NAME

       vmod_vtc - Utility module for varnishtest

SYNOPSIS

          import vtc [as name] [from "path"]

          VOID barrier_sync(STRING addr, DURATION timeout)

          BACKEND no_backend()

          STEVEDORE no_stevedore()

          IP no_ip()

          VOID panic(STRING)

          VOID sleep(DURATION)

          VOID workspace_alloc(ENUM, INT size)

          BYTES workspace_reserve(ENUM, INT size)

          INT workspace_free(ENUM)

          VOID workspace_snapshot(ENUM)

          VOID workspace_reset(ENUM)

          BOOL workspace_overflowed(ENUM)

          VOID workspace_overflow(ENUM)

          BLOB workspace_dump(ENUM, ENUM, BYTES off, BYTES len)

          INT typesize(STRING)

          BLOB proxy_header(ENUM version, IP client, IP server, STRING authority)

DESCRIPTION

       The goal for this VMOD is to provide VCL users and VMOD authors means to test corner cases
       or reach certain conditions with varnishtest.

   VOID barrier_sync(STRING addr, DURATION timeout=0)
       When writing test cases, the most common pattern is to start a  mock  server  instance,  a
       Varnish instance, and spin up a mock client. Those entities run asynchronously, and others
       exist like background processes (process)  or  log  readers  (logexpect).  While  you  can
       synchronize with individual entities and wait for their completion, you must use a barrier
       if you need to synchronize two or more entities, or wait until a certain point instead  of
       completion.

       Not  only  is  it  possible  to  synchronize  between test entities, with the barrier_sync
       function you can even synchronize VCL code:

          sub vcl_recv {
              # wait for some barrier b1 to complete
              vtc.barrier_sync("${b1_sock}");
          }

       If the function fails to synchronize with the barrier for some reason, or  if  it  reaches
       the optional timeout, it fails the VCL transaction.

MISCELLANEOUS

   BACKEND no_backend()
       Fails at backend selection.

   STEVEDORE no_stevedore()
       Fails at storage selection.

   IP no_ip()
       Returns a null IP address, not even a bogo_ip.

   VOID panic(STRING)
       It can be useful to crash the child process in order to test the robustness of a VMOD.

   VOID sleep(DURATION)
       Block the current worker thread.

WORKSPACES

       It  can  be  useful  to  put  a  workspace in a given state when testing corner cases like
       resource exhaustion for a transaction, especially  for  VMOD  development.  All  functions
       available  allow  to  pick  which  workspace you need to tamper with, available values are
       client, backend, session and thread.

   VOID workspace_alloc(ENUM, INT size)
          VOID workspace_alloc(
             ENUM {client, backend, session, thread},
             INT size
          )

       Allocate and zero out memory from a workspace. A negative size will allocate  as  much  as
       needed  to  leave that many bytes free. The actual allocation size may be higher to comply
       with memory alignment requirements of the CPU architecture. A failed allocation fails  the
       transaction.

   BYTES workspace_reserve(ENUM, INT size)
          BYTES workspace_reserve(
             ENUM {client, backend, session, thread},
             INT size
          )

       Attempt  to  reserve size bytes and release the reservation right away. Return the size of
       the reservation.

       See vtc.workspace_alloc() for semantics of the size argument.

   INT workspace_free(ENUM {client, backend, session, thread})
       Find how much unallocated space there is left in a workspace.

   VOID workspace_snapshot(ENUM)
          VOID workspace_snapshot(ENUM {client, backend, session, thread})

       Snapshot a workspace. Only one snapshot may be active at a time and each VCL can save only
       one snapshot, so concurrent tasks requiring snapshots are not supported.

   VOID workspace_reset(ENUM)
          VOID workspace_reset(ENUM {client, backend, session, thread})

       Reset to the previous snapshot of a workspace, it must be the same workspace too.

   BOOL workspace_overflowed(ENUM)
          BOOL workspace_overflowed(ENUM {client, backend, session, thread})

       Find whether the workspace overflow mark is set or not.

   VOID workspace_overflow(ENUM)
          VOID workspace_overflow(ENUM {client, backend, session, thread})

       Mark a workspace as overflowed.

   BLOB workspace_dump(ENUM, ENUM, BYTES off, BYTES len)
          BLOB workspace_dump(
             ENUM {client, backend, session, thread},
             ENUM {s, f, r},
             BYTES off=0,
             BYTES len=64
          )

       Return  data  from  a  workspace's  s,  f, or r pointer as a blob. Data is copied onto the
       primary workspace to avoid it being subsequently overwritten.

       The maximum len is 1KB.

   INT typesize(STRING)
       Returns the size in bytes of a collection of C-datatypes:

       • 'p': pointer

       • 'i': int

       • 'd': double

       • 'f': float

       • 'l': long

       • 's': short

       • 'z': size_t

       • 'o': off_t

       • 'j': intmax_t

       This can be useful for VMOD authors in conjunction with workspace operations.

   BLOB proxy_header(ENUM version, IP client, IP server, STRING authority)
          BLOB proxy_header(
             ENUM {v1, v2} version,
             IP client,
             IP server,
             STRING authority=0
          )

       Format a proxy header of the given version v1 or v2 and addresses (The VCL  IP  type  also
       conatins the port number).

       Optionally also send an authority TLV with version v2 (ignored for version v1).

       Candidate for moving into vmod_proxy, but there were concerns about the interface design

SEE ALSO

       • vtc(7)

       • vcl(7)

COPYRIGHT

          Copyright (c) 2017 Varnish Software AS
          All rights reserved.

          Author: Dridi Boukelmoune <dridi.boukelmoune@gmail.com>

          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
          OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
          HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
          LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
          OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
          SUCH DAMAGE.

                                                                                      VMOD_VTC(3)