buffer/paged: simplify paged buffer
This commit is contained in:
parent
3925431838
commit
4643beac82
|
|
@ -20,27 +20,20 @@ using cruft::memory::buffer::paged;
|
|||
|
||||
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
paged::paged (size_t bytes, size_t _window):
|
||||
m_window (round_up (_window, pagesize ()))
|
||||
paged::paged (size_t bytes)
|
||||
: m_data (nullptr)
|
||||
{
|
||||
auto const allocated_bytes = round_up (bytes, pagesize ());
|
||||
|
||||
// reserve the address region with no access permissions
|
||||
m_begin = reinterpret_cast<char*> (
|
||||
mmap (nullptr, bytes, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)
|
||||
auto ptr = reinterpret_cast<value_type*> (
|
||||
mmap (nullptr, allocated_bytes, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)
|
||||
);
|
||||
|
||||
if (m_begin == MAP_FAILED)
|
||||
if (ptr == MAP_FAILED)
|
||||
posix::error::throw_code ();
|
||||
|
||||
// remap the initial window with read/write permissions
|
||||
m_cursor = m_begin + round_up (min (m_window, bytes), pagesize ());
|
||||
if (MAP_FAILED == mmap (m_begin,
|
||||
m_cursor - m_begin,
|
||||
PROT_READ | PROT_WRITE,
|
||||
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0))
|
||||
posix::error::throw_code ();
|
||||
|
||||
// record the nominal end address
|
||||
m_end = m_begin + round_up (bytes, pagesize ());
|
||||
m_data = { ptr, allocated_bytes };
|
||||
}
|
||||
|
||||
|
||||
|
|
@ -48,112 +41,59 @@ paged::paged (size_t bytes, size_t _window):
|
|||
paged::~paged ()
|
||||
{
|
||||
// ignore errors in production; we don't want to double throw.
|
||||
auto res = munmap (m_begin, m_end - m_begin);
|
||||
auto res = munmap (m_data.data (), capacity ());
|
||||
(void)res;
|
||||
CHECK_ZERO (res);
|
||||
}
|
||||
|
||||
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
char*
|
||||
paged::value_type *
|
||||
paged::begin (void)&
|
||||
{
|
||||
return m_begin;
|
||||
return m_data.begin ();
|
||||
}
|
||||
|
||||
|
||||
//-----------------------------------------------------------------------------
|
||||
char*
|
||||
paged::value_type *
|
||||
paged::end (void)&
|
||||
{
|
||||
return m_end;
|
||||
return m_data.end ();
|
||||
}
|
||||
|
||||
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
void
|
||||
paged::access (char *cursor)
|
||||
paged::commit (cruft::view<value_type*> region)
|
||||
{
|
||||
if (cursor < m_cursor)
|
||||
release (cursor);
|
||||
else
|
||||
commit (cursor);
|
||||
apply_prot (region, PROT_READ | PROT_WRITE);
|
||||
}
|
||||
|
||||
|
||||
//-----------------------------------------------------------------------------
|
||||
void
|
||||
paged::commit (char *cursor)
|
||||
paged::release (cruft::view<value_type*> region)
|
||||
{
|
||||
// bail if it's already mapped
|
||||
if (cursor <= m_cursor)
|
||||
return;
|
||||
|
||||
if (cursor > m_end || cursor < m_begin)
|
||||
throw std::out_of_range ("invalid commit cursor");
|
||||
|
||||
// bump the request up to page aligned and tack on a little to amortize
|
||||
// syscall overheads
|
||||
cursor = align (cursor, pagesize ()) + m_window;
|
||||
cursor = min (cursor, m_end);
|
||||
|
||||
if (MAP_FAILED == mmap (m_cursor,
|
||||
cursor - m_cursor,
|
||||
PROT_READ | PROT_WRITE,
|
||||
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
|
||||
-1, 0))
|
||||
posix::error::throw_code ();
|
||||
|
||||
m_cursor = cursor;
|
||||
apply_prot (region, PROT_NONE);
|
||||
}
|
||||
|
||||
|
||||
//-----------------------------------------------------------------------------
|
||||
void
|
||||
paged::release (char *desired)
|
||||
paged::apply_prot (cruft::view<value_type*> region, int prot)
|
||||
{
|
||||
if (desired > m_end || desired < m_begin)
|
||||
throw std::out_of_range ("invalid release cursor");
|
||||
if (!covers (m_data, region))
|
||||
throw std::out_of_range ("invalid commit region");
|
||||
|
||||
align (desired, pagesize ());
|
||||
// bump the request up to page aligned
|
||||
static_assert (sizeof (value_type) == 1);
|
||||
auto const alignment = pagesize ();
|
||||
auto const first = align_down (region.begin (), alignment);
|
||||
auto const last = align_up (region.end (), alignment);
|
||||
|
||||
// bail if the region is alread unmapped, or if it's not sufficiently
|
||||
// behind the current cursor.
|
||||
if (desired >= m_cursor || cruft::cast::sign<size_t> (m_cursor - desired) < m_window)
|
||||
return;
|
||||
|
||||
desired += m_window;
|
||||
|
||||
if (MAP_FAILED == mmap (desired,
|
||||
m_end - desired,
|
||||
PROT_NONE,
|
||||
if (MAP_FAILED == mmap (first, last - first, prot,
|
||||
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
|
||||
-1, 0))
|
||||
posix::error::throw_code ();
|
||||
|
||||
m_cursor = desired;
|
||||
}
|
||||
|
||||
|
||||
///////////////////////////////////////////////////////////////////////////////
|
||||
size_t
|
||||
paged::size (void) const
|
||||
{
|
||||
return m_cursor - m_begin;
|
||||
}
|
||||
|
||||
|
||||
//-----------------------------------------------------------------------------
|
||||
size_t
|
||||
paged::capacity (void) const
|
||||
{
|
||||
return m_end - m_begin;
|
||||
}
|
||||
|
||||
|
||||
//-----------------------------------------------------------------------------
|
||||
size_t
|
||||
paged::window (void) const
|
||||
{
|
||||
return m_window;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -6,46 +6,55 @@
|
|||
* Copyright 2015 Danny Robson <danny@nerdcruft.net>
|
||||
*/
|
||||
|
||||
#ifndef __UTIL_MEMORY_BUFFER_PAGED_HPP
|
||||
#define __UTIL_MEMORY_BUFFER_PAGED_HPP
|
||||
#pragma once
|
||||
|
||||
#include "../../std.hpp"
|
||||
#include "../../view.hpp"
|
||||
|
||||
#include <cstddef>
|
||||
|
||||
|
||||
namespace cruft::memory::buffer {
|
||||
/// Implements a manually paged memory buffer of a fixed length.
|
||||
///
|
||||
/// It can be used to ensure a contiguous memory region of bounded size
|
||||
/// is available at a later point in execution.
|
||||
class paged {
|
||||
public:
|
||||
using value_type = char;
|
||||
using value_type = u08;
|
||||
|
||||
paged (size_t bytes, size_t window);
|
||||
paged (size_t bytes);
|
||||
~paged ();
|
||||
|
||||
paged (const paged&) = delete;
|
||||
paged (paged &&) = delete;
|
||||
paged (paged &&);
|
||||
paged& operator= (const paged&) = delete;
|
||||
paged& operator= (paged &&) = delete;
|
||||
|
||||
char* begin (void)&;
|
||||
char* end (void)&;
|
||||
value_type* begin (void)&;
|
||||
value_type* end (void)&;
|
||||
|
||||
const char* cbegin (void)&;
|
||||
const char* cend (void)&;
|
||||
const value_type* cbegin (void)&;
|
||||
const value_type* cend (void)&;
|
||||
|
||||
const char* begin (void) const&;
|
||||
const char* end (void) const&;
|
||||
const value_type* begin (void) const&;
|
||||
const value_type* end (void) const&;
|
||||
|
||||
void access (char*);
|
||||
void commit (value_type *ptr) { return commit ({ ptr, 1 }); }
|
||||
void release (value_type *ptr) { return release ({ ptr, 1 }); }
|
||||
|
||||
size_t size (void) const;
|
||||
size_t capacity (void) const;
|
||||
size_t window (void) const;
|
||||
/// Populates the memory range and ensures it is read/write.
|
||||
void commit (cruft::view<value_type*>);
|
||||
/// Returns the memory range to the system.
|
||||
void release (cruft::view<value_type*>);
|
||||
|
||||
auto size (void) const { return m_data.size (); }
|
||||
auto capacity (void) const { return m_data.size (); }
|
||||
|
||||
private:
|
||||
void commit (char*);
|
||||
void release (char*);
|
||||
/// Applies memory protection flags to the given memory region.
|
||||
void apply_prot (cruft::view<value_type*>, int prot);
|
||||
|
||||
char *m_begin, *m_end, *m_cursor;
|
||||
size_t m_window;
|
||||
cruft::view<value_type*> m_data;
|
||||
};
|
||||
}
|
||||
|
||||
#endif
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user