absl/status/status_payload_printer.h

0001 // Copyright 2019 The Abseil Authors.
0002 //
0003 // Licensed under the Apache License, Version 2.0 (the "License");
0004 // you may not use this file except in compliance with the License.
0005 // You may obtain a copy of the License at
0006 //
0007 //      https://www.apache.org/licenses/LICENSE-2.0
0008 //
0009 // Unless required by applicable law or agreed to in writing, software
0010 // distributed under the License is distributed on an "AS IS" BASIS,
0011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0012 // See the License for the specific language governing permissions and
0013 // limitations under the License.
0014 #ifndef ABSL_STATUS_STATUS_PAYLOAD_PRINTER_H_
0015 #define ABSL_STATUS_STATUS_PAYLOAD_PRINTER_H_
0016
0017 #include <string>
0018
0019 #include "absl/base/nullability.h"
0020 #include "absl/strings/cord.h"
0021 #include "absl/strings/string_view.h"
0022 #include "absl/types/optional.h"
0023
0024 namespace absl {
0025 ABSL_NAMESPACE_BEGIN
0026 namespace status_internal {
0027
0028 // By default, `Status::ToString` and `operator<<(Status)` print a payload by
0029 // dumping the type URL and the raw bytes. To help debugging, we provide an
0030 // extension point, which is a global printer function that can be set by users
0031 // to specify how to print payloads. The function takes the type URL and the
0032 // payload as input, and should return a valid human-readable string on success
0033 // or `absl::nullopt` on failure (in which case it falls back to the default
0034 // approach of printing the raw bytes).
0035 // NOTE: This is an internal API and the design is subject to change in the
0036 // future in a non-backward-compatible way. Since it's only meant for debugging
0037 // purpose, you should not rely on it in any critical logic.
0038 using StatusPayloadPrinter = absl::Nullable<absl::optional<std::string> (*)(
0039     absl::string_view, const absl::Cord&)>;
0040
0041 // Sets the global payload printer. Only one printer should be set per process.
0042 // If multiple printers are set, it's undefined which one will be used.
0043 void SetStatusPayloadPrinter(StatusPayloadPrinter);
0044
0045 // Returns the global payload printer if previously set, otherwise `nullptr`.
0046 StatusPayloadPrinter GetStatusPayloadPrinter();
0047
0048 }  // namespace status_internal
0049 ABSL_NAMESPACE_END
0050 }  // namespace absl
0051
0052 #endif  // ABSL_STATUS_STATUS_PAYLOAD_PRINTER_H_