118 lines
3.9 KiB
C++
118 lines
3.9 KiB
C++
/*
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* Copyright (C) 2021 The Android Open Source Project
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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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*/
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#pragma once
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#include <ostream>
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#include <string>
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#include <unordered_map>
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#include <unordered_set>
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#include <vector>
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#include <android-base/logging.h>
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#include "common/libs/utils/result.h"
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namespace cuttlefish {
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template <typename Subclass>
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class Feature {
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public:
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virtual ~Feature() = default;
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virtual std::string Name() const = 0;
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static Result<void> TopologicalVisit(
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const std::unordered_set<Subclass*>& features,
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const std::function<bool(Subclass*)>& callback);
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private:
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virtual std::unordered_set<Subclass*> Dependencies() const = 0;
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};
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class SetupFeature : public virtual Feature<SetupFeature> {
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public:
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virtual ~SetupFeature();
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static Result<void> RunSetup(const std::vector<SetupFeature*>& features);
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virtual bool Enabled() const = 0;
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private:
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virtual Result<void> ResultSetup();
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virtual bool Setup();
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};
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class FlagFeature : public Feature<FlagFeature> {
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public:
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static Result<void> ProcessFlags(const std::vector<FlagFeature*>& features,
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std::vector<std::string>& flags);
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static bool WriteGflagsHelpXml(const std::vector<FlagFeature*>& features,
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std::ostream& out);
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private:
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// Must be executed in dependency order following Dependencies(). Expected to
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// mutate the `flags` argument to remove handled flags, and possibly introduce
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// new flag values (e.g. from a file).
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virtual bool Process(std::vector<std::string>& flags) = 0;
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// TODO(schuffelen): Migrate the xml help to human-readable help output after
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// the gflags migration is done.
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// Write an xml fragment that is compatible with gflags' `--helpxml` format.
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virtual bool WriteGflagsCompatHelpXml(std::ostream& out) const = 0;
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};
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template <typename Subclass>
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Result<void> Feature<Subclass>::TopologicalVisit(
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const std::unordered_set<Subclass*>& features,
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const std::function<bool(Subclass*)>& callback) {
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enum class Status { UNVISITED, VISITING, VISITED };
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std::unordered_map<Subclass*, Status> features_status;
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for (const auto& feature : features) {
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features_status[feature] = Status::UNVISITED;
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}
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std::function<Result<void>(Subclass*)> visit;
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visit = [&callback, &features_status,
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&visit](Subclass* feature) -> Result<void> {
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CF_EXPECT(features_status.count(feature) > 0,
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"Dependency edge to "
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<< feature->Name() << " but it is not part of the feature "
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<< "graph. This feature is either disabled or not correctly "
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<< "registered.");
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if (features_status[feature] == Status::VISITED) {
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return {};
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}
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CF_EXPECT(features_status[feature] != Status::VISITING,
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"Cycle detected while visiting " << feature->Name());
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features_status[feature] = Status::VISITING;
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for (const auto& dependency : feature->Dependencies()) {
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CF_EXPECT(dependency != nullptr,
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"SetupFeature " << feature->Name() << " has a null dependency.");
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CF_EXPECT(visit(dependency),
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"Error detected while visiting " << feature->Name());
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}
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features_status[feature] = Status::VISITED;
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CF_EXPECT(callback(feature), "Callback error on " << feature->Name());
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return {};
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};
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for (const auto& feature : features) {
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CF_EXPECT(visit(feature)); // `visit` will log the error chain.
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}
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return {};
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}
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} // namespace cuttlefish
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