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/*++
/* NAME
/* qmgr_feedback 3
/* SUMMARY
/* delivery agent feedback management
/* SYNOPSIS
/* #include "qmgr.h"
/*
/* void qmgr_feedback_init(fbck_ctl, name_prefix, name_tail,
/* def_name, def_value)
/* QMGR_FEEDBACK *fbck_ctl;
/* const char *name_prefix;
/* const char *name_tail;
/* const char *def_name;
/* const char *def_value;
/*
/* double QMGR_FEEDBACK_VAL(fbck_ctl, concurrency)
/* QMGR_FEEDBACK *fbck_ctl;
/* const int concurrency;
/* DESCRIPTION
/* Upon completion of a delivery request, a delivery agent
/* provides a hint that the scheduler should dedicate fewer or
/* more resources to a specific destination.
/*
/* qmgr_feedback_init() looks up transport-dependent positive
/* or negative concurrency feedback control information from
/* main.cf, and converts it to internal form.
/*
/* QMGR_FEEDBACK_VAL() computes a concurrency adjustment based
/* on a preprocessed feedback control information and the
/* current concurrency window. This is an "unsafe" macro that
/* evaluates some arguments multiple times.
/*
/* Arguments:
/* .IP fbck_ctl
/* Pointer to QMGR_FEEDBACK structure where the result will
/* be stored.
/* .IP name_prefix
/* Mail delivery transport name, used as the initial portion
/* of a transport-dependent concurrency feedback parameter
/* name.
/* .IP name_tail
/* The second, and fixed, portion of a transport-dependent
/* concurrency feedback parameter.
/* .IP def_name
/* The name of a default feedback parameter.
/* .IP def_val
/* The value of the default feedback parameter.
/* .IP concurrency
/* Delivery concurrency for concurrency-dependent feedback calculation.
/* DIAGNOSTICS
/* Warning: configuration error or unreasonable input. The program
/* uses name_tail feedback instead.
/* Panic: consistency check failure.
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <stdlib.h>
#include <limits.h> /* INT_MAX */
#include <stdio.h> /* sscanf() */
#include <string.h>
/* Utility library. */
#include <msg.h>
#include <name_code.h>
#include <stringops.h>
#include <mymalloc.h>
/* Global library. */
#include <mail_params.h>
#include <mail_conf.h>
/* Application-specific. */
#include "qmgr.h"
/*
* Lookup tables for main.cf feedback method names.
*/
const NAME_CODE qmgr_feedback_map[] = {
CONC_FDBACK_NAME_WIN, QMGR_FEEDBACK_IDX_WIN,
#ifdef QMGR_FEEDBACK_IDX_SQRT_WIN
CONC_FDBACK_NAME_SQRT_WIN, QMGR_FEEDBACK_IDX_SQRT_WIN,
#endif
0, QMGR_FEEDBACK_IDX_NONE,
};
/* qmgr_feedback_init - initialize feedback control */
void qmgr_feedback_init(QMGR_FEEDBACK *fb,
const char *name_prefix,
const char *name_tail,
const char *def_name,
const char *def_val)
{
double enum_val;
char denom_str[30 + 1];
double denom_val;
char slash;
char junk;
char *fbck_name;
char *fbck_val;
/*
* Look up the transport-dependent feedback value.
*/
fbck_name = concatenate(name_prefix, name_tail, (char *) 0);
fbck_val = get_mail_conf_str(fbck_name, def_val, 1, 0);
/*
* We allow users to express feedback as 1/8, as a more user-friendly
* alternative to 0.125 (or worse, having users specify the number of
* events in a feedback hysteresis cycle).
*
* We use some sscanf() fu to parse the value into numerator and optional
* "/" followed by denominator. We're doing this only a few times during
* the process life time, so we strive for convenience instead of speed.
*/
#define INCLUSIVE_BOUNDS(val, low, high) ((val) >= (low) && (val) <= (high))
fb->hysteresis = 1; /* legacy */
fb->base = -1; /* assume error */
switch (sscanf(fbck_val, "%lf %1[/] %30s%c",
&enum_val, &slash, denom_str, &junk)) {
case 1:
fb->index = QMGR_FEEDBACK_IDX_NONE;
fb->base = enum_val;
break;
case 3:
if ((fb->index = name_code(qmgr_feedback_map, NAME_CODE_FLAG_NONE,
denom_str)) != QMGR_FEEDBACK_IDX_NONE) {
fb->base = enum_val;
} else if (INCLUSIVE_BOUNDS(enum_val, 0, INT_MAX)
&& sscanf(denom_str, "%lf%c", &denom_val, &junk) == 1
&& INCLUSIVE_BOUNDS(denom_val, 1.0 / INT_MAX, INT_MAX)) {
fb->base = enum_val / denom_val;
}
break;
}
/*
* Sanity check. If input is bad, we just warn and use a reasonable
* default.
*/
if (!INCLUSIVE_BOUNDS(fb->base, 0, 1)) {
msg_warn("%s: ignoring malformed or unreasonable feedback: %s",
strcmp(fbck_val, def_val) ? fbck_name : def_name, fbck_val);
fb->index = QMGR_FEEDBACK_IDX_NONE;
fb->base = 1;
}
/*
* Performance debugging/analysis.
*/
if (var_conc_feedback_debug)
msg_info("%s: %s feedback type %d value at %d: %g",
name_prefix, strcmp(fbck_val, def_val) ?
fbck_name : def_name, fb->index, var_init_dest_concurrency,
QMGR_FEEDBACK_VAL(*fb, var_init_dest_concurrency));
myfree(fbck_name);
myfree(fbck_val);
}
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