add DbTxn::abort. closes #232

git-svn-id: file:///svn/tokudb@1439 c7de825b-a66e-492c-adef-691d508d4ae1

cxx/txn.cpp

@@ -19,3 +19,10 @@ int DbTxn::commit (u_int32_t flags) {
     the_txn=0; // So we don't touch it my mistake.
     return env->maybe_throw_error(ret);
 }
+
+int DbTxn::abort () {
+    DbEnv *env = (DbEnv*)the_txn->mgrp->api1_internal; // Must grab the env before committing the txn (because that releases the txn memory.)
+    int ret = the_txn->abort(the_txn);
+    the_txn=0; // So we don't touch it my mistake.
+    return env->maybe_throw_error(ret);
+}

include/db_cxx.h

@@ -161,6 +161,7 @@ class DbEnv {
 class DbTxn {
  public:
     int commit (u_int32_t /*flags*/);
+    int abort ();
 
     virtual ~DbTxn();