mirror of https://github.com/grpc/grpc.git
[promises] Add some status-like types for TrySeq (#34906)
`StatusFlag` acts like a status, but is just a boolean (we don't want to accidentally treat a boolean as something that indicates failure in case it's not) Similarly `ValueOrFailure` looks like `StatusOr` but reduces the failure space to one value. --------- Co-authored-by: ctiller <ctiller@users.noreply.github.com>pull/34918/head
Craig Tiller
1 year ago
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GitHub
parent
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dc41f42073
7 changed files with 303 additions and 40 deletions
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// Copyright 2023 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef GRPC_SRC_CORE_LIB_PROMISE_STATUS_FLAG_H |
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#define GRPC_SRC_CORE_LIB_PROMISE_STATUS_FLAG_H |
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#include <grpc/support/port_platform.h> |
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#include "absl/status/status.h" |
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#include "absl/status/statusor.h" |
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#include "absl/types/optional.h" |
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#include "src/core/lib/promise/detail/status.h" |
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namespace grpc_core { |
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// A boolean representing whether an operation succeeded (true) or failed
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// (false).
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class StatusFlag { |
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public: |
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explicit StatusFlag(bool value) : value_(value) {} |
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bool ok() const { return value_; } |
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private: |
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bool value_; |
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}; |
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inline bool IsStatusOk(const StatusFlag& flag) { return flag.ok(); } |
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template <> |
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struct StatusCastImpl<absl::Status, StatusFlag> { |
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static absl::Status Cast(StatusFlag flag) { |
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return flag.ok() ? absl::OkStatus() : absl::CancelledError(); |
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} |
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}; |
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struct Failure {}; |
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// A value if an operation was successful, or a failure flag if not.
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template <typename T> |
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class ValueOrFailure { |
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public: |
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explicit ValueOrFailure(T value) : value_(std::move(value)) {} |
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explicit ValueOrFailure(Failure) {} |
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static ValueOrFailure FromOptional(absl::optional<T> value) { |
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return ValueOrFailure{std::move(value)}; |
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} |
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bool ok() const { return value_.has_value(); } |
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const T& value() const { return value_.value(); } |
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T& value() { return value_.value(); } |
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const T& operator*() const { return *value_; } |
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T& operator*() { return *value_; } |
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private: |
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absl::optional<T> value_; |
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}; |
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template <typename T> |
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inline bool IsStatusOk(const ValueOrFailure<T>& value) { |
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return value.ok(); |
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} |
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template <typename T> |
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struct StatusCastImpl<absl::Status, ValueOrFailure<T>> { |
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static absl::Status Cast(const ValueOrFailure<T> flag) { |
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return flag.ok() ? absl::OkStatus() : absl::CancelledError(); |
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} |
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}; |
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template <typename T> |
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struct StatusCastImpl<absl::StatusOr<T>, ValueOrFailure<T>> { |
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static absl::StatusOr<T> Cast(ValueOrFailure<T> value) { |
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return value.ok() ? absl::StatusOr<T>(std::move(value.value())) |
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: absl::CancelledError(); |
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} |
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}; |
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} // namespace grpc_core
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#endif // GRPC_SRC_CORE_LIB_PROMISE_STATUS_FLAG_H
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// Copyright 2023 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "src/core/lib/promise/status_flag.h" |
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#include <memory> |
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#include <utility> |
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#include "gtest/gtest.h" |
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namespace grpc_core { |
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TEST(StatusFlagTest, Basics) { |
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EXPECT_TRUE(StatusFlag(true).ok()); |
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EXPECT_FALSE(StatusFlag(false).ok()); |
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EXPECT_TRUE(StatusCast<absl::Status>(StatusFlag(true)).ok()); |
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EXPECT_FALSE(StatusCast<absl::Status>(StatusFlag(false)).ok()); |
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EXPECT_TRUE(ValueOrFailure<int>(42).ok()); |
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EXPECT_FALSE(ValueOrFailure<int>(Failure{}).ok()); |
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EXPECT_TRUE(StatusCast<absl::Status>(ValueOrFailure<int>(42)).ok()); |
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EXPECT_FALSE(StatusCast<absl::Status>(ValueOrFailure<int>(Failure{})).ok()); |
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EXPECT_EQ(ValueOrFailure<int>(42).value(), 42); |
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EXPECT_EQ(StatusCast<absl::StatusOr<int>>(ValueOrFailure<int>(42)).value(), |
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42); |
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} |
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} // namespace grpc_core
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int main(int argc, char** argv) { |
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::testing::InitGoogleTest(&argc, argv); |
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return RUN_ALL_TESTS(); |
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} |
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