Re: [gnugo-devel] arend_1_30.2: random seed in crash report

[Gunnar Farneback]

Arend wrote:
> Actually, I think this problem is practically important. As far as I
> understand, all the twogtp that we are running currently would be made
> impossible.

Right.
 
> So I guess we should not have a release that contains this patch but not
> the "another patch" you are planning.

It turned out not to be quite as easy to fix as I thought. Or
actually, it's easy to fix but not in a way I like. For the time being
I have left this part of the patch out. Revised patch below.

- seed field removed from Gameinfo struct
- new global variable random_seed
- doc revision

/Gunnar

Index: doc/api.texi
===================================================================
RCS file: /cvsroot/gnugo/gnugo/doc/api.texi,v
retrieving revision 1.7
diff -u -r1.7 api.texi
--- doc/api.texi        20 Mar 2002 20:55:30 -0000      1.7
+++ doc/api.texi        31 Mar 2002 18:06:20 -0000
@@ -356,7 +356,6 @@
   int       to_move;            /* whose move it currently is */
   SGFTree   game_record;        /* Game record in sgf format. */
 
-  int       seed;               /* random seed */
   int       computer_player;    /* BLACK, WHITE, or EMPTY (used as BOTH) */
 
   char      outfilename[128];   /* Trickle file */
@@ -373,14 +372,8 @@
 game, including a header node which contains, among other things, komi
 and handicap.
 
-If one or both of the opponents is the computer, the fields @code{seed}
-and @code{computer_player} are used. Otherwise they can be
-ignored. @code{seed} is used to store the number used to seed the random
-number generator. Given the same moves from the opponent, GNU Go will
-try to vary its game somewhat using a random function. But if the random
-generator is given the same seed, GNU Go will always play the same
-move. This is good, e.g. when we debug the engine but could also be used
-for other purposes.
+If one or both of the opponents is the computer, the field
address@hidden is used. Otherwise it can be ignored.
 
 GNU Go can use a trickle file to continuously save all the moves of an
 ongoing game. This file can also contain information about internal
Index: engine/globals.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/globals.c,v
retrieving revision 1.23
diff -u -r1.23 globals.c
--- engine/globals.c    22 Mar 2002 08:18:32 -0000      1.23
+++ engine/globals.c    31 Mar 2002 18:06:20 -0000
@@ -102,6 +102,7 @@
 int count_variations = 0;  /* used by decide_string */
 int sgf_dump         = 0;  /* used by decide_string */
 SGFTree *sgf_dumptree = NULL;
+int random_seed      = 0;  /* random seed */
 int loading          = 0;  /* TRUE if last loaded move comes from file */
 int life             = 0;  /* use eye reading code */
 int life_eyesize     = 0;  /* max eyesize for life code */
Index: engine/gnugo.h
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/gnugo.h,v
retrieving revision 1.48
diff -u -r1.48 gnugo.h
--- engine/gnugo.h      22 Mar 2002 08:18:32 -0000      1.48
+++ engine/gnugo.h      31 Mar 2002 18:06:20 -0000
@@ -162,7 +162,6 @@
   int       to_move;           /* whose move it currently is */
   SGFTree   game_record;       /* Game record in sgf format. */
 
-  int       seed;              /* random seed */
   int       computer_player;   /* BLACK, WHITE, or EMPTY (used as BOTH) */
 
   char      outfilename[128];  /* Trickle file */
@@ -183,6 +182,8 @@
 /*                           global variables                       */
 /* ================================================================ */
 
+/* Random seed */
+extern int random_seed;
 
 /* Miscellaneous debug options. */
 extern int quiet;              /* Minimal output. */
Index: engine/interface.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/interface.c,v
retrieving revision 1.16
diff -u -r1.16 interface.c
--- engine/interface.c  10 Mar 2002 14:05:07 -0000      1.16
+++ engine/interface.c  31 Mar 2002 18:06:20 -0000
@@ -385,7 +385,6 @@
   sgftree_clear(&ginfo->game_record);
 
   /* Info relevant to the computer player. */
-  ginfo->seed = 0;
   ginfo->computer_player = WHITE; /* Make an assumption. */
 
   ginfo->outfilename[0] = '\0';
Index: engine/move_reasons.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/move_reasons.c,v
retrieving revision 1.76
diff -u -r1.76 move_reasons.c
--- engine/move_reasons.c       31 Mar 2002 04:40:00 -0000      1.76
+++ engine/move_reasons.c       31 Mar 2002 18:06:21 -0000
@@ -103,6 +103,24 @@
   next_all = 0;
   next_eye = 0;
   next_lunch = 0;
+
+  /* To improve the reproducability of games, we restart the random
+   * number generator with the same seed for each move. Thus we don't
+   * have to know how many previous moves have been played, nor
+   * actually play through them, in order to get the right random
+   * numbers.
+   *
+   * Comment: This means we might set these numbers only once instead
+   *          of before each move. This is not without complications
+   *          though, since we don't have full control of when the
+   *          random seed is changed. Better to do it for each move.
+   *
+   * Comment 2: While this is a good idea, we're not yet quite ready
+   *            to make use of it.
+   */
+#if 0
+  gg_srand(random_seed);
+#endif
   
   for (i = 0; i < board_size; i++)
     for (j = 0; j < board_size; j++) {
Index: engine/printutils.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/printutils.c,v
retrieving revision 1.21
diff -u -r1.21 printutils.c
--- engine/printutils.c 25 Mar 2002 07:39:18 -0000      1.21
+++ engine/printutils.c 31 Mar 2002 18:06:21 -0000
@@ -251,13 +251,13 @@
 
 #if 0
   if (sgf_root) {
-    /* FIXME: How should we get seed and komi in here? */
-    sgf_write_header(sgf_root, 1, 0, 0.0);
+    sgf_write_header(sgf_root, 1, random_seed, komi, level);
     writesgf(sgf_root, "abortgo.sgf");
   }
 #endif
 
-  fprintf(stderr, "\ngnugo %s: You stepped on a bug.\n", gg_version());
+  fprintf(stderr, "\ngnugo %s (seed %d): You stepped on a bug.\n",
+          gg_version(), random_seed);
   if (board_size >= 9 && board_size <= 19) {
     fprintf(stderr, "\
 Please save this game as an sgf file and mail it to address@hidden
Index: engine/sgffile.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/sgffile.c,v
retrieving revision 1.13
diff -u -r1.13 sgffile.c
--- engine/sgffile.c    7 Mar 2002 05:35:28 -0000       1.13
+++ engine/sgffile.c    31 Mar 2002 18:06:22 -0000
@@ -205,7 +205,7 @@
   fprintf(sgfout, "HA[%d]", ginfo->handicap);
   fprintf(sgfout, "KM[%.1f]", komi);
   fprintf(sgfout, "GN[GNU Go %s %s ", VERSION, gametype);
-  fprintf(sgfout, "Random Seed %d", ginfo->seed);
+  fprintf(sgfout, "Random Seed %d", random_seed);
   fprintf(sgfout, "] ");
   fprintf(sgfout, "\n");
   
Index: interface/main.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/interface/main.c,v
retrieving revision 1.35
diff -u -r1.35 main.c
--- interface/main.c    25 Mar 2002 04:47:27 -0000      1.35
+++ interface/main.c    31 Mar 2002 18:06:22 -0000
@@ -824,7 +824,7 @@
   if (!seed)
     seed = time(0);
   gg_srand(seed);
-  gameinfo.seed = seed;
+  random_seed = seed;
 
   
   /* Initialize the GNU Go engine. */
Index: interface/play_ascii.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/interface/play_ascii.c,v
retrieving revision 1.15
diff -u -r1.15 play_ascii.c
--- interface/play_ascii.c      7 Mar 2002 05:35:28 -0000       1.15
+++ interface/play_ascii.c      31 Mar 2002 18:06:22 -0000
@@ -894,7 +894,7 @@
          if (tmpstring) {
            /* discard newline */
            tmpstring[strlen(tmpstring)-1] = 0;
-           sgf_write_header(sgftree.root, 1, gameinfo->seed, komi, level);
+           sgf_write_header(sgftree.root, 1, random_seed, komi, level);
            writesgf(sgftree.root, tmpstring);
            sgf_initialized = 0;
            printf("You may resume the game");
@@ -961,7 +961,7 @@
        if (tmpstring) {
          /* discard newline */
          tmpstring[strlen(tmpstring)-1] = 0;
-         sgf_write_header(sgftree.root, 1, gameinfo->seed, komi, level);
+         sgf_write_header(sgftree.root, 1, random_seed, komi, level);
          writesgf(sgftree.root, tmpstring);
            sgf_initialized = 0;
        }