server/common/shstr.C

/*
 * shstr.C
 */

#include <cstring>
#include <cstdlib>

#include <tr1/unordered_set>

#include "shstr.h"
#include "util.h"

typedef std::tr1::unordered_set<const char *, str_hash, str_equal> HT;

static HT ht;

static const char *makevec (const char *s)
{
  int len = strlen (s);

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

  shstr::length (v) = len;
  shstr::refcnt (v) = 1;

  memcpy ((char *)v, s, len + 1);

  return v;
}

const char *shstr::null = makevec ("<nil>");

// what weird misoptimisation is this again?
const shstr undead_name ("undead");

const char *
shstr::find (const char *s)
{
  if (!s)
    return s;

  HT::iterator i = ht.find (s);

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

const char *
shstr::intern (const char *s)
{
  if (!s)
    return null;

  if (const char *found = find (s))
    {
      ++refcnt (found);
      return found;
    }

  s = makevec (s);
  ht.insert (s);
  return s;
}

// periodically test refcounts == 0 for a few strings
// this is the ONLY thing that erases stuff from ht. keep it that way.
void
shstr::gc ()
{
  static const char *curpos;

  HT::iterator i = curpos ? ht.find (curpos) : ht.begin ();

  if (i == ht.end ())
    i = ht.begin ();

  // go through all strings roughly once every 4 minutes
  int n = ht.size () / 256 + 16;

  for (;;)
    {
      if (i == ht.end ())
        {
          curpos = 0;
          return;
        }
      else if (!--n)
        break;
      else if (!refcnt (*i))
        {
          HT::iterator o = i++;
          const char *s = *o;
          ht.erase (o);

          //printf ("GC %4d %3d %d >%s<%d\n", (int)ht.size (), n, shstr::refcnt (s), s, shstr::length (s));
          free (-2 + (int *)s);
        }
      else
        ++i;
    }

  curpos = *i;
}

//TODO: this should of course not be here
/* 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:	1.9
Committed:	Mon Sep 4 17:16:19 2006 UTC (17 years, 9 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.8:	+2 -36 lines
Log Message:	* empty log message *
#	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	root	1.9	#include "util.h"
12	elmex	1.1
13	root	1.9	typedef std::tr1::unordered_set<const char *, str_hash, str_equal> HT;
14	elmex	1.1
15	root	1.3	static HT ht;
16	elmex	1.1
17	root	1.7	static const char makevec (const char s)
18			{
19			int len = strlen (s);
20
21			const char v = (const char )(2 + (int )malloc (sizeof (int) 2 + len + 1));
22
23			shstr::length (v) = len;
24			shstr::refcnt (v) = 1;
25
26			memcpy ((char *)v, s, len + 1);
27
28	root	1.8	return v;
29	root	1.7	}
30
31			const char *shstr::null = makevec ("<nil>");
32
33	root	1.8	// what weird misoptimisation is this again?
34			const shstr undead_name ("undead");
35
36	elmex	1.1	const char *
37	root	1.3	shstr::find (const char *s)
38			{
39	root	1.4	if (!s)
40			return s;
41
42	root	1.3	HT::iterator i = ht.find (s);
43	elmex	1.1
44	root	1.3	return i != ht.end ()
45	root	1.5	? *i
46	root	1.3	: 0;
47	elmex	1.1	}
48
49			const char *
50	root	1.3	shstr::intern (const char *s)
51			{
52	root	1.4	if (!s)
53	root	1.7	return null;
54	elmex	1.1
55	root	1.4	if (const char *found = find (s))
56	root	1.5	{
57			++refcnt (found);
58			return found;
59			}
60	elmex	1.1
61	root	1.7	s = makevec (s);
62			ht.insert (s);
63			return s;
64	elmex	1.1	}
65
66	root	1.5	// periodically test refcounts == 0 for a few strings
67			// this is the ONLY thing that erases stuff from ht. keep it that way.
68	elmex	1.1	void
69	root	1.3	shstr::gc ()
70			{
71	root	1.5	static const char *curpos;
72
73			HT::iterator i = curpos ? ht.find (curpos) : ht.begin ();
74
75			if (i == ht.end ())
76			i = ht.begin ();
77
78			// go through all strings roughly once every 4 minutes
79	root	1.6	int n = ht.size () / 256 + 16;
80
81			for (;;)
82	root	1.5	{
83			if (i == ht.end ())
84			{
85			curpos = 0;
86			return;
87			}
88	root	1.6	else if (!--n)
89			break;
90			else if (!refcnt (*i))
91	root	1.5	{
92			HT::iterator o = i++;
93			const char s = o;
94			ht.erase (o);
95
96			//printf ("GC %4d %3d %d >%s<%d\n", (int)ht.size (), n, shstr::refcnt (s), s, shstr::length (s));
97			free (-2 + (int *)s);
98			}
99			else
100			++i;
101			}
102
103			curpos = *i;
104	elmex	1.1	}
105
106	root	1.5	//TODO: this should of course not be here
107	elmex	1.1	/* buf_overflow() - we don't want to exceed the buffer size of
108			* buf1 by adding on buf2! Returns true if overflow will occur.
109			*/
110
111			int
112			buf_overflow (const char buf1, const char buf2, int bufsize)
113			{
114	root	1.3	int len1 = 0, len2 = 0;
115	elmex	1.1
116			if (buf1)
117	root	1.2	len1 = strlen (buf1);
118	elmex	1.1	if (buf2)
119	root	1.2	len2 = strlen (buf2);
120	elmex	1.1	if ((len1 + len2) >= bufsize)
121	root	1.2	return 1;
122	elmex	1.1	return 0;
123			}
124