xref: /redis-3.2.3/src/intset.c (revision 22c9c407) 
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <string.h>
4 #include "intset.h"
5 #include "zmalloc.h"
6 #include "endianconv.h"
7 
8 /* Note that these encodings are ordered, so:
9  * INTSET_ENC_INT16 < INTSET_ENC_INT32 < INTSET_ENC_INT64. */
10 #define INTSET_ENC_INT16 (sizeof(int16_t))
11 #define INTSET_ENC_INT32 (sizeof(int32_t))
12 #define INTSET_ENC_INT64 (sizeof(int64_t))
13 
14 /* Return the required encoding for the provided value. */
15 static uint8_t _intsetValueEncoding(int64_t v) {
16     if (v < INT32_MIN || v > INT32_MAX)
17         return INTSET_ENC_INT64;
18     else if (v < INT16_MIN || v > INT16_MAX)
19         return INTSET_ENC_INT32;
20     else
21         return INTSET_ENC_INT16;
22 }
23 
24 /* Return the value at pos, given an encoding. */
25 static int64_t _intsetGetEncoded(intset *is, int pos, uint8_t enc) {
26     int64_t v64;
27     int32_t v32;
28     int16_t v16;
29 
30     if (enc == INTSET_ENC_INT64) {
31         memcpy(&v64,((int64_t*)is->contents)+pos,sizeof(v64));
32         memrev64ifbe(&v64);
33         return v64;
34     } else if (enc == INTSET_ENC_INT32) {
35         memcpy(&v32,((int32_t*)is->contents)+pos,sizeof(v32));
36         memrev32ifbe(&v32);
37         return v32;
38     } else {
39         memcpy(&v16,((int16_t*)is->contents)+pos,sizeof(v16));
40         memrev16ifbe(&v16);
41         return v16;
42     }
43 }
44 
45 /* Return the value at pos, using the configured encoding. */
46 static int64_t _intsetGet(intset *is, int pos) {
47     return _intsetGetEncoded(is,pos,intrev32ifbe(is->encoding));
48 }
49 
50 /* Set the value at pos, using the configured encoding. */
51 static void _intsetSet(intset *is, int pos, int64_t value) {
52     uint32_t encoding = intrev32ifbe(is->encoding);
53 
54     if (encoding == INTSET_ENC_INT64) {
55         ((int64_t*)is->contents)[pos] = value;
56         memrev64ifbe(((int64_t*)is->contents)+pos);
57     } else if (encoding == INTSET_ENC_INT32) {
58         ((int32_t*)is->contents)[pos] = value;
59         memrev32ifbe(((int32_t*)is->contents)+pos);
60     } else {
61         ((int16_t*)is->contents)[pos] = value;
62         memrev16ifbe(((int16_t*)is->contents)+pos);
63     }
64 }
65 
66 /* Create an empty intset. */
67 intset *intsetNew(void) {
68     intset *is = zmalloc(sizeof(intset));
69     is->encoding = intrev32ifbe(INTSET_ENC_INT16);
70     is->length = 0;
71     return is;
72 }
73 
74 /* Resize the intset */
75 static intset *intsetResize(intset *is, uint32_t len) {
76     uint32_t size = len*intrev32ifbe(is->encoding);
77     is = zrealloc(is,sizeof(intset)+size);
78     return is;
79 }
80 
81 /* Search for the position of "value". Return 1 when the value was found and
82  * sets "pos" to the position of the value within the intset. Return 0 when
83  * the value is not present in the intset and sets "pos" to the position
84  * where "value" can be inserted. */
85 static uint8_t intsetSearch(intset *is, int64_t value, uint32_t *pos) {
86     int min = 0, max = intrev32ifbe(is->length)-1, mid = -1;
87     int64_t cur = -1;
88 
89     /* The value can never be found when the set is empty */
90     if (intrev32ifbe(is->length) == 0) {
91         if (pos) *pos = 0;
92         return 0;
93     } else {
94         /* Check for the case where we know we cannot find the value,
95          * but do know the insert position. */
96         if (value > _intsetGet(is,intrev32ifbe(is->length)-1)) {
97             if (pos) *pos = intrev32ifbe(is->length);
98             return 0;
99         } else if (value < _intsetGet(is,0)) {
100             if (pos) *pos = 0;
101             return 0;
102         }
103     }
104 
105     while(max >= min) {
106         mid = (min+max)/2;
107         cur = _intsetGet(is,mid);
108         if (value > cur) {
109             min = mid+1;
110         } else if (value < cur) {
111             max = mid-1;
112         } else {
113             break;
114         }
115     }
116 
117     if (value == cur) {
118         if (pos) *pos = mid;
119         return 1;
120     } else {
121         if (pos) *pos = min;
122         return 0;
123     }
124 }
125 
126 /* Upgrades the intset to a larger encoding and inserts the given integer. */
127 static intset *intsetUpgradeAndAdd(intset *is, int64_t value) {
128     uint8_t curenc = intrev32ifbe(is->encoding);
129     uint8_t newenc = _intsetValueEncoding(value);
130     int length = intrev32ifbe(is->length);
131     int prepend = value < 0 ? 1 : 0;
132 
133     /* First set new encoding and resize */
134     is->encoding = intrev32ifbe(newenc);
135     is = intsetResize(is,intrev32ifbe(is->length)+1);
136 
137     /* Upgrade back-to-front so we don't overwrite values.
138      * Note that the "prepend" variable is used to make sure we have an empty
139      * space at either the beginning or the end of the intset. */
140     while(length--)
141         _intsetSet(is,length+prepend,_intsetGetEncoded(is,length,curenc));
142 
143     /* Set the value at the beginning or the end. */
144     if (prepend)
145         _intsetSet(is,0,value);
146     else
147         _intsetSet(is,intrev32ifbe(is->length),value);
148     is->length = intrev32ifbe(intrev32ifbe(is->length)+1);
149     return is;
150 }
151 
152 static void intsetMoveTail(intset *is, uint32_t from, uint32_t to) {
153     void *src, *dst;
154     uint32_t bytes = intrev32ifbe(is->length)-from;
155     uint32_t encoding = intrev32ifbe(is->encoding);
156 
157     if (encoding == INTSET_ENC_INT64) {
158         src = (int64_t*)is->contents+from;
159         dst = (int64_t*)is->contents+to;
160         bytes *= sizeof(int64_t);
161     } else if (encoding == INTSET_ENC_INT32) {
162         src = (int32_t*)is->contents+from;
163         dst = (int32_t*)is->contents+to;
164         bytes *= sizeof(int32_t);
165     } else {
166         src = (int16_t*)is->contents+from;
167         dst = (int16_t*)is->contents+to;
168         bytes *= sizeof(int16_t);
169     }
170     memmove(dst,src,bytes);
171 }
172 
173 /* Insert an integer in the intset */
174 intset *intsetAdd(intset *is, int64_t value, uint8_t *success) {
175     uint8_t valenc = _intsetValueEncoding(value);
176     uint32_t pos;
177     if (success) *success = 1;
178 
179     /* Upgrade encoding if necessary. If we need to upgrade, we know that
180      * this value should be either appended (if > 0) or prepended (if < 0),
181      * because it lies outside the range of existing values. */
182     if (valenc > intrev32ifbe(is->encoding)) {
183         /* This always succeeds, so we don't need to curry *success. */
184         return intsetUpgradeAndAdd(is,value);
185     } else {
186         /* Abort if the value is already present in the set.
187          * This call will populate "pos" with the right position to insert
188          * the value when it cannot be found. */
189         if (intsetSearch(is,value,&pos)) {
190             if (success) *success = 0;
191             return is;
192         }
193 
194         is = intsetResize(is,intrev32ifbe(is->length)+1);
195         if (pos < intrev32ifbe(is->length)) intsetMoveTail(is,pos,pos+1);
196     }
197 
198     _intsetSet(is,pos,value);
199     is->length = intrev32ifbe(intrev32ifbe(is->length)+1);
200     return is;
201 }
202 
203 /* Delete integer from intset */
204 intset *intsetRemove(intset *is, int64_t value, int *success) {
205     uint8_t valenc = _intsetValueEncoding(value);
206     uint32_t pos;
207     if (success) *success = 0;
208 
209     if (valenc <= intrev32ifbe(is->encoding) && intsetSearch(is,value,&pos)) {
210         uint32_t len = intrev32ifbe(is->length);
211 
212         /* We know we can delete */
213         if (success) *success = 1;
214 
215         /* Overwrite value with tail and update length */
216         if (pos < (len-1)) intsetMoveTail(is,pos+1,pos);
217         is = intsetResize(is,len-1);
218         is->length = intrev32ifbe(len-1);
219     }
220     return is;
221 }
222 
223 /* Determine whether a value belongs to this set */
224 uint8_t intsetFind(intset *is, int64_t value) {
225     uint8_t valenc = _intsetValueEncoding(value);
226     return valenc <= intrev32ifbe(is->encoding) && intsetSearch(is,value,NULL);
227 }
228 
229 /* Return random member */
230 int64_t intsetRandom(intset *is) {
231     return _intsetGet(is,rand()%intrev32ifbe(is->length));
232 }
233 
234 /* Sets the value to the value at the given position. When this position is
235  * out of range the function returns 0, when in range it returns 1. */
236 uint8_t intsetGet(intset *is, uint32_t pos, int64_t *value) {
237     if (pos < intrev32ifbe(is->length)) {
238         *value = _intsetGet(is,pos);
239         return 1;
240     }
241     return 0;
242 }
243 
244 /* Return intset length */
245 uint32_t intsetLen(intset *is) {
246     return intrev32ifbe(is->length);
247 }
248 
249 /* Return intset blob size in bytes. */
250 size_t intsetBlobLen(intset *is) {
251     return sizeof(intset)+intrev32ifbe(is->length)*intrev32ifbe(is->encoding);
252 }
253 
254 #ifdef INTSET_TEST_MAIN
255 #include <sys/time.h>
256 
257 void intsetRepr(intset *is) {
258     int i;
259     for (i = 0; i < intrev32ifbe(is->length); i++) {
260         printf("%lld\n", (uint64_t)_intsetGet(is,i));
261     }
262     printf("\n");
263 }
264 
265 void error(char *err) {
266     printf("%s\n", err);
267     exit(1);
268 }
269 
270 void ok(void) {
271     printf("OK\n");
272 }
273 
274 long long usec(void) {
275     struct timeval tv;
276     gettimeofday(&tv,NULL);
277     return (((long long)tv.tv_sec)*1000000)+tv.tv_usec;
278 }
279 
280 #define assert(_e) ((_e)?(void)0:(_assert(#_e,__FILE__,__LINE__),exit(1)))
281 void _assert(char *estr, char *file, int line) {
282     printf("\n\n=== ASSERTION FAILED ===\n");
283     printf("==> %s:%d '%s' is not true\n",file,line,estr);
284 }
285 
286 intset *createSet(int bits, int size) {
287     uint64_t mask = (1<<bits)-1;
288     uint64_t i, value;
289     intset *is = intsetNew();
290 
291     for (i = 0; i < size; i++) {
292         if (bits > 32) {
293             value = (rand()*rand()) & mask;
294         } else {
295             value = rand() & mask;
296         }
297         is = intsetAdd(is,value,NULL);
298     }
299     return is;
300 }
301 
302 void checkConsistency(intset *is) {
303     int i;
304 
305     for (i = 0; i < (intrev32ifbe(is->length)-1); i++) {
306         uint32_t encoding = intrev32ifbe(is->encoding);
307 
308         if (encoding == INTSET_ENC_INT16) {
309             int16_t *i16 = (int16_t*)is->contents;
310             assert(i16[i] < i16[i+1]);
311         } else if (encoding == INTSET_ENC_INT32) {
312             int32_t *i32 = (int32_t*)is->contents;
313             assert(i32[i] < i32[i+1]);
314         } else {
315             int64_t *i64 = (int64_t*)is->contents;
316             assert(i64[i] < i64[i+1]);
317         }
318     }
319 }
320 
321 int main(int argc, char **argv) {
322     uint8_t success;
323     int i;
324     intset *is;
325     sranddev();
326 
327     printf("Value encodings: "); {
328         assert(_intsetValueEncoding(-32768) == INTSET_ENC_INT16);
329         assert(_intsetValueEncoding(+32767) == INTSET_ENC_INT16);
330         assert(_intsetValueEncoding(-32769) == INTSET_ENC_INT32);
331         assert(_intsetValueEncoding(+32768) == INTSET_ENC_INT32);
332         assert(_intsetValueEncoding(-2147483648) == INTSET_ENC_INT32);
333         assert(_intsetValueEncoding(+2147483647) == INTSET_ENC_INT32);
334         assert(_intsetValueEncoding(-2147483649) == INTSET_ENC_INT64);
335         assert(_intsetValueEncoding(+2147483648) == INTSET_ENC_INT64);
336         assert(_intsetValueEncoding(-9223372036854775808ull) == INTSET_ENC_INT64);
337         assert(_intsetValueEncoding(+9223372036854775807ull) == INTSET_ENC_INT64);
338         ok();
339     }
340 
341     printf("Basic adding: "); {
342         is = intsetNew();
343         is = intsetAdd(is,5,&success); assert(success);
344         is = intsetAdd(is,6,&success); assert(success);
345         is = intsetAdd(is,4,&success); assert(success);
346         is = intsetAdd(is,4,&success); assert(!success);
347         ok();
348     }
349 
350     printf("Large number of random adds: "); {
351         int inserts = 0;
352         is = intsetNew();
353         for (i = 0; i < 1024; i++) {
354             is = intsetAdd(is,rand()%0x800,&success);
355             if (success) inserts++;
356         }
357         assert(intrev32ifbe(is->length) == inserts);
358         checkConsistency(is);
359         ok();
360     }
361 
362     printf("Upgrade from int16 to int32: "); {
363         is = intsetNew();
364         is = intsetAdd(is,32,NULL);
365         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT16);
366         is = intsetAdd(is,65535,NULL);
367         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT32);
368         assert(intsetFind(is,32));
369         assert(intsetFind(is,65535));
370         checkConsistency(is);
371 
372         is = intsetNew();
373         is = intsetAdd(is,32,NULL);
374         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT16);
375         is = intsetAdd(is,-65535,NULL);
376         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT32);
377         assert(intsetFind(is,32));
378         assert(intsetFind(is,-65535));
379         checkConsistency(is);
380         ok();
381     }
382 
383     printf("Upgrade from int16 to int64: "); {
384         is = intsetNew();
385         is = intsetAdd(is,32,NULL);
386         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT16);
387         is = intsetAdd(is,4294967295,NULL);
388         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT64);
389         assert(intsetFind(is,32));
390         assert(intsetFind(is,4294967295));
391         checkConsistency(is);
392 
393         is = intsetNew();
394         is = intsetAdd(is,32,NULL);
395         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT16);
396         is = intsetAdd(is,-4294967295,NULL);
397         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT64);
398         assert(intsetFind(is,32));
399         assert(intsetFind(is,-4294967295));
400         checkConsistency(is);
401         ok();
402     }
403 
404     printf("Upgrade from int32 to int64: "); {
405         is = intsetNew();
406         is = intsetAdd(is,65535,NULL);
407         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT32);
408         is = intsetAdd(is,4294967295,NULL);
409         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT64);
410         assert(intsetFind(is,65535));
411         assert(intsetFind(is,4294967295));
412         checkConsistency(is);
413 
414         is = intsetNew();
415         is = intsetAdd(is,65535,NULL);
416         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT32);
417         is = intsetAdd(is,-4294967295,NULL);
418         assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT64);
419         assert(intsetFind(is,65535));
420         assert(intsetFind(is,-4294967295));
421         checkConsistency(is);
422         ok();
423     }
424 
425     printf("Stress lookups: "); {
426         long num = 100000, size = 10000;
427         int i, bits = 20;
428         long long start;
429         is = createSet(bits,size);
430         checkConsistency(is);
431 
432         start = usec();
433         for (i = 0; i < num; i++) intsetSearch(is,rand() % ((1<<bits)-1),NULL);
434         printf("%ld lookups, %ld element set, %lldusec\n",num,size,usec()-start);
435     }
436 
437     printf("Stress add+delete: "); {
438         int i, v1, v2;
439         is = intsetNew();
440         for (i = 0; i < 0xffff; i++) {
441             v1 = rand() % 0xfff;
442             is = intsetAdd(is,v1,NULL);
443             assert(intsetFind(is,v1));
444 
445             v2 = rand() % 0xfff;
446             is = intsetRemove(is,v2,NULL);
447             assert(!intsetFind(is,v2));
448         }
449         checkConsistency(is);
450         ok();
451     }
452 }
453 #endif
454