admission-policy.vtc
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Authored by • ema on Oct 25 2017, 11:42 AM.

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	F10427132: admission-policy.vtc
	Oct 25 2017, 11:42 AM

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	varnishtest "Admission probability with different CL values"

	server s1 {
	# CL == 0
	rxreq
	expect req.url == "/1"
	txresp -nolen -hdr "Content-Length: 0"

	# CL > 0
	rxreq
	expect req.url == "/2"
	txresp -bodylen 65536

	# No CL
	rxreq
	expect req.url == "/3"
	txresp -nolen

	# CL == 0
	rxreq
	expect req.url == "/4"
	txresp -nolen -hdr "Content-Length: 0"
	} -start

	varnish v1 -arg "-p vcc_err_unref=false -p vcc_allow_inline_c=true" -vcl+backend {
	backend vtc_backend {
	.host = "${s1_addr}"; .port = "${s1_port}";
	}
	C{
	#include <stdlib.h>
	#include <math.h>

	const int adm_param = 32768;
	}C

	sub vcl_backend_response {
	C{
	const struct gethdr_s prob_hdr = { HDR_BERESP, "\030X-Admission-Probability:" };
	const struct gethdr_s urand_hdr = { HDR_BERESP, "\022X-Admission-Urand:" };
	const struct gethdr_s hdr = { HDR_BERESP, "\017Content-Length:" };
	const char *clen_hdr = VRT_GetHdr(ctx, &hdr);
	const double urand = drand48();
	double admissionprob;
	// Set CL:0 by default
	int clen = 0;

	// If Content-Length has been specified
	if (clen_hdr)
	clen = atoi(clen_hdr);

	admissionprob = exp(-clen/adm_param);

	VRT_SetHdr(ctx, &prob_hdr, VRT_REAL_string(ctx, admissionprob), vrt_magic_string_end);
	VRT_SetHdr(ctx, &urand_hdr, VRT_REAL_string(ctx, urand), vrt_magic_string_end);

	// If admission test succeeds, mark as uncacheable (set ttl=0, do not
	// create hit-for-pass)
	if (admissionprob < urand) {
	VRT_l_beresp_ttl(ctx,0);
	VRT_l_beresp_uncacheable(ctx,1);
	}
	}C
	}
	} -start

	client c1 {
	txreq -url "/1" -hdr "X-Forwarded-Proto: https" -hdr "Host: upload.wikimedia.org"
	rxresp

	expect resp.status == 200
	expect resp.http.X-Admission-Probability == 1.000

	txreq -url "/2" -hdr "X-Forwarded-Proto: https" -hdr "Host: upload.wikimedia.org"
	rxresp

	expect resp.status == 200
	expect resp.http.X-Admission-Probability > 0
	expect resp.http.X-Admission-Probability < 1

	txreq -url "/3" -hdr "X-Forwarded-Proto: https" -hdr "Host: upload.wikimedia.org"
	rxresp

	expect resp.status == 200
	expect resp.http.X-Admission-Probability == 1.000

	txreq -url "/4" -hdr "X-Forwarded-Proto: https" -hdr "Host: upload.wikimedia.org"
	rxresp

	expect resp.status == 200
	expect resp.http.X-Admission-Probability == 1.000
	} -run

Event Timeline

• ema created this paste.Oct 25 2017, 11:42 AM

PangolinMexico mentioned this in T311301: What's in a name? - AuthorBot: Process and Progress.Jun 24 2022, 11:25 AM

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