函数buf_LRU_block_remove_hashed_page

/******************************************************************//**
Takes a block out of the LRU list and page hash table.
If the block is compressed-only (BUF_BLOCK_ZIP_PAGE),
the object will be freed and buf_pool->zip_mutex will be released.

If a compressed page or a compressed-only block descriptor is freed,
other compressed pages or compressed-only block descriptors may be
relocated.
@return the new state of the block (BUF_BLOCK_ZIP_FREE if the state
was BUF_BLOCK_ZIP_PAGE, or BUF_BLOCK_REMOVE_HASH otherwise) */
static
enum buf_page_state
buf_LRU_block_remove_hashed_page(
/*=============================*/
    buf_page_t*    bpage,    /*!< in: block, must contain a file page and
                be in a state where it can be freed; there
                may or may not be a hash index to the page */
    ibool        zip)    /*!< in: TRUE if should remove also the
                compressed page of an uncompressed page */
{
    ulint            fold;
    const buf_page_t*    hashed_bpage;
    buf_pool_t*        buf_pool = buf_pool_from_bpage(bpage);

    ut_ad(bpage);
    ut_ad(buf_pool_mutex_own(buf_pool));
    ut_ad(mutex_own(buf_page_get_mutex(bpage)));

    ut_a(buf_page_get_io_fix(bpage) == BUF_IO_NONE);
    ut_a(bpage->buf_fix_count == );

#if UNIV_WORD_SIZE == 4
    /* On 32-bit systems, there is no padding in
    buf_page_t.  On other systems, Valgrind could complain
    about uninitialized pad bytes. */
    UNIV_MEM_ASSERT_RW(bpage, sizeof *bpage);
#endif

    buf_LRU_remove_block(bpage);

    buf_pool->freed_page_clock += ;

    switch (buf_page_get_state(bpage)) {
    case BUF_BLOCK_FILE_PAGE:
        UNIV_MEM_ASSERT_W(bpage, sizeof(buf_block_t));
        UNIV_MEM_ASSERT_W(((buf_block_t*) bpage)->frame,
                  UNIV_PAGE_SIZE);
        buf_block_modify_clock_inc((buf_block_t*) bpage);
        if (bpage->zip.data) {
            const page_t*    page = ((buf_block_t*) bpage)->frame;
            const ulint    zip_size
                = page_zip_get_size(&bpage->zip);

            ut_a(!zip || bpage->oldest_modification == );

            switch (UNIV_EXPECT(fil_page_get_type(page),
                        FIL_PAGE_INDEX)) {
            case FIL_PAGE_TYPE_ALLOCATED:
            case FIL_PAGE_INODE:
            case FIL_PAGE_IBUF_BITMAP:
            case FIL_PAGE_TYPE_FSP_HDR:
            case FIL_PAGE_TYPE_XDES:
                /* These are essentially uncompressed pages. */
                if (!zip) {
                    /* InnoDB writes the data to the
                    uncompressed page frame.  Copy it
                    to the compressed page, which will
                    be preserved. */
                    memcpy(bpage->zip.data, page,
                           zip_size);
                }
                break;
            case FIL_PAGE_TYPE_ZBLOB:
            case FIL_PAGE_TYPE_ZBLOB2:
                break;
            case FIL_PAGE_INDEX:
#ifdef UNIV_ZIP_DEBUG
                ut_a(page_zip_validate(
                         &bpage->zip, page,
                         ((buf_block_t*) bpage)->index));
#endif /* UNIV_ZIP_DEBUG */
                break;
            default:
                ut_print_timestamp(stderr);
                fputs("  InnoDB: ERROR: The compressed page"
                      " to be evicted seems corrupt:", stderr);
                ut_print_buf(stderr, page, zip_size);
                fputs("\nInnoDB: Possibly older version"
                      " of the page:", stderr);
                ut_print_buf(stderr, bpage->zip.data,
                         zip_size);
                putc('\n', stderr);
                ut_error;
            }

            break;
        }
        /* fall through */
    case BUF_BLOCK_ZIP_PAGE:
        ut_a(bpage->oldest_modification == );
        UNIV_MEM_ASSERT_W(bpage->zip.data,
                  page_zip_get_size(&bpage->zip));
        break;
    case BUF_BLOCK_ZIP_FREE:
    case BUF_BLOCK_ZIP_DIRTY:
    case BUF_BLOCK_NOT_USED:
    case BUF_BLOCK_READY_FOR_USE:
    case BUF_BLOCK_MEMORY:
    case BUF_BLOCK_REMOVE_HASH:
        ut_error;
        break;
    }

    fold = buf_page_address_fold(bpage->space, bpage->offset);
    hashed_bpage = buf_page_hash_get_low(
        buf_pool, bpage->space, bpage->offset, fold);

    if (UNIV_UNLIKELY(bpage != hashed_bpage)) {
        fprintf(stderr,
            "InnoDB: Error: page %lu %lu not found"
            " in the hash table\n",
            (ulong) bpage->space,
            (ulong) bpage->offset);
        if (hashed_bpage) {
            fprintf(stderr,
                "InnoDB: In hash table we find block"
                " %p of %lu %lu which is not %p\n",
                (const void*) hashed_bpage,
                (ulong) hashed_bpage->space,
                (ulong) hashed_bpage->offset,
                (const void*) bpage);
        }

#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
        mutex_exit(buf_page_get_mutex(bpage));
        buf_pool_mutex_exit(buf_pool);
        buf_print();
        buf_LRU_print();
        buf_validate();
        buf_LRU_validate();
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */
        ut_error;
    }

    ut_ad(!bpage->in_zip_hash);
    ut_ad(bpage->in_page_hash);
    ut_d(bpage->in_page_hash = FALSE);
    HASH_DELETE(buf_page_t, hash, buf_pool->page_hash, fold, bpage); //这里    switch (buf_page_get_state(bpage)) {
    case BUF_BLOCK_ZIP_PAGE:
        ut_ad(!bpage->in_free_list);
        ut_ad(!bpage->in_flush_list);
        ut_ad(!bpage->in_LRU_list);
        ut_a(bpage->zip.data);
        ut_a(buf_page_get_zip_size(bpage));

#if defined UNIV_DEBUG || defined UNIV_BUF_DEBUG
        UT_LIST_REMOVE(list, buf_pool->zip_clean, bpage);
#endif /* UNIV_DEBUG || UNIV_BUF_DEBUG */

        mutex_exit(&buf_pool->zip_mutex);
        buf_pool_mutex_exit_forbid(buf_pool);

        buf_buddy_free(
            buf_pool, bpage->zip.data,
            page_zip_get_size(&bpage->zip));

        buf_pool_mutex_exit_allow(buf_pool);
        buf_page_free_descriptor(bpage);
        return(BUF_BLOCK_ZIP_FREE);

    case BUF_BLOCK_FILE_PAGE:
        memset(((buf_block_t*) bpage)->frame
               + FIL_PAGE_OFFSET, );
        memset(((buf_block_t*) bpage)->frame
               + FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID, );
        UNIV_MEM_INVALID(((buf_block_t*) bpage)->frame,
                 UNIV_PAGE_SIZE);
        buf_page_set_state(bpage, BUF_BLOCK_REMOVE_HASH);

        if (zip && bpage->zip.data) {
            /* Free the compressed page. */
            void*    data = bpage->zip.data;
            bpage->zip.data = NULL;

            ut_ad(!bpage->in_free_list);
            ut_ad(!bpage->in_flush_list);
            ut_ad(!bpage->in_LRU_list);
            mutex_exit(&((buf_block_t*) bpage)->mutex);
            buf_pool_mutex_exit_forbid(buf_pool);

            buf_buddy_free(
                buf_pool, data,
                page_zip_get_size(&bpage->zip));

            buf_pool_mutex_exit_allow(buf_pool);
            mutex_enter(&((buf_block_t*) bpage)->mutex);
            page_zip_set_size(&bpage->zip, );
        }

        return(BUF_BLOCK_REMOVE_HASH);

    case BUF_BLOCK_ZIP_FREE:
    case BUF_BLOCK_ZIP_DIRTY:
    case BUF_BLOCK_NOT_USED:
    case BUF_BLOCK_READY_FOR_USE:
    case BUF_BLOCK_MEMORY:
    case BUF_BLOCK_REMOVE_HASH:
        break;
    }

    ut_error;
    return(BUF_BLOCK_ZIP_FREE);
}