external/ibm-public/postfix/dist/src/qmgr/qmgr_feedback.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      qmgr_feedback 3
   6 /* SUMMARY
   7 /*      delivery agent feedback management
   8 /* SYNOPSIS
   9 /*      #include "qmgr.h"
  10 /*
  11 /*      void    qmgr_feedback_init(fbck_ctl, name_prefix, name_tail,
  12 /*                                      def_name, def_value)
  13 /*      QMGR_FEEDBACK *fbck_ctl;
  14 /*      const char *name_prefix;
  15 /*      const char *name_tail;
  16 /*      const char *def_name;
  17 /*      const char *def_value;
  18 /*
  19 /*      double  QMGR_FEEDBACK_VAL(fbck_ctl, concurrency)
  20 /*      QMGR_FEEDBACK *fbck_ctl;
  21 /*      const int concurrency;
  22 /* DESCRIPTION
  23 /*      Upon completion of a delivery request, a delivery agent
  24 /*      provides a hint that the scheduler should dedicate fewer or
  25 /*      more resources to a specific destination.
  26 /*
  27 /*      qmgr_feedback_init() looks up transport-dependent positive
  28 /*      or negative concurrency feedback control information from
  29 /*      main.cf, and converts it to internal form.
  30 /*
  31 /*      QMGR_FEEDBACK_VAL() computes a concurrency adjustment based
  32 /*      on a preprocessed feedback control information and the
  33 /*      current concurrency window. This is an "unsafe" macro that
  34 /*      evaluates some arguments multiple times.
  35 /*
  36 /*      Arguments:
  37 /* .IP fbck_ctl
  38 /*      Pointer to QMGR_FEEDBACK structure where the result will
  39 /*      be stored.
  40 /* .IP name_prefix
  41 /*      Mail delivery transport name, used as the initial portion
  42 /*      of a transport-dependent concurrency feedback parameter
  43 /*      name.
  44 /* .IP name_tail
  45 /*      The second, and fixed, portion of a transport-dependent
  46 /*      concurrency feedback parameter.
  47 /* .IP def_name
  48 /*      The name of a default feedback parameter.
  49 /* .IP def_val
  50 /*      The value of the default feedback parameter.
  51 /* .IP concurrency
  52 /*      Delivery concurrency for concurrency-dependent feedback calculation.
  53 /* DIAGNOSTICS
  54 /*      Warning: configuration error or unreasonable input. The program
  55 /*      uses name_tail feedback instead.
  56 /*      Panic: consistency check failure.
  57 /* LICENSE
  58 /* .ad
  59 /* .fi
  60 /*      The Secure Mailer license must be distributed with this software.
  61 /* AUTHOR(S)
  62 /*      Wietse Venema
  63 /*      IBM T.J. Watson Research
  64 /*      P.O. Box 704
  65 /*      Yorktown Heights, NY 10598, USA
  66 /*--*/
  67
  68 /* System library. */
  69
  70 #include <sys_defs.h>
  71 #include <stdlib.h>
  72 #include <limits.h>                     /* INT_MAX */
  73 #include <stdio.h>                      /* sscanf() */
  74 #include <string.h>
  75
  76 /* Utility library. */
  77
  78 #include <msg.h>
  79 #include <name_code.h>
  80 #include <stringops.h>
  81 #include <mymalloc.h>
  82
  83 /* Global library. */
  84
  85 #include <mail_params.h>
  86 #include <mail_conf.h>
  87
  88 /* Application-specific. */
  89
  90 #include "qmgr.h"
  91
  92  /*
  93   * Lookup tables for main.cf feedback method names.
  94   */
  95 const NAME_CODE qmgr_feedback_map[] = {
  96     CONC_FDBACK_NAME_WIN, QMGR_FEEDBACK_IDX_WIN,
  97 #ifdef QMGR_FEEDBACK_IDX_SQRT_WIN
  98     CONC_FDBACK_NAME_SQRT_WIN, QMGR_FEEDBACK_IDX_SQRT_WIN,
  99 #endif
 100     0, QMGR_FEEDBACK_IDX_NONE,
 101 };
 102
 103 /* qmgr_feedback_init - initialize feedback control */
 104
 105 void    qmgr_feedback_init(QMGR_FEEDBACK *fb,
 106                                    const char *name_prefix,
 107                                    const char *name_tail,
 108                                    const char *def_name,
 109                                    const char *def_val)
 110 {
 111     double  enum_val;
 112     char    denom_str[30 + 1];
 113     double  denom_val;
 114     char    slash;
 115     char    junk;
 116     char   *fbck_name;
 117     char   *fbck_val;
 118
 119     /*
 120      * Look up the transport-dependent feedback value.
 121      */
 122     fbck_name = concatenate(name_prefix, name_tail, (char *) 0);
 123     fbck_val = get_mail_conf_str(fbck_name, def_val, 1, 0);
 124
 125     /*
 126      * We allow users to express feedback as 1/8, as a more user-friendly
 127      * alternative to 0.125 (or worse, having users specify the number of
 128      * events in a feedback hysteresis cycle).
 129      *
 130      * We use some sscanf() fu to parse the value into numerator and optional
 131      * "/" followed by denominator. We're doing this only a few times during
 132      * the process life time, so we strive for convenience instead of speed.
 133      */
 134 #define INCLUSIVE_BOUNDS(val, low, high) ((val) >= (low) && (val) <= (high))
 135
 136     fb->hysteresis = 1;                         /* legacy */
 137     fb->base = -1;                              /* assume error */
 138
 139     switch (sscanf(fbck_val, "%lf %1[/] %30s%c",
 140                    &enum_val, &slash, denom_str, &junk)) {
 141     case 1:
 142         fb->index = QMGR_FEEDBACK_IDX_NONE;
 143         fb->base = enum_val;
 144         break;
 145     case 3:
 146         if ((fb->index = name_code(qmgr_feedback_map, NAME_CODE_FLAG_NONE,
 147                                    denom_str)) != QMGR_FEEDBACK_IDX_NONE) {
 148             fb->base = enum_val;
 149         } else if (INCLUSIVE_BOUNDS(enum_val, 0, INT_MAX)
 150                    && sscanf(denom_str, "%lf%c", &denom_val, &junk) == 1
 151                    && INCLUSIVE_BOUNDS(denom_val, 1.0 / INT_MAX, INT_MAX)) {
 152             fb->base = enum_val / denom_val;
 153         }
 154         break;
 155     }
 156
 157     /*
 158      * Sanity check. If input is bad, we just warn and use a reasonable
 159      * default.
 160      */
 161     if (!INCLUSIVE_BOUNDS(fb->base, 0, 1)) {
 162         msg_warn("%s: ignoring malformed or unreasonable feedback: %s",
 163                  strcmp(fbck_val, def_val) ? fbck_name : def_name, fbck_val);
 164         fb->index = QMGR_FEEDBACK_IDX_NONE;
 165         fb->base = 1;
 166     }
 167
 168     /*
 169      * Performance debugging/analysis.
 170      */
 171     if (var_conc_feedback_debug)
 172         msg_info("%s: %s feedback type %d value at %d: %g",
 173                  name_prefix, strcmp(fbck_val, def_val) ?
 174                  fbck_name : def_name, fb->index, var_init_dest_concurrency,
 175                  QMGR_FEEDBACK_VAL(*fb, var_init_dest_concurrency));
 176
 177     myfree(fbck_name);
 178     myfree(fbck_val);
 179 }