af8ef54d5a
A large managed_bytes blob can be scattered in lsa memory. Usually this is fine, but someone we want to examine it in place without copying it out, but using contiguous iterators for efficiency. For this use case, introduce with_linearized_managed_bytes(Func), which runs a function in a "linearization context". Within the linearization context, reads of managed_bytes object will see temporarily linearized copies instead of scattered data.
51 lines
1.5 KiB
C++
51 lines
1.5 KiB
C++
|
|
/*
|
|
* Copyright 2015 ScyllaDB
|
|
*/
|
|
|
|
/*
|
|
* This file is part of Scylla.
|
|
*
|
|
* Scylla is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU Affero General Public License as published by
|
|
* the Free Software Foundation, either version 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* Scylla is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
|
|
#include "managed_bytes.hh"
|
|
|
|
thread_local managed_bytes::linearization_context managed_bytes::_linearization_context;
|
|
|
|
void
|
|
managed_bytes::linearization_context::forget(const blob_storage* p) {
|
|
_state.erase(p);
|
|
}
|
|
|
|
const bytes_view::value_type*
|
|
managed_bytes::do_linearize() const {
|
|
auto& lc = _linearization_context;
|
|
assert(lc._nesting);
|
|
auto b = _u.ptr;
|
|
auto i = lc._state.find(b);
|
|
if (i == lc._state.end()) {
|
|
auto data = std::unique_ptr<bytes_view::value_type[]>(new bytes_view::value_type[b->size]);
|
|
auto e = data.get();
|
|
while (b) {
|
|
e = std::copy_n(b->data, b->frag_size, e);
|
|
b = b->next;
|
|
}
|
|
i = lc._state.emplace(_u.ptr, std::move(data)).first;
|
|
}
|
|
return i->second.get();
|
|
}
|
|
|