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| 3 | */ |
3 | */ |
| 4 | |
4 | |
| 5 | #include <cstring> |
5 | #include <cstring> |
| 6 | #include <cstdlib> |
6 | #include <cstdlib> |
| 7 | |
7 | |
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8 | #include <glib.h> |
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9 | |
| 8 | #include <tr1/unordered_set> |
10 | #include <tr1/unordered_set> |
| 9 | |
11 | |
| 10 | #include "shstr.h" |
12 | #include "shstr.h" |
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13 | #include "util.h" |
| 11 | |
14 | |
| 12 | // NOTE: even with lots of stuff loaded, we do not usually have >>20000 strings. |
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| 13 | // maybe refcounting is just overhead? |
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| 14 | |
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| 15 | struct hash |
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| 16 | { |
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| 17 | std::size_t operator ()(const char *s) const |
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| 18 | { |
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| 19 | unsigned long hash = 0; |
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| 20 | unsigned int i = 0; |
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| 21 | |
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| 22 | /* use the one-at-a-time hash function, which supposedly is |
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| 23 | * better than the djb2-like one used by perl5.005, but |
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| 24 | * certainly is better then the bug used here before. |
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| 25 | * see http://burtleburtle.net/bob/hash/doobs.html |
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| 26 | */ |
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| 27 | while (*s) |
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| 28 | { |
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| 29 | hash += *s++; |
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| 30 | hash += hash << 10; |
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| 31 | hash ^= hash >> 6; |
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| 32 | } |
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| 33 | |
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| 34 | hash += hash << 3; |
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| 35 | hash ^= hash >> 11; |
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| 36 | hash += hash << 15; |
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| 37 | |
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| 38 | return hash; |
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| 39 | } |
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| 40 | }; |
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| 41 | |
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| 42 | struct equal |
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| 43 | { |
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| 44 | bool operator ()(const char *a, const char *b) const |
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| 45 | { |
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| 46 | return !strcmp (a, b); |
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| 47 | } |
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| 48 | }; |
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| 49 | |
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| 50 | typedef std::tr1::unordered_set<const char *, hash, equal> HT; |
15 | typedef std::tr1::unordered_set<const char *, str_hash, str_equal> HT; |
| 51 | |
16 | |
| 52 | static HT ht; |
17 | static HT ht; |
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18 | |
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19 | static const char *makevec (const char *s) |
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20 | { |
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21 | int len = strlen (s); |
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22 | |
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23 | const char *v = (const char *)(2 + (int *)g_slice_alloc (sizeof (int) * 2 + len + 1)); |
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24 | |
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25 | shstr::length (v) = len; |
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26 | shstr::refcnt (v) = 1; |
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27 | |
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28 | memcpy ((char *)v, s, len + 1); |
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29 | |
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30 | return v; |
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31 | } |
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32 | |
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33 | const char *shstr::null = makevec ("<nil>"); |
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34 | |
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35 | // what weird misoptimisation is this again? |
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36 | const shstr undead_name ("undead"); |
| 53 | |
37 | |
| 54 | const char * |
38 | const char * |
| 55 | shstr::find (const char *s) |
39 | shstr::find (const char *s) |
| 56 | { |
40 | { |
| 57 | if (!s) |
41 | if (!s) |
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| 66 | |
50 | |
| 67 | const char * |
51 | const char * |
| 68 | shstr::intern (const char *s) |
52 | shstr::intern (const char *s) |
| 69 | { |
53 | { |
| 70 | if (!s) |
54 | if (!s) |
| 71 | return s; |
55 | return null; |
| 72 | |
56 | |
| 73 | if (const char *found = find (s)) |
57 | if (const char *found = find (s)) |
| 74 | { |
58 | { |
| 75 | ++refcnt (found); |
59 | ++refcnt (found); |
| 76 | return found; |
60 | return found; |
| 77 | } |
61 | } |
| 78 | |
62 | |
| 79 | int len = strlen (s); |
63 | s = makevec (s); |
| 80 | |
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| 81 | const char *v = (const char *)(2 + (int *)malloc (sizeof (int) * 2 + len + 1)); |
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| 82 | |
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| 83 | length (v) = len; |
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| 84 | refcnt (v) = 1; |
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| 85 | |
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| 86 | memcpy ((char *)v, s, len + 1); |
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| 87 | |
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| 88 | ht.insert (v); |
64 | ht.insert (s); |
| 89 | |
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| 90 | return v; |
65 | return s; |
| 91 | } |
66 | } |
| 92 | |
67 | |
| 93 | // periodically test refcounts == 0 for a few strings |
68 | // periodically test refcounts == 0 for a few strings |
| 94 | // this is the ONLY thing that erases stuff from ht. keep it that way. |
69 | // this is the ONLY thing that erases stuff from ht. keep it that way. |
| 95 | void |
70 | void |
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| 101 | |
76 | |
| 102 | if (i == ht.end ()) |
77 | if (i == ht.end ()) |
| 103 | i = ht.begin (); |
78 | i = ht.begin (); |
| 104 | |
79 | |
| 105 | // go through all strings roughly once every 4 minutes |
80 | // go through all strings roughly once every 4 minutes |
| 106 | for (int n = ht.size () / 256 + 16; --n; ) |
81 | int n = ht.size () / 256 + 16; |
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82 | |
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83 | for (;;) |
| 107 | { |
84 | { |
| 108 | if (i == ht.end ()) |
85 | if (i == ht.end ()) |
| 109 | { |
86 | { |
| 110 | curpos = 0; |
87 | curpos = 0; |
| 111 | return; |
88 | return; |
| 112 | } |
89 | } |
| 113 | |
90 | else if (!--n) |
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91 | break; |
| 114 | if (!refcnt (*i)) |
92 | else if (!refcnt (*i)) |
| 115 | { |
93 | { |
| 116 | HT::iterator o = i++; |
94 | HT::iterator o = i++; |
| 117 | const char *s = *o; |
95 | const char *s = *o; |
| 118 | ht.erase (o); |
96 | ht.erase (o); |
| 119 | |
97 | |
| 120 | //printf ("GC %4d %3d %d >%s<%d\n", (int)ht.size (), n, shstr::refcnt (s), s, shstr::length (s)); |
98 | //printf ("GC %4d %3d %d >%s<%d\n", (int)ht.size (), n, shstr::refcnt (s), s, shstr::length (s)); |
| 121 | free (-2 + (int *)s); |
99 | g_slice_free1 (sizeof (int) * 2 + length (s) + 1, -2 + (int *)s); |
| 122 | } |
100 | } |
| 123 | else |
101 | else |
| 124 | ++i; |
102 | ++i; |
| 125 | } |
103 | } |
| 126 | |
104 | |
