thin-provisioning-tools/block.tcc
2011-10-24 18:04:19 +01:00

339 lines
7.8 KiB
C++

#include "block.h"
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <boost/bind.hpp>
#include <stdexcept>
using namespace boost;
using namespace persistent_data;
using namespace std;
//----------------------------------------------------------------
template <uint32_t BlockSize>
block_io<BlockSize>::block_io(std::string const &path, block_address nr_blocks, bool writeable)
: nr_blocks_(nr_blocks),
writeable_(writeable)
{
fd_ = ::open(path.c_str(), writeable ? (O_RDWR | O_CREAT) : O_RDONLY, 0666);
if (fd_ < 0)
throw std::runtime_error("couldn't open file");
}
template <uint32_t BlockSize>
block_io<BlockSize>::~block_io()
{
::close(fd_);
}
template <uint32_t BlockSize>
void
block_io<BlockSize>::read_buffer(block_address location, buffer &buffer) const
{
off_t r;
r = ::lseek(fd_, BlockSize * location, SEEK_SET);
if (r == (off_t) -1)
throw std::runtime_error("lseek failed");
ssize_t n;
size_t remaining = BlockSize;
unsigned char *buf = buffer;
do {
n = ::read(fd_, buf, remaining);
if (n > 0) {
remaining -= n;
buf += n;
}
} while (remaining && ((n > 0) || (n == EINTR) || (n == EAGAIN)));
if (n < 0)
throw std::runtime_error("read failed");
}
template <uint32_t BlockSize>
void
block_io<BlockSize>::write_buffer(block_address location, const_buffer &buffer)
{
off_t r;
r = ::lseek(fd_, BlockSize * location, SEEK_SET);
if (r == (off_t) -1)
throw std::runtime_error("lseek failed");
ssize_t n;
size_t remaining = BlockSize;
unsigned char const *buf = buffer;
do {
n = ::write(fd_, buf, remaining);
if (n > 0) {
remaining -= n;
buf += n;
}
} while (remaining && ((n > 0) || (n == EINTR) || (n == EAGAIN)));
if (n < 0)
throw std::runtime_error("write failed");
}
//----------------------------------------------------------------
template <uint32_t BlockSize>
block_manager<BlockSize>::block::block(typename block_io<BlockSize>::ptr io,
block_address location,
block_type bt,
typename validator::ptr v,
bool zero)
: io_(io),
location_(location),
validator_(v),
bt_(bt),
dirty_(false)
{
if (zero) {
memset(&data_, 0, sizeof(data_));
dirty_ = true;
} else {
io_->read_buffer(location_, data_);
validator_->check(data_, location_);
}
}
template <uint32_t BlockSize>
block_manager<BlockSize>::block::~block()
{
flush();
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::block::flush()
{
if (dirty_) {
validator_->prepare(data_, location_);
io_->write_buffer(location_, data_);
}
}
//----------------------------------------------------------------
template <uint32_t BlockSize>
block_manager<BlockSize>::read_ref::read_ref(block_manager<BlockSize> const &bm,
block_ptr b)
: bm_(bm),
block_(b),
holders_(new unsigned)
{
*holders_ = 1;
}
template <uint32_t BlockSize>
block_manager<BlockSize>::read_ref::read_ref(read_ref const &rhs)
: bm_(rhs.bm_),
block_(rhs.block_),
holders_(rhs.holders_)
{
(*holders_)++;
}
template <uint32_t BlockSize>
block_manager<BlockSize>::read_ref::~read_ref()
{
if (!--(*holders_)) {
if (block_->bt_ == BT_SUPERBLOCK) {
bm_.flush();
bm_.cache_.put(block_);
bm_.flush();
} else
bm_.cache_.put(block_);
delete holders_;
}
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::read_ref const &
block_manager<BlockSize>::read_ref::operator =(read_ref const &rhs)
{
if (this != &rhs) {
block_ = rhs.block_;
bm_ = rhs.bm_;
holders_ = rhs.holders_;
(*holders_)++;
}
}
template <uint32_t BlockSize>
block_address
block_manager<BlockSize>::read_ref::get_location() const
{
return block_->location_;
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::const_buffer &
block_manager<BlockSize>::read_ref::data() const
{
return block_->data_;
}
//--------------------------------
template <uint32_t BlockSize>
block_manager<BlockSize>::write_ref::write_ref(block_manager<BlockSize> const &bm,
block_ptr b)
: read_ref(bm, b)
{
b->dirty_ = true;
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::buffer &
block_manager<BlockSize>::write_ref::data()
{
return read_ref::block_->data_;
}
//----------------------------------------------------------------
template <uint32_t BlockSize>
block_manager<BlockSize>::block_manager(std::string const &path,
block_address nr_blocks,
unsigned max_concurrent_blocks,
bool writeable)
: io_(new block_io<BlockSize>(path, nr_blocks, writeable)),
cache_(max(64u, max_concurrent_blocks))
{
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::read_ref
block_manager<BlockSize>::read_lock(block_address location,
typename block_manager<BlockSize>::validator::ptr v) const
{
check(location);
boost::optional<block_ptr> cached_block = cache_.get(location);
if (cached_block) {
(*cached_block)->check_read_lockable();
return read_ref(*this, *cached_block);
}
block_ptr b(new block(io_, location, BT_NORMAL, v));
cache_.insert(b);
return read_ref(*this, b);
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::write_lock(block_address location,
typename block_manager<BlockSize>::validator::ptr v)
{
check(location);
boost::optional<block_ptr> cached_block = cache_.get(location);
if (cached_block) {
(*cached_block)->check_write_lockable();
return write_ref(*this, *cached_block);
}
block_ptr b(new block(io_, location, BT_NORMAL, v));
cache_.insert(b);
return write_ref(*this, b);
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::write_lock_zero(block_address location,
typename block_manager<BlockSize>::validator::ptr v)
{
check(location);
boost::optional<block_ptr> cached_block = cache_.get(location);
if (cached_block) {
(*cached_block)->check_write_lockable();
memset(&(*cached_block)->data_, 0, BlockSize);
return write_ref(*this, *cached_block);
}
block_ptr b(new block(io_, location, BT_NORMAL, v, true));
cache_.insert(b);
return write_ref(*this, b);
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::superblock(block_address location,
typename block_manager<BlockSize>::validator::ptr v)
{
check(location);
boost::optional<block_ptr> cached_block = cache_.get(location);
if (cached_block) {
(*cached_block)->check_write_lockable();
(*cached_block)->bt_ = BT_SUPERBLOCK;
return write_ref(*this, *cached_block);
}
block_ptr b(new block(io_, location, BT_SUPERBLOCK, v));
cache_.insert(b);
return write_ref(*this, b);
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::superblock_zero(block_address location,
typename block_manager<BlockSize>::validator::ptr v)
{
check(location);
boost::optional<block_ptr> cached_block = cache_.get(location);
if (cached_block) {
(*cached_block)->check_write_lockable();
memset(&(*cached_block)->data_, 0, BlockSize);
return write_ref(*this, *cached_block);
}
block_ptr b(new block(io_, location, BT_SUPERBLOCK, v, true));
cache_.insert(b);
return write_ref(*this, b);
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::check(block_address b) const
{
if (b >= io_->get_nr_blocks())
throw std::runtime_error("block address out of bounds");
}
template <uint32_t BlockSize>
block_address
block_manager<BlockSize>::get_nr_blocks() const
{
return io_->get_nr_blocks();
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::write_block(block_ptr b) const
{
b->flush();
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::flush() const
{
cache_.iterate_unheld(
boost::bind(&block_manager<BlockSize>::write_block, this, _1));
}
//----------------------------------------------------------------