mariadb/newbrt/key.c

#include "brt-internal.h"
#include <assert.h>
#include <string.h>

#if 0
int toku_keycompare (bytevec key1b, ITEMLEN key1len, bytevec key2b, ITEMLEN key2len) {
    const unsigned char *key1 = key1b;
    const unsigned char *key2 = key2b;
    while (key1len > 0 && key2len > 0) {
	unsigned char b1 = key1[0];
	unsigned char b2 = key2[0];
	if (b1<b2) return -1;
	if (b1>b2) return 1;
	key1len--; key1++;
	key2len--; key2++;
    }
    if (key1len<key2len) return -1;
    if (key1len>key2len) return 1;
    return 0;
}

#elif 0
int toku_keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
    if (key1len==key2len) {
	return memcmp(key1,key2,key1len);
    } else if (key1len<key2len) {
	int r = memcmp(key1,key2,key1len);
	if (r<=0) return -1; /* If the keys are the same up to 1's length, then return -1, since key1 is shorter than key2. */
	else return 1;
    } else {
	return -toku_keycompare(key2,key2len,key1,key1len);
    }
}
#elif 0

int toku_keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
    if (key1len==key2len) {
	return memcmp(key1,key2,key1len);
    } else if (key1len<key2len) {
	int r = memcmp(key1,key2,key1len);
	if (r<=0) return -1; /* If the keys are the same up to 1's length, then return -1, since key1 is shorter than key2. */
	else return 1;
    } else {
	int r = memcmp(key1,key2,key2len);
	if (r>=0) return 1; /* If the keys are the same up to 2's length, then return 1 since key1 is longer than key2 */
	else return -1;
    }
}
#elif 0
/* This one looks tighter, but it does use memcmp... */
int toku_keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
    int comparelen = key1len<key2len ? key1len : key2len;
    const unsigned char *k1;
    const unsigned char *k2;
    for (k1=key1, k2=key2;
	 comparelen>0;
	 k1++, k2++, comparelen--) {
	if (*k1 != *k2) {
	    return (int)*k1-(int)*k2;
	}
    }
    return key1len-key2len;
}
#else
/* unroll that one four times */
int toku_keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
    int comparelen = key1len<key2len ? key1len : key2len;
    const unsigned char *k1;
    const unsigned char *k2;
    for (k1=key1, k2=key2;
	 comparelen>4;
	 k1+=4, k2+=4, comparelen-=4) {
	{ int v1=k1[0], v2=k2[0]; if (v1!=v2) return v1-v2; }
	{ int v1=k1[1], v2=k2[1]; if (v1!=v2) return v1-v2; }
	{ int v1=k1[2], v2=k2[2]; if (v1!=v2) return v1-v2; }
	{ int v1=k1[3], v2=k2[3]; if (v1!=v2) return v1-v2; }
    }
    for (;
	 comparelen>0;
	 k1++, k2++, comparelen--) {
	if (*k1 != *k2) {
	    return (int)*k1-(int)*k2;
	}
    }
    return key1len-key2len;
}

#endif

void toku_test_keycompare (void) {
    assert(toku_keycompare("a",1, "a",1)==0);
    assert(toku_keycompare("aa",2, "a",1)>0);
    assert(toku_keycompare("a",1, "aa",2)<0);
    assert(toku_keycompare("b",1, "aa",2)>0);
    assert(toku_keycompare("aa",2, "b",1)<0);
    assert(toku_keycompare("aaaba",5, "aaaba",5)==0);
    assert(toku_keycompare("aaaba",5, "aaaaa",5)>0);
    assert(toku_keycompare("aaaaa",5, "aaaba",5)<0);
    assert(toku_keycompare("aaaaa",3, "aaaba",3)==0);
}

int toku_default_compare_fun (DB *db __attribute__((__unused__)), const DBT *a, const DBT*b) {
    return toku_keycompare(a->data, a->size, b->data, b->size);
}

int dont_call_this_compare_fun (DB *db __attribute__((__unused__)), const DBT *a __attribute__((__unused__)), const DBT*b __attribute__((__unused__))) {
    assert(0);
}