#pragma once
#include <memory>
#include <session/config.hpp>
#include <type_traits>
#include <variant>
#include "base.h"
#include "namespaces.hpp"
namespace session::config {
template <typename T, typename... U>
static constexpr bool is_one_of = (std::is_same_v<T, U> || ...);
/// True for a dict_value direct subtype, but not scalar sub-subtypes.
template <typename T>
static constexpr bool is_dict_subtype = is_one_of<T, config::scalar, config::set, config::dict>;
/// True for a dict_value or any of the types containable within a dict value
template <typename T>
static constexpr bool is_dict_value =
is_dict_subtype<T> || is_one_of<T, dict_value, int64_t, std::string>;
// Levels for the logging callback
enum class LogLevel { debug, info, warning, error };
/// Our current config state
enum class ConfigState : int {
/// Clean means the config is confirmed stored on the server and we haven't changed anything.
Clean = 0,
/// Dirty means we have local changes, and the changes haven't been serialized yet for sending
/// to the server.
Dirty = 1,
/// Waiting is halfway in-between clean and dirty: the caller has serialized the data, but
/// hasn't yet reported back that the data has been stored, *and* we haven't made any changes
/// since the data was serialize.
Waiting = 2,
};
/// Base config type for client-side configs containing common functionality needed by all config
/// sub-types.
class ConfigBase {
private:
// The object (either base config message or MutableConfigMessage) that stores the current
// config message. Subclasses do not directly access this: instead they call `dirty()` if they
// intend to make changes, or the `set_config_field` wrapper.
std::unique_ptr<ConfigMessage> _config;
// Tracks our current state
ConfigState _state = ConfigState::Clean;
protected:
// Constructs an empty base config with no config settings and seqno set to 0.
ConfigBase();
// Constructs a base config by loading the data from a dump as produced by `dump()`.
explicit ConfigBase(std::string_view dump);
// Tracks whether we need to dump again; most mutating methods should set this to true (unless
// calling set_state, which sets to to true implicitly).
bool _needs_dump = false;
// Sets the current state; this also sets _needs_dump to true.
void set_state(ConfigState s) {
_state = s;
_needs_dump = true;
}
// If set then we log things by calling this callback
std::function<void(LogLevel lvl, std::string msg)> logger;
// Invokes the above if set, does nothing if there is no logger.
void log(LogLevel lvl, std::string msg) {
if (logger)
logger(lvl, std::move(msg));
}
// Returns a reference to the current MutableConfigMessage. If the current message is not
// already dirty (i.e. Clean or Waiting) then calling this increments the seqno counter.
MutableConfigMessage& dirty();
// class for proxying subfield access; this class should never be stored but only used
// ephemerally (most of its methods are rvalue-qualified). This lets constructs such as
// foo["abc"]["def"]["ghi"] = 12;
// work, auto-vivifying (or trampling, if not a dict) subdicts to reach the target. It also
// allows non-vivifying value retrieval via .string(), .integer(), etc. methods.
class DictFieldProxy {
private:
ConfigBase& _conf;
std::vector<std::string> _inter_keys;
std::string _last_key;
// See if we can find the key without needing to create anything, so that we can attempt to
// access values without mutating anything (which allows, among other things, for assigning
// of the existing value to not dirty anything). Returns nullptr if the value or something
// along its path would need to be created, or has the wrong type; otherwise a const pointer
// to the value. The templated type, if provided, can be one of the types a dict_value can
// hold to also check that the returned value has a particular type; if omitted you get back
// the dict_value pointer itself.
template <typename T = dict_value, typename = std::enable_if_t<is_dict_value<T>>>
const T* get_clean() const {
const config::dict* data = &_conf._config->data();
// All but the last need to be dicts:
for (const auto& key : _inter_keys) {
auto it = data->find(key);
data = it != data->end() ? std::get_if<config::dict>(&it->second) : nullptr;
if (!data)
return nullptr;
}
const dict_value* val;
// The last can be any value type:
if (auto it = data->find(_last_key); it != data->end())
val = &it->second;
else
return nullptr;
if constexpr (std::is_same_v<T, dict_value>)
return val;
else if constexpr (is_dict_subtype<T>) {
if (auto* v = std::get_if<T>(val))
return v;
} else { // int64 or std::string, i.e. the config::scalar sub-types.
if (auto* scalar = std::get_if<config::scalar>(val))
return std::get_if<T>(scalar);
}
return nullptr;
}
// Returns a lvalue reference to the value, stomping its way through the dict as it goes to
// create subdicts as needed to reach the target value. If given a template type then we
// also cast the final dict_value variant into the given type (and replace if with a
// default-constructed value if it has the wrong type) then return a reference to that.
template <typename T = dict_value, typename = std::enable_if_t<is_dict_value<T>>>
T& get_dirty() {
config::dict* data = &_conf.dirty().data();
for (const auto& key : _inter_keys) {
auto& val = (*data)[key];
data = std::get_if<config::dict>(&val);
if (!data)
data = &val.emplace<config::dict>();
}
auto& val = (*data)[_last_key];
if constexpr (std::is_same_v<T, dict_value>)
return val;
else if constexpr (is_dict_subtype<T>) {
if (auto* v = std::get_if<T>(&val))
return *v;
return val.emplace<T>();
} else { // int64 or std::string, i.e. the config::scalar sub-types.
if (auto* scalar = std::get_if<config::scalar>(&val)) {
if (auto* v = std::get_if<T>(scalar))
return *v;
return scalar->emplace<T>();
}
return val.emplace<scalar>().emplace<T>();
}
}
template <typename T>
void assign_if_changed(T value) {
// Try to avoiding dirtying the config if this assignment isn't changing anything
if (!_conf.is_dirty())
if (auto current = get_clean<T>(); current && *current == value)
return;
get_dirty<T>() = std::move(value);
}
void insert_if_missing(config::scalar&& value) {
if (!_conf.is_dirty())
if (auto current = get_clean<config::set>(); current && current->count(value))
return;
get_dirty<config::set>().insert(std::move(value));
}
void set_erase_impl(const config::scalar& value) {
if (!_conf.is_dirty())
if (auto current = get_clean<config::set>(); current && !current->count(value))
return;
config::dict* data = &_conf.dirty().data();
for (const auto& key : _inter_keys) {
auto it = data->find(key);
data = it != data->end() ? std::get_if<config::dict>(&it->second) : nullptr;
if (!data)
return;
}
auto it = data->find(_last_key);
if (it == data->end())
return;
auto& val = it->second;
if (auto* current = std::get_if<config::set>(&val))
current->erase(value);
else
val.emplace<config::set>();
}
public:
DictFieldProxy(ConfigBase& b, std::string key) : _conf{b}, _last_key{std::move(key)} {}
/// Descends into a dict, returning a copied proxy object for the path to the requested
/// field. Nothing is created by doing this unless you actually assign to a value.
DictFieldProxy operator[](std::string subkey) const& {
DictFieldProxy subfield{_conf, std::move(subkey)};
subfield._inter_keys.reserve(_inter_keys.size() + 1);
subfield._inter_keys.insert(
subfield._inter_keys.end(), _inter_keys.begin(), _inter_keys.end());
subfield._inter_keys.push_back(_last_key);
return subfield;
}
// Same as above, but when called on an rvalue reference we just mutate the current proxy to
// the new dict path.
DictFieldProxy&& operator[](std::string subkey) && {
_inter_keys.push_back(std::move(_last_key));
_last_key = std::move(subkey);
return std::move(*this);
}
/// Returns a const pointer to the string if one exists at the given location, nullptr
/// otherwise.
const std::string* string() const { return get_clean<std::string>(); }
/// returns the value as a string_view or a fallback if the value doesn't exist (or isn't a
/// string). The returned view is directly into the value (or fallback) and so mustn't be
/// used beyond the validity of either.
std::string_view string_view_or(std::string_view fallback) const {
if (auto* s = string())
return {*s};
return fallback;
}
/// Returns a copy of the value as a string, if it exists and is a string; returns
/// `fallback` otherwise.
std::string string_or(std::string fallback) const {
if (auto* s = string())
return *s;
return std::move(fallback);
}
/// Returns a const pointer to the integer if one exists at the given location, nullptr
/// otherwise.
const int64_t* integer() const { return get_clean<int64_t>(); }
/// Returns the value as an integer or a fallback if the value doesn't exist (or isn't an
/// integer).
int64_t integer_or(int64_t fallback) const {
if (auto* i = integer())
return *i;
return fallback;
}
/// Returns a const pointer to the set if one exists at the given location, nullptr
/// otherwise.
const config::set* set() const { return get_clean<config::set>(); }
/// Returns a const pointer to the dict if one exists at the given location, nullptr
/// otherwise. (You typically don't need to use this but can rather just use [] to descend
/// into the dict).
const config::dict* dict() const { return get_clean<config::dict>(); }
/// Replaces the current value with the given string. This also auto-vivifies any
/// intermediate dicts needed to reach the given key, including replacing non-dict values if
/// they currently exist along the path.
void operator=(std::string value) { assign_if_changed(std::move(value)); }
/// Same as above, but takes a string_view for convenience.
void operator=(std::string_view value) { *this = std::string{value}; }
/// Replace the current value with the given integer. See above.
void operator=(int64_t value) { assign_if_changed(value); }
/// Replace the current value with the given set. See above.
void operator=(config::set value) { assign_if_changed(std::move(value)); }
/// Replace the current value with the given dict. See above. This often isn't needed
/// because of how other assignment operations work.
void operator=(config::dict value) { assign_if_changed(std::move(value)); }
/// Returns true if there is a value at the current key. If a template type T is given, it
/// only returns true if that value also is a `T`.
template <typename T = dict_value, typename = std::enable_if_t<is_dict_value<T>>>
bool exists() const {
return get_clean<T>() != nullptr;
}
// Alias for `exists<T>()`
template <typename T>
bool is() const {
return exists<T>();
}
/// Removes the value at the current location, regardless of what it currently is. This
/// does nothing if the current location does not have a value.
void erase() {
if (!_conf.is_dirty() && !get_clean())
return;
config::dict* data = &_conf.dirty().data();
for (const auto& key : _inter_keys) {
auto it = data->find(key);
data = it != data->end() ? std::get_if<config::dict>(&it->second) : nullptr;
if (!data)
return;
}
data->erase(_last_key);
}
/// Adds a value to the set at the current location. If the current value is not a set or
/// does not exist then dicts will be created to reach it and a new set will be created.
void set_insert(std::string_view value) {
insert_if_missing(config::scalar{std::string{value}});
}
void set_insert(int64_t value) { insert_if_missing(config::scalar{value}); }
/// Removes a value from the set at the current location. If the current value does not
/// exist then nothing happens. If it does exist, but is not a set, it will be replaced
/// with an empty set. Otherwise the given value will be removed from the set, if present.
void set_erase(std::string_view value) {
set_erase_impl(config::scalar{std::string{value}});
}
void set_erase(int64_t value) { set_erase_impl(scalar{value}); }
/// Emplaces a value at the current location. As with assignment, this creates dicts as
/// needed along the keys to reach the target. The existing value (if present) is destroyed
/// to make room for the new one.
template <
typename T,
typename... Args,
typename = std::enable_if_t<
is_one_of<T, config::set, config::dict, int64_t, std::string>>>
T& emplace(Args&&... args) {
if constexpr (is_one_of<T, int64_t, std::string>)
return get_dirty<scalar>().emplace<T>(std::forward<Args>(args)...);
return get_dirty().emplace<T>(std::forward<Args>(args)...);
}
};
/// Wrapper for the ConfigBase's root `data` field to provide data access. Only provides a []
/// that gets you into a DictFieldProxy.
class DictFieldRoot {
ConfigBase& _conf;
DictFieldRoot(DictFieldRoot&&) = delete;
DictFieldRoot(const DictFieldRoot&) = delete;
DictFieldRoot& operator=(DictFieldRoot&&) = delete;
DictFieldRoot& operator=(const DictFieldRoot&) = delete;
public:
DictFieldRoot(ConfigBase& b) : _conf{b} {}
/// Access a dict element. This returns a proxy object for accessing the value, but does
/// *not* auto-vivify the path (unless/until you assign to it).
DictFieldProxy operator[](std::string key) const& {
return DictFieldProxy{_conf, std::move(key)};
}
};
// Called when dumping to obtain any extra data that a subclass needs to store to reconstitute
// the object. The base implementation does nothing. The counterpart to this,
// `load_extra_data()`, is called when loading from a dump that has extra data; a subclass
// should either override both (if it needs to serialize extra data) or neither (if it needs no
// extra data). Internally this extra data (if non-empty) is stored in the "+" key of the dump.
virtual oxenc::bt_dict extra_data() const { return {}; }
// Called when constructing from a dump that has extra data. The base implementation does
// nothing.
virtual void load_extra_data(oxenc::bt_dict extra) {}
public:
virtual ~ConfigBase() = default;
// Proxy class providing read and write access to the contained config data.
const DictFieldRoot data{*this};
// Accesses the storage namespace where this config type is to be stored/loaded from. See
// namespaces.hpp for the underlying integer values.
virtual Namespace storage_namespace() const = 0;
// How many config lags should be used for this object; default to 5. Implementing subclasses
// can override to return a different constant if desired. More lags require more "diff"
// storage in the config messages, but also allow for a higher tolerance of simultaneous message
// conflicts.
virtual int config_lags() const { return 5; }
// This takes all of the messages pulled down from the server and does whatever is necessary to
// merge (or replace) the current values.
//
// After this call the caller should check `needs_push()` to see if the data on hand was updated
// and needs to be pushed to the server again.
//
// Will throw on serious error (i.e. if neither the current nor any of the given configs are
// parseable).
virtual void merge(const std::vector<std::string_view>& configs);
// Returns true if we are currently dirty (i.e. have made changes that haven't been serialized
// yet).
bool is_dirty() const { return _state == ConfigState::Dirty; }
// Returns true if we are curently clean (i.e. our current config is stored on the server and
// unmodified).
bool is_clean() const { return _state == ConfigState::Clean; }
// Returns true if this object contains updated data that has not yet been confirmed stored on
// the server. This will be true whenever `is_clean()` is false: that is, if we are currently
// "dirty" (i.e. have changes that haven't been pushed) or are still awaiting confirmation of
// storage of the most recent serialized push data.
virtual bool needs_push() const;
// Returns the data to push to the server along with the seqno value of the data. If the config
// is currently dirty (i.e. has previously unsent modifications) then this marks it as
// awaiting-confirmation instead of dirty so that any future change immediately increments the
// seqno.
virtual std::pair<std::string, seqno_t> push();
// Should be called after the push is confirmed stored on the storage server swarm to let the
// object know the data is stored. (Once this is called `needs_push` will start returning false
// until something changes). Takes the seqno that was pushed so that the object can ensure that
// the latest version was pushed (i.e. in case there have been other changes since the `push()`
// call that returned this seqno).
//
// It is safe to call this multiple times with the same seqno value, and with out-of-order
// seqnos (e.g. calling with seqno 122 after having called with 123; the duplicates and earlier
// ones will just be ignored).
virtual void confirm_pushed(seqno_t seqno);
// Returns a dump of the current state for storage in the database; this value would get passed
// into the constructor to reconstitute the object (including the push/not pushed status). This
// method is *not* virtual: if subclasses need to store extra data they should set it in the
// `subclass_data` field.
std::string dump();
// Returns true if something has changed since the last call to `dump()` that requires calling
// and saving the `dump()` data again.
virtual bool needs_dump() const { return _needs_dump; }
};
// The C++ struct we hold opaquely inside the C internals struct. This is designed so that any
// internals<T> has the same layout so that it doesn't matter whether we unbox to an
// internals<ConfigBase> or internals<SubType>.
template <
typename ConfigT = ConfigBase,
std::enable_if_t<std::is_base_of_v<ConfigBase, ConfigT>, int> = 0>
struct internals final {
std::unique_ptr<ConfigBase> config;
std::string error;
// Dereferencing falls through to the ConfigBase object
ConfigT* operator->() {
if constexpr (std::is_same_v<ConfigT, ConfigBase>)
return config.get();
else {
auto* c = dynamic_cast<ConfigT*>(config.get());
assert(c);
return c;
}
}
const ConfigT* operator->() const {
if constexpr (std::is_same_v<ConfigT, ConfigBase>)
return config.get();
else {
auto* c = dynamic_cast<ConfigT*>(config.get());
assert(c);
return c;
}
}
ConfigT& operator*() { return *operator->(); }
const ConfigT& operator*() const { return *operator->(); }
};
template <typename T = ConfigBase, std::enable_if_t<std::is_base_of_v<ConfigBase, T>, int> = 0>
inline internals<T>& unbox(config_object* conf) {
return *static_cast<internals<T>*>(conf->internals);
}
template <typename T = ConfigBase, std::enable_if_t<std::is_base_of_v<ConfigBase, T>, int> = 0>
inline const internals<T>& unbox(const config_object* conf) {
return *static_cast<const internals<T>*>(conf->internals);
}
// Sets an error message in the internals.error string and updates the last_error pointer in the
// outer (C) config_object struct to point at it.
void set_error(config_object* conf, std::string e);
// Same as above, but gets the error string out of an exception and passed through a return value.
// Intended to simplify catch-and-return-error such as:
// try {
// whatever();
// } catch (const std::exception& e) {
// return set_error(conf, LIB_SESSION_ERR_OHNOES, e);
// }
inline int set_error(config_object* conf, int errcode, const std::exception& e) {
set_error(conf, e.what());
return errcode;
}
// Copies a value contained in a string into a new malloced char buffer, returning the buffer and
// size via the two pointer arguments.
void copy_out(const std::string& data, char** out, size_t* outlen);
} // namespace session::config