[cassandra] properly clear cached containers.

clear containers before we use them rather than after, so that in the case of
exceptions we can recover.

closes #127

cassandra/src/main/java/com/yahoo/ycsb/db/CassandraClient10.java

@@ -453,6 +453,10 @@ public class CassandraClient10 extends DB {
     }
 
     for (int i = 0; i < operationRetries; i++) {
+      mutations.clear();
+      mutationMap.clear();
+      record.clear();
+
       if (debug) {
         System.out.println("Inserting key: " + key);
       }
@@ -479,10 +483,6 @@ public class CassandraClient10 extends DB {
 
         client.batch_mutate(record, writeConsistencyLevel);
 
-        mutations.clear();
-        mutationMap.clear();
-        record.clear();
-
         if (debug) {
           System.out
               .println("ConsistencyLevel=" + writeConsistencyLevel.toString());

cassandra/src/main/java/com/yahoo/ycsb/db/CassandraClient7.java

@@ -418,6 +418,10 @@ public class CassandraClient7 extends DB {
     }
 
     for (int i = 0; i < operationRetries; i++) {
+      mutations.clear();
+      mutationMap.clear();
+      record.clear();
+
       if (debug) {
         System.out.println("Inserting key: " + key);
       }
@@ -444,10 +448,6 @@ public class CassandraClient7 extends DB {
 
         client.batch_mutate(record, ConsistencyLevel.ONE);
 
-        mutations.clear();
-        mutationMap.clear();
-        record.clear();
-
         return Status.OK;
       } catch (Exception e) {
         errorexception = e;

cassandra/src/main/java/com/yahoo/ycsb/db/CassandraClient8.java

@@ -397,6 +397,10 @@ public class CassandraClient8 extends DB {
     }
 
     for (int i = 0; i < operationRetries; i++) {
+      mutations.clear();
+      mutationMap.clear();
+      record.clear();
+
       if (debug) {
         System.out.println("Inserting key: " + key);
       }
@@ -423,10 +427,6 @@ public class CassandraClient8 extends DB {
 
         client.batch_mutate(record, ConsistencyLevel.ONE);
 
-        mutations.clear();
-        mutationMap.clear();
-        record.clear();
-
         return Status.OK;
       } catch (Exception e) {
         errorexception = e;