* bcache.c: Include "gdb_assert.h".

	(struct bcache): Add fields "expand_count" and
	"expand_hash_count".
	(expand_hash_table): Update the expand counts.
	(print_bcache_statistics): Use XCALLOC, not alloca.  Print stats
	on object sizes and hashes.
	* Makefile.in (bcache.o): Update dependencies.

1 files changed, 52 insertions, 4 deletions

diff --git a/gdb/bcache.c b/gdb/bcache.c
index 5a310f3..32454ce 100644
--- a/gdb/bcache.c
+++ b/gdb/bcache.c
@@ -2,7 +2,7 @@
    Written by Fred Fish <fnf@cygnus.com>
    Rewritten by Jim Blandy <jimb@cygnus.com>
 
-   Copyright 1999, 2000, 2002 Free Software Foundation, Inc.
+   Copyright 1999, 2000, 2002, 2003 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -25,6 +25,7 @@
 #include "gdb_obstack.h"
 #include "bcache.h"
 #include "gdb_string.h"		/* For memcpy declaration */
+#include "gdb_assert.h"
 
 #include <stddef.h>
 #include <stdlib.h>
@@ -71,6 +72,13 @@ struct bcache
   long unique_size;	/* size of unique strings, in bytes */
   long total_size;      /* total number of bytes cached, including dups */
   long structure_size;	/* total size of bcache, including infrastructure */
+  /* Number of times that the hash table is expanded and hence
+     re-built, and the corresponding number of times that a string is
+     [re]hashed as part of entering it into the expanded table.  The
+     total number of hashes can be computed by adding TOTAL_COUNT to
+     expand_hash_count.  */
+  unsigned long expand_count;
+  unsigned long expand_hash_count;
 };
 
 /* The old hash function was stolen from SDBM. This is what DB 3.0 uses now,
@@ -117,6 +125,11 @@ expand_hash_table (struct bcache *bcache)
   struct bstring **new_buckets;
   unsigned int i;
 
+  /* Count the stats.  Every unique item needs to be re-hashed and
+     re-entered.  */
+  bcache->expand_count++;
+  bcache->expand_hash_count += bcache->unique_count;
+
   /* Find the next size.  */
   new_num_buckets = bcache->num_buckets * 2;
   for (i = 0; i < (sizeof (sizes) / sizeof (sizes[0])); i++)
@@ -265,12 +278,16 @@ print_bcache_statistics (struct bcache *c, char *type)
   int occupied_buckets;
   int max_chain_length;
   int median_chain_length;
+  int max_entry_size;
+  int median_entry_size;
 
-  /* Count the number of occupied buckets, and measure chain lengths.  */
+  /* Count the number of occupied buckets, tally the various string
+     lengths, and measure chain lengths.  */
   {
     unsigned int b;
-    int *chain_length
-      = (int *) alloca (c->num_buckets * sizeof (*chain_length));
+    int *chain_length = XCALLOC (c->num_buckets + 1, int);
+    int *entry_size = XCALLOC (c->unique_count + 1, int);
+    int stringi = 0;
 
     occupied_buckets = 0;
 
@@ -286,7 +303,10 @@ print_bcache_statistics (struct bcache *c, char *type)
 	    
 	    while (s)
 	      {
+		gdb_assert (b < c->num_buckets);
 		chain_length[b]++;
+		gdb_assert (stringi < c->unique_count);
+		entry_size[stringi++] = s->length;
 		s = s->next;
 	      }
 	  }
@@ -295,6 +315,8 @@ print_bcache_statistics (struct bcache *c, char *type)
     /* To compute the median, we need the set of chain lengths sorted.  */
     qsort (chain_length, c->num_buckets, sizeof (chain_length[0]),
 	   compare_ints);
+    qsort (entry_size, c->unique_count, sizeof (entry_size[0]),
+	   compare_ints);
 
     if (c->num_buckets > 0)
       {
@@ -306,6 +328,19 @@ print_bcache_statistics (struct bcache *c, char *type)
 	max_chain_length = 0;
 	median_chain_length = 0;
       }
+    if (c->unique_count > 0)
+      {
+	max_entry_size = entry_size[c->unique_count - 1];
+	median_entry_size = entry_size[c->unique_count / 2];
+      }
+    else
+      {
+	max_entry_size = 0;
+	median_entry_size = 0;
+      }
+
+    xfree (chain_length);
+    xfree (entry_size);
   }
 
   printf_filtered ("  Cached '%s' statistics:\n", type);
@@ -321,6 +356,15 @@ print_bcache_statistics (struct bcache *c, char *type)
   print_percentage (c->total_size - c->unique_size, c->total_size);
   printf_filtered ("\n");
 
+  printf_filtered ("    Max entry size:     %d\n", max_entry_size);
+  printf_filtered ("    Average entry size: ");
+  if (c->unique_count > 0)
+    printf_filtered ("%ld\n", c->unique_size / c->unique_count);
+  else
+    printf_filtered ("(not applicable)\n");    
+  printf_filtered ("    Median entry size:  %d\n", median_entry_size);
+  printf_filtered ("\n");
+
   printf_filtered ("    Total memory used by bcache, including overhead: %ld\n",
 		   c->structure_size);
   printf_filtered ("    Percentage memory overhead: ");
@@ -330,6 +374,10 @@ print_bcache_statistics (struct bcache *c, char *type)
   printf_filtered ("\n");
 
   printf_filtered ("    Hash table size:           %3d\n", c->num_buckets);
+  printf_filtered ("    Hash table expands:        %lu\n",
+		   c->expand_count);
+  printf_filtered ("    Hash table hashes:         %lu\n",
+		   c->total_count + c->expand_hash_count);
   printf_filtered ("    Hash table population:     ");
   print_percentage (occupied_buckets, c->num_buckets);
   printf_filtered ("    Median hash chain length:  %3d\n",