Speedup toku_hashtable_random_pick

git-svn-id: file:///svn/tokudb@134 c7de825b-a66e-492c-adef-691d508d4ae1

newbrt/brt.c

@@ -709,9 +709,10 @@ static int push_some_kvpairs_down (BRT t, BRTNODE node, int childnum,
     {
 	bytevec key,val;
 	ITEMLEN keylen, vallen;
+	long int randomnumber = random();
 	//printf("%s:%d Try random_pick, weight=%d \n", __FILE__, __LINE__, node->u.n.n_bytes_in_hashtable[childnum]);
 	assert(toku_hashtable_n_entries(node->u.n.htables[childnum])>0);
-	while(0==toku_hashtable_random_pick(node->u.n.htables[childnum], &key, &keylen, &val, &vallen)) {
+	while(0==toku_hashtable_random_pick(node->u.n.htables[childnum], &key, &keylen, &val, &vallen, &randomnumber)) {
 	    int child_did_split=0; BRTNODE childa, childb;
 	    DBT hk,hv;
 	    DBT childsplitk;

newbrt/hashtable.c

@@ -134,9 +134,9 @@ int toku_hash_delete (HASHTABLE tab, const void *key, ITEMLEN keylen) {
 }
 
 
-int toku_hashtable_random_pick(HASHTABLE h, bytevec *key, ITEMLEN *keylen, bytevec *data, ITEMLEN *datalen) {
+int toku_hashtable_random_pick(HASHTABLE h, bytevec *key, ITEMLEN *keylen, bytevec *data, ITEMLEN *datalen, long int *randomnumber) {
     unsigned int i;
-    unsigned int usei = random()%h->arraysize;
+    unsigned int usei = (*randomnumber)%h->arraysize;
     for (i=0; i<h->arraysize; i++, usei++) {
 	if (usei>=h->arraysize) usei=0;
 	HASHELT he=h->array[usei];
@@ -145,6 +145,7 @@ int toku_hashtable_random_pick(HASHTABLE h, bytevec *key, ITEMLEN *keylen, bytev
 	    *keylen = he->keylen;
 	    *data = &he->keyval[he->keylen];
 	    *datalen = he->vallen;
+	    *randomnumber = usei;
 	    return 0;
 	}
     }

newbrt/hashtable.h

@@ -24,7 +24,7 @@ int toku_hashtable_n_entries(HASHTABLE);
   
 void toku_hashtable_clear(HASHTABLE);
 
-int toku_hashtable_random_pick(HASHTABLE h, bytevec *key, ITEMLEN *keylen, bytevec *data, ITEMLEN *datalen);
+int toku_hashtable_random_pick(HASHTABLE h, bytevec *key, ITEMLEN *keylen, bytevec *data, ITEMLEN *datalen, long int *randomnumber);
 //int hashtable_find_last(HASHTABLE h, bytevec *key, ITEMLEN *keylen, bytevec *data, ITEMLEN *datalen);
 
 typedef struct hashelt *HASHELT;

newbrt/hashtest.c

@@ -127,7 +127,8 @@ void test1(void) {
 	for (j=0; j<4; j++) {
 	    bytevec key, val;
 	    ITEMLEN keylen, vallen;
-	    r = toku_hashtable_random_pick(table, &key, &keylen, &val, &vallen);
+	    long int randnum=random();
+	    r = toku_hashtable_random_pick(table, &key, &keylen, &val, &vallen, &randnum);
 	    assert(r==0);
 	    r = toku_hash_delete(table, key, keylen);
 	    assert(r==0);

newbrt/key.c

@@ -62,7 +62,7 @@ int keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
     return key1len-key2len;
 }
 #else
-/* unroll that one twice */
+/* unroll that one four times */
 int keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
     int comparelen = key1len<key2len ? key1len : key2len;
     const unsigned char *k1;