thin-provisioning-tools/block.tcc
2011-07-22 16:32:47 +01:00

386 lines
9.6 KiB
C++

#include "block.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_manager<BlockSize>::read_ref::read_ref(typename block_manager::block::ptr b)
: block_(b)
{
}
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(typename block_manager::block::ptr b)
: read_ref(b)
{
}
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)
: nr_blocks_(nr_blocks),
lock_count_(0),
superblock_count_(0),
ordinary_count_(0)
{
fd_ = ::open(path.c_str(), O_RDWR | O_CREAT, 0666);
if (fd_ < 0)
throw std::runtime_error("couldn't open file");
}
template <uint32_t BlockSize>
block_manager<BlockSize>::~block_manager()
{
::close(fd_);
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::read_ref
block_manager<BlockSize>::read_lock(block_address location) const
{
check(location);
buffer buf;
read_buffer(location, buf);
register_lock(location, READ_LOCK);
return read_ref(
typename block::ptr(
new block(location, buf, lock_count_, ordinary_count_),
bind(&block_manager::read_release, this, _1)));
}
template <uint32_t BlockSize>
optional<typename block_manager<BlockSize>::read_ref>
block_manager<BlockSize>::read_try_lock(block_address location) const
{
return read_lock(location);
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::write_lock(block_address location)
{
check(location);
buffer buf;
read_buffer(location, buf);
register_lock(location, WRITE_LOCK);
return write_ref(
typename block::ptr(
new block(location, buf, lock_count_, ordinary_count_),
bind(&block_manager::write_release, this, _1)));
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::write_lock_zero(block_address location)
{
check(location);
buffer buf;
zero_buffer(buf);
register_lock(location, WRITE_LOCK);
typename block::ptr b(new block(location, buf, lock_count_, ordinary_count_),
bind(&block_manager<BlockSize>::write_release, this, _1));
return write_ref(b);
}
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);
buffer buf;
read_buffer(location, buf);
typename block::ptr b(new block(location, buf, lock_count_, ordinary_count_, false, v),
bind(&block_manager::read_release, this, _1));
register_lock(location, READ_LOCK);
return read_ref(b);
}
template <uint32_t BlockSize>
optional<typename block_manager<BlockSize>::read_ref>
block_manager<BlockSize>::read_try_lock(block_address location,
typename block_manager<BlockSize>::validator::ptr v) const
{
return read_lock(location, v);
}
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);
buffer buf;
read_buffer(location, buf);
typename block::ptr b(new block(location, buf, lock_count_, ordinary_count_, false, v),
bind(&block_manager::write_release, this, _1));
register_lock(location, WRITE_LOCK);
return write_ref(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);
buffer buf;
zero_buffer(buf);
typename block::ptr b(new block(location, buf, lock_count_, ordinary_count_, false, v),
bind(&block_manager::write_release, this, _1));
register_lock(location, WRITE_LOCK);
return write_ref(b);
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::superblock(block_address location)
{
check(location);
if (superblock_count_ > 0)
throw runtime_error("already have superblock");
buffer buf;
read_buffer(location, buf);
typename block::ptr b(new block(location, buf, lock_count_, superblock_count_, true),
bind(&block_manager::write_release, this, _1));
register_lock(location, WRITE_LOCK);
return write_ref(b);
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::superblock_zero(block_address location)
{
check(location);
if (superblock_count_ > 0)
throw runtime_error("already have superblock");
buffer buf;
zero_buffer(buf);
typename block::ptr b(new block(location, buf, lock_count_, superblock_count_, true),
bind(&block_manager::write_release, this, _1));
register_lock(location, WRITE_LOCK);
return write_ref(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)
{
if (superblock_count_ > 0)
throw runtime_error("already have superblock");
check(location);
buffer buf;
read_buffer(location, buf);
typename block::ptr b(new block(location, buf, lock_count_, superblock_count_, true, v),
bind(&block_manager::write_release, this, _1));
register_lock(location, WRITE_LOCK);
return write_ref(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)
{
if (superblock_count_ > 0)
throw runtime_error("already have superblock");
check(location);
buffer buf;
zero_buffer(buf);
typename block::ptr b(new block(location, buf, lock_count_, superblock_count_, true, v),
bind(&block_manager::write_release, this, _1));
register_lock(location, WRITE_LOCK);
return write_ref(b);
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::flush()
{
if (lock_count_ > 0)
throw runtime_error("asked to flush while locks are still held");
::fsync(fd_);
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::read_buffer(block_address b, block_manager<BlockSize>::buffer &buffer) const
{
off_t r;
r = ::lseek(fd_, BlockSize * b, 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_manager<BlockSize>::write_buffer(block_address b, block_manager<BlockSize>::const_buffer &buffer)
{
off_t r;
r = ::lseek(fd_, BlockSize * b, 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>
void
block_manager<BlockSize>::zero_buffer(block_manager<BlockSize>::buffer &buffer) const
{
::memset(buffer, 0, BlockSize);
}
// FIXME: we don't need this anymore
template <uint32_t BlockSize>
void
block_manager<BlockSize>::read_release(block *b) const
{
unregister_lock(b->location_, READ_LOCK);
delete b;
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::write_release(block *b)
{
if (b->is_superblock_) {
if (lock_count_ != 1)
throw runtime_error("superblock isn't the last block");
}
if (b->validator_)
(*b->validator_)->prepare(*b);
write_buffer(b->location_, b->data_);
unregister_lock(b->location_, WRITE_LOCK);
delete b;
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::check(block_address b) const
{
if (b >= 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 nr_blocks_;
}
// FIXME: how do we unregister if block construction throws?
template <uint32_t BlockSize>
void
block_manager<BlockSize>::register_lock(block_address b, lock_type t) const
{
auto it = held_locks_.find(b);
if (it == held_locks_.end())
held_locks_.insert(make_pair(b, make_pair(t, 1)));
else {
if (it->second.first != t)
throw std::runtime_error("lock type mismatch when locking");
if (it->second.first == WRITE_LOCK)
throw std::runtime_error("cannot hold concurrent write locks");
it->second.second++;
}
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::unregister_lock(block_address b, lock_type t) const
{
auto it = held_locks_.find(b);
if (it == held_locks_.end())
throw std::runtime_error("lock not held");
if (it->second.first != t)
throw std::runtime_error("lock type mismatch when unlocking");
it->second.second--;
if (it->second.second == 0)
held_locks_.erase(it);
}
//----------------------------------------------------------------