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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2016 Red Hat
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#ifndef INTERVAL_MAP_H
#define INTERVAL_MAP_H
#include "include/interval_set.h"
#include <initializer_list>
template <typename K, typename V, typename S>
/**
* interval_map
*
* Maps intervals to values. Erasing or inserting over an existing
* range will use S::operator() to split any overlapping existing
* values.
*
* Surprisingly, boost/icl/interval_map doesn't seem to be appropriate
* for this use case. The aggregation concept seems to assume
* commutativity, which doesn't work if we want more recent insertions
* to overwrite previous ones.
*/
class interval_map {
S s;
using map = std::map<K, std::pair<K, V> >;
using mapiter = typename std::map<K, std::pair<K, V> >::iterator;
using cmapiter = typename std::map<K, std::pair<K, V> >::const_iterator;
map m;
std::pair<mapiter, mapiter> get_range(K off, K len) {
// fst is first iterator with end after off (may be end)
auto fst = m.upper_bound(off);
if (fst != m.begin())
--fst;
if (fst != m.end() && off >= (fst->first + fst->second.first))
++fst;
// lst is first iterator with start after off + len (may be end)
auto lst = m.lower_bound(off + len);
return std::make_pair(fst, lst);
}
std::pair<cmapiter, cmapiter> get_range(K off, K len) const {
// fst is first iterator with end after off (may be end)
auto fst = m.upper_bound(off);
if (fst != m.begin())
--fst;
if (fst != m.end() && off >= (fst->first + fst->second.first))
++fst;
// lst is first iterator with start after off + len (may be end)
auto lst = m.lower_bound(off + len);
return std::make_pair(fst, lst);
}
void try_merge(mapiter niter) {
if (niter != m.begin()) {
auto prev = niter;
prev--;
if (prev->first + prev->second.first == niter->first &&
s.can_merge(prev->second.second, niter->second.second)) {
V n = s.merge(
std::move(prev->second.second),
std::move(niter->second.second));
K off = prev->first;
K len = niter->first + niter->second.first - off;
niter++;
m.erase(prev, niter);
auto p = m.insert(
std::make_pair(
off,
std::make_pair(len, std::move(n))));
ceph_assert(p.second);
niter = p.first;
}
}
auto next = niter;
next++;
if (next != m.end() &&
niter->first + niter->second.first == next->first &&
s.can_merge(niter->second.second, next->second.second)) {
V n = s.merge(
std::move(niter->second.second),
std::move(next->second.second));
K off = niter->first;
K len = next->first + next->second.first - off;
next++;
m.erase(niter, next);
auto p = m.insert(
std::make_pair(
off,
std::make_pair(len, std::move(n))));
ceph_assert(p.second);
}
}
public:
interval_map() = default;
interval_map(std::initializer_list<typename map::value_type> l) {
for (auto& v : l) {
insert(v.first, v.second.first, v.second.second);
}
}
interval_map intersect(K off, K len) const {
interval_map ret;
auto limits = get_range(off, len);
for (auto i = limits.first; i != limits.second; ++i) {
K o = i->first;
K l = i->second.first;
V v = i->second.second;
if (o < off) {
V p = v;
l -= (off - o);
v = s.split(off - o, l, p);
o = off;
}
if ((o + l) > (off + len)) {
V p = v;
l -= (o + l) - (off + len);
v = s.split(0, l, p);
}
ret.insert(o, l, v);
}
return ret;
}
void clear() {
m.clear();
}
void erase(K off, K len) {
if (len == 0)
return;
auto range = get_range(off, len);
std::vector<
std::pair<
K,
std::pair<K, V>
>> to_insert;
for (auto i = range.first; i != range.second; ++i) {
if (i->first < off) {
to_insert.emplace_back(
std::make_pair(
i->first,
std::make_pair(
off - i->first,
s.split(0, off - i->first, i->second.second))));
}
if ((off + len) < (i->first + i->second.first)) {
K nlen = (i->first + i->second.first) - (off + len);
to_insert.emplace_back(
std::make_pair(
off + len,
std::make_pair(
nlen,
s.split(i->second.first - nlen, nlen, i->second.second))));
}
}
m.erase(range.first, range.second);
m.insert(to_insert.begin(), to_insert.end());
}
void insert(K off, K len, V &&v) {
ceph_assert(len > 0);
ceph_assert(len == s.length(v));
erase(off, len);
auto p = m.insert(make_pair(off, std::make_pair(len, std::forward<V>(v))));
ceph_assert(p.second);
try_merge(p.first);
}
void insert(interval_map &&other) {
for (auto i = other.m.begin();
i != other.m.end();
other.m.erase(i++)) {
insert(i->first, i->second.first, std::move(i->second.second));
}
}
void insert(K off, K len, const V &v) {
ceph_assert(len > 0);
ceph_assert(len == s.length(v));
erase(off, len);
auto p = m.insert(make_pair(off, std::make_pair(len, v)));
ceph_assert(p.second);
try_merge(p.first);
}
void insert(const interval_map &other) {
for (auto &&i: other) {
insert(i.get_off(), i.get_len(), i.get_val());
}
}
bool empty() const {
return m.empty();
}
interval_set<K> get_interval_set() const {
interval_set<K> ret;
for (auto &&i: *this) {
ret.insert(i.get_off(), i.get_len());
}
return ret;
}
class const_iterator {
cmapiter it;
const_iterator(cmapiter &&it) : it(std::move(it)) {}
const_iterator(const cmapiter &it) : it(it) {}
friend class interval_map;
public:
const_iterator(const const_iterator &) = default;
const_iterator &operator=(const const_iterator &) = default;
const_iterator &operator++() {
++it;
return *this;
}
const_iterator operator++(int) {
return const_iterator(it++);
}
const_iterator &operator--() {
--it;
return *this;
}
const_iterator operator--(int) {
return const_iterator(it--);
}
bool operator==(const const_iterator &rhs) const {
return it == rhs.it;
}
bool operator!=(const const_iterator &rhs) const {
return it != rhs.it;
}
K get_off() const {
return it->first;
}
K get_len() const {
return it->second.first;
}
const V &get_val() const {
return it->second.second;
}
const_iterator &operator*() {
return *this;
}
};
const_iterator begin() const {
return const_iterator(m.begin());
}
const_iterator end() const {
return const_iterator(m.end());
}
std::pair<const_iterator, const_iterator> get_containing_range(
K off,
K len) const {
auto rng = get_range(off, len);
return std::make_pair(const_iterator(rng.first), const_iterator(rng.second));
}
unsigned ext_count() const {
return m.size();
}
bool operator==(const interval_map &rhs) const {
return m == rhs.m;
}
std::ostream &print(std::ostream &out) const {
bool first = true;
out << "{";
for (auto &&i: *this) {
if (first) {
first = false;
} else {
out << ",";
}
out << i.get_off() << "~" << i.get_len() << "("
<< s.length(i.get_val()) << ")";
}
return out << "}";
}
};
template <typename K, typename V, typename S>
std::ostream &operator<<(std::ostream &out, const interval_map<K, V, S> &m) {
return m.print(out);
}
#endif
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