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[thin_delta] tidy up the comparison function

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This commit is contained in:
Joe Thornber 2016-02-17 15:17:02 +00:00
parent 7c2b3fb671
commit 1f10017635
1 changed files with 74 additions and 49 deletions
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123
thin-provisioning/thin_delta.cc
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@ -103,13 +103,6 @@ namespace local {
len_(len) {
}
void consume(uint64_t delta) {
delta = min<uint64_t>(delta, len_);
vbegin_ += delta;
dbegin_ += delta;
len_ -= delta;
}
uint64_t vbegin_, dbegin_, len_;
};
@ -120,6 +113,51 @@ namespace local {
return out;
}
//--------------------------------
template <typename Container>
class mapping_stream {
public:
mapping_stream(Container const &c)
: it_(c.begin()),
end_(c.end()) {
m_ = *it_;
}
mapping const &get_mapping() const {
return m_;
}
bool more_mappings() const {
return it_ != end_;
}
void consume(uint64_t delta) {
if (it_ == end_)
throw runtime_error("end of stream already reached");
if (delta > m_.len_)
throw runtime_error("delta too long");
if (delta == m_.len_) {
++it_;
m_ = *it_;
} else {
m_.vbegin_ += delta;
m_.dbegin_ += delta;
m_.len_ -= delta;
}
}
private:
typename Container::const_iterator it_;
typename Container::const_iterator end_;
mapping m_;
};
//--------------------------------
typedef std::deque<mapping> mapping_deque;
// Builds up an in core rep of the mappings for a device.
@ -426,58 +464,45 @@ namespace local {
// We iterate through both sets of mappings in parallel
// noting any differences.
mapping_deque::const_iterator left_it = left.begin();
mapping_deque::const_iterator right_it = right.begin();
mapping_stream<mapping_deque> ls{left};
mapping_stream<mapping_deque> rs{right};
mapping left_mapping;
mapping right_mapping;
while (ls.more_mappings() && rs.more_mappings()) {
auto &lm = ls.get_mapping();
auto &rm = rs.get_mapping();
while ((left_mapping.len_ || left_it != left.end()) &&
(right_mapping.len_ || right_it != right.end())) {
if (!left_mapping.len_ && left_it != left.end())
left_mapping = *left_it++;
if (lm.vbegin_ < rm.vbegin_) {
auto delta = min<uint64_t>(lm.len_, rm.vbegin_ - lm.vbegin_);
e.left_only(lm.vbegin_, lm.dbegin_, delta);
ls.consume(delta);
if (!right_mapping.len_ && right_it != right.end())
right_mapping = *right_it++;
} else if (lm.vbegin_ > rm.vbegin_) {
auto delta = min<uint64_t>(rm.len_, lm.vbegin_ - rm.vbegin_);
e.right_only(rm.vbegin_, rm.dbegin_, delta);
rs.consume(delta);
while (left_mapping.len_ && right_mapping.len_) {
if (left_mapping.vbegin_ < right_mapping.vbegin_) {
uint64_t delta = min<uint64_t>(left_mapping.len_, right_mapping.vbegin_ - left_mapping.vbegin_);
e.left_only(left_mapping.vbegin_, left_mapping.dbegin_, delta);
left_mapping.consume(delta);
} else if (lm.dbegin_ != rm.dbegin_) {
auto delta = min<uint64_t>(lm.len_, rm.len_);
e.blocks_differ(lm.vbegin_, lm.dbegin_, rm.dbegin_, delta);
ls.consume(delta);
rs.consume(delta);
} else if (left_mapping.vbegin_ > right_mapping.vbegin_) {
uint64_t delta = min<uint64_t>(right_mapping.len_, left_mapping.vbegin_ - right_mapping.vbegin_);
e.right_only(right_mapping.vbegin_, right_mapping.dbegin_, delta);
right_mapping.consume(delta);
} else if (left_mapping.dbegin_ != right_mapping.dbegin_) {
uint64_t delta = min<uint64_t>(left_mapping.len_, right_mapping.len_);
e.blocks_differ(left_mapping.vbegin_, left_mapping.dbegin_, right_mapping.dbegin_, delta);
left_mapping.consume(delta);
right_mapping.consume(delta);
} else {
uint64_t delta = min<uint64_t>(left_mapping.len_, right_mapping.len_);
e.blocks_same(left_mapping.vbegin_, left_mapping.dbegin_, delta);
left_mapping.consume(delta);
right_mapping.consume(delta);
}
} else {
auto delta = min<uint64_t>(lm.len_, rm.len_);
e.blocks_same(lm.vbegin_, lm.dbegin_, delta);
ls.consume(delta);
rs.consume(delta);
}
}
while (left_it != left.end()) {
left_mapping = *left_it++;
if (left_mapping.len_)
e.left_only(left_mapping.vbegin_, left_mapping.dbegin_, left_mapping.len_);
while (ls.more_mappings()) {
auto &lm = ls.get_mapping();
e.left_only(lm.vbegin_, lm.dbegin_, lm.len_);
}
while (right_it != right.end()) {
right_mapping = *right_it++;
if (right_mapping.len_)
e.right_only(right_mapping.vbegin_, right_mapping.dbegin_, right_mapping.len_);
while (rs.more_mappings()) {
auto &rm = rs.get_mapping();
e.right_only(rm.vbegin_, rm.dbegin_, rm.len_);
}
e.complete();