Addresses #1576 Removed (return a-b) comparison trick in tests, added comments about the issue

git-svn-id: file:///svn/toku/tokudb@10392 c7de825b-a66e-492c-adef-691d508d4ae1

newbrt/key.c

@@ -64,6 +64,7 @@ int toku_keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2le
 }
 #else
 /* unroll that one four times */
+// when a and b are chars, return a-b is safe here because return type is int.  No over/underflow possible.
 int toku_keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
     int comparelen = key1len<key2len ? key1len : key2len;
     const unsigned char *k1;
@@ -83,6 +84,7 @@ int toku_keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2le
 	    return (int)*k1-(int)*k2;
 	}
     }
+    //See #1576.  For very large keylengths this is a problem.  Our maximum keysize is << INT_MAX so this is not an issue.
     return key1len-key2len;
 }
 

src/lock_tree/tests/test.h

@@ -23,7 +23,9 @@ static inline int intcmp(DB *db __attribute__((__unused__)), const DBT* a, const
     int x = *(int*)a->data;
     int y = *(int*)b->data;
 
-    return x - y;
+    if (x<y) return -1;
+    if (x>y) return 1;
+    return 0;
 }
 
 

src/range_tree/tests/test.h

@@ -63,13 +63,16 @@ static inline int
 int_cmp (const toku_point* a, const toku_point*b) {
     int x = *(int*)a;
     int y = *(int*)b;
-    return x -y;
+    if (x<y) return -1;
+    if (x>y) return 1;
+    return 0;
 }
 
 static inline int
 char_cmp (const TXNID a, const TXNID b) {
     int x = (char)a;
     int y = (char)b;
+    //x-y is safe because no over/underflow is possible.  Range of values is 8bit
     return x -y;
 }
 

src/tests/test.h

@@ -97,7 +97,9 @@ int_dbt_cmp (DB *db, const DBT *a, const DBT *b) {
   int x = *(int *) a->data;
   int y = *(int *) b->data;
 
-  return x - y;
+    if (x<y) return -1;
+    if (x>y) return 1;
+    return 0;
 }
 
 #if !TOKU_WINDOWS