176 lines
3.5 KiB
C++
176 lines
3.5 KiB
C++
#include "base/container_of.h"
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#include "block-cache/io_engine.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <sstream>
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#include <stdexcept>
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#include <sys/stat.h>
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#include <sys/types.h>
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using namespace bcache;
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using namespace boost;
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using namespace std;
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#define SECTOR_SHIFT 9
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//----------------------------------------------------------------
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control_block_set::control_block_set(unsigned nr)
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: cbs_(nr)
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{
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for (auto i = 0u; i < nr; i++)
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free_cbs_.insert(i);
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}
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iocb *
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control_block_set::alloc(unsigned context)
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{
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if (free_cbs_.empty())
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return nullptr;
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auto it = free_cbs_.begin();
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cblock &cb = cbs_[*it];
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cb.context = context;
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free_cbs_.erase(it);
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return &cb.cb;
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}
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void
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control_block_set::free(iocb *cb)
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{
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cblock *b = base::container_of(cb, &cblock::cb);
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unsigned index = b - &cbs_[0];
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free_cbs_.insert(index);
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}
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unsigned
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control_block_set::context(iocb *cb) const
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{
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cblock *b = base::container_of(cb, &cblock::cb);
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return b->context;
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}
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//----------------------------------------------------------------
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io_engine::io_engine(unsigned max_io)
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: aio_context_(0),
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cbs_(max_io),
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events_(max_io)
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{
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int r = io_setup(max_io, &aio_context_);
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if (r < 0)
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throw runtime_error("io_setup failed");
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}
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io_engine::~io_engine()
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{
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io_destroy(aio_context_);
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}
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io_engine::handle
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io_engine:: open_file(std::string const &path, mode m)
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{
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int flags = (m == READ_ONLY) ? O_RDONLY : O_RDWR;
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int fd = ::open(path.c_str(), O_DIRECT | flags);
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if (fd < 0) {
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ostringstream out;
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out << "unable to open '" << path << "'";
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throw runtime_error(out.str());
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}
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descriptors_.push_back(base::unique_fd(fd));
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return static_cast<handle>(fd);
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}
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void
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io_engine::close_file(handle h)
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{
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for (auto it = descriptors_.begin(); it != descriptors_.end(); ++it) {
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unsigned it_h = it->get();
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if (it_h == h) {
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descriptors_.erase(it);
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return;
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}
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}
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ostringstream out;
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out << "unknown descriptor (" << h << ")";
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throw runtime_error(out.str());
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}
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bool
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io_engine::issue_io(handle h, dir d, sector_t b, sector_t e, void *data, unsigned context)
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{
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auto cb = cbs_.alloc(context);
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if (!cb)
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return false;
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memset(cb, 0, sizeof(*cb));
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cb->aio_fildes = static_cast<int>(h);
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cb->u.c.buf = data;
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cb->u.c.offset = b << SECTOR_SHIFT;
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cb->u.c.nbytes = (e - b) << SECTOR_SHIFT;
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cb->aio_lio_opcode = (d == READ) ? IO_CMD_PREAD : IO_CMD_PWRITE;
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int r = io_submit(aio_context_, 1, &cb);
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if (r != 1) {
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std::ostringstream out;
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out << "couldn't issue "
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<< ((d == READ) ? "READ" : "WRITE")
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<< " io: io_submit ";
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if (r < 0)
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out << "failed with " << r;
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else
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out << "succeeded, but queued no io";
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throw std::runtime_error(out.str());
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}
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return true;
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}
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std::pair<bool, io_engine::handle>
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io_engine::wait()
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{
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int r;
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unsigned i;
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r = io_getevents(aio_context_, 1, events_.size(), &events_[0], NULL);
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if (r < 0) {
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std::ostringstream out;
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out << "io_getevents failed: " << r;
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throw std::runtime_error(out.str());
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}
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for (i = 0; i < static_cast<unsigned>(r); i++) {
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io_event const &e = events_[i];
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iocb *cb = reinterpret_cast<iocb *>(e.obj);
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unsigned context = cbs_.context(cb);
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cbs_.free(cb);
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if (e.res == cb->u.c.nbytes)
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return make_pair(true, context);
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else {
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std::ostringstream out;
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out << "io failed"
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<< ", e.res = " << e.res
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<< ", e.res2 = " << e.res2
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<< ", offset = " << cb->u.c.offset
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<< ", nbytes = " << cb->u.c.nbytes;
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return make_pair(false, context);
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}
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}
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// shouldn't get here
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return make_pair(false, 0);
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}
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//----------------------------------------------------------------
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