implemented basic redis operations

db/redis/com/yahoo/ycsb/db/RedisClient.java

@@ -8,6 +8,8 @@ import com.yahoo.ycsb.DB;
 import com.yahoo.ycsb.DBException;
 
 import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
 import java.util.Properties;
 import java.util.Set;
 import java.util.Vector;
@@ -46,30 +48,48 @@ public class RedisClient extends DB {
         }
     }
 
+    //XXX jedis.select(int index) to switch to `table`
+
     @Override
     public int read(String table, String key, Set<String> fields,
             HashMap<String, String> result) {
-        return 0;
+        if (fields == null) {
+            result.putAll(jedis.hgetAll(key));
+        }
+        else {
+            String[] fieldArray = (String[])fields.toArray(new String[fields.size()]);
+            List<String> values = jedis.hmget(key, fieldArray);
+
+            Iterator<String> fieldIterator = fields.iterator();
+            Iterator<String> valueIterator = values.iterator();
+
+            while (fieldIterator.hasNext() && valueIterator.hasNext()) {
+                result.put(fieldIterator.next(), valueIterator.next());
+            }
+            assert !fieldIterator.hasNext() && !valueIterator.hasNext();
+        }
+        return result.isEmpty() ? 1 : 0;
     }
 
     @Override
     public int insert(String table, String key, HashMap<String, String> values) {
-        return 0;
+        return jedis.hmset(key, values).equals("OK") ? 0 : 1;
     }
 
     @Override
     public int delete(String table, String key) {
-        return 0;
+        return jedis.del(key) == 0 ? 1 : 0;
     }
 
     @Override
     public int update(String table, String key, HashMap<String, String> values) {
-        return 0;
+        return jedis.hmset(key, values).equals("OK") ? 0 : 1;
     }
 
     @Override
     public int scan(String table, String startkey, int recordcount,
             Set<String> fields, Vector<HashMap<String, String>> result) {
+        //XXX
         return 0;
     }