SERVER-7668 further cleanup related to extending range bounds

This removes the complicated modifiedRangeBound method in
dbhelpers.h/cpp and replaces it with calls to the extendRangeBound
method defined in the previous SERVER-7668 patch, as well as the
toKeyFormat method. The latter has been split into two functions,
toKeyFormat and inferKeyPattern, which have more intuitive behavior.

1 files changed, 8 insertions, 29 deletions

diff --git a/src/mongo/db/dbhelpers.h b/src/mongo/db/dbhelpers.h
index ff479bc1d11..9474289bfc6 100644
--- a/src/mongo/db/dbhelpers.h
+++ b/src/mongo/db/dbhelpers.h
@@ -108,38 +108,17 @@ namespace mongo {
 
         // TODO: this should be somewhere else probably
         /* Takes object o, and returns a new object with the
-         * same field elements but the names stripped out.  Also,
-         * fills in "key" with an ascending keyPattern that matches o
+         * same field elements but the names stripped out.
          * Example:
-         *    o = {a : 5 , b : 6} -->
-         *      sets key= {a : 1, b :1}, returns {"" : 5, "" : 6}
+         *    o = {a : 5 , b : 6} --> {"" : 5, "" : 6}
          */
-        static BSONObj toKeyFormat( const BSONObj& o , BSONObj& key );
-
-        /* Takes a BSONObj indicating the min or max boundary of a range,
-         * and a keyPattern corresponding to an index that is useful
-         * for locating items in the range, and returns an "extension"
-         * of the bound, modified to fit the given pattern.  In other words,
-         * it appends MinKey or MaxKey values to the bound, so that the extension
-         * has the same number of fields as keyPattern.
-         * minOrMax should be -1/+1 to indicate whether the extension
-         * corresponds to the min or max bound for the range.
-         * Also, strips out the field names to put the bound in key format.
-         * Examples:
-         *   {a : 55}, {a :1}, -1 --> {"" : 55}
-         *   {a : 55}, {a : 1, b : 1}, -1 -> {"" : 55, "" : minKey}
-         *   {a : 55}, {a : 1, b : 1}, 1 -> {"" : 55, "" : maxKey}
-         *   {a : 55}, {a : 1, b : -1}, -1 -> {"" : 55, "" : maxKey}
-         *   {a : 55}, {a : 1, b : -1}, 1 -> {"" : 55, "" : minKey}
-         *
-         * This function is useful for modifying chunk ranges in sharding,
-         * when the shard key is a prefix of the index actually used
-         * (also useful when the shard key is equal to the index used,
-         * since it strips out the field names).
+        static BSONObj toKeyFormat( const BSONObj& o );
+
+        /* Takes object o, and infers an ascending keyPattern with the same fields as o
+         * Example:
+         *    o = {a : 5 , b : 6} --> {a : 1 , b : 1 }
          */
-        static BSONObj modifiedRangeBound( const BSONObj& bound ,
-                                           const BSONObj& keyPattern ,
-                                           int minOrMax );
+        static BSONObj inferKeyPattern( const BSONObj& o );
 
         class RemoveCallback {
         public: