eio_readahead

    (PECL eio >= 0.0.1dev)

    eio_readahead — Perform file readahead into page cache

    说明

    eio_readahead(
        mixed $fd,
        int $offset,
        int $length,
        int $pri = EIO_PRI_DEFAULT,
        callable $callback = NULL,
        mixed $data = NULL
    ): resource

    eio_readahead() populates the page cache with data from a file so that subsequent reads from that file will not block on disk I/O. See READAHEAD(2) man page for details.

    参数

    fd

    Stream, Socket resource, or numeric file descriptor

    offset

    Starting point from which data is to be read.

    length

    Number of bytes to be read.

    pri

    请求的优先级：EIO_PRI_DEFAULT，EIO_PRI_MIN，EIO_PRI_MAX 或 null。如果是 null，pri 将设为 EIO_PRI_DEFAULT。

    callback

    callback 函数在请求完成时被调用。其应匹配一下原型：

    void callback(mixed $data, int $result[, resource $req]);
    data

    传递给请求的用户数据。

    result

    针对请求的结果的值。通常是相应的系统调用返回的值。

    req

    可选的请求资源，可被 eio_get_last_error() 之类的函数使用。

    data

    Arbitrary variable passed to callback.

    返回值

    eio_readahead() returns request resource on success, 或者在失败时返回 false.

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