VMOD_H2(3)

NAME
vmod_h2 - Module to control the built-in HTTP2 transport

SYNOPSIS

    import h2 [as name] [from "path"]
    BOOL is()
    DURATION rapid_reset([DURATION threshold])
    INT rapid_reset_limit([INT number])
    DURATION rapid_reset_period([DURATION duration])
    REAL rapid_reset_budget()

DESCRIPTION

This VMOD contains functions to control the HTTP2 transport built into Varnish-Cache.

  BOOL is()

Restricted to: client.

Returns true when called on a session handled by the built-in HTTP2 transport.

  DURATION rapid_reset([DURATION threshold])

Restricted to: client.

Get and optionally set the h2_rapid_reset parameter (See varnishd(1)) for this HTTP2 session only.

Returns -1 when used outside the HTTP2 transport. Otherwise returns the previous value.

If the call leads to a change in the rate limit parameters, the current budget as retuned by h2.rapid_reset_budget() is reset.

  INT rapid_reset_limit([INT number])

Restricted to: client.

Get and optionally set the h2_rapid_reset_limit parameter (See varnishd(1)) for this HTTP2 session only.

Returns -1 when used outside the HTTP2 transport. Otherwise returns the previous value.

If the call leads to a change in the rate limit parameters, the current budget as retuned by h2.rapid_reset_budget() is reset.

  DURATION rapid_reset_period([DURATION duration])

Restricted to: client.

Get and optionally set the h2_rapid_reset_period parameter (See varnishd(1)) for this HTTP2 session only.

Returns -1 when used outside the HTTP2 transport. Otherwise returns the previous value.

If the call leads to a change in the rate limit parameters, the current budget as retuned by h2.rapid_reset_budget() is reset.

  REAL rapid_reset_budget()

Restricted to: client.

Return how many RST frames classified as "rapid" the client is still allowed to send before the session is going to be closed.

SEE ALSO

•   varnishd(1)

•   vsl(7)

COPYRIGHT

    Copyright 2023 UPLEX - Nils Goroll Systemoptimierung
    All rights reserved.
    Author: Nils Goroll <nils.goroll@uplex.de>
    SPDX-License-Identifier: BSD-2-Clause
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:
    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.
    THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
    FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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