Retry, Backoff, and Idempotency Policies.
Application developers can override the default retry and backoff policies.
The default policies are to continue retrying for up to 15 minutes, and to use truncated (at 5 minutes) exponential backoff, doubling the maximum backoff period between retries.
namespace spanner = ::google::cloud::spanner;
using ::google::cloud::StatusOr;
[](std::string const& project_id, std::string const& instance_id,
std::string const& database_id) {
// Use a truncated exponential backoff with jitter to wait between
// retries:
// https://en.wikipedia.org/wiki/Exponential_backoff
// https://cloud.google.com/storage/docs/exponential-backoff
auto client = spanner::Client(spanner::MakeConnection(
spanner::Database(project_id, instance_id, database_id),
google::cloud::Options{}
.set<spanner::SpannerRetryPolicyOption>(
std::make_shared<spanner::LimitedTimeRetryPolicy>(
/*maximum_duration=*/std::chrono::seconds(60)))
.set<spanner::SpannerBackoffPolicyOption>(
std::make_shared<spanner::ExponentialBackoffPolicy>(
/*initial_delay=*/std::chrono::milliseconds(500),
/*maximum_delay=*/std::chrono::seconds(64),
/*scaling=*/1.5))));
std::int64_t rows_inserted;
auto commit_result = client.Commit(
[&client, &rows_inserted](
spanner::Transaction txn) -> StatusOr<spanner::Mutations> {
auto insert = client.ExecuteDml(
std::move(txn),
spanner::SqlStatement(
"INSERT INTO Singers (SingerId, FirstName, LastName)"
" VALUES (20, 'George', 'Washington')"));
if (!insert) return std::move(insert).status();
rows_inserted = insert->RowsModified();
return spanner::Mutations{};
});
if (!commit_result) throw std::move(commit_result).status();
std::cout << "Rows inserted: " << rows_inserted;
}
See Also
LimitedTimeRetryPolicy and LimitedErrorCountRetryPolicy for alternative retry policies.
See Also
ExponentialBackoffPolicy to configure different parameters for the exponential backoff policy.