server/common/shstr.C

/*
 * shstr.C
 */

#include <cstring>
#include <cstdlib>

#include <tr1/unordered_set>

#include "shstr.h"

struct hash
{
  std::size_t operator ()(const char *s) const
  {
    unsigned long hash = 0;
    unsigned int i = 0;

    /* use the one-at-a-time hash function, which supposedly is
     * better than the djb2-like one used by perl5.005, but
     * certainly is better then the bug used here before.
     * see http://burtleburtle.net/bob/hash/doobs.html
     */
    while (*s)
      {
        hash += *s++;
        hash += hash << 10;
        hash ^= hash >>  6;
      }

    hash += hash <<  3;
    hash ^= hash >> 11;
    hash += hash << 15;

    return hash;
  }
};

struct equal
{
  bool operator ()(const char *a, const char *b) const
  {
    return !strcmp (a, b);
  }
};

typedef std::tr1::unordered_set<const char *, hash, equal> HT;

static HT ht;

const char *
shstr::find (const char *s)
{
  HT::iterator i = ht.find (s);

  return i != ht.end ()
    ? (char *)*i
    : 0;
}

const char *
shstr::intern (const char *s)
{
  HT::iterator i = ht.find (s);

  if (i != ht.end ())
    return (char *)*i;

  int len = strlen (s);

  int *v = (int *)malloc (sizeof (int) * 2 + len + 1);

  v [0] = len;
  v [1] = 0;

  v += 2;

  memcpy (v, s, len + 1);

  ht.insert ((char *)v);

  return (char *)v;
}

// TODO: periodically test refcounts == 0 for a few strings (e.g. one hash bucket,
// exploiting the fatc that iterators stay valid for unordered_set).
void
shstr::gc ()
{
}

/* buf_overflow() - we don't want to exceed the buffer size of 
 * buf1 by adding on buf2! Returns true if overflow will occur.
 */

int 
buf_overflow (const char *buf1, const char *buf2, int bufsize)
{
    int len1 = 0, len2 = 0;

    if (buf1)
        len1 = strlen (buf1);
    if (buf2)
        len2 = strlen (buf2);
    if ((len1 + len2) >= bufsize)
        return 1;
    return 0;
}

Revision:	1.3
Committed:	Sun Sep 3 00:18:40 2006 UTC (17 years, 8 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.2:	+61 -373 lines
Log Message:	THIS CODE WILL NOT COMPILE use the STABLE tag instead. - major changes in object lifetime and memory management - replaced manual refcounting by shstr class - removed quest system - many optimisations - major changes
#	User	Rev	Content
1	elmex	1.1	/*
2	root	1.3	* shstr.C
3	elmex	1.1	*/
4
5	root	1.3	#include <cstring>
6			#include <cstdlib>
7
8			#include <tr1/unordered_set>
9	elmex	1.1
10			#include "shstr.h"
11
12	root	1.3	struct hash
13			{
14			std::size_t operator ()(const char *s) const
15			{
16	elmex	1.1	unsigned long hash = 0;
17	root	1.3	unsigned int i = 0;
18	elmex	1.1
19	root	1.3	/* use the one-at-a-time hash function, which supposedly is
20			* better than the djb2-like one used by perl5.005, but
21			* certainly is better then the bug used here before.
22			* see http://burtleburtle.net/bob/hash/doobs.html
23	elmex	1.1	*/
24	root	1.3	while (*s)
25			{
26			hash += *s++;
27			hash += hash << 10;
28			hash ^= hash >> 6;
29			}
30
31			hash += hash << 3;
32			hash ^= hash >> 11;
33			hash += hash << 15;
34
35			return hash;
36			}
37			};
38	elmex	1.1
39	root	1.3	struct equal
40			{
41			bool operator ()(const char a, const char b) const
42			{
43			return !strcmp (a, b);
44			}
45			};
46	elmex	1.1
47	root	1.3	typedef std::tr1::unordered_set<const char *, hash, equal> HT;
48	elmex	1.1
49	root	1.3	static HT ht;
50	elmex	1.1
51			const char *
52	root	1.3	shstr::find (const char *s)
53			{
54			HT::iterator i = ht.find (s);
55	elmex	1.1
56	root	1.3	return i != ht.end ()
57			? (char )i
58			: 0;
59	elmex	1.1	}
60
61			const char *
62	root	1.3	shstr::intern (const char *s)
63			{
64			HT::iterator i = ht.find (s);
65	elmex	1.1
66	root	1.3	if (i != ht.end ())
67			return (char )i;
68	elmex	1.1
69	root	1.3	int len = strlen (s);
70	elmex	1.1
71	root	1.3	int v = (int )malloc (sizeof (int) * 2 + len + 1);
72	elmex	1.1
73	root	1.3	v [0] = len;
74			v [1] = 0;
75	elmex	1.1
76	root	1.3	v += 2;
77	elmex	1.1
78	root	1.3	memcpy (v, s, len + 1);
79	elmex	1.1
80	root	1.3	ht.insert ((char *)v);
81	elmex	1.1
82	root	1.3	return (char *)v;
83	elmex	1.1	}
84
85	root	1.3	// TODO: periodically test refcounts == 0 for a few strings (e.g. one hash bucket,
86			// exploiting the fatc that iterators stay valid for unordered_set).
87	elmex	1.1	void
88	root	1.3	shstr::gc ()
89			{
90	elmex	1.1	}
91
92			/* buf_overflow() - we don't want to exceed the buffer size of
93			* buf1 by adding on buf2! Returns true if overflow will occur.
94			*/
95
96			int
97			buf_overflow (const char buf1, const char buf2, int bufsize)
98			{
99	root	1.3	int len1 = 0, len2 = 0;
100	elmex	1.1
101			if (buf1)
102	root	1.2	len1 = strlen (buf1);
103	elmex	1.1	if (buf2)
104	root	1.2	len2 = strlen (buf2);
105	elmex	1.1	if ((len1 + len2) >= bufsize)
106	root	1.2	return 1;
107	elmex	1.1	return 0;
108			}
109