tvl-depot/absl/flags/internal/registry.cc
Abseil Team f3840bc5e3 Export of internal Abseil changes.
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dcff7cc4eb3837d39d1e083cbf1d4f082054cbf6 by Laramie Leavitt <lar@google.com>:

Add default and fallback modes for SaltedSeedSeq::generate().

SeedSeq::generate will often be called with contiguous ranges of uint32_t.
Detect this case and use the currently direct code paths to handle it.
Otherwise use a fallback mechanism which does an additional copy.
PiperOrigin-RevId: 258853656

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59ec88845ac2ee6567c493021b54385940d66762 by Gennadiy Rozental <rogeeff@google.com>:

Internal change

PiperOrigin-RevId: 258822137

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eb2d1ab21f6f94c24c51c1cd3719846be259e8e7 by Abseil Team <absl-team@google.com>:

Add iOS version 11 to the mix of Apple OS versions that have various C++17 header files
but do not support them.

PiperOrigin-RevId: 258820405

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452cea3e13b29797b2c385d7c6da7613d36bdc45 by Gennadiy Rozental <rogeeff@google.com>:

Internal change

PiperOrigin-RevId: 258802436
GitOrigin-RevId: dcff7cc4eb3837d39d1e083cbf1d4f082054cbf6
Change-Id: I2261cb58e142eb15017ef646a56710dd64f06496
2019-07-19 13:04:45 -04:00

443 lines
15 KiB
C++

//
// 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 "absl/base/dynamic_annotations.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/flags/config.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 {
namespace flags_internal {
namespace {
void DestroyFlag(CommandLineFlag* flag) NO_THREAD_SAFETY_ANALYSIS {
flag->Destroy();
// CommandLineFlag handle object is heap allocated for non Abseil Flags.
if (!flag->IsAbseilFlag()) {
delete flag;
}
}
} // namespace
// --------------------------------------------------------------------
// 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() {
for (auto& p : flags_) {
DestroyFlag(p.second);
}
}
// Store a flag in this registry. Takes ownership of *flag.
void RegisterFlag(CommandLineFlag* flag);
void Lock() EXCLUSIVE_LOCK_FUNCTION(lock_) { lock_.Lock(); }
void Unlock() 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_;
};
} // 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->op != old_flag->op) {
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 definitions are idempotent. Just keep the old one.
DestroyFlag(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:
// Constructs an empty FlagSaverImpl object.
FlagSaverImpl() {}
~FlagSaverImpl() {
// reclaim memory from each of our CommandLineFlags
for (const SavedFlag& src : backup_registry_) {
Delete(src.op, src.current);
Delete(src.op, src.default_value);
}
}
// Saves the flag states from the flag registry into this object.
// It's an error to call this more than once.
// Must be called when the registry mutex is not held.
void SaveFromRegistry() {
assert(backup_registry_.empty()); // call only once!
SavedFlag saved;
flags_internal::ForEachFlag([&](flags_internal::CommandLineFlag* flag) {
if (flag->IsRetired()) return;
saved.name = flag->Name();
saved.op = flag->op;
saved.marshalling_op = flag->marshalling_op;
{
absl::MutexLock l(flag->InitFlagIfNecessary());
saved.validator = flag->validator;
saved.modified = flag->modified;
saved.on_command_line = flag->on_command_line;
saved.current = Clone(saved.op, flag->cur);
saved.default_value = Clone(saved.op, flag->def);
saved.counter = flag->counter;
}
backup_registry_.push_back(saved);
});
}
// Restores the saved flag states into the flag registry. We
// assume no flags were added or deleted from the registry since
// the SaveFromRegistry; if they were, that's trouble! Must be
// called when the registry mutex is not held.
void RestoreToRegistry() {
FlagRegistry* const global_registry = FlagRegistry::GlobalRegistry();
FlagRegistryLock frl(global_registry);
for (const SavedFlag& src : backup_registry_) {
CommandLineFlag* flag = global_registry->FindFlagLocked(src.name);
// If null, flag got deleted from registry.
if (!flag) continue;
bool restored = false;
{
absl::MutexLock l(flag->InitFlagIfNecessary());
flag->validator = src.validator;
flag->modified = src.modified;
flag->on_command_line = src.on_command_line;
if (flag->counter != src.counter ||
ChangedDirectly(flag, src.default_value, flag->def)) {
restored = true;
Copy(src.op, src.default_value, flag->def);
}
if (flag->counter != src.counter ||
ChangedDirectly(flag, src.current, flag->cur)) {
restored = true;
Copy(src.op, src.current, flag->cur);
UpdateCopy(flag);
flag->InvokeCallback();
}
}
if (restored) {
flag->counter++;
// Revalidate the flag because the validator might store state based
// on the flag's value, which just changed due to the restore.
// Failing validation is ignored because it's assumed that the flag
// was valid previously and there's little that can be done about it
// here, anyway.
flag->ValidateInputValue(flag->CurrentValue());
ABSL_INTERNAL_LOG(
INFO, absl::StrCat("Restore saved value of ", flag->Name(), ": ",
Unparse(src.marshalling_op, src.current)));
}
}
}
private:
struct SavedFlag {
absl::string_view name;
FlagOpFn op;
FlagMarshallingOpFn marshalling_op;
int64_t counter;
bool modified;
bool on_command_line;
bool (*validator)();
const void* current; // nullptr after restore
const void* default_value; // nullptr after restore
};
std::vector<SavedFlag> backup_registry_;
FlagSaverImpl(const FlagSaverImpl&); // no copying!
void operator=(const FlagSaverImpl&);
};
FlagSaver::FlagSaver() : impl_(new FlagSaverImpl()) {
impl_->SaveFromRegistry();
}
void FlagSaver::Ignore() {
delete impl_;
impl_ = nullptr;
}
FlagSaver::~FlagSaver() {
if (!impl_) return;
impl_->RestoreToRegistry();
delete impl_;
}
// --------------------------------------------------------------------
// GetAllFlags()
// The main way the FlagRegistry class exposes its data. This
// returns, as strings, all the info about all the flags in
// the main registry, sorted first by filename they are defined
// in, and then by flagname.
// --------------------------------------------------------------------
struct FilenameFlagnameLess {
bool operator()(const CommandLineFlagInfo& a,
const CommandLineFlagInfo& b) const {
int cmp = absl::string_view(a.filename).compare(b.filename);
if (cmp != 0) return cmp < 0;
return a.name < b.name;
}
};
void FillCommandLineFlagInfo(CommandLineFlag* flag,
CommandLineFlagInfo* result) {
result->name = std::string(flag->Name());
result->type = std::string(flag->Typename());
result->description = flag->Help();
result->filename = flag->Filename();
if (!flag->IsAbseilFlag()) {
if (!flag->IsModified() && ChangedDirectly(flag, flag->cur, flag->def)) {
flag->modified = true;
}
}
result->current_value = flag->CurrentValue();
result->default_value = flag->DefaultValue();
result->is_default = !flag->IsModified();
result->has_validator_fn = flag->HasValidatorFn();
absl::MutexLock l(flag->InitFlagIfNecessary());
result->flag_ptr = flag->IsAbseilFlag() ? nullptr : flag->cur;
}
// --------------------------------------------------------------------
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);
}
// --------------------------------------------------------------------
void GetAllFlags(std::vector<CommandLineFlagInfo>* OUTPUT) {
flags_internal::ForEachFlag([&](CommandLineFlag* flag) {
if (flag->IsRetired()) return;
CommandLineFlagInfo fi;
FillCommandLineFlagInfo(flag, &fi);
OUTPUT->push_back(fi);
});
// Now sort the flags, first by filename they occur in, then alphabetically
std::sort(OUTPUT->begin(), OUTPUT->end(), FilenameFlagnameLess());
}
// --------------------------------------------------------------------
bool RegisterCommandLineFlag(CommandLineFlag* flag) {
FlagRegistry::GlobalRegistry()->RegisterFlag(flag);
return true;
}
// --------------------------------------------------------------------
bool Retire(FlagOpFn ops, FlagMarshallingOpFn marshalling_ops,
const char* name) {
auto* flag = new CommandLineFlag(
name,
/*help_text=*/absl::flags_internal::HelpText::FromStaticCString(nullptr),
/*filename_arg=*/"RETIRED", ops, marshalling_ops,
/*initial_value_gen=*/nullptr,
/*retired_arg=*/true, nullptr, nullptr);
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
} // namespace absl