src/StatHist.cc

   1
   2 /*
   3  * $Id: StatHist.cc,v 1.25 2001/01/12 00:37:14 wessels Exp $
   4  *
   5  * DEBUG: section 62    Generic Histogram
   6  * AUTHOR: Duane Wessels
   7  *
   8  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   9  * ----------------------------------------------------------
  10  *
  11  *  Squid is the result of efforts by numerous individuals from
  12  *  the Internet community; see the CONTRIBUTORS file for full
  13  *  details.   Many organizations have provided support for Squid's
  14  *  development; see the SPONSORS file for full details.  Squid is
  15  *  Copyrighted (C) 2001 by the Regents of the University of
  16  *  California; see the COPYRIGHT file for full details.  Squid
  17  *  incorporates software developed and/or copyrighted by other
  18  *  sources; see the CREDITS file for full details.
  19  *
  20  *  This program is free software; you can redistribute it and/or modify
  21  *  it under the terms of the GNU General Public License as published by
  22  *  the Free Software Foundation; either version 2 of the License, or
  23  *  (at your option) any later version.
  24  *
  25  *  This program is distributed in the hope that it will be useful,
  26  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  27  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  28  *  GNU General Public License for more details.
  29  *
  30  *  You should have received a copy of the GNU General Public License
  31  *  along with this program; if not, write to the Free Software
  32  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  33  *
  34  */
  35
  36 /*
  37  * Important restrictions on val_in and val_out functions:
  38  *
  39  *   - val_in:  ascending, defined on [0, oo), val_in(0) == 0;
  40  *   - val_out: x == val_out(val_in(x)) where val_in(x) is defined
  41  *
  42  *  In practice, the requirements are less strict,
  43  *  but then it gets hard to define them without math notation.
  44  *  val_in is applied after offseting the value but before scaling
  45  *  See log and linear based histograms for examples
  46  */
  47
  48 #include "squid.h"
  49
  50 /* Local functions */
  51 static void statHistInit(StatHist * H, int capacity, hbase_f * val_in, hbase_f * val_out, double min, double max);
  52 static int statHistBin(const StatHist * H, double v);
  53 static double statHistVal(const StatHist * H, int bin);
  54 static StatHistBinDumper statHistBinDumper;
  55 #if !defined(_SQUID_HPUX_) || !defined(__GNUC__)
  56     /*
  57      * HP-UX and GCC (2.8?) give strange errors when these simple
  58      * functions are static.
  59      */
  60 static hbase_f Log;
  61 static hbase_f Exp;
  62 static hbase_f Null;
  63 #endif
  64
  65 /* low level init, higher level functions has less params */
  66 static void
  67 statHistInit(StatHist * H, int capacity, hbase_f * val_in, hbase_f * val_out, double min, double max)
  68 {
  69     assert(H);
  70     assert(capacity > 0);
  71     assert(val_in && val_out);
  72     /* check before we divide to get scale */
  73     assert(val_in(max - min) > 0);
  74     H->bins = xcalloc(capacity, sizeof(int));
  75     H->min = min;
  76     H->max = max;
  77     H->capacity = capacity;
  78     H->scale = capacity / val_in(max - min);
  79     H->val_in = val_in;
  80     H->val_out = val_out;
  81
  82     /* HPUX users: If you get one of the assertions below, please send
  83      * [at least] the values of all variables involved in the assertions
  84      * when reporting a bug!
  85      */
  86
  87     /* check that functions are valid */
  88     /* a min value should go into bin[0] */
  89     assert(statHistBin(H, min) == 0);
  90     /* a max value should go into the last bin */
  91     assert(statHistBin(H, max) == H->capacity - 1);
  92     /* it is hard to test val_out, here is a crude test */
  93     assert(((int) floor(0.99L + statHistVal(H, 0) - min)) == 0);
  94 }
  95
  96 void
  97 statHistClean(StatHist * H)
  98 {
  99     xfree(H->bins);
 100     H->bins = NULL;
 101 }
 102
 103 /* assumes that somebody already called init for Dest */
 104 void
 105 statHistCopy(StatHist * Dest, const StatHist * Orig)
 106 {
 107     assert(Dest);
 108     assert(Orig);
 109     debug(62, 3) ("statHistCopy: Dest=%p, Orig=%p\n", Dest, Orig);
 110     assert(Dest->bins);
 111     /* better be safe than sorry */
 112     debug(62, 3) ("statHistCopy: capacity %d %d\n",
 113         Dest->capacity, Orig->capacity);
 114     assert(Dest->capacity == Orig->capacity);
 115     debug(62, 3) ("statHistCopy: min %f %f\n", Dest->min, Orig->min);
 116     assert(Dest->min == Orig->min);
 117     debug(62, 3) ("statHistCopy: max %f %f\n", Dest->max, Orig->max);
 118     assert(Dest->max == Orig->max);
 119     debug(62, 3) ("statHistCopy: scale %f %f\n", Dest->scale, Orig->scale);
 120     assert(Dest->scale == Orig->scale);
 121     assert(Dest->val_in == Orig->val_in);
 122     assert(Dest->val_out == Orig->val_out);
 123     /* actual copy */
 124     debug(62, 3) ("statHistCopy: copying %d bytes to %p from %p\n",
 125         Dest->capacity * sizeof(*Dest->bins),
 126         Dest->bins,
 127         Orig->bins);
 128     xmemcpy(Dest->bins, Orig->bins, Dest->capacity * sizeof(*Dest->bins));
 129 }
 130
 131 /*
 132  * same as statHistCopy but will do nothing if capacities do not match; the
 133  * latter happens, for example, when #peers changes during reconfiguration;
 134  * if it happens too often we should think about more general solution..
 135  */
 136 void
 137 statHistSafeCopy(StatHist * Dest, const StatHist * Orig)
 138 {
 139     assert(Dest && Orig);
 140     assert(Dest->bins);
 141     if (Dest->capacity == Orig->capacity)
 142         statHistCopy(Dest, Orig);
 143 }
 144
 145 void
 146 statHistCount(StatHist * H, double val)
 147 {
 148     const int bin = statHistBin(H, val);
 149     assert(H->bins);            /* make sure it got initialized */
 150     assert(0 <= bin && bin < H->capacity);
 151     H->bins[bin]++;
 152 }
 153
 154 static int
 155 statHistBin(const StatHist * H, double v)
 156 {
 157     int bin;
 158 #if BROKEN_STAT_HIST_BIN
 159     return 0;
 160     /* NOTREACHED */
 161 #endif
 162     v -= H->min;                /* offset */
 163     if (v <= 0.0)               /* too small */
 164         return 0;
 165     bin = (int) floor(H->scale * H->val_in(v) + 0.5);
 166     if (bin < 0)                /* should not happen */
 167         bin = 0;
 168     if (bin >= H->capacity)     /* too big */
 169         bin = H->capacity - 1;
 170     return bin;
 171 }
 172
 173 static double
 174 statHistVal(const StatHist * H, int bin)
 175 {
 176     return H->val_out((double) bin / H->scale) + H->min;
 177 }
 178
 179 double
 180 statHistDeltaMedian(const StatHist * A, const StatHist * B)
 181 {
 182     int i;
 183     int s1 = 0;
 184     int h = 0;
 185     int a = 0;
 186     int b = 0;
 187     int I = 0;
 188     int J = A->capacity;
 189     int K;
 190     double f;
 191     int *D = xcalloc(A->capacity, sizeof(int));
 192     assert(A->capacity == B->capacity);
 193     for (i = 0; i < A->capacity; i++) {
 194         D[i] = B->bins[i] - A->bins[i];
 195         assert(D[i] >= 0);
 196     }
 197     for (i = 0; i < A->capacity; i++)
 198         s1 += D[i];
 199     h = s1 >> 1;
 200     for (i = 0; i < A->capacity; i++) {
 201         J = i;
 202         b += D[J];
 203         if (a <= h && h <= b)
 204             break;
 205         I = i;
 206         a += D[I];
 207     }
 208     xfree(D);
 209     if (s1 == 0)
 210         return 0.0;
 211     if (a > h)
 212         return 0.0;
 213     if (a >= b)
 214         return 0.0;
 215     if (I >= J)
 216         return 0.0;
 217     f = (h - a) / (b - a);
 218     K = (int) floor(f * (double) (J - I) + I);
 219     return statHistVal(A, K);
 220 }
 221
 222 static void
 223 statHistBinDumper(StoreEntry * sentry, int idx, double val, double size, int count)
 224 {
 225     if (count)
 226         storeAppendPrintf(sentry, "\t%3d/%f\t%d\t%f\n",
 227             idx, val, count, count / size);
 228 }
 229
 230 void
 231 statHistDump(const StatHist * H, StoreEntry * sentry, StatHistBinDumper * bd)
 232 {
 233     int i;
 234     double left_border = H->min;
 235     if (!bd)
 236         bd = statHistBinDumper;
 237     for (i = 0; i < H->capacity; i++) {
 238         const double right_border = statHistVal(H, i + 1);
 239         assert(right_border - left_border > 0.0);
 240         bd(sentry, i, left_border, right_border - left_border, H->bins[i]);
 241         left_border = right_border;
 242     }
 243 }
 244
 245 /* log based histogram */
 246 #if !defined(_SQUID_HPUX_) || !defined(__GNUC__)
 247 static
 248 #endif
 249 double
 250 Log(double x)
 251 {
 252     assert((x + 1.0) >= 0.0);
 253     return log(x + 1.0);
 254 }
 255
 256 #if !defined(_SQUID_HPUX_) || !defined(__GNUC__)
 257 static
 258 #endif
 259 double
 260 Exp(double x)
 261 {
 262     return exp(x) - 1.0;
 263 }
 264
 265 void
 266 statHistLogInit(StatHist * H, int capacity, double min, double max)
 267 {
 268     statHistInit(H, capacity, Log, Exp, min, max);
 269 }
 270
 271 /* linear histogram for enums */
 272 /* we want to be have [-1,last_enum+1] range to track out of range enums */
 273 #if !defined(_SQUID_HPUX_) || !defined(__GNUC__)
 274 static
 275 #endif
 276 double
 277 Null(double x)
 278 {
 279     return x;
 280 }
 281
 282 void
 283 statHistEnumInit(StatHist * H, int last_enum)
 284 {
 285     statHistInit(H, last_enum + 3, Null, Null, (double) -1, (double) (last_enum + 1 + 1));
 286 }
 287
 288 void
 289 statHistEnumDumper(StoreEntry * sentry, int idx, double val, double size, int count)
 290 {
 291     if (count)
 292         storeAppendPrintf(sentry, "%2d\t %5d\t %5d\n",
 293             idx, (int) val, count);
 294 }
 295
 296 void
 297 statHistIntInit(StatHist * H, int n)
 298 {
 299     statHistInit(H, n, Null, Null, (double) 0, (double) n - 1);
 300 }
 301
 302 void
 303 statHistIntDumper(StoreEntry * sentry, int idx, double val, double size, int count)
 304 {
 305     if (count)
 306         storeAppendPrintf(sentry, "%9d\t%9d\n", (int) val, count);
 307 }