diff options
Diffstat (limited to 'third_party/abseil_cpp/absl/flags/internal/flag.cc')
| -rw-r--r-- | third_party/abseil_cpp/absl/flags/internal/flag.cc | 568 |
1 files changed, 0 insertions, 568 deletions
diff --git a/third_party/abseil_cpp/absl/flags/internal/flag.cc b/third_party/abseil_cpp/absl/flags/internal/flag.cc deleted file mode 100644 index 1502e7f11d..0000000000 --- a/third_party/abseil_cpp/absl/flags/internal/flag.cc +++ /dev/null @@ -1,568 +0,0 @@ -// -// 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/flag.h" - -#include <assert.h> -#include <stddef.h> -#include <stdint.h> -#include <string.h> - -#include <array> -#include <atomic> -#include <memory> -#include <new> -#include <string> -#include <typeinfo> - -#include "absl/base/call_once.h" -#include "absl/base/casts.h" -#include "absl/base/config.h" -#include "absl/base/optimization.h" -#include "absl/flags/config.h" -#include "absl/flags/internal/commandlineflag.h" -#include "absl/flags/usage_config.h" -#include "absl/memory/memory.h" -#include "absl/strings/str_cat.h" -#include "absl/strings/string_view.h" -#include "absl/synchronization/mutex.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace flags_internal { - -// The help message indicating that the commandline flag has been -// 'stripped'. It will not show up when doing "-help" and its -// variants. The flag is stripped if ABSL_FLAGS_STRIP_HELP is set to 1 -// before including absl/flags/flag.h -const char kStrippedFlagHelp[] = "\001\002\003\004 (unknown) \004\003\002\001"; - -namespace { - -// Currently we only validate flag values for user-defined flag types. -bool ShouldValidateFlagValue(FlagFastTypeId flag_type_id) { -#define DONT_VALIDATE(T, _) \ - if (flag_type_id == base_internal::FastTypeId<T>()) return false; - ABSL_FLAGS_INTERNAL_SUPPORTED_TYPES(DONT_VALIDATE) -#undef DONT_VALIDATE - - return true; -} - -// RAII helper used to temporarily unlock and relock `absl::Mutex`. -// This is used when we need to ensure that locks are released while -// invoking user supplied callbacks and then reacquired, since callbacks may -// need to acquire these locks themselves. -class MutexRelock { - public: - explicit MutexRelock(absl::Mutex& mu) : mu_(mu) { mu_.Unlock(); } - ~MutexRelock() { mu_.Lock(); } - - MutexRelock(const MutexRelock&) = delete; - MutexRelock& operator=(const MutexRelock&) = delete; - - private: - absl::Mutex& mu_; -}; - -} // namespace - -/////////////////////////////////////////////////////////////////////////////// -// Persistent state of the flag data. - -class FlagImpl; - -class FlagState : public flags_internal::FlagStateInterface { - public: - template <typename V> - FlagState(FlagImpl& flag_impl, const V& v, bool modified, - bool on_command_line, int64_t counter) - : flag_impl_(flag_impl), - value_(v), - modified_(modified), - on_command_line_(on_command_line), - counter_(counter) {} - - ~FlagState() override { - if (flag_impl_.ValueStorageKind() != FlagValueStorageKind::kAlignedBuffer) - return; - flags_internal::Delete(flag_impl_.op_, value_.heap_allocated); - } - - private: - friend class FlagImpl; - - // Restores the flag to the saved state. - void Restore() const override { - if (!flag_impl_.RestoreState(*this)) return; - - ABSL_INTERNAL_LOG(INFO, - absl::StrCat("Restore saved value of ", flag_impl_.Name(), - " to: ", flag_impl_.CurrentValue())); - } - - // Flag and saved flag data. - FlagImpl& flag_impl_; - union SavedValue { - explicit SavedValue(void* v) : heap_allocated(v) {} - explicit SavedValue(int64_t v) : one_word(v) {} - explicit SavedValue(flags_internal::AlignedTwoWords v) : two_words(v) {} - - void* heap_allocated; - int64_t one_word; - flags_internal::AlignedTwoWords two_words; - } value_; - bool modified_; - bool on_command_line_; - int64_t counter_; -}; - -/////////////////////////////////////////////////////////////////////////////// -// Flag implementation, which does not depend on flag value type. - -DynValueDeleter::DynValueDeleter(FlagOpFn op_arg) : op(op_arg) {} - -void DynValueDeleter::operator()(void* ptr) const { - if (op == nullptr) return; - - Delete(op, ptr); -} - -void FlagImpl::Init() { - new (&data_guard_) absl::Mutex; - - auto def_kind = static_cast<FlagDefaultKind>(def_kind_); - - switch (ValueStorageKind()) { - case FlagValueStorageKind::kAlignedBuffer: - // For this storage kind the default_value_ always points to gen_func - // during initialization. - assert(def_kind == FlagDefaultKind::kGenFunc); - (*default_value_.gen_func)(AlignedBufferValue()); - break; - case FlagValueStorageKind::kOneWordAtomic: { - alignas(int64_t) std::array<char, sizeof(int64_t)> buf{}; - if (def_kind == FlagDefaultKind::kGenFunc) { - (*default_value_.gen_func)(buf.data()); - } else { - assert(def_kind != FlagDefaultKind::kDynamicValue); - std::memcpy(buf.data(), &default_value_, Sizeof(op_)); - } - OneWordValue().store(absl::bit_cast<int64_t>(buf), - std::memory_order_release); - break; - } - case FlagValueStorageKind::kTwoWordsAtomic: { - // For this storage kind the default_value_ always points to gen_func - // during initialization. - assert(def_kind == FlagDefaultKind::kGenFunc); - alignas(AlignedTwoWords) std::array<char, sizeof(AlignedTwoWords)> buf{}; - (*default_value_.gen_func)(buf.data()); - auto atomic_value = absl::bit_cast<AlignedTwoWords>(buf); - TwoWordsValue().store(atomic_value, std::memory_order_release); - break; - } - } -} - -absl::Mutex* FlagImpl::DataGuard() const { - absl::call_once(const_cast<FlagImpl*>(this)->init_control_, &FlagImpl::Init, - const_cast<FlagImpl*>(this)); - - // data_guard_ is initialized inside Init. - return reinterpret_cast<absl::Mutex*>(&data_guard_); -} - -void FlagImpl::AssertValidType(FlagFastTypeId rhs_type_id, - const std::type_info* (*gen_rtti)()) const { - FlagFastTypeId lhs_type_id = flags_internal::FastTypeId(op_); - - // `rhs_type_id` is the fast type id corresponding to the declaration - // visibile at the call site. `lhs_type_id` is the fast type id - // corresponding to the type specified in flag definition. They must match - // for this operation to be well-defined. - if (ABSL_PREDICT_TRUE(lhs_type_id == rhs_type_id)) return; - - const std::type_info* lhs_runtime_type_id = - flags_internal::RuntimeTypeId(op_); - const std::type_info* rhs_runtime_type_id = (*gen_rtti)(); - - if (lhs_runtime_type_id == rhs_runtime_type_id) return; - -#if defined(ABSL_FLAGS_INTERNAL_HAS_RTTI) - if (*lhs_runtime_type_id == *rhs_runtime_type_id) return; -#endif - - ABSL_INTERNAL_LOG( - FATAL, absl::StrCat("Flag '", Name(), - "' is defined as one type and declared as another")); -} - -std::unique_ptr<void, DynValueDeleter> FlagImpl::MakeInitValue() const { - void* res = nullptr; - switch (DefaultKind()) { - case FlagDefaultKind::kDynamicValue: - res = flags_internal::Clone(op_, default_value_.dynamic_value); - break; - case FlagDefaultKind::kGenFunc: - res = flags_internal::Alloc(op_); - (*default_value_.gen_func)(res); - break; - default: - res = flags_internal::Clone(op_, &default_value_); - break; - } - return {res, DynValueDeleter{op_}}; -} - -void FlagImpl::StoreValue(const void* src) { - switch (ValueStorageKind()) { - case FlagValueStorageKind::kAlignedBuffer: - Copy(op_, src, AlignedBufferValue()); - break; - case FlagValueStorageKind::kOneWordAtomic: { - int64_t one_word_val = 0; - std::memcpy(&one_word_val, src, Sizeof(op_)); - OneWordValue().store(one_word_val, std::memory_order_release); - break; - } - case FlagValueStorageKind::kTwoWordsAtomic: { - AlignedTwoWords two_words_val{0, 0}; - std::memcpy(&two_words_val, src, Sizeof(op_)); - TwoWordsValue().store(two_words_val, std::memory_order_release); - break; - } - } - - modified_ = true; - ++counter_; - InvokeCallback(); -} - -absl::string_view FlagImpl::Name() const { return name_; } - -std::string FlagImpl::Filename() const { - return flags_internal::GetUsageConfig().normalize_filename(filename_); -} - -std::string FlagImpl::Help() const { - return HelpSourceKind() == FlagHelpKind::kLiteral ? help_.literal - : help_.gen_func(); -} - -FlagFastTypeId FlagImpl::TypeId() const { - return flags_internal::FastTypeId(op_); -} - -bool FlagImpl::IsSpecifiedOnCommandLine() const { - absl::MutexLock l(DataGuard()); - return on_command_line_; -} - -std::string FlagImpl::DefaultValue() const { - absl::MutexLock l(DataGuard()); - - auto obj = MakeInitValue(); - return flags_internal::Unparse(op_, obj.get()); -} - -std::string FlagImpl::CurrentValue() const { - auto* guard = DataGuard(); // Make sure flag initialized - switch (ValueStorageKind()) { - case FlagValueStorageKind::kAlignedBuffer: { - absl::MutexLock l(guard); - return flags_internal::Unparse(op_, AlignedBufferValue()); - } - case FlagValueStorageKind::kOneWordAtomic: { - const auto one_word_val = - absl::bit_cast<std::array<char, sizeof(int64_t)>>( - OneWordValue().load(std::memory_order_acquire)); - return flags_internal::Unparse(op_, one_word_val.data()); - } - case FlagValueStorageKind::kTwoWordsAtomic: { - const auto two_words_val = - absl::bit_cast<std::array<char, sizeof(AlignedTwoWords)>>( - TwoWordsValue().load(std::memory_order_acquire)); - return flags_internal::Unparse(op_, two_words_val.data()); - } - } - - return ""; -} - -void FlagImpl::SetCallback(const FlagCallbackFunc mutation_callback) { - absl::MutexLock l(DataGuard()); - - if (callback_ == nullptr) { - callback_ = new FlagCallback; - } - callback_->func = mutation_callback; - - InvokeCallback(); -} - -void FlagImpl::InvokeCallback() const { - if (!callback_) return; - - // Make a copy of the C-style function pointer that we are about to invoke - // before we release the lock guarding it. - FlagCallbackFunc cb = callback_->func; - - // If the flag has a mutation callback this function invokes it. While the - // callback is being invoked the primary flag's mutex is unlocked and it is - // re-locked back after call to callback is completed. Callback invocation is - // guarded by flag's secondary mutex instead which prevents concurrent - // callback invocation. Note that it is possible for other thread to grab the - // primary lock and update flag's value at any time during the callback - // invocation. This is by design. Callback can get a value of the flag if - // necessary, but it might be different from the value initiated the callback - // and it also can be different by the time the callback invocation is - // completed. Requires that *primary_lock be held in exclusive mode; it may be - // released and reacquired by the implementation. - MutexRelock relock(*DataGuard()); - absl::MutexLock lock(&callback_->guard); - cb(); -} - -std::unique_ptr<FlagStateInterface> FlagImpl::SaveState() { - absl::MutexLock l(DataGuard()); - - bool modified = modified_; - bool on_command_line = on_command_line_; - switch (ValueStorageKind()) { - case FlagValueStorageKind::kAlignedBuffer: { - return absl::make_unique<FlagState>( - *this, flags_internal::Clone(op_, AlignedBufferValue()), modified, - on_command_line, counter_); - } - case FlagValueStorageKind::kOneWordAtomic: { - return absl::make_unique<FlagState>( - *this, OneWordValue().load(std::memory_order_acquire), modified, - on_command_line, counter_); - } - case FlagValueStorageKind::kTwoWordsAtomic: { - return absl::make_unique<FlagState>( - *this, TwoWordsValue().load(std::memory_order_acquire), modified, - on_command_line, counter_); - } - } - return nullptr; -} - -bool FlagImpl::RestoreState(const FlagState& flag_state) { - absl::MutexLock l(DataGuard()); - - if (flag_state.counter_ == counter_) { - return false; - } - - switch (ValueStorageKind()) { - case FlagValueStorageKind::kAlignedBuffer: - StoreValue(flag_state.value_.heap_allocated); - break; - case FlagValueStorageKind::kOneWordAtomic: - StoreValue(&flag_state.value_.one_word); - break; - case FlagValueStorageKind::kTwoWordsAtomic: - StoreValue(&flag_state.value_.two_words); - break; - } - - modified_ = flag_state.modified_; - on_command_line_ = flag_state.on_command_line_; - - return true; -} - -template <typename StorageT> -StorageT* FlagImpl::OffsetValue() const { - char* p = reinterpret_cast<char*>(const_cast<FlagImpl*>(this)); - // The offset is deduced via Flag value type specific op_. - size_t offset = flags_internal::ValueOffset(op_); - - return reinterpret_cast<StorageT*>(p + offset); -} - -void* FlagImpl::AlignedBufferValue() const { - assert(ValueStorageKind() == FlagValueStorageKind::kAlignedBuffer); - return OffsetValue<void>(); -} - -std::atomic<int64_t>& FlagImpl::OneWordValue() const { - assert(ValueStorageKind() == FlagValueStorageKind::kOneWordAtomic); - return OffsetValue<FlagOneWordValue>()->value; -} - -std::atomic<AlignedTwoWords>& FlagImpl::TwoWordsValue() const { - assert(ValueStorageKind() == FlagValueStorageKind::kTwoWordsAtomic); - return OffsetValue<FlagTwoWordsValue>()->value; -} - -// Attempts to parse supplied `value` string using parsing routine in the `flag` -// argument. If parsing successful, this function replaces the dst with newly -// parsed value. In case if any error is encountered in either step, the error -// message is stored in 'err' -std::unique_ptr<void, DynValueDeleter> FlagImpl::TryParse( - absl::string_view value, std::string& err) const { - std::unique_ptr<void, DynValueDeleter> tentative_value = MakeInitValue(); - - std::string parse_err; - if (!flags_internal::Parse(op_, value, tentative_value.get(), &parse_err)) { - absl::string_view err_sep = parse_err.empty() ? "" : "; "; - err = absl::StrCat("Illegal value '", value, "' specified for flag '", - Name(), "'", err_sep, parse_err); - return nullptr; - } - - return tentative_value; -} - -void FlagImpl::Read(void* dst) const { - auto* guard = DataGuard(); // Make sure flag initialized - switch (ValueStorageKind()) { - case FlagValueStorageKind::kAlignedBuffer: { - absl::MutexLock l(guard); - flags_internal::CopyConstruct(op_, AlignedBufferValue(), dst); - break; - } - case FlagValueStorageKind::kOneWordAtomic: { - const int64_t one_word_val = - OneWordValue().load(std::memory_order_acquire); - std::memcpy(dst, &one_word_val, Sizeof(op_)); - break; - } - case FlagValueStorageKind::kTwoWordsAtomic: { - const AlignedTwoWords two_words_val = - TwoWordsValue().load(std::memory_order_acquire); - std::memcpy(dst, &two_words_val, Sizeof(op_)); - break; - } - } -} - -void FlagImpl::Write(const void* src) { - absl::MutexLock l(DataGuard()); - - if (ShouldValidateFlagValue(flags_internal::FastTypeId(op_))) { - std::unique_ptr<void, DynValueDeleter> obj{flags_internal::Clone(op_, src), - DynValueDeleter{op_}}; - std::string ignored_error; - std::string src_as_str = flags_internal::Unparse(op_, src); - if (!flags_internal::Parse(op_, src_as_str, obj.get(), &ignored_error)) { - ABSL_INTERNAL_LOG(ERROR, absl::StrCat("Attempt to set flag '", Name(), - "' to invalid value ", src_as_str)); - } - } - - StoreValue(src); -} - -// Sets the value of the flag based on specified string `value`. If the flag -// was successfully set to new value, it returns true. Otherwise, sets `err` -// to indicate the error, leaves the flag unchanged, and returns false. There -// are three ways to set the flag's value: -// * Update the current flag value -// * Update the flag's default value -// * Update the current flag value if it was never set before -// The mode is selected based on 'set_mode' parameter. -bool FlagImpl::ParseFrom(absl::string_view value, FlagSettingMode set_mode, - ValueSource source, std::string& err) { - absl::MutexLock l(DataGuard()); - - switch (set_mode) { - case SET_FLAGS_VALUE: { - // set or modify the flag's value - auto tentative_value = TryParse(value, err); - if (!tentative_value) return false; - - StoreValue(tentative_value.get()); - - if (source == kCommandLine) { - on_command_line_ = true; - } - break; - } - case SET_FLAG_IF_DEFAULT: { - // set the flag's value, but only if it hasn't been set by someone else - if (modified_) { - // TODO(rogeeff): review and fix this semantic. Currently we do not fail - // in this case if flag is modified. This is misleading since the flag's - // value is not updated even though we return true. - // *err = absl::StrCat(Name(), " is already set to ", - // CurrentValue(), "\n"); - // return false; - return true; - } - auto tentative_value = TryParse(value, err); - if (!tentative_value) return false; - - StoreValue(tentative_value.get()); - break; - } - case SET_FLAGS_DEFAULT: { - auto tentative_value = TryParse(value, err); - if (!tentative_value) return false; - - if (DefaultKind() == FlagDefaultKind::kDynamicValue) { - void* old_value = default_value_.dynamic_value; - default_value_.dynamic_value = tentative_value.release(); - tentative_value.reset(old_value); - } else { - default_value_.dynamic_value = tentative_value.release(); - def_kind_ = static_cast<uint8_t>(FlagDefaultKind::kDynamicValue); - } - - if (!modified_) { - // Need to set both default value *and* current, in this case. - StoreValue(default_value_.dynamic_value); - modified_ = false; - } - break; - } - } - - return true; -} - -void FlagImpl::CheckDefaultValueParsingRoundtrip() const { - std::string v = DefaultValue(); - - absl::MutexLock lock(DataGuard()); - - auto dst = MakeInitValue(); - std::string error; - if (!flags_internal::Parse(op_, v, dst.get(), &error)) { - ABSL_INTERNAL_LOG( - FATAL, - absl::StrCat("Flag ", Name(), " (from ", Filename(), - "): string form of default value '", v, - "' could not be parsed; error=", error)); - } - - // We do not compare dst to def since parsing/unparsing may make - // small changes, e.g., precision loss for floating point types. -} - -bool FlagImpl::ValidateInputValue(absl::string_view value) const { - absl::MutexLock l(DataGuard()); - - auto obj = MakeInitValue(); - std::string ignored_error; - return flags_internal::Parse(op_, value, obj.get(), &ignored_error); -} - -} // namespace flags_internal -ABSL_NAMESPACE_END -} // namespace absl |