/*
 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */

/* DEBUG: section 79    Squid-side Disk I/O functions. */

#include "squid.h"
#include "DiskThreadsDiskFile.h"
#include "DiskThreadsIOStrategy.h"
#include "fde.h"
#include "mgr/Registration.h"
#include "SquidConfig.h"
#include "StatCounters.h"
#include "Store.h"

/* squidaio_ctrl_t uses explicit alloc()/freeOne().
 * XXX: convert to MEMPROXY_CLASS() API
 */
#include "mem/Pool.h"

void
DiskThreadsIOStrategy::init(void)
{
    if (initialised)
        return;

    initialised = true;

    /*
     * We'd like to call squidaio_init() here, but the configuration
     * hasn't been parsed yet and we don't know how many cache_dirs
     * there are, which means we don't know how many threads to start.
     */

    registerWithCacheManager();
}

void
DiskThreadsIOStrategy::registerWithCacheManager(void)
{
    Mgr::RegisterAction("squidaio_counts", "Async IO Function Counters",
                        aioStats, 0, 1);
}

void
DiskThreadsIOStrategy::done(void)
{
    if (!initialised)
        return;

    squidaio_shutdown();

    initialised = false;
}

int
DiskThreadsIOStrategy::callback()
{
    squidaio_result_t *resultp;
    squidaio_ctrl_t *ctrlp;
    int retval = 0;

    assert(initialised);
    ++squidaio_counts.check_callback;

    for (;;) {
        if ((resultp = squidaio_poll_done()) == nullptr)
            break;

        ctrlp = (squidaio_ctrl_t *) resultp->data;

        switch (resultp->result_type) {

        case _AIO_OP_NONE:

        case _AIO_OP_OPENDIR:
            break;

        case _AIO_OP_OPEN:
            ++squidaio_counts.open_finish;
            break;

        case _AIO_OP_READ:
            ++squidaio_counts.read_finish;
            break;

        case _AIO_OP_WRITE:
            ++squidaio_counts.write_finish;
            break;

        case _AIO_OP_CLOSE:
            ++squidaio_counts.close_finish;
            break;

        case _AIO_OP_UNLINK:
            ++squidaio_counts.unlink_finish;
            break;

        case _AIO_OP_STAT:
            ++squidaio_counts.stat_finish;
            break;
        }

        if (ctrlp == nullptr)
            continue;       /* XXX Should not happen */

        dlinkDelete(&ctrlp->node, &used_list);

        if (ctrlp->done_handler) {
            AIOCB *done_callback = ctrlp->done_handler;
            void *cbdata;
            ctrlp->done_handler = nullptr;

            if (cbdataReferenceValidDone(ctrlp->done_handler_data, &cbdata)) {
                retval = 1; /* Return that we've actually done some work */
                done_callback(ctrlp->fd, cbdata, ctrlp->bufp,
                              ctrlp->result.aio_return, ctrlp->result.aio_errno);
            } else {
                if (ctrlp->operation == _AIO_OPEN) {
                    /* The open operation was aborted.. */
                    int fd = ctrlp->result.aio_return;

                    if (fd >= 0)
                        aioClose(fd);
                }
            }
        }

        /* free data if requested to aioWrite() */
        if (ctrlp->free_func)
            ctrlp->free_func(ctrlp->bufp);

        /* free temporary read buffer */
        if (ctrlp->operation == _AIO_READ)
            squidaio_xfree(ctrlp->bufp, ctrlp->len);

        delete ctrlp;
    }

    return retval;
}

/* Flush all pending I/O */
void
DiskThreadsIOStrategy::sync()
{
    if (!initialised)
        return;         /* nothing to do then */

    /* Flush all pending operations */
    debugs(32, 2, "aioSync: flushing pending I/O operations");

    do {
        callback();
    } while (squidaio_sync());

    debugs(32, 2, "aioSync: done");
}

DiskThreadsIOStrategy::DiskThreadsIOStrategy() :
    initialised(false)
{}

void
DiskThreadsIOStrategy::aioStats(StoreEntry * sentry)
{
    storeAppendPrintf(sentry, "ASYNC IO Counters:\n");
    storeAppendPrintf(sentry, "  Operation\t# Requests\tNumber serviced\n");
    storeAppendPrintf(sentry, "  open\t%" PRIu64 "\t%" PRIu64 "\n", squidaio_counts.open_start, squidaio_counts.open_finish);
    storeAppendPrintf(sentry, "  close\t%" PRIu64 "\t%" PRIu64 "\n", squidaio_counts.close_start, squidaio_counts.close_finish);
    storeAppendPrintf(sentry, "  cancel\t%" PRIu64 "\t-\n", squidaio_counts.cancel);
    storeAppendPrintf(sentry, "  write\t%" PRIu64 "\t%" PRIu64 "\n", squidaio_counts.write_start, squidaio_counts.write_finish);
    storeAppendPrintf(sentry, "  read\t%" PRIu64 "\t%" PRIu64 "\n", squidaio_counts.read_start, squidaio_counts.read_finish);
    storeAppendPrintf(sentry, "  stat\t%" PRIu64 "\t%" PRIu64 "\n", squidaio_counts.stat_start, squidaio_counts.stat_finish);
    storeAppendPrintf(sentry, "  unlink\t%" PRIu64 "\t%" PRIu64 "\n", squidaio_counts.unlink_start, squidaio_counts.unlink_finish);
    storeAppendPrintf(sentry, "  check_callback\t%" PRIu64 "\t-\n", squidaio_counts.check_callback);
    storeAppendPrintf(sentry, "  queue\t%d\t-\n", squidaio_get_queue_len());
    squidaio_stats(sentry);
}

DiskThreadsIOStrategy DiskThreadsIOStrategy::Instance;
bool
DiskThreadsIOStrategy::shedLoad()
{
    /*
     * we should detect some 'too many files open' condition and return
     * NULL here.
     */
#ifdef MAGIC2

    if (aioQueueSize() > MAGIC2)
        return true;

#endif

    return false;
}

int
DiskThreadsIOStrategy::load()
{
    int loadav;
    int ql;

    ql = aioQueueSize();

    if (ql == 0)
        loadav = 0;

    loadav = ql * 1000 / MAGIC1;

    debugs(47, 9, "DiskThreadsIOStrategy::load: load=" << loadav);

    return loadav;
}

DiskFile::Pointer
DiskThreadsIOStrategy::newFile (char const *path)
{
    if (shedLoad()) {
        return nullptr;
    }

    return new DiskThreadsDiskFile(path);
}

bool
DiskThreadsIOStrategy::unlinkdUseful() const
{
    return false;
}

void
DiskThreadsIOStrategy::unlinkFile(char const *path)
{
    ++statCounter.syscalls.disk.unlinks;
    aioUnlink(path, nullptr, nullptr);
}

