vmod_vtc(3)

1VMOD_VTC(3)                                                        VMOD_VTC(3)
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NAME

6       vmod_vtc - Utility module for varnishtest
7

SYNOPSIS

9          import vtc [from "path"] ;
10
11          VOID barrier_sync(STRING addr, DURATION timeout)
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13          BACKEND no_backend()
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15          STEVEDORE no_stevedore()
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17          VOID panic(STRING)
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19          VOID sleep(DURATION)
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21          VOID workspace_alloc(ENUM, INT size)
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23          INT workspace_free(ENUM)
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25          VOID workspace_snapshot(ENUM)
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27          VOID workspace_reset(ENUM)
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29          BOOL workspace_overflowed(ENUM)
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31          VOID workspace_overflow(ENUM)
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33          INT typesize(STRING)
34

DESCRIPTION

36       The  goal  for this VMOD is to provide VCL users and VMOD authors means
37       to test corner cases or reach certain conditions with varnishtest.
38
39   VOID barrier_sync(STRING addr, DURATION timeout=0)
40       When writing test cases, the most common pattern is  to  start  a  mock
41       server  instance,  a Varnish instance, and spin up a mock client. Those
42       entities run asynchronously, and others exist like background processes
43       (process)  or  log  readers (logexpect). While you can synchronize with
44       individual entities and wait for their completion, you must use a  bar‐
45       rier  if  you need to synchronize two or more entities, or wait until a
46       certain point instead of completion.
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48       Not only is it possible to synchronize between test entities, with  the
49       barrier_sync function you can even synchronize VCL code:
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51          sub vcl_recv {
52              # wait for some barrier b1 to complete
53              vtc.barrier_sync("${b1_sock}");
54          }
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56       If  the function fails to synchronize with the barrier for some reason,
57       or if it reaches the optional timeout, it fails the VCL transaction.
58

MISCELLANEOUS

60   BACKEND no_backend()
61       Fails at backend selection.
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63   STEVEDORE no_stevedore()
64       Fails at storage selection.
65
66   VOID panic(STRING)
67       It can be useful to crash the  child  process  in  order  to  test  the
68       robustness of a VMOD.
69
70   VOID sleep(DURATION)
71       Block the current worker thread.
72

WORKSPACES

74       It  can be useful to put a workspace in a given state when testing cor‐
75       ner cases like resource exhaustion for a  transaction,  especially  for
76       VMOD development. All functions available allow to pick which workspace
77       you need to tamper with, available values are client, backend,  session
78       and thread.
79
80   VOID workspace_alloc(ENUM, INT size)
81          VOID workspace_alloc(
82             ENUM {client, backend, session, thread},
83             INT size
84          )
85
86       Allocate  and  zero  out  memory from a workspace. A negative size will
87       allocate as much as needed to leave that many bytes  free.  The  actual
88       allocation  size may be higher to comply with memory alignment require‐
89       ments of the CPU architecture. A failed allocation fails  the  transac‐
90       tion.
91
92   INT workspace_free(ENUM {client, backend, session, thread})
93       Find how much unallocated space there is left in a workspace.
94
95   VOID workspace_snapshot(ENUM)
96          VOID workspace_snapshot(ENUM {client, backend, session, thread})
97
98       Snapshot a workspace. Only one snapshot may be active at a time.
99
100   VOID workspace_reset(ENUM)
101          VOID workspace_reset(ENUM {client, backend, session, thread})
102
103       Reset  to  the  previous  snapshot  of a workspace, it must be the same
104       workspace too.
105
106   BOOL workspace_overflowed(ENUM)
107          BOOL workspace_overflowed(ENUM {client, backend, session, thread})
108
109       Find whether the workspace overflow mark is set or not.
110
111   VOID workspace_overflow(ENUM)
112          VOID workspace_overflow(ENUM {client, backend, session, thread})
113
114       Mark a workspace as overflowed.
115
116   INT typesize(STRING)
117       Returns the size in bytes of a collection of C-datatypes:
118
119       · 'p': pointer
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121       · 'i': int
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123       · 'd': double
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125       · 'f': float
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127       · 'l': long
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129       · 's': short
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131       · 'z': size_t
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133       · 'o': off_t
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135       · 'j': intmax_t
136
137       This can be useful for VMOD authors in conjunction with workspace oper‐
138       ations.
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COPYRIGHT

146          Copyright (c) 2017 Varnish Software AS
147          All rights reserved.
148
149          Author: Dridi Boukelmoune <dridi.boukelmoune@gmail.com>
150
151          Redistribution and use in source and binary forms, with or without
152          modification, are permitted provided that the following conditions
153          are met:
154          1. Redistributions of source code must retain the above copyright
155             notice, this list of conditions and the following disclaimer.
156          2. Redistributions in binary form must reproduce the above copyright
157             notice, this list of conditions and the following disclaimer in the
158             documentation and/or other materials provided with the distribution.
159
160          THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
161          ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
162          IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
163          ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
164          FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
165          DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
166          OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
167          HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
168          LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
169          OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
170          SUCH DAMAGE.
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175                                                                   VMOD_VTC(3)

NAME

SYNOPSIS

DESCRIPTION

MISCELLANEOUS

WORKSPACES

SEE ALSO

COPYRIGHT