diff options
Diffstat (limited to 'third_party/abseil-cpp/absl/flags/internal/registry.cc')
| -rw-r--r-- | third_party/abseil-cpp/absl/flags/internal/registry.cc | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/third_party/abseil-cpp/absl/flags/internal/registry.cc b/third_party/abseil-cpp/absl/flags/internal/registry.cc new file mode 100644 index 0000000000..e434a85912 --- /dev/null +++ b/third_party/abseil-cpp/absl/flags/internal/registry.cc @@ -0,0 +1,351 @@ +// +// Copyright 2019 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include "absl/flags/internal/registry.h" + +#include <assert.h> +#include <stdlib.h> + +#include <functional> +#include <map> +#include <memory> +#include <string> +#include <utility> +#include <vector> + +#include "absl/base/config.h" +#include "absl/base/internal/raw_logging.h" +#include "absl/base/thread_annotations.h" +#include "absl/flags/internal/commandlineflag.h" +#include "absl/flags/usage_config.h" +#include "absl/strings/str_cat.h" +#include "absl/strings/string_view.h" +#include "absl/synchronization/mutex.h" + +// -------------------------------------------------------------------- +// FlagRegistry implementation +// A FlagRegistry holds all flag objects indexed +// by their names so that if you know a flag's name you can access or +// set it. + +namespace absl { +ABSL_NAMESPACE_BEGIN +namespace flags_internal { + +// -------------------------------------------------------------------- +// FlagRegistry +// A FlagRegistry singleton object holds all flag objects indexed +// by their names so that if you know a flag's name (as a C +// string), you can access or set it. If the function is named +// FooLocked(), you must own the registry lock before calling +// the function; otherwise, you should *not* hold the lock, and +// the function will acquire it itself if needed. +// -------------------------------------------------------------------- + +class FlagRegistry { + public: + FlagRegistry() = default; + ~FlagRegistry() = default; + + // Store a flag in this registry. Takes ownership of *flag. + void RegisterFlag(CommandLineFlag* flag); + + void Lock() ABSL_EXCLUSIVE_LOCK_FUNCTION(lock_) { lock_.Lock(); } + void Unlock() ABSL_UNLOCK_FUNCTION(lock_) { lock_.Unlock(); } + + // Returns the flag object for the specified name, or nullptr if not found. + // Will emit a warning if a 'retired' flag is specified. + CommandLineFlag* FindFlagLocked(absl::string_view name); + + // Returns the retired flag object for the specified name, or nullptr if not + // found or not retired. Does not emit a warning. + CommandLineFlag* FindRetiredFlagLocked(absl::string_view name); + + static FlagRegistry* GlobalRegistry(); // returns a singleton registry + + private: + friend class FlagSaverImpl; // reads all the flags in order to copy them + friend void ForEachFlagUnlocked( + std::function<void(CommandLineFlag*)> visitor); + + // The map from name to flag, for FindFlagLocked(). + using FlagMap = std::map<absl::string_view, CommandLineFlag*>; + using FlagIterator = FlagMap::iterator; + using FlagConstIterator = FlagMap::const_iterator; + FlagMap flags_; + + absl::Mutex lock_; + + // Disallow + FlagRegistry(const FlagRegistry&); + FlagRegistry& operator=(const FlagRegistry&); +}; + +FlagRegistry* FlagRegistry::GlobalRegistry() { + static FlagRegistry* global_registry = new FlagRegistry; + return global_registry; +} + +namespace { + +class FlagRegistryLock { + public: + explicit FlagRegistryLock(FlagRegistry* fr) : fr_(fr) { fr_->Lock(); } + ~FlagRegistryLock() { fr_->Unlock(); } + + private: + FlagRegistry* const fr_; +}; + +void DestroyRetiredFlag(CommandLineFlag* flag); +} // namespace + +void FlagRegistry::RegisterFlag(CommandLineFlag* flag) { + FlagRegistryLock registry_lock(this); + std::pair<FlagIterator, bool> ins = + flags_.insert(FlagMap::value_type(flag->Name(), flag)); + if (ins.second == false) { // means the name was already in the map + CommandLineFlag* old_flag = ins.first->second; + if (flag->IsRetired() != old_flag->IsRetired()) { + // All registrations must agree on the 'retired' flag. + flags_internal::ReportUsageError( + absl::StrCat( + "Retired flag '", flag->Name(), + "' was defined normally in file '", + (flag->IsRetired() ? old_flag->Filename() : flag->Filename()), + "'."), + true); + } else if (flag->TypeId() != old_flag->TypeId()) { + flags_internal::ReportUsageError( + absl::StrCat("Flag '", flag->Name(), + "' was defined more than once but with " + "differing types. Defined in files '", + old_flag->Filename(), "' and '", flag->Filename(), + "' with types '", old_flag->Typename(), "' and '", + flag->Typename(), "', respectively."), + true); + } else if (old_flag->IsRetired()) { + // Retired flag can just be deleted. + DestroyRetiredFlag(flag); + return; + } else if (old_flag->Filename() != flag->Filename()) { + flags_internal::ReportUsageError( + absl::StrCat("Flag '", flag->Name(), + "' was defined more than once (in files '", + old_flag->Filename(), "' and '", flag->Filename(), + "')."), + true); + } else { + flags_internal::ReportUsageError( + absl::StrCat( + "Something wrong with flag '", flag->Name(), "' in file '", + flag->Filename(), "'. One possibility: file '", flag->Filename(), + "' is being linked both statically and dynamically into this " + "executable. e.g. some files listed as srcs to a test and also " + "listed as srcs of some shared lib deps of the same test."), + true); + } + // All cases above are fatal, except for the retired flags. + std::exit(1); + } +} + +CommandLineFlag* FlagRegistry::FindFlagLocked(absl::string_view name) { + FlagConstIterator i = flags_.find(name); + if (i == flags_.end()) { + return nullptr; + } + + if (i->second->IsRetired()) { + flags_internal::ReportUsageError( + absl::StrCat("Accessing retired flag '", name, "'"), false); + } + + return i->second; +} + +CommandLineFlag* FlagRegistry::FindRetiredFlagLocked(absl::string_view name) { + FlagConstIterator i = flags_.find(name); + if (i == flags_.end() || !i->second->IsRetired()) { + return nullptr; + } + + return i->second; +} + +// -------------------------------------------------------------------- +// FlagSaver +// FlagSaverImpl +// This class stores the states of all flags at construct time, +// and restores all flags to that state at destruct time. +// Its major implementation challenge is that it never modifies +// pointers in the 'main' registry, so global FLAG_* vars always +// point to the right place. +// -------------------------------------------------------------------- + +class FlagSaverImpl { + public: + FlagSaverImpl() = default; + FlagSaverImpl(const FlagSaverImpl&) = delete; + void operator=(const FlagSaverImpl&) = delete; + + // Saves the flag states from the flag registry into this object. + // It's an error to call this more than once. + void SaveFromRegistry() { + assert(backup_registry_.empty()); // call only once! + flags_internal::ForEachFlag([&](flags_internal::CommandLineFlag* flag) { + if (auto flag_state = flag->SaveState()) { + backup_registry_.emplace_back(std::move(flag_state)); + } + }); + } + + // Restores the saved flag states into the flag registry. + void RestoreToRegistry() { + for (const auto& flag_state : backup_registry_) { + flag_state->Restore(); + } + } + + private: + std::vector<std::unique_ptr<flags_internal::FlagStateInterface>> + backup_registry_; +}; + +FlagSaver::FlagSaver() : impl_(new FlagSaverImpl) { impl_->SaveFromRegistry(); } + +void FlagSaver::Ignore() { + delete impl_; + impl_ = nullptr; +} + +FlagSaver::~FlagSaver() { + if (!impl_) return; + + impl_->RestoreToRegistry(); + delete impl_; +} + +// -------------------------------------------------------------------- + +CommandLineFlag* FindCommandLineFlag(absl::string_view name) { + if (name.empty()) return nullptr; + FlagRegistry* const registry = FlagRegistry::GlobalRegistry(); + FlagRegistryLock frl(registry); + + return registry->FindFlagLocked(name); +} + +CommandLineFlag* FindRetiredFlag(absl::string_view name) { + FlagRegistry* const registry = FlagRegistry::GlobalRegistry(); + FlagRegistryLock frl(registry); + + return registry->FindRetiredFlagLocked(name); +} + +// -------------------------------------------------------------------- + +void ForEachFlagUnlocked(std::function<void(CommandLineFlag*)> visitor) { + FlagRegistry* const registry = FlagRegistry::GlobalRegistry(); + for (FlagRegistry::FlagConstIterator i = registry->flags_.begin(); + i != registry->flags_.end(); ++i) { + visitor(i->second); + } +} + +void ForEachFlag(std::function<void(CommandLineFlag*)> visitor) { + FlagRegistry* const registry = FlagRegistry::GlobalRegistry(); + FlagRegistryLock frl(registry); + ForEachFlagUnlocked(visitor); +} + +// -------------------------------------------------------------------- + +bool RegisterCommandLineFlag(CommandLineFlag* flag) { + FlagRegistry::GlobalRegistry()->RegisterFlag(flag); + return true; +} + +// -------------------------------------------------------------------- + +namespace { + +class RetiredFlagObj final : public flags_internal::CommandLineFlag { + public: + constexpr RetiredFlagObj(const char* name, FlagStaticTypeId type_id) + : name_(name), type_id_(type_id) {} + + private: + absl::string_view Name() const override { return name_; } + std::string Filename() const override { return "RETIRED"; } + absl::string_view Typename() const override { return ""; } + FlagStaticTypeId TypeId() const override { return type_id_; } + std::string Help() const override { return ""; } + bool IsRetired() const override { return true; } + bool IsModified() const override { return false; } + bool IsSpecifiedOnCommandLine() const override { return false; } + std::string DefaultValue() const override { return ""; } + std::string CurrentValue() const override { return ""; } + + // Any input is valid + bool ValidateInputValue(absl::string_view) const override { return true; } + + std::unique_ptr<flags_internal::FlagStateInterface> SaveState() override { + return nullptr; + } + + bool SetFromString(absl::string_view, flags_internal::FlagSettingMode, + flags_internal::ValueSource, std::string*) override { + return false; + } + + void CheckDefaultValueParsingRoundtrip() const override {} + + void Read(void*) const override {} + + // Data members + const char* const name_; + const FlagStaticTypeId type_id_; +}; + +void DestroyRetiredFlag(flags_internal::CommandLineFlag* flag) { + assert(flag->IsRetired()); + delete static_cast<RetiredFlagObj*>(flag); +} + +} // namespace + +bool Retire(const char* name, FlagStaticTypeId type_id) { + auto* flag = new flags_internal::RetiredFlagObj(name, type_id); + FlagRegistry::GlobalRegistry()->RegisterFlag(flag); + return true; +} + +// -------------------------------------------------------------------- + +bool IsRetiredFlag(absl::string_view name, bool* type_is_bool) { + assert(!name.empty()); + CommandLineFlag* flag = flags_internal::FindRetiredFlag(name); + if (flag == nullptr) { + return false; + } + assert(type_is_bool); + *type_is_bool = flag->IsOfType<bool>(); + return true; +} + +} // namespace flags_internal +ABSL_NAMESPACE_END +} // namespace absl |