Class IOURingImpl

core/src/main/java/io/questdb/std/IOURingImpl.java:33–186

import static io.questdb.std.IOUringAccessor.*;

public class IOURingImpl implements IOURing {

    // Holds <id, res> tuples for recently consumed cqes.
    private final long[] cachedCqes;
    private final long cqKheadAddr;
    private final int cqKringMask;
    private final long cqKtailAddr;
    private final long cqesAddr;
    private final IOURingFacade facade;
    private final long ringAddr;
    private final long ringFd;
    private final long sqKheadAddr;
    private final int sqKringEntries;
    private final int sqKringMask;
    private final long sqesAddr;
    // Index of cached cqe tuple.
    private int cachedIndex;
    // Count of cached cqe tuples.
    private int cachedSize;
    private boolean closed = false;
    private long idSeq;

    public IOURingImpl(IOURingFacade facade, int capacity) {
        assert Numbers.isPow2(capacity);
        this.facade = facade;
        final long res = facade.create(capacity);
        if (res < 0) {
            throw CairoException.critical((int) -res).put("Cannot create io_uring instance");
        }
        this.ringAddr = res;

        int ringFd = Unsafe.getInt(ringAddr + RING_FD_OFFSET);

        this.sqesAddr = Unsafe.getLong(ringAddr + SQ_SQES_OFFSET);
        this.sqKheadAddr = Unsafe.getLong(ringAddr + SQ_KHEAD_OFFSET);
        final long sqMaskAddr = Unsafe.getLong(ringAddr + SQ_KRING_MASK_OFFSET);
        this.sqKringMask = Unsafe.getInt(sqMaskAddr);
        final long sqEntriesAddr = Unsafe.getLong(ringAddr + SQ_KRING_ENTRIES_OFFSET);
        this.sqKringEntries = Unsafe.getInt(sqEntriesAddr);

        this.cqesAddr = Unsafe.getLong(ringAddr + CQ_CQES_OFFSET);
        this.cqKheadAddr = Unsafe.getLong(ringAddr + CQ_KHEAD_OFFSET);
        this.cqKtailAddr = Unsafe.getLong(ringAddr + CQ_KTAIL_OFFSET);
        final long cqMaskAddr = Unsafe.getLong(ringAddr + CQ_KRING_MASK_OFFSET);
        this.cqKringMask = Unsafe.getInt(cqMaskAddr);
        final long cqEntriesAddr = Unsafe.getLong(ringAddr + CQ_KRING_ENTRIES_OFFSET);
        int cqKringEntries = Unsafe.getInt(cqEntriesAddr);
        cachedCqes = new long[2 * cqKringEntries];

        this.ringFd = Files.createUniqueFd(ringFd);
    }

    @Override
    public void close() {
        if (closed) {
            return;
        }
        Files.detach(ringFd);