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Export of internal Abseil changes

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b770d03c2f1042d399c3f9576e881691cbe962c4 by Abseil Team <absl-team@google.com>:

Avoid applying the workaround for MSVC's static initialization problems when using clang-cl.

PiperOrigin-RevId: 275870089

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2b8fc02ec49aeb5ad56cef20259cdd7f6ee0c917 by Abseil Team <absl-team@google.com>:

Document return values.

PiperOrigin-RevId: 275839042

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baa99064f9a28b188661df7fba989fcd558818af by Abseil Team <absl-team@google.com>:

Support "auto" and other uncommon builtin types in absl::debugging_internal::Demangle.

PiperOrigin-RevId: 275556195

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f9d5c6a3a0d374dbf105d6e2e9e0c8fa949ed187 by Gennadiy Rozental <rogeeff@google.com>:

Internal rework.

PiperOrigin-RevId: 275550005

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2679a77db5b26349e8c8b2059621af55d2fca139 by Mark Barolak <mbar@google.com>:

Remove a comment reference to the no longer extant ::string implementation.

PiperOrigin-RevId: 275531987

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7b427a7613c44a98c6f13da43b2bff2837ca6b19 by Derek Mauro <dmauro@google.com>:

Upgrade to Bazel 1.0.0 and CMake 3.15.4

PiperOrigin-RevId: 275500823

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81f7d20905debf9d1e300bd2e9899f88d27f632a by Derek Mauro <dmauro@google.com>:

Fix -Wimplicit-int-float-conversion warning in latest clang

PiperOrigin-RevId: 275492439
GitOrigin-RevId: b770d03c2f1042d399c3f9576e881691cbe962c4
Change-Id: I9b39dad524489f0d62c912d02e8ac43761c81e55
This commit is contained in:
Abseil Team 2019-10-21 10:21:03 -07:00 • committed by Derek Mauro
parent e4c8d0eb8e
commit 2796d500ae
23 changed files with 639 additions and 635 deletions
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183
absl/flags/internal/commandlineflag.h
View file

@ -16,12 +16,10 @@
#ifndef ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
#define ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
#include <atomic>
#include <memory>
#include "absl/base/macros.h"
#include "absl/flags/marshalling.h"
#include "absl/synchronization/mutex.h"
#include "absl/types/optional.h"
namespace absl {
@ -151,14 +149,6 @@ inline size_t Sizeof(FlagOpFn op) {
op(flags_internal::kSizeof, nullptr, nullptr)));
}
// The following struct contains the locks in a CommandLineFlag struct.
// They are in a separate struct that is lazily allocated to avoid problems
// with static initialization and to avoid multiple allocations.
struct CommandLineFlagLocks {
absl::Mutex primary_mu; // protects several fields in CommandLineFlag
absl::Mutex callback_mu; // used to serialize callbacks
};
// Holds either a pointer to help text or a function which produces it. This is
// needed for supporting both static initialization of Flags while supporting
// the legacy registration framework. We can't use absl::variant<const char*,
@ -200,25 +190,9 @@ class FlagStateInterface {
// Holds all information for a flag.
class CommandLineFlag {
public:
constexpr CommandLineFlag(
const char* name, HelpText help_text, const char* filename,
const flags_internal::FlagOpFn op,
const flags_internal::FlagMarshallingOpFn marshalling_op,
const flags_internal::InitialValGenFunc initial_value_gen, void* def,
void* cur)
: name_(name),
help_(help_text),
filename_(filename),
op_(op),
marshalling_op_(marshalling_op),
make_init_value_(initial_value_gen),
inited_(false),
modified_(false),
on_command_line_(false),
def_(def),
cur_(cur),
counter_(0),
locks_(nullptr) {}
constexpr CommandLineFlag(const char* name, HelpText help_text,
const char* filename)
: name_(name), help_(help_text), filename_(filename) {}
// Virtual destructor
virtual void Destroy() const = 0;
@ -227,60 +201,73 @@ class CommandLineFlag {
CommandLineFlag(const CommandLineFlag&) = delete;
CommandLineFlag& operator=(const CommandLineFlag&) = delete;
// Access methods.
// Returns true iff this object corresponds to retired flag
virtual bool IsRetired() const { return false; }
// Returns true iff this is a handle to an Abseil Flag.
virtual bool IsAbseilFlag() const { return true; }
// Non-polymorphic access methods.
absl::string_view Name() const { return name_; }
std::string Help() const { return help_.GetHelpText(); }
bool IsModified() const;
void SetModified(bool is_modified);
bool IsSpecifiedOnCommandLine() const;
absl::string_view Typename() const;
std::string Filename() const;
std::string DefaultValue() const;
std::string CurrentValue() const;
// Interface to store the value in atomic if one used. This is short term
// interface. To be reworked once cur_ is moved.
virtual void StoreAtomic() {}
// Interfaces to operate on validators.
virtual bool InvokeValidator(const void* /*value*/) const { return true; }
// Invoke the flag validators for old flags.
// TODO(rogeeff): implement proper validators for Abseil Flags
bool ValidateDefaultValue() const;
bool ValidateInputValue(absl::string_view value) const;
// Return true iff flag has type T.
template <typename T>
inline bool IsOfType() const {
return op_ == &flags_internal::FlagOps<T>;
return TypeId() == &flags_internal::FlagOps<T>;
}
// Attempts to retrieve the flag value. Returns value on success,
// absl::nullopt otherwise.
template <typename T>
absl::optional<T> Get() const {
if (IsRetired() || flags_internal::FlagOps<T> != op_) return absl::nullopt;
if (IsRetired() || !IsOfType<T>()) {
return absl::nullopt;
}
T res;
Read(&res, flags_internal::FlagOps<T>);
// Implementation notes:
//
// We are wrapping a union around the value of `T` to serve three purposes:
//
// 1. `U.value` has correct size and alignment for a value of type `T`
// 2. The `U.value` constructor is not invoked since U's constructor does
// not
// do it explicitly.
// 3. The `U.value` destructor is invoked since U's destructor does it
// explicitly. This makes `U` a kind of RAII wrapper around non default
// constructible value of T, which is destructed when we leave the
// scope. We do need to destroy U.value, which is constructed by
// CommandLineFlag::Read even though we left it in a moved-from state
// after std::move.
//
// All of this serves to avoid requiring `T` being default constructible.
union U {
T value;
U() {}
~U() { value.~T(); }
};
U u;
return res;
Read(&u.value);
return std::move(u.value);
}
// Polymorphic access methods
// Returns true iff this object corresponds to retired flag
virtual bool IsRetired() const { return false; }
// Returns true iff this is a handle to an Abseil Flag.
virtual bool IsAbseilFlag() const { return true; }
// Returns id of the flag's value type.
virtual flags_internal::FlagOpFn TypeId() const = 0;
virtual bool IsModified() const = 0;
virtual bool IsSpecifiedOnCommandLine() const = 0;
virtual std::string DefaultValue() const = 0;
virtual std::string CurrentValue() const = 0;
// Interfaces to operate on validators.
virtual bool ValidateInputValue(absl::string_view value) const = 0;
// Interface to save flag to some persistent state. Returns current flag state
// or nullptr if flag does not support saving and restoring a state.
virtual std::unique_ptr<FlagStateInterface> SaveState() = 0;
// Interfaces to overate on callbacks.
virtual void InvokeCallback() {}
// Sets the value of the flag based on specified std::string `value`. If the flag
// was successfully set to new value, it returns true. Otherwise, sets `error`
// to indicate the error, leaves the flag unchanged, and returns false. There
@ -289,75 +276,29 @@ class CommandLineFlag {
// * 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 SetFromString(absl::string_view value,
flags_internal::FlagSettingMode set_mode,
flags_internal::ValueSource source, std::string* error);
virtual bool SetFromString(absl::string_view value,
flags_internal::FlagSettingMode set_mode,
flags_internal::ValueSource source,
std::string* error) = 0;
void CheckDefaultValueParsingRoundtrip() const;
// Checks that flags default value can be converted to std::string and back to the
// flag's value type.
virtual void CheckDefaultValueParsingRoundtrip() const = 0;
// Constant configuration for a particular flag.
protected:
~CommandLineFlag() = default;
// Thread safe access to mutation counter.
int64_t MutationCounter() const;
const char* const name_; // Flags name passed to ABSL_FLAG as second arg.
const HelpText help_; // The function generating help message.
const char* const filename_; // The file name where ABSL_FLAG resides.
const char* const name_;
const HelpText help_;
const char* const filename_;
const FlagOpFn op_; // Type-specific handler
const FlagMarshallingOpFn marshalling_op_; // Marshalling ops handler
const InitialValGenFunc make_init_value_; // Makes initial value for the flag
std::atomic<bool> inited_; // fields have been lazily initialized
// Mutable state (guarded by locks_->primary_mu).
bool modified_; // Has flag value been modified?
bool on_command_line_; // Specified on command line.
void* def_; // Lazily initialized pointer to default value
void* cur_; // Lazily initialized pointer to current value
int64_t counter_; // Mutation counter
// Lazily initialized mutexes for this flag value. We cannot inline a
// SpinLock or Mutex here because those have non-constexpr constructors and
// so would prevent constant initialization of this type.
// TODO(rogeeff): fix it once Mutex has constexpr constructor
struct CommandLineFlagLocks* locks_; // locks, laziliy allocated.
// Ensure that the lazily initialized fields of *flag have been initialized,
// and return the lock which should be locked when flag's state is mutated.
absl::Mutex* InitFlagIfNecessary() const ABSL_LOCK_RETURNED(locks_->primary_mu);
// copy construct new value of flag's type in a memory referenced by dst
// based on current flag's value
void Read(void* dst, const flags_internal::FlagOpFn dst_op) const;
// updates flag's value to *src (locked)
void Write(const void* src, const flags_internal::FlagOpFn src_op);
friend class FlagRegistry;
friend class FlagPtrMap;
friend class FlagSaverImpl;
friend bool TryParseLocked(CommandLineFlag* flag, void* dst,
absl::string_view value, std::string* err);
friend absl::Mutex* InitFlag(CommandLineFlag* flag);
private:
// Copy-construct a new value of the flag's type in a memory referenced by
// the dst based on the current flag's value.
virtual void Read(void* dst) const = 0;
};
// Update any copy of the flag value that is stored in an atomic word.
// In addition if flag has a mutation callback this function invokes it. While
// 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.
void UpdateCopy(CommandLineFlag* flag);
// Return true iff flag value was changed via direct-access.
bool ChangedDirectly(CommandLineFlag* flag, const void* a, const void* b);
// This macro is the "source of truth" for the list of supported flag types we
// expect to perform lock free operations on. Specifically it generates code,
// a one argument macro operating on a type, supplied as a macro argument, for