initial implementation for the intset

intset.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include "intset.h"
+#include "zmalloc.h"
+
+/* Note that these encodings are ordered, so:
+ * INTSET_ENC_INT16 < INTSET_ENC_INT32 < INTSET_ENC_INT64. */
+#define INTSET_ENC_INT16 (sizeof(int16_t))
+#define INTSET_ENC_INT32 (sizeof(int32_t))
+#define INTSET_ENC_INT64 (sizeof(int64_t))
+
+/* Accessors for each type of encoding */
+#define INTSET_VALUE_ENCODING(__val) (((__val) < INT32_MIN || (__val) > INT32_MAX) ? \
+    INTSET_ENC_INT64 : (((__val) < INT16_MIN || (__val) > INT16_MAX) ? \
+    INTSET_ENC_INT32 : INTSET_ENC_INT16))
+#define INTSET_GET_ENCODED(__is,__pos,__enc) ((__enc == INTSET_ENC_INT64) ? \
+    ((int64_t*)(__is)->contents)[__pos] : ((__enc == INTSET_ENC_INT32) ? \
+    ((int32_t*)(__is)->contents)[__pos] : ((int16_t*)(__is)->contents)[__pos]))
+#define INTSET_GET(__is,__pos) (INTSET_GET_ENCODED(__is,__pos,(__is)->encoding))
+#define INTSET_SET(__is,__pos,__val) { \
+    if ((__is)->encoding == INTSET_ENC_INT64) \
+        ((int64_t*)(__is)->contents)[__pos] = (__val); \
+    else if ((__is)->encoding == INTSET_ENC_INT32) \
+        ((int32_t*)(__is)->contents)[__pos] = (__val); \
+    else \
+        ((int16_t*)(__is)->contents)[__pos] = (__val); }
+
+/* Create an empty intset. */
+intset *intsetNew(void) {
+    intset *is = zmalloc(sizeof(intset));
+    is->encoding = INTSET_ENC_INT16;
+    is->length = 0;
+    return is;
+}
+
+/* Resize the intset */
+static intset *intsetResize(intset *is, uint32_t len) {
+    uint32_t size = len*is->encoding;
+    is = zrealloc(is,sizeof(intset)+size);
+    return is;
+}
+
+static intset *intsetUpgrade(intset *is, uint8_t newenc, uint8_t extra, uint8_t offset) {
+    uint8_t curenc = is->encoding;
+    int length = is->length;
+
+    /* First set new encoding and resize */
+    is->encoding = newenc;
+    is = intsetResize(is,is->length+extra);
+
+    /* Upgrade back-to-front so we don't overwrite values */
+    while(length--)
+        INTSET_SET(is,length+offset,INTSET_GET_ENCODED(is,length,curenc));
+    return is;
+}
+
+/* Search for the position of "value". Return 1 when the value was found and
+ * sets "pos" to the position of the value within the intset. Return 0 when
+ * the value is not present in the intset and sets "pos" to the position
+ * where "value" can be inserted. */
+static uint8_t intsetSearch(intset *is, int64_t value, uint32_t *pos) {
+    int min = 0, max = is->length-1, mid;
+    int64_t cur;
+
+    /* The value can never be found when the set is empty */
+    if (is->length == 0) {
+        if (pos) *pos = 0;
+        return 0;
+    }
+
+    while(max >= min) {
+        mid = (min+max)/2;
+        cur = INTSET_GET(is,mid);
+        if (value > cur) {
+            min = mid+1;
+        } else if (value < cur) {
+            max = mid-1;
+        } else {
+            break;
+        }
+    }
+
+    if (value == cur) {
+        if (pos) *pos = mid;
+        return 1;
+    } else {
+        if (pos) *pos = min;
+        return 0;
+    }
+}
+
+static void intsetMoveTail(intset *is, uint32_t from, uint32_t to) {
+    void *src, *dst;
+    uint32_t bytes = is->length-from;
+    if (is->encoding == INTSET_ENC_INT64) {
+        src = (int64_t*)is->contents+from;
+        dst = (int64_t*)is->contents+to;
+        bytes *= sizeof(int64_t);
+    } else if (is->encoding == INTSET_ENC_INT32) {
+        src = (int32_t*)is->contents+from;
+        dst = (int32_t*)is->contents+to;
+        bytes *= sizeof(int32_t);
+    } else {
+        src = (int16_t*)is->contents+from;
+        dst = (int16_t*)is->contents+to;
+        bytes *= sizeof(int16_t);
+    }
+    memmove(dst,src,bytes);
+}
+
+/* Insert an integer in the intset */
+intset *intsetAdd(intset *is, int64_t value, uint8_t *success) {
+    uint8_t valenc = INTSET_VALUE_ENCODING(value);
+    uint32_t pos, offset;
+    if (success) *success = 1;
+
+    /* Upgrade encoding if necessary. If we need to upgrade, we know that
+     * this value should be either appended (if > 0) or prepended (if < 0),
+     * because it lies outside the range of existing values. */
+    if (valenc > is->encoding) {
+        offset = value < 0 ? 1 : 0;
+        is = intsetUpgrade(is,valenc,1,offset);
+        pos = (value < 0) ? 0 : is->length;
+    } else {
+        if (is->length == 0) {
+            pos = 0;
+        } else {
+            /* Check for the case where we know the insert position */
+            if (value > INTSET_GET(is,is->length-1)) {
+                pos = is->length;
+            } else if (value < INTSET_GET(is,0)) {
+                pos = 0;
+            } else {
+                /* Abort if the value is already present in the set */
+                if (intsetSearch(is,value,&pos)) {
+                    if (success) *success = 0;
+                    return is;
+                }
+            }
+        }
+
+        is = intsetResize(is,is->length+1);
+        if (pos < is->length) intsetMoveTail(is,pos,pos+1);
+    }
+
+    INTSET_SET(is,pos,value);
+    is->length++;
+    return is;
+}
+
+/* Delete integer from intset */
+intset *intsetDelete(intset *is, int64_t value, uint8_t *success) {
+    uint8_t valenc = INTSET_VALUE_ENCODING(value);
+    uint32_t pos;
+    if (success) *success = 0;
+
+    if (valenc <= is->encoding && intsetSearch(is,value,&pos)) {
+        /* We know we can delete */
+        if (success) *success = 1;
+
+        /* Overwrite value with tail and update length */
+        if (pos < (is->length-1)) intsetMoveTail(is,pos+1,pos);
+        is = intsetResize(is,is->length-1);
+        is->length--;
+    }
+    return is;
+}
+
+/* Determine whether a value belongs to this set */
+uint8_t intsetFind(intset *is, int64_t value) {
+    uint8_t valenc = INTSET_VALUE_ENCODING(value);
+    return valenc <= is->encoding && intsetSearch(is,value,NULL);
+}
+
+/* Return random member */
+int64_t intsetRandom(intset *is) {
+    return INTSET_GET(is,rand()%is->length);
+}
+
+#ifdef INTSET_TEST_MAIN
+#include <sys/time.h>
+
+void intsetRepr(intset *is) {
+    int i;
+    for (i = 0; i < is->length; i++) {
+        printf("%lld\n", (uint64_t)INTSET_GET(is,i));
+    }
+    printf("\n");
+}
+
+void error(char *err) {
+    printf("%s\n", err);
+    exit(1);
+}
+
+void ok(void) {
+    printf("OK\n");
+}
+
+long long usec(void) {
+    struct timeval tv;
+    gettimeofday(&tv,NULL);
+    return (((long long)tv.tv_sec)*1000000)+tv.tv_usec;
+}
+
+#define assert(_e) ((_e)?(void)0:(_assert(#_e,__FILE__,__LINE__),exit(1)))
+void _assert(char *estr, char *file, int line) {
+    printf("\n\n=== ASSERTION FAILED ===\n");
+    printf("==> %s:%d '%s' is not true\n",file,line,estr);
+}
+
+intset *createSet(int bits, int size) {
+    uint64_t mask = (1<<bits)-1;
+    uint64_t i, value;
+    intset *is = intsetNew();
+
+    for (i = 0; i < size; i++) {
+        if (bits > 32) {
+            value = (rand()*rand()) & mask;
+        } else {
+            value = rand() & mask;
+        }
+        is = intsetAdd(is,value,NULL);
+    }
+    return is;
+}
+
+void checkConsistency(intset *is) {
+    int i;
+
+    for (i = 0; i < (is->length-1); i++) {
+        if (is->encoding == INTSET_ENC_INT16) {
+            int16_t *i16 = (int16_t*)is->contents;
+            assert(i16[i] < i16[i+1]);
+        } else if (is->encoding == INTSET_ENC_INT32) {
+            int32_t *i32 = (int32_t*)is->contents;
+            assert(i32[i] < i32[i+1]);
+        } else {
+            int64_t *i64 = (int64_t*)is->contents;
+            assert(i64[i] < i64[i+1]);
+        }
+    }
+}
+
+int main(int argc, char **argv) {
+    uint8_t success;
+    int i;
+    intset *is;
+    sranddev();
+
+    printf("Value encodings: "); {
+        assert(INTSET_VALUE_ENCODING(-32768) == INTSET_ENC_INT16);
+        assert(INTSET_VALUE_ENCODING(+32767) == INTSET_ENC_INT16);
+        assert(INTSET_VALUE_ENCODING(-32769) == INTSET_ENC_INT32);
+        assert(INTSET_VALUE_ENCODING(+32768) == INTSET_ENC_INT32);
+        assert(INTSET_VALUE_ENCODING(-2147483648) == INTSET_ENC_INT32);
+        assert(INTSET_VALUE_ENCODING(+2147483647) == INTSET_ENC_INT32);
+        assert(INTSET_VALUE_ENCODING(-2147483649) == INTSET_ENC_INT64);
+        assert(INTSET_VALUE_ENCODING(+2147483648) == INTSET_ENC_INT64);
+        assert(INTSET_VALUE_ENCODING(-9223372036854775808ull) == INTSET_ENC_INT64);
+        assert(INTSET_VALUE_ENCODING(+9223372036854775807ull) == INTSET_ENC_INT64);
+        ok();
+    }
+
+    printf("Basic adding: "); {
+        is = intsetNew();
+        is = intsetAdd(is,5,&success); assert(success);
+        is = intsetAdd(is,6,&success); assert(success);
+        is = intsetAdd(is,4,&success); assert(success);
+        is = intsetAdd(is,4,&success); assert(!success);
+        ok();
+    }
+
+    printf("Large number of random adds: "); {
+        int inserts = 0;
+        is = intsetNew();
+        for (i = 0; i < 1024; i++) {
+            is = intsetAdd(is,rand()%0x800,&success);
+            if (success) inserts++;
+        }
+        assert(is->length == inserts);
+        checkConsistency(is);
+        ok();
+    }
+
+    printf("Upgrade from int16 to int32: "); {
+        is = intsetNew();
+        is = intsetAdd(is,32,NULL);
+        assert(is->encoding == INTSET_ENC_INT16);
+        is = intsetAdd(is,65535,NULL);
+        assert(is->encoding == INTSET_ENC_INT32);
+        assert(intsetFind(is,32));
+        assert(intsetFind(is,65535));
+        checkConsistency(is);
+
+        is = intsetNew();
+        is = intsetAdd(is,32,NULL);
+        assert(is->encoding == INTSET_ENC_INT16);
+        is = intsetAdd(is,-65535,NULL);
+        assert(is->encoding == INTSET_ENC_INT32);
+        assert(intsetFind(is,32));
+        assert(intsetFind(is,-65535));
+        checkConsistency(is);
+        ok();
+    }
+
+    printf("Upgrade from int16 to int64: "); {
+        is = intsetNew();
+        is = intsetAdd(is,32,NULL);
+        assert(is->encoding == INTSET_ENC_INT16);
+        is = intsetAdd(is,4294967295,NULL);
+        assert(is->encoding == INTSET_ENC_INT64);
+        assert(intsetFind(is,32));
+        assert(intsetFind(is,4294967295));
+        checkConsistency(is);
+
+        is = intsetNew();
+        is = intsetAdd(is,32,NULL);
+        assert(is->encoding == INTSET_ENC_INT16);
+        is = intsetAdd(is,-4294967295,NULL);
+        assert(is->encoding == INTSET_ENC_INT64);
+        assert(intsetFind(is,32));
+        assert(intsetFind(is,-4294967295));
+        checkConsistency(is);
+        ok();
+    }
+
+    printf("Upgrade from int32 to int64: "); {
+        is = intsetNew();
+        is = intsetAdd(is,65535,NULL);
+        assert(is->encoding == INTSET_ENC_INT32);
+        is = intsetAdd(is,4294967295,NULL);
+        assert(is->encoding == INTSET_ENC_INT64);
+        assert(intsetFind(is,65535));
+        assert(intsetFind(is,4294967295));
+        checkConsistency(is);
+
+        is = intsetNew();
+        is = intsetAdd(is,65535,NULL);
+        assert(is->encoding == INTSET_ENC_INT32);
+        is = intsetAdd(is,-4294967295,NULL);
+        assert(is->encoding == INTSET_ENC_INT64);
+        assert(intsetFind(is,65535));
+        assert(intsetFind(is,-4294967295));
+        checkConsistency(is);
+        ok();
+    }
+
+    printf("Stress lookups: "); {
+        long num = 100000, size = 10000;
+        int i, bits = 20;
+        long long start;
+        is = createSet(bits,size);
+        checkConsistency(is);
+
+        start = usec();
+        for (i = 0; i < num; i++) intsetSearch(is,rand() % ((1<<bits)-1),NULL);
+        printf("%ld lookups, %ld element set, %lldusec\n",num,size,usec()-start);
+    }
+
+    printf("Stress add+delete: "); {
+        int i, v1, v2;
+        is = intsetNew();
+        for (i = 0; i < 0xffff; i++) {
+            v1 = rand() % 0xfff;
+            is = intsetAdd(is,v1,NULL);
+            assert(intsetFind(is,v1));
+
+            v2 = rand() % 0xfff;
+            is = intsetDelete(is,v2,NULL);
+            assert(!intsetFind(is,v2));
+        }
+        checkConsistency(is);
+        ok();
+    }
+}
+#endif

intset.h

+#ifndef __INTSET_H
+#define __INTSET_H
+
+typedef struct intset {
+    uint32_t encoding;
+    uint32_t length;
+    int8_t contents[];
+} intset;
+
+intset *intsetNew(void);
+intset *intsetAdd(intset *is, int64_t value, uint8_t *success);
+intset *intsetDelete(intset *is, int64_t value, uint8_t *success);
+uint8_t intsetFind(intset *is, int64_t value);
+int64_t intsetRandom(intset *is);
+
+#endif // __INTSET_H