.Conflict)
{
// this element already exists or was created in a failed retry
// this is not a fatal error; continue adding elements
Log.Write(EventKind.Warning, string.Format(CultureInfo.InstalledUICulture, "The user {0} already exists in the role {1}.", user, role));
svc.Detach(row);
}
else
{
throw new ProviderException(string.Format(CultureInfo.InstalledUICulture, "Error adding user {0} to role {1}", user, role));
}
}
}
}
}
catch (InvalidOperationException e)
{
throw new ProviderException("Error while accessing the data store.", e);
}
}
public override bool RoleExists(string roleName)
{
SecUtility.CheckParameter(ref roleName, true, true, true, MaxTableRoleNameLength, "rolename");
try
{
TableStorageDataServiceContext svc = CreateDataServiceContext();
DataServiceQuery <RoleRow> queryObj = svc.CreateQuery <RoleRow>(_tableName);
IEnumerable <RoleRow> query = from role in queryObj
where role.PartitionKey == SecUtility.CombineToKey(_applicationName, string.Empty) &&
role.RowKey == SecUtility.Escape(roleName)
select role;
TableStorageDataServiceQuery <RoleRow> q = new TableStorageDataServiceQuery <RoleRow>(query as DataServiceQuery <RoleRow>, _tableRetry);
try
{
// this query addresses exactly one result
// we thus should get an exception if there is no element
q.ExecuteWithRetries();
return(true);
}
catch (DataServiceQueryException e)
{
HttpStatusCode s;
if (TableStorageHelpers.EvaluateException(e, out s) && s == HttpStatusCode.NotFound)
{
return(false);
}
else
{
throw;
}
}
}
catch (InvalidOperationException e)
{
throw new ProviderException("Error while accessing the data store.", e);
}
}
private RoleRow GetUserInRole(DataServiceContext svc, string rolename, string username)
{
SecUtility.CheckParameter(ref username, true, true, true, Constants.MaxTableUsernameLength, "username");
SecUtility.CheckParameter(ref rolename, true, true, true, MaxTableRoleNameLength, "rolename");
try
{
DataServiceQuery <RoleRow> queryObj = svc.CreateQuery <RoleRow>(_tableName);
IEnumerable <RoleRow> query = from user in queryObj
where user.PartitionKey == SecUtility.CombineToKey(_applicationName, username) &&
user.RowKey == SecUtility.Escape(rolename)
select user;
TableStorageDataServiceQuery <RoleRow> q = new TableStorageDataServiceQuery <RoleRow>(query as DataServiceQuery <RoleRow>, _tableRetry);
try
{
IEnumerable <RoleRow> userRows = q.ExecuteAllWithRetries();
return(userRows.First());
}
catch (DataServiceQueryException e)
{
HttpStatusCode s;
if (TableStorageHelpers.EvaluateException(e, out s) && s == HttpStatusCode.NotFound)
{
return(null);
}
else
{
throw;
}
}
}
catch (InvalidOperationException e)
{
throw new ProviderException("Error while accessing the data store.", e);
}
}
public override void CreateRole(string roleName)
{
SecUtility.CheckParameter(ref roleName, true, true, true, MaxTableRoleNameLength, "rolename");
try
{
TableStorageDataServiceContext svc = CreateDataServiceContext();
RoleRow newRole = new RoleRow(_applicationName, roleName, string.Empty);
svc.AddObject(_tableName, newRole);
svc.SaveChangesWithRetries();
}
catch (InvalidOperationException e)
{
HttpStatusCode status;
// when retry policies are used we cannot distinguish between a conflict and success
// so, in the case of a conflict, we just retrun success here
if (TableStorageHelpers.EvaluateException(e, out status) && status == HttpStatusCode.Conflict)
{
return;
// the role already exists
}
throw new ProviderException("Error accessing role table.", e);
}
}
private static string GetExceptionMessage(Exception exception)
{
HttpStatusCode statusCode;
StorageExtendedErrorInformation extendedErrorInfo;
if (TableStorageHelpers.EvaluateException(exception, out statusCode, out extendedErrorInfo))
{
if (extendedErrorInfo != null)
{
return(string.Format(CultureInfo.InvariantCulture, "{0} {1}", extendedErrorInfo.ErrorCode ?? "", extendedErrorInfo.ErrorMessage ?? ""));
}
}
DataServiceClientException dse = exception.InnerException as DataServiceClientException;
if (dse != null)
{
return(dse.Message);
}
else
{
return(exception.Message);
}
}
public override bool DeleteRole(string roleName, bool throwOnPopulatedRole)
{
SecUtility.CheckParameter(ref roleName, true, true, true, MaxTableRoleNameLength, "rolename");
try
{
TableStorageDataServiceContext svc = CreateDataServiceContext();
DataServiceQuery <RoleRow> queryObj = svc.CreateQuery <RoleRow>(_tableName);
IEnumerable <RoleRow> query = from userRole in queryObj
where userRole.PartitionKey.CompareTo(SecUtility.EscapedFirst(_applicationName)) >= 0 &&
userRole.PartitionKey.CompareTo(SecUtility.NextComparisonString(SecUtility.EscapedFirst(_applicationName))) < 0 &&
userRole.RowKey == SecUtility.Escape(roleName)
select userRole;
TableStorageDataServiceQuery <RoleRow> q = new TableStorageDataServiceQuery <RoleRow>(query as DataServiceQuery <RoleRow>, _tableRetry);
IEnumerable <RoleRow> userRows = q.ExecuteAllWithRetries();
if (userRows == null)
{
return(false);
}
List <RoleRow> l = new List <RoleRow>(userRows);
if (l.Count == 0)
{
// the role does not exist
return(false);
}
RoleRow role;
if (IsStaleRole(l, out role))
{
return(false);
}
if (l.Count > 1 && throwOnPopulatedRole)
{
throw new ProviderException("Cannot delete populated role.");
}
svc.DeleteObject(role);
svc.SaveChangesWithRetries();
// lets try to remove all remaining elements in the role
foreach (RoleRow row in l)
{
if (row != role)
{
try
{
svc.DeleteObject(row);
svc.SaveChangesWithRetries();
}
catch (InvalidOperationException ex)
{
HttpStatusCode status;
if (TableStorageHelpers.EvaluateException(ex, out status) && (status == HttpStatusCode.NoContent || status == HttpStatusCode.NotFound))
{
// this element already was already deleted by another process or during a failed retry
// this is not a fatal error; continue deleting elements
Log.Write(EventKind.Warning, string.Format(CultureInfo.InstalledUICulture, "The user {0} does not exist in the role {1}.", row.UserName, row.RoleName));
}
else
{
throw new ProviderException(string.Format(CultureInfo.InstalledUICulture, "Error deleting user {0} from role {1}.", row.UserName, row.RoleName));
}
}
}
}
return(true);
}
catch (InvalidOperationException e)
{
throw new ProviderException("Error while accessing the data store.", e);
}
}
// we don't use the retry policy itself in this function because out parameters are not well handled by
// retry policies
private SessionStateStoreData GetSession(HttpContext context, string id, out bool locked, out TimeSpan lockAge,
out object lockId, out SessionStateActions actions,
bool exclusive)
{
Debug.Assert(context != null);
SecUtility.CheckParameter(ref id, true, true, false, TableStorageConstants.MaxStringPropertySizeInChars, "id");
SessionRow session = null;
int curRetry = 0;
bool retry = false;
// Assign default values to out parameters
locked = false;
lockId = null;
lockAge = TimeSpan.Zero;
actions = SessionStateActions.None;
do
{
retry = false;
try
{
TableStorageDataServiceContext svc = CreateDataServiceContext();
session = GetSession(id, svc);
// Assign default values to out parameters
locked = false;
lockId = null;
lockAge = TimeSpan.Zero;
actions = SessionStateActions.None;
// if the blob does not exist, we return null
// ASP.NET will call the corresponding method for creating the session
if (session == null)
{
return(null);
}
if (session.Initialized == false)
{
Debug.Assert(session.Locked == false);
actions = SessionStateActions.InitializeItem;
session.Initialized = true;
}
session.ExpiresUtc = DateTime.UtcNow.AddMinutes(session.Timeout);
if (exclusive)
{
if (!session.Locked)
{
if (session.Lock == Int32.MaxValue)
{
session.Lock = 0;
}
else
{
session.Lock++;
}
session.LockDateUtc = DateTime.UtcNow;
}
lockId = session.Lock;
locked = session.Locked;
session.Locked = true;
}
lockAge = DateTime.UtcNow.Subtract(session.LockDateUtc);
lockId = session.Lock;
if (locked == true)
{
return(null);
}
// let's try to write this back to the data store
// in between, someone else could have written something to the store for the same session
// we retry a number of times; if all fails, we throw an exception
svc.UpdateObject(session);
svc.SaveChangesWithRetries();
}
catch (InvalidOperationException e)
{
HttpStatusCode status;
// precondition fails indicates problems with the status code
if (TableStorageHelpers.EvaluateException(e, out status) && status == HttpStatusCode.PreconditionFailed)
{
retry = true;
}
else
{
throw new ProviderException("Error accessing the data store.", e);
}
}
} while (retry && curRetry++ < NumRetries);
// ok, now we have successfully written back our state
// we can now read the blob
// note that we do not need to care about read/write locking when accessing the
// blob because each time we write a new session we create a new blob with a different name
SessionStateStoreData result = null;
MemoryStream stream = null;
StreamReader reader = null;
BlobProperties properties;
try
{
try
{
stream = _blobProvider.GetBlobContent(session.BlobName, out properties);
}
catch (StorageException e)
{
throw new ProviderException("Couldn't read session blob!", e);
}
reader = new StreamReader(stream);
if (actions == SessionStateActions.InitializeItem)
{
// Return an empty SessionStateStoreData
result = new SessionStateStoreData(new SessionStateItemCollection(),
SessionStateUtility.GetSessionStaticObjects(context), session.Timeout);
}
else
{
// Read Items, StaticObjects, and Timeout from the file
byte[] items = Convert.FromBase64String(reader.ReadLine());
byte[] statics = Convert.FromBase64String(reader.ReadLine());
int timeout = session.Timeout;
// Deserialize the session
result = DeserializeSession(items, statics, timeout);
}
}
finally
{
if (stream != null)
{
stream.Close();
}
if (reader != null)
{
reader.Close();
}
}
return(result);
}
// shows alternative ways of generating DataServiceContext objects
internal static void RunSamples2()
{
StorageAccountInfo account = null;
try
{
account = StorageAccountInfo.GetDefaultTableStorageAccountFromConfiguration();
TableStorage tableStorage = TableStorage.Create(account);
tableStorage.RetryPolicy = RetryPolicies.RetryN(3, TimeSpan.FromSeconds(1));
// the DataServiceContext object inherits its retry policy from tableStorage in this case
TableStorageDataServiceContext svc = tableStorage.GetDataServiceContext();
Console.WriteLine("Table creation, delete and list samples...");
string sampleTableName = SampleDataServiceContext.SampleTableName;
tableStorage.TryCreateTable(sampleTableName);
DeleteAllEntriesFromSampleTable(svc, sampleTableName);
Console.WriteLine("List all tables in the account.");
IEnumerable <string> tables2 = tableStorage.ListTables();
foreach (string n1 in tables2)
{
Console.WriteLine(n1);
}
Console.WriteLine("Inserting entities into the table...");
SampleEntity t = new SampleEntity("samplepartitionkey", "samplerowkey");
svc.AddObject(sampleTableName, t);
svc.SaveChangesWithRetries();
//Detach the existing entity so that we can demonstrate the server side
//error when you try to insert an same object with the same keys
svc.Detach(t);
// Insert an entity with the same keys
Console.WriteLine("Try to insert the same entity into the table and show how to deal with error conditions.");
t = new SampleEntity("samplepartitionkey", "samplerowkey");
svc.AddObject(sampleTableName, t);
try
{
svc.SaveChangesWithRetries();
// getting here is an error because inserting the same row twice raises an exception
Console.WriteLine("Should not get here. Succeeded inserting two entities with the same keys");
}
catch (Exception e)
{
HttpStatusCode status;
StorageExtendedErrorInformation errorInfo;
if (TableStorageHelpers.EvaluateException(e, out status, out errorInfo) &&
status == HttpStatusCode.Conflict)
{
// the row has already been inserted before, this is expected here
if (errorInfo != null)
{
Console.WriteLine("Attempting to insert row with same keys resulted in error {0} : {1}",
errorInfo.ErrorCode, errorInfo.ErrorMessage);
}
}
else
{
throw;
}
}
svc.Detach(t);
Console.WriteLine("Insert a large item into the table.");
t = new SampleEntity("samplepartitionkey", "samplerowkey1");
t.B = new String('a', 1000);
svc.AddObject(sampleTableName, t);
svc.SaveChangesWithRetries();
Console.WriteLine("Create a normal DataServiceContext object (not TableStorageDataServiceContext) and attach it to a TableStorage object.");
DataServiceContext svc2 = new DataServiceContext(
TableStorage.GetServiceBaseUri(account.BaseUri, account.UsePathStyleUris, account.AccountName));
tableStorage.Attach(svc2);
var qResult = from c in svc2.CreateQuery <SampleEntity>(sampleTableName)
where c.RowKey == "samplerowkey1"
select c;
foreach (SampleEntity cust in qResult)
{
if (cust.B != t.B)
{
Console.WriteLine("Sample failed. Did not read the entity property just written");
}
}
Console.WriteLine("Insert many rows in a table and show the API for dealing with query result pagination.");
int num = 2100;
Console.WriteLine("Inserting {0} rows.", num.ToString(CultureInfo.CurrentUICulture));
for (int i = 0; i < num; i++)
{
t = new SampleEntity("samplestring", i.ToString(CultureInfo.InvariantCulture));
svc.AddObject(sampleTableName, t);
svc.SaveChangesWithRetries();
if ((i + 1) % 50 == 0)
{
Console.WriteLine("Inserted row {0}.", (i + 1).ToString(CultureInfo.CurrentUICulture));
}
}
Console.WriteLine("Executing query that will return many results. This can take a while...");
var qResult2 = from c in svc.CreateQuery <SampleEntity>(sampleTableName)
where c.PartitionKey == "samplestring"
select c;
TableStorageDataServiceQuery <SampleEntity> tableStorageQuery = new TableStorageDataServiceQuery <SampleEntity>(qResult2 as DataServiceQuery <SampleEntity>);
IEnumerable <SampleEntity> res = tableStorageQuery.ExecuteAllWithRetries();
Console.WriteLine("Retrieved query results:");
foreach (SampleEntity entity in res)
{
Console.WriteLine("Partition key: {0}, row key: {1}.", entity.PartitionKey, entity.RowKey);
}
Console.WriteLine("Delete all entries in the sample table.");
DeleteAllEntriesFromSampleTable(tableStorage.GetDataServiceContext(), sampleTableName);
tableStorage.DeleteTable(sampleTableName);
Console.WriteLine("Table samples finished!");
}
catch (DataServiceRequestException dsre)
{
Console.WriteLine("DataServiceRequestException: " + GetExceptionMessage(dsre));
ShowTableStorageErrorMessage(account.BaseUri.ToString());
}
catch (InvalidOperationException ioe)
{
Console.WriteLine("Storage service error: " + GetExceptionMessage(ioe));
ShowTableStorageErrorMessage(account.BaseUri.ToString());
}
}
// this method shows an alternative way of accessing/creating DataServiceContext objects
// this approach is closer to what tools generate for normal ADO.NET Data Services projects
internal static void RunSamples1()
{
StorageAccountInfo account = null;
try
{
Console.WriteLine("Show how to create tables and queries using the SampleDataServiceContext class...");
account = StorageAccountInfo.GetDefaultTableStorageAccountFromConfiguration();
SampleDataServiceContext svc = new SampleDataServiceContext(account);
svc.RetryPolicy = RetryPolicies.RetryN(3, TimeSpan.FromSeconds(1));
// Create 'SampleTable'
// this uses the SampleDataServiceContext class
TableStorage.CreateTablesFromModel(typeof(SampleDataServiceContext), account);
string sampleTableName = SampleDataServiceContext.SampleTableName;
DeleteAllEntriesFromSampleTable(svc, sampleTableName);
svc.AddObject(SampleDataServiceContext.SampleTableName, new SampleEntity("sample", "entity"));
svc.SaveChangesWithRetries();
var qResult = from c in svc.SampleTable
where c.PartitionKey == "samplepartitionkey" && c.RowKey == "samplerowkey1"
select c;
TableStorageDataServiceQuery <SampleEntity> q = new TableStorageDataServiceQuery <SampleEntity>(qResult as DataServiceQuery <SampleEntity>, svc.RetryPolicy);
try {
// the query references the whole key and explicitly addresses one entity
// thus, this query can generate an exception if there are 0 results during enumeration
IEnumerable <SampleEntity> res = q.ExecuteAllWithRetries();
foreach (SampleEntity s in res)
{
Console.WriteLine("This code is not reached. " + s.PartitionKey);
}
} catch (DataServiceQueryException e) {
HttpStatusCode s;
if (TableStorageHelpers.EvaluateException(e, out s) && s == HttpStatusCode.NotFound)
{
// this would mean the entity was not found
Console.WriteLine("The entity was not found. This is expected here.");
}
}
Console.WriteLine("Delete all entries in the sample table.");
DeleteAllEntriesFromSampleTable(svc, sampleTableName);
Console.WriteLine("Table sample 1 finished!");
}
catch (DataServiceRequestException dsre)
{
Console.WriteLine("DataServiceRequestException: " + GetExceptionMessage(dsre));
ShowTableStorageErrorMessage(account.BaseUri.ToString());
}
catch (InvalidOperationException ioe)
{
Console.WriteLine("Storage service error: " + GetExceptionMessage(ioe));
ShowTableStorageErrorMessage(account.BaseUri.ToString());
}
}