/// <summary>
/// Reads the next row of values from Cloud Spanner.
/// Important: Cloud Spanner supports limited cancellation of this task.
/// </summary>
/// <param name="cancellationToken">A cancellation token to cancel the read. Cloud Spanner currently
/// supports limited cancellation while advancing the read to the next row.</param>
/// <returns>True if another row was read.</returns>
public override Task <bool> ReadAsync(CancellationToken cancellationToken)
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(
async() =>
{
if (_metadata == null)
{
await PopulateMetadataAsync(cancellationToken).ConfigureAwait(false);
}
_innerList.Clear();
//read # values == # fields.
var first = await _resultSet.NextAsync(cancellationToken).ConfigureAwait(false);
if (first == null)
{
return false;
}
_innerList.Add(first);
//we expect to get full rows...
for (var i = 1; i < _metadata.RowType.Fields.Count; i++)
{
_innerList.Add(await _resultSet.NextAsync(cancellationToken).ConfigureAwait(false));
}
return true;
},
"SpannerDataReader.Read", Logger));
}
internal Task <ResultSetMetadata> PopulateMetadataAsync(CancellationToken cancellationToken)
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(
async()
=> _metadata ?? (_metadata = await _resultSet.GetMetadataAsync(cancellationToken)
.ConfigureAwait(false)), "SpannerDataReader.GetMetadata", Logger));
}
private void CommitToSpanner()
{
// If it's a read-only transaction, then just tell the outer transaction that everything is good.
// This can happen with a read-only transaction or a write transaction where we never
// executed any mutations.
if (_transaction != null && _transaction.Mode != TransactionMode.ReadOnly)
{
ExecuteHelper.WithErrorTranslationAndProfiling(() => _transaction.Commit(), "VolatileResourceManager.Commit", Logger);
}
}
/// <summary>
/// Rolls back a transaction asynchronously.
/// </summary>
public Task RollbackAsync()
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(
() =>
{
GaxPreconditions.CheckState(
Mode != TransactionMode.ReadOnly, "You cannot roll back a readonly transaction.");
return WireTransaction.RollbackAsync(Session);
}, "SpannerTransaction.Rollback"));
}
/// <summary>
/// Reads the next row of values from Cloud Spanner.
/// Important: Cloud Spanner supports limited cancellation of this task.
/// </summary>
/// <param name="cancellationToken">A cancellation token to cancel the read. Cloud Spanner currently
/// supports limited cancellation while advancing the read to the next row.</param>
/// <returns>True if another row was read.</returns>
public override Task <bool> ReadAsync(CancellationToken cancellationToken) =>
ExecuteHelper.WithErrorTranslationAndProfiling(async() =>
{
using (var timeoutCts = new CancellationTokenSource(TimeSpan.FromSeconds(_readTimeoutSeconds)))
{
var timeoutToken = timeoutCts.Token;
using (var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, timeoutToken))
{
try
{
var effectiveToken = linkedCts.Token;
if (_metadata == null)
{
await PopulateMetadataAsync(effectiveToken).ConfigureAwait(false);
}
_rowValid = false;
_innerList.Clear();
var first = await _resultSet.NextAsync(effectiveToken).ConfigureAwait(false);
if (first == null)
{
// If this is the first thing we've tried to read, then we know there are no rows.
if (_hasRows == null)
{
_hasRows = false;
}
return(false);
}
_innerList.Add(first);
// We expect to get full rows...
for (var i = 1; i < _metadata.RowType.Fields.Count; i++)
{
var value = await _resultSet.NextAsync(effectiveToken).ConfigureAwait(false);
GaxPreconditions.CheckState(value != null, "Incomplete row returned by Spanner server");
_innerList.Add(value);
}
_rowValid = true;
_hasRows = true;
return(true);
}
// Translate timeouts from our own cancellation token into a Spanner exception.
// This mimics the behavior of SqlDataReader, which throws a SqlException on timeout.
// It's *possible* that the operation was cancelled due to the user-provided cancellation token,
// and that it just happens that the timeout has been fired as well... but there's a race
// condition anyway in that case, so it's probably reasonable to take the simple path.
catch (OperationCanceledException) when(timeoutToken.IsCancellationRequested)
{
throw new SpannerException(ErrorCode.DeadlineExceeded, "Read operation timed out");
}
}
}
},
"SpannerDataReader.Read", Logger);
/// <summary>
/// Commits the database transaction asynchronously.
/// </summary>
/// <returns>Returns the UTC timestamp when the data was written to the database.</returns>
public Task <DateTime?> CommitAsync()
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(
async() =>
{
GaxPreconditions.CheckState(
Mode != TransactionMode.ReadOnly, "You cannot commit a readonly transaction.");
var response = await WireTransaction.CommitAsync(Session, Mutations).ConfigureAwait(false);
return response.CommitTimestamp?.ToDateTime();
}, "SpannerTransaction.Commit"));
}
public Task <long> ExecuteDmlAsync(ExecuteSqlRequest request, CancellationToken cancellationToken, int timeoutSeconds) =>
ExecuteHelper.WithErrorTranslationAndProfiling(
async() =>
{
using (var transaction = await _connection.BeginTransactionAsync(cancellationToken).ConfigureAwait(false))
{
transaction.CommitTimeout = timeoutSeconds;
long count = await((ISpannerTransaction)transaction).ExecuteDmlAsync(request, cancellationToken, timeoutSeconds).ConfigureAwait(false);
await transaction.CommitAsync(cancellationToken).ConfigureAwait(false);
return(count);
}
}, "EphemeralTransaction.ExecuteDmlAsync", Logger);
/// <summary>
/// Commits the database transaction asynchronously.
/// </summary>
/// <returns>Returns the UTC timestamp when the data was written to the database.</returns>
public Task <DateTime?> CommitAsync()
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(
async() =>
{
GaxPreconditions.CheckState(
Mode != TransactionMode.ReadOnly, "You cannot commit a readonly transaction.");
// We allow access to _mutations outside of a lock here because multithreaded
// access at this point should be done and only one caller can call commit.
var response = await WireTransaction.CommitAsync(Session, _mutations).ConfigureAwait(false);
return response.CommitTimestamp?.ToDateTime();
}, "SpannerTransaction.Commit"));
}
/// <summary>
/// Gets the read timestamp if <see cref="TimestampBound.ReturnReadTimestamp" /> was true
/// else returns <c>null</c>.
/// </summary>
/// <returns>The value converted to a <see cref="Timestamp"/>, or <c>null</c> if
/// <see cref="TimestampBound.ReturnReadTimestamp" /> was false.</returns>
public Task <Timestamp> GetReadTimestampAsync(CancellationToken cancellationToken)
{
if (_readTimestamp != null)
{
return(Task.FromResult(_readTimestamp));
}
return(ExecuteHelper.WithErrorTranslationAndProfiling(
async() =>
{
var metadata = await PopulateMetadataAsync(cancellationToken).ConfigureAwait(false);
_readTimestamp = metadata.Transaction?.ReadTimestamp;
return _readTimestamp;
}, "SpannerDataReader.GetReadTimestamp", Logger));
}
public Task <ReliableStreamReader> ExecuteQueryAsync(ExecuteSqlRequest request, CancellationToken cancellationToken, int timeoutSeconds)
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(Impl, "EphemeralTransaction.ExecuteQuery", _connection.Logger));
async Task <ReliableStreamReader> Impl()
{
PooledSession session = await _connection.AcquireSessionAsync(_transactionOptions, cancellationToken).ConfigureAwait(false);
var reader = session.ExecuteSqlStreamReader(request, timeoutSeconds);
reader.StreamClosed += delegate { session.ReleaseToPool(forceDelete: false); };
return(reader);
}
}
public Task <ReliableStreamReader> ExecuteQueryAsync(
ExecuteSqlRequest request,
CancellationToken cancellationToken)
{
GaxPreconditions.CheckNotNull(request, nameof(request));
return(ExecuteHelper.WithErrorTranslationAndProfiling(
() =>
{
request.Transaction = new TransactionSelector {
SingleUse = _options
};
return Task.FromResult(_spannerConnection.SpannerClient.GetSqlStreamReader(request, _session));
},
"SingleUseTransaction.ExecuteQuery"));
}
Task <int> ISpannerTransaction.ExecuteMutationsAsync(
List <Mutation> mutations,
CancellationToken cancellationToken)
{
GaxPreconditions.CheckNotNull(mutations, nameof(mutations));
CheckCompatibleMode(TransactionMode.ReadWrite);
return(ExecuteHelper.WithErrorTranslationAndProfiling(
() =>
{
var taskCompletionSource = new TaskCompletionSource <int>();
cancellationToken.ThrowIfCancellationRequested();
_mutations.AddRange(mutations);
taskCompletionSource.SetResult(mutations.Count);
return taskCompletionSource.Task;
}, "SpannerTransaction.ExecuteMutations"));
}
Task <ReliableStreamReader> ISpannerTransaction.ExecuteQueryAsync(
ExecuteSqlRequest request,
CancellationToken cancellationToken)
{
GaxPreconditions.CheckNotNull(request, nameof(request));
return(ExecuteHelper.WithErrorTranslationAndProfiling(
() =>
{
var taskCompletionSource =
new TaskCompletionSource <ReliableStreamReader>();
request.Transaction = GetTransactionSelector(TransactionMode.ReadOnly);
taskCompletionSource.SetResult(_connection.SpannerClient.GetSqlStreamReader(request, Session));
return taskCompletionSource.Task;
}, "SpannerTransaction.ExecuteQuery"));
}
public Task <ReliableStreamReader> ExecuteReadOrQueryAsync(ReadOrQueryRequest request, CancellationToken cancellationToken, int timeoutSeconds /* ignored */)
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(Impl, "EphemeralTransaction.ExecuteReadOrQuery", _connection.Logger));
async Task <ReliableStreamReader> Impl()
{
PooledSession session = await _connection.AcquireSessionAsync(_transactionOptions, cancellationToken).ConfigureAwait(false);
var callSettings = _connection.CreateCallSettings(
request.GetCallSettings,
cancellationToken);
var reader = request.ExecuteReadOrQueryStreamReader(session, callSettings);
reader.StreamClosed += delegate { session.ReleaseToPool(forceDelete: false); };
return(reader);
}
}
public void Rollback(Enlistment enlistment)
{
try
{
ExecuteHelper.WithErrorTranslationAndProfiling(() =>
_transaction?.Rollback(), "VolatileResourceManager.Rollback", Logger);
enlistment.Done();
}
catch (Exception e)
{
Logger.Error(
() =>
"Error attempting to rollback a transaction.", e);
}
finally
{
Dispose();
}
}
public void Rollback(Enlistment enlistment)
{
try
{
// We don't need to roll back if we're in a read-only transaction, and indeed doing so will cause an error.
if (_transaction != null && _transaction.Mode != TransactionMode.ReadOnly)
{
ExecuteHelper.WithErrorTranslationAndProfiling(() => _transaction.Rollback(), "VolatileResourceManager.Rollback", Logger);
}
enlistment.Done();
}
catch (Exception e)
{
Logger.Error("Error attempting to rollback a transaction.", e);
}
finally
{
Dispose();
}
}
/// <summary>
/// Acquires a read/write transaction from Spannerconnection and releases the transaction back into the pool
/// after the operation is complete.
/// SpannerCommand never uses implicit Transactions for write operations because they are non idempotent and
/// may result in unexpected errors if retry is used.
/// </summary>
/// <param name="mutations"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
public Task <int> ExecuteMutationsAsync(List <Mutation> mutations, CancellationToken cancellationToken)
{
GaxPreconditions.CheckNotNull(mutations, nameof(mutations));
Logger.Debug(() => "Executing a mutation change through an ephemeral transaction.");
int count;
return(ExecuteHelper.WithErrorTranslationAndProfiling(
async() =>
{
using (var transaction = await _connection.BeginTransactionAsync(cancellationToken)
.ConfigureAwait(false))
{
count = await((ISpannerTransaction)transaction)
.ExecuteMutationsAsync(mutations, cancellationToken)
.ConfigureAwait(false);
await transaction.CommitAsync().ConfigureAwait(false);
}
return count;
}, "EphemeralTransaction.ExecuteMutations"));
}
public void SinglePhaseCommit(SinglePhaseEnlistment singlePhaseEnlistment)
{
try
{
ExecuteHelper.WithErrorTranslationAndProfiling(() =>
_transaction?.Commit(), "VolatileResourceManager.Commit");
singlePhaseEnlistment.Committed();
}
catch (SpannerException e)
{
singlePhaseEnlistment.Aborted(e);
}
catch (Exception e)
{
singlePhaseEnlistment.InDoubt(e);
}
finally
{
Dispose();
}
}
/// <summary>
/// Acquires a read/write transaction from Spannerconnection and releases the transaction back into the pool
/// after the operation is complete.
/// SpannerCommand never uses implicit Transactions for write operations because they are non idempotent and
/// may result in unexpected errors if retry is used.
/// </summary>
/// <param name="mutations">The list of changes to apply.</param>
/// <param name="cancellationToken">A cancellation token used for this task.</param>
/// <param name="timeoutSeconds">The timeout which will apply to the commit part of this method.</param>
/// <returns>The number of rows modified.</returns>
public Task <int> ExecuteMutationsAsync(List <Mutation> mutations, CancellationToken cancellationToken, int timeoutSeconds)
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(Impl, "EphemeralTransaction.ExecuteMutationsAsync", _connection.Logger));
async Task <int> Impl()
{
using (var transaction = await _connection.BeginTransactionImplAsync(_transactionOptions, TransactionMode.ReadWrite, cancellationToken).ConfigureAwait(false))
{
// Importantly, we need to set timeout on the transaction, because
// ExecuteMutations on SpannerTransaction doesnt actually hit the network
// until you commit or rollback.
transaction.CommitTimeout = timeoutSeconds;
int count = await((ISpannerTransaction)transaction)
.ExecuteMutationsAsync(mutations, cancellationToken, timeoutSeconds)
.ConfigureAwait(false);
await transaction.CommitAsync(cancellationToken).ConfigureAwait(false);
return(count);
}
}
}
public Task <IEnumerable <long> > ExecuteBatchDmlAsync(ExecuteBatchDmlRequest request, CancellationToken cancellationToken, int timeoutSeconds)
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(Impl, "EphemeralTransaction.ExecuteBatchDmlAsync", _connection.Logger));
async Task <IEnumerable <long> > Impl()
{
using (var transaction = await _connection.BeginTransactionImplAsync(_transactionOptions, TransactionMode.ReadWrite, cancellationToken).ConfigureAwait(false))
{
transaction.CommitTimeout = timeoutSeconds;
IEnumerable <long> result;
result = await((ISpannerTransaction)transaction)
.ExecuteBatchDmlAsync(request, cancellationToken, timeoutSeconds)
.ConfigureAwait(false);
await transaction.CommitAsync(cancellationToken).ConfigureAwait(false);
return(result);
}
}
}
public Task <long> ExecuteDmlAsync(ExecuteSqlRequest request, CancellationToken cancellationToken, int timeoutSeconds)
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(Impl, "EphemeralTransaction.ExecuteDmlAsync", _connection.Logger));
async Task <long> Impl()
{
using (var transaction = await _connection.BeginTransactionImplAsync(_transactionOptions, TransactionMode.ReadWrite, cancellationToken).ConfigureAwait(false))
{
transaction.CommitTimeout = timeoutSeconds;
transaction.CommitPriority = _commitPriority;
while (true)
{
try
{
long count = await((ISpannerTransaction)transaction)
.ExecuteDmlAsync(request, cancellationToken, timeoutSeconds)
.ConfigureAwait(false);
// This is somewhat ugly. PDML commits as it goes, so we don't need to, whereas non-partitioned
// DML needs the commit afterwards to finish up.
if (_transactionOptions.ModeCase != TransactionOptions.ModeOneofCase.PartitionedDml)
{
await transaction.CommitAsync(cancellationToken).ConfigureAwait(false);
}
return(count);
}
catch (SpannerException e) when(
_transactionOptions.ModeCase == TransactionOptions.ModeOneofCase.PartitionedDml &&
e.ErrorCode == ErrorCode.Internal &&
e.Message.Contains("Received unexpected EOS on DATA frame from server"))
{
// Retry with the same transaction. Since this error happens in long-lived
// transactions (>= 30 mins), it's unnecessary to do exponential backoff.
continue;
}
}
}
}
}
public Task <long> ExecuteDmlAsync(ExecuteSqlRequest request, CancellationToken cancellationToken, int timeoutSeconds)
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(Impl, "EphemeralTransaction.ExecuteDmlAsync", _connection.Logger));
async Task <long> Impl()
{
using (var transaction = await _connection.BeginTransactionImplAsync(_transactionOptions, TransactionMode.ReadWrite, cancellationToken).ConfigureAwait(false))
{
transaction.CommitTimeout = timeoutSeconds;
long count = await((ISpannerTransaction)transaction)
.ExecuteDmlAsync(request, cancellationToken, timeoutSeconds)
.ConfigureAwait(false);
// This is somewhat ugly. PDML commits as it goes, so we don't need to, whereas non-partitioned
// DML needs the commit afterwards to finish up.
if (_transactionOptions.ModeCase != TransactionOptions.ModeOneofCase.PartitionedDml)
{
await transaction.CommitAsync(cancellationToken).ConfigureAwait(false);
}
return(count);
}
}
}
public Task <ReliableStreamReader> ExecuteQueryAsync(
ExecuteSqlRequest request,
CancellationToken cancellationToken)
{
return(ExecuteHelper.WithErrorTranslationAndProfiling(
async() =>
{
GaxPreconditions.CheckNotNull(request, nameof(request));
Logger.Debug(() => "Executing a query through an ephemeral transaction.");
using (var holder = await SpannerConnection.SessionHolder
.Allocate(_connection, cancellationToken)
.ConfigureAwait(false))
{
var streamReader = _connection.SpannerClient.GetSqlStreamReader(request, holder.Session);
holder.TakeOwnership();
streamReader.StreamClosed += (o, e) => { _connection.ReleaseSession(streamReader.Session); };
return streamReader;
}
}, "EphemeralTransaction.ExecuteQuery"));
}
/// <summary>
/// Acquires a read/write transaction from Spannerconnection and releases the transaction back into the pool
/// after the operation is complete.
/// SpannerCommand never uses implicit Transactions for write operations because they are non idempotent and
/// may result in unexpected errors if retry is used.
/// </summary>
/// <param name="mutations">The list of changes to apply.</param>
/// <param name="cancellationToken">A cancellation token used for this task.</param>
/// <param name="timeoutSeconds">The timeout which will apply to the commit part of this method.</param>
/// <returns></returns>
public Task <int> ExecuteMutationsAsync(List <Mutation> mutations, CancellationToken cancellationToken, int timeoutSeconds)
{
GaxPreconditions.CheckNotNull(mutations, nameof(mutations));
Logger.Debug(() => "Executing a mutation change through an ephemeral transaction.");
int count;
return(ExecuteHelper.WithErrorTranslationAndProfiling(
async() =>
{
using (var transaction = await _connection.BeginTransactionAsync(cancellationToken)
.ConfigureAwait(false))
{
// Importantly, we need to set timeout on the transaction, because
// ExecuteMutations on SpannerTransaction doesnt actually hit the network
// until you commit or rollback.
transaction.CommitTimeout = timeoutSeconds;
count = await((ISpannerTransaction)transaction)
.ExecuteMutationsAsync(mutations, cancellationToken, timeoutSeconds)
.ConfigureAwait(false);
await transaction.CommitAsync().ConfigureAwait(false);
}
return count;
}, "EphemeralTransaction.ExecuteMutations"));
}
internal async Task <TResult> RunAsync <TResult>(Func <SpannerTransaction, Task <TResult> > asyncWork, CancellationToken cancellationToken = default)
{
GaxPreconditions.CheckNotNull(asyncWork, nameof(asyncWork));
// Session will be initialized and subsequently modified by CommitAttempt.
PooledSession session = null;
try
{
return(await ExecuteWithRetryAsync(CommitAttempt, cancellationToken).ConfigureAwait(false));
}
finally
{
session?.Dispose();
}
async Task <TResult> CommitAttempt()
{
return(await ExecuteHelper.WithErrorTranslationAndProfiling(
async() =>
{
SpannerTransaction transaction = null;
try
{
session = await(session?.WithFreshTransactionOrNewAsync(SpannerConnection.s_readWriteTransactionOptions, cancellationToken) ?? _connection.AcquireReadWriteSessionAsync(cancellationToken)).ConfigureAwait(false);
transaction = new SpannerTransaction(_connection, TransactionMode.ReadWrite, session, null);
TResult result = await asyncWork(transaction).ConfigureAwait(false);
await transaction.CommitAsync(cancellationToken).ConfigureAwait(false);
return result;
}
// We only catch to attempt a rollback, and that is possible if we have a transaction already.
// If the exception was thrown when refreshing the session the we don't have a transaction yet.
catch when(transaction != null)
{
try
{
await transaction.RollbackAsync(cancellationToken).ConfigureAwait(false);
}
catch (Exception e)
{
// If the commit failed, calling Rollback will fail as well.
// We don't want that or any other rollback exception to propagate,
// it will not trigger the retry
_connection.Logger.Warn("A rollback attempt failed on RetriableTransaction.RunAsync.CommitAttempt", e);
}
// Throw, the retry helper will know when to retry.
throw;
}
finally
{
if (transaction != null)
{
// Let's make sure that the associated session is not released to the pool
// because we'll be attempting to get a fresh transaction for this same session first.
// If that fails will attempt a new session acquisition.
// This session will be disposed of by the pool if it can't be refreshed or by the RunAsync method
// if we are not retrying anymore.
transaction.DisposeBehavior = DisposeBehavior.Detach;
transaction.Dispose();
}
}
}, "RetriableTransaction.RunAsync.CommitAttempt", _connection.Logger).ConfigureAwait(false));
}
}
