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xo-alloc2: + Allocator.expand() + streamlining _Any

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This commit is contained in:
Roland Conybeare 2025-12-12 11:19:05 -05:00
commit 12ade26a79
8 changed files with 167 additions and 18 deletions
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73
src/alloc2/IAllocator_DArena.cpp
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@ -4,8 +4,10 @@
**/
#include "IAllocator_DArena.hpp"
#include "padding.hpp"
#include <cassert>
#include <cstddef>
#include <sys/mman.h>
namespace xo {
namespace mm {
@ -37,6 +39,77 @@ namespace xo {
return (s.lo_ <= p) && (p < s.hi_);
}
bool
IAllocator_DArena::expand(DArena & s, size_t target_z)
{
// scope log(XO_DEBUG(debug_flag_),
// xtag("offset_z", offset_z),
// xtag("committed_z", committed_z_));
if (target_z <= s.committed_z_) {
// log && log("trivial success, offset within committed range",
// xtag("offset_z", offset_z),
// xtag("committed_z", committed_z_));
return true;
}
if (s.lo_ + target_z > s.hi_) {
// throw std::runtime_error(tostr("ArenaAlloc::expand: requested size exceeds reserved size",
// xtag("requested", offset_z), xtag("reserved", reserved())));
return false;
}
/*
* pre:
*
* _______________...................................
* ^ ^ ^
* lo limit hi
*
* < committed_z >
* <----------target_z----------->
* > <- z: 0 <= z < hugepage_z
* <---------aligned_target_z--------->
* <--- add_commit_z -->
*
* post:
* ____________________________________..............
* ^ ^ ^
* lo limit hi
*
*/
std::size_t aligned_target_z = padding::with_padding(target_z, s.config_.hugepage_z_);
std::byte * commit_start = s.limit_; // = s.lo_ + s.committed_z_;
std::size_t add_commit_z = aligned_target_z - s.committed_z_;
assert(s.limit_ == s.lo_ + s.committed_z_);
// log && log(xtag("aligned_offset_z", aligned_offset_z),
// xtag("add_commit_z", add_commit_z));
// log && log("expand committed range",
// xtag("commit_start", commit_start),
// xtag("add_commit_z", add_commit_z),
// xtag("commit_end", commit_start + add_commit_z));
if (::mprotect(commit_start, add_commit_z, PROT_READ | PROT_WRITE) != 0) {
assert(false);
// throw std::runtime_error(tostr("ArenaAlloc::expand: commit failure",
// xtag("committed_z", committed_z_),
// xtag("add_commit_z", add_commit_z)));
return false;
}
s.committed_z_ = aligned_target_z;
s.limit_ = s.lo_ + s.committed_z_;
assert(s.committed_z_ % s.config_.hugepage_z_ == 0);
assert(reinterpret_cast<size_t>(s.limit_) % s.config_.hugepage_z_ == 0);
return true;
}
std::byte *
IAllocator_DArena::alloc(const DArena & s,
std::size_t z)