#4771 use a txn mutex to protect the txn lock tree set refs[t:4771]

git-svn-id: file:///svn/toku/tokudb@42930 c7de825b-a66e-492c-adef-691d508d4ae1

src/ydb-internal.h

@@ -215,6 +215,7 @@ struct __toku_db_txn_internal {
     TOKU_ISOLATION iso;
     DB_TXN *child;
     struct toku_list dbs_that_must_close_before_abort;
+    toku_pthread_mutex_t txn_mutex;
 };
 struct __toku_db_txn_external {
     struct __toku_db_txn           external_part;

src/ydb_row_lock.c

@@ -12,6 +12,7 @@ static int
 toku_txn_add_lt(DB_TXN* txn, toku_lock_tree* lt) {
     int r = ENOSYS;
     assert(txn && lt);
+    toku_mutex_lock(&db_txn_struct_i(txn)->txn_mutex);
     toku_lth* lth = db_txn_struct_i(txn)->lth;
     // we used to initialize the transaction's lth during begin.
     // Now we initialize the lth only if the transaction needs the lth, here
@@ -33,6 +34,7 @@ toku_txn_add_lt(DB_TXN* txn, toku_lock_tree* lt) {
     toku_lt_add_ref(lt);
     r = 0;
 cleanup:
+    toku_mutex_unlock(&db_txn_struct_i(txn)->txn_mutex);
     return r;
 }
 

src/ydb_txn.c

@@ -53,6 +53,7 @@ toku_txn_destroy(DB_TXN *txn) {
     (void) __sync_fetch_and_sub(&txn->mgrp->i->open_txns, 1);
     assert(txn->mgrp->i->open_txns>=0);
     toku_txn_destroy_txn(db_txn_struct_i(txn)->tokutxn);
+    toku_mutex_destroy(&db_txn_struct_i(txn)->txn_mutex);
 #if !TOKUDB_NATIVE_H
     toku_free(db_txn_struct_i(txn));
 #endif
@@ -502,6 +503,7 @@ toku_txn_begin(DB_ENV *env, DB_TXN * stxn, DB_TXN ** txn, u_int32_t flags, bool
         db_txn_struct_i(result->parent)->child = result;
     }
 
+    toku_mutex_init(&db_txn_struct_i(result)->txn_mutex, NULL);
     (void) __sync_fetch_and_add(&env->i->open_txns, 1);
 
     *txn = result;