Files
scylladb/compound.hh
Paweł Dziepak 13e8ca96f1 compound: make compound_type::type() const
Signed-off-by: Paweł Dziepak <pdziepak@cloudius-systems.com>
2015-06-02 14:11:34 +02:00

281 lines
9.5 KiB
C++

/*
* Copyright (C) 2015 Cloudius Systems, Ltd.
*/
#pragma once
#include "types.hh"
#include <iostream>
#include <algorithm>
#include <vector>
#include <boost/range/iterator_range.hpp>
#include "util/serialization.hh"
#include "unimplemented.hh"
// value_traits is meant to abstract away whether we are working on 'bytes'
// elements or 'bytes_opt' elements. We don't support optional values, but
// there are some generic layers which use this code which provide us with
// data in that format. In order to avoid allocation and rewriting that data
// into a new vector just to throw it away soon after that, we accept that
// format too.
template <typename T>
struct value_traits {
static const T& unwrap(const T& t) { return t; }
};
template<>
struct value_traits<bytes_opt> {
static const bytes& unwrap(const bytes_opt& t) {
assert(t);
return *t;
}
};
enum class allow_prefixes { no, yes };
template<allow_prefixes AllowPrefixes = allow_prefixes::no>
class compound_type final {
private:
const std::vector<data_type> _types;
const bool _byte_order_equal;
const bool _byte_order_comparable;
public:
static constexpr bool is_prefixable = AllowPrefixes == allow_prefixes::yes;
using prefix_type = compound_type<allow_prefixes::yes>;
using value_type = std::vector<bytes>;
compound_type(std::vector<data_type> types)
: _types(std::move(types))
, _byte_order_equal(std::all_of(_types.begin(), _types.end(), [] (auto t) {
return t->is_byte_order_equal();
}))
, _byte_order_comparable(_types.size() == 1 && _types[0]->is_byte_order_comparable())
{ }
compound_type(compound_type&&) = default;
auto const& types() const {
return _types;
}
bool is_singular() const {
return _types.size() == 1;
}
prefix_type as_prefix() {
return prefix_type(_types);
}
/*
* Format:
* <len(value1)><value1><len(value2)><value2>...<len(value_n-1)><value_n-1>(len(value_n))?<value_n>
*
* For non-prefixable compounds, the value corresponding to the last component of types doesn't
* have its length encoded, its length is deduced from the input range.
*
* serialize_value() and serialize_optionals() for single element rely on the fact that for a single-element
* compounds their serialized form is equal to the serialized form of the component.
*/
template<typename Wrapped>
void serialize_value(const std::vector<Wrapped>& values, bytes::iterator& out) {
if (AllowPrefixes == allow_prefixes::yes) {
assert(values.size() <= _types.size());
} else {
assert(values.size() == _types.size());
}
size_t n_left = _types.size();
for (auto&& wrapped : values) {
auto&& val = value_traits<Wrapped>::unwrap(wrapped);
assert(val.size() <= std::numeric_limits<uint16_t>::max());
if (--n_left || AllowPrefixes == allow_prefixes::yes) {
write<uint16_t>(out, uint16_t(val.size()));
}
out = std::copy(val.begin(), val.end(), out);
}
}
template <typename Wrapped>
size_t serialized_size(const std::vector<Wrapped>& values) {
size_t len = 0;
size_t n_left = _types.size();
for (auto&& wrapped : values) {
auto&& val = value_traits<Wrapped>::unwrap(wrapped);
assert(val.size() <= std::numeric_limits<uint16_t>::max());
if (--n_left || AllowPrefixes == allow_prefixes::yes) {
len += sizeof(uint16_t);
}
len += val.size();
}
return len;
}
bytes serialize_single(bytes&& v) {
if (AllowPrefixes == allow_prefixes::no) {
assert(_types.size() == 1);
return std::move(v);
} else {
// FIXME: Optimize
std::vector<bytes> vec;
vec.reserve(1);
vec.emplace_back(std::move(v));
return ::serialize_value(*this, vec);
}
}
bytes serialize_value(const std::vector<bytes>& values) {
return ::serialize_value(*this, values);
}
bytes serialize_value(std::vector<bytes>&& values) {
if (AllowPrefixes == allow_prefixes::no && _types.size() == 1 && values.size() == 1) {
return std::move(values[0]);
}
return ::serialize_value(*this, values);
}
bytes serialize_optionals(const std::vector<bytes_opt>& values) {
return ::serialize_value(*this, values);
}
bytes serialize_optionals(std::vector<bytes_opt>&& values) {
if (AllowPrefixes == allow_prefixes::no && _types.size() == 1 && values.size() == 1) {
assert(values[0]);
return std::move(*values[0]);
}
return ::serialize_value(*this, values);
}
bytes serialize_value_deep(const std::vector<boost::any>& values) {
// TODO: Optimize
std::vector<bytes> partial;
partial.reserve(values.size());
auto i = _types.begin();
for (auto&& component : values) {
assert(i != _types.end());
partial.push_back((*i++)->decompose(component));
}
return serialize_value(partial);
}
bytes decompose_value(const value_type& values) {
return ::serialize_value(*this, values);
}
class iterator : public std::iterator<std::input_iterator_tag, bytes_view> {
private:
ssize_t _types_left;
bytes_view _v;
value_type _current;
private:
void read_current() {
if (_types_left == 0) {
if (!_v.empty()) {
throw marshal_exception();
}
_v = bytes_view(nullptr, 0);
return;
}
--_types_left;
uint16_t len;
if (_types_left == 0 && AllowPrefixes == allow_prefixes::no) {
len = _v.size();
} else {
if (_v.empty()) {
if (AllowPrefixes == allow_prefixes::yes) {
_v = bytes_view(nullptr, 0);
return;
} else {
throw marshal_exception();
}
}
len = read_simple<uint16_t>(_v);
if (_v.size() < len) {
throw marshal_exception();
}
}
_current = bytes_view(_v.begin(), len);
_v.remove_prefix(len);
}
public:
struct end_iterator_tag {};
iterator(const compound_type& t, const bytes_view& v) : _types_left(t._types.size()), _v(v) {
read_current();
}
iterator(end_iterator_tag, const bytes_view& v) : _v(nullptr, 0) {}
iterator& operator++() {
read_current();
return *this;
}
iterator operator++(int) {
iterator i(*this);
++(*this);
return i;
}
const value_type& operator*() const { return _current; }
const value_type* operator->() const { return &_current; }
bool operator!=(const iterator& i) const { return _v.begin() != i._v.begin(); }
bool operator==(const iterator& i) const { return _v.begin() == i._v.begin(); }
};
iterator begin(const bytes_view& v) const {
return iterator(*this, v);
}
iterator end(const bytes_view& v) const {
return iterator(typename iterator::end_iterator_tag(), v);
}
boost::iterator_range<iterator> components(const bytes_view& v) const {
return { begin(v), end(v) };
}
auto iter_items(const bytes_view& v) {
return boost::iterator_range<iterator>(begin(v), end(v));
}
value_type deserialize_value(bytes_view v) {
std::vector<bytes> result;
result.reserve(_types.size());
std::transform(begin(v), end(v), std::back_inserter(result), [] (auto&& v) {
return bytes(v.begin(), v.end());
});
return result;
}
bool less(bytes_view b1, bytes_view b2) {
return compare(b1, b2) < 0;
}
size_t hash(bytes_view v) {
if (_byte_order_equal) {
return std::hash<bytes_view>()(v);
}
auto t = _types.begin();
size_t h = 0;
for (auto&& value : iter_items(v)) {
h ^= (*t)->hash(value);
++t;
}
return h;
}
int compare(bytes_view b1, bytes_view b2) {
if (_byte_order_comparable) {
return compare_unsigned(b1, b2);
}
return lexicographical_tri_compare(_types.begin(), _types.end(),
begin(b1), end(b1), begin(b2), end(b2), [] (auto&& type, auto&& v1, auto&& v2) {
return type->compare(v1, v2);
});
}
bytes from_string(sstring_view s) {
throw std::runtime_error("not implemented");
}
sstring to_string(const bytes& b) {
throw std::runtime_error("not implemented");
}
// Retruns true iff given prefix has no missing components
bool is_full(bytes_view v) const {
assert(AllowPrefixes == allow_prefixes::yes);
return std::distance(begin(v), end(v)) == (ssize_t)_types.size();
}
void validate(bytes_view v) {
// FIXME: implement
warn(unimplemented::cause::VALIDATION);
}
bool equal(bytes_view v1, bytes_view v2) {
if (_byte_order_equal) {
return compare_unsigned(v1, v2) == 0;
}
// FIXME: call equal() on each component
return compare(v1, v2) == 0;
}
};
using compound_prefix = compound_type<allow_prefixes::yes>;