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