tbuildbuck.c - plan9port - [fork] Plan 9 from user space
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tbuildbuck.c (2837B)
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1 #include "stdinc.h"
2 #include "dat.h"
3 #include "fns.h"
4
5 /*
6 * An IEStream is a sorted list of index entries.
7 */
8 struct IEStream
9 {
10 Part *part;
11 u64int off; /* read position within part */
12 u64int n; /* number of valid ientries left to read */
13 u32int size; /* allocated space in buffer */
14 u8int *buf;
15 u8int *pos; /* current place in buffer */
16 u8int *epos; /* end of valid buffer contents */
17 };
18
19 IEStream*
20 initiestream(Part *part, u64int off, u64int clumps, u32int size)
21 {
22 IEStream *ies;
23
24 /* out of memory? */
25 ies = MKZ(IEStream);
26 ies->buf = MKN(u8int, size);
27 ies->epos = ies->buf;
28 ies->pos = ies->epos;
29 ies->off = off;
30 ies->n = clumps;
31 ies->size = size;
32 ies->part = part;
33 return ies;
34 }
35
36 void
37 freeiestream(IEStream *ies)
38 {
39 if(ies == nil)
40 return;
41 free(ies->buf);
42 free(ies);
43 }
44
45 /*
46 * Return the next IEntry (still packed) in the stream.
47 */
48 static u8int*
49 peekientry(IEStream *ies)
50 {
51 u32int n, nn;
52
53 n = ies->epos - ies->pos;
54 if(n < IEntrySize){
55 memmove(ies->buf, ies->pos, n);
56 ies->epos = &ies->buf[n];
57 ies->pos = ies->buf;
58 nn = ies->size;
59 if(nn > ies->n * IEntrySize)
60 nn = ies->n * IEntrySize;
61 nn -= n;
62 if(nn == 0)
63 return nil;
64 //fprint(2, "peek %d from %llud into %p\n", nn, ies->off, ies->epos);
65 if(readpart(ies->part, ies->off, ies->epos, nn) < 0){
66 seterr(EOk, "can't read sorted index entries: %r");
67 return nil;
68 }
69 ies->epos += nn;
70 ies->off += nn;
71 }
72 return ies->pos;
73 }
74
75 /*
76 * Compute the bucket number for the given IEntry.
77 * Knows that the score is the first thing in the packed
78 * representation.
79 */
80 static u32int
81 iebuck(Index *ix, u8int *b, IBucket *ib, IEStream *ies)
82 {
83 USED(ies);
84 USED(ib);
85 return hashbits(b, 32) / ix->div;
86 }
87
88 /*
89 * Fill ib with the next bucket in the stream.
90 */
91 u32int
92 buildbucket(Index *ix, IEStream *ies, IBucket *ib, uint maxdata)
93 {
94 IEntry ie1, ie2;
95 u8int *b;
96 u32int buck;
97
98 buck = TWID32;
99 ib->n = 0;
100 while(ies->n){
101 b = peekientry(ies);
102 if(b == nil)
103 return TWID32;
104 /* fprint(2, "b=%p ies->n=%lld ib.n=%d buck=%d score=%V\n", b, ies->n, ib->n, iebuck(ix, b, ib, ies), b); */
105 if(ib->n == 0)
106 buck = iebuck(ix, b, ib, ies);
107 else{
108 if(buck != iebuck(ix, b, ib, ies))
109 break;
110 if(ientrycmp(&ib->data[(ib->n - 1)* IEntrySize], b) == 0){
111 /*
112 * guess that the larger address is the correct one to use
113 */
114 unpackientry(&ie1, &ib->data[(ib->n - 1)* IEntrySize]);
115 unpackientry(&ie2, b);
116 seterr(EOk, "duplicate index entry for score=%V type=%d", ie1.score, ie1.ia.type);
117 ib->n--;
118 if(ie1.ia.addr > ie2.ia.addr)
119 memmove(b, &ib->data[ib->n * IEntrySize], IEntrySize);
120 }
121 }
122 if((ib->n+1)*IEntrySize > maxdata){
123 seterr(EOk, "bucket overflow");
124 return TWID32;
125 }
126 memmove(&ib->data[ib->n * IEntrySize], b, IEntrySize);
127 ib->n++;
128 ies->n--;
129 ies->pos += IEntrySize;
130 }
131 return buck;
132 }