Bug#34843889 Handle temporary error during load table

Temporary errors can occur while opening a table from the NDB dictionary, this kind of error is rare but can be provoked by repeatedly performing schema operations. Since failing to open the NDB table definition most often causes fatal errors down the line, it's most likely better to take some time and attempt to resolve the temporary error by retrying to open the table. These kind of temporary errors are primarily important to get rid of when distributing schema operations throughout the cluster, where many MySQL Server simultaneously attempts to open table from NDB. Fix by handling temporary errors while opening table from NDB with retry. It is acceptable with some delays during these operations in order for temporary resource shortages to subside while opening tables. Change-Id: Ie26426d7f4892828d1e759d131fdbda810a5c846

Author: blaudden

storage/ndb/plugin/ndb_table_guard.h

@@ -31,6 +31,7 @@
 #include "storage/ndb/include/ndbapi/Ndb.hpp"
 #include "storage/ndb/include/ndbapi/NdbDictionary.hpp"
 #include "storage/ndb/plugin/ndb_dbname_guard.h"
+#include "storage/ndb/plugin/ndb_sleep.h"
 
 /*
  @brief This class maintains the reference to a NDB table definition retrieved
@@ -81,11 +82,47 @@ class Ndb_table_guard {
  return;
  }
 
+ /**
+ @brief Initialize the NDB Dictionary table by loading it from NDB while
+ handling temporary errors by retrying a few times
+
+ @param dbname The database name of table to load
+ @param tabname The table name of table to load
+ */
  void init(const char *dbname, const char *tabname) {
  DBUG_TRACE;
  /* Don't allow init() if already initialized */
  assert(m_ndbtab == nullptr);
 
+ int attempt = 1;
+ constexpr int retries = 10;
+ do {
+ open_table_from_NDB(dbname, tabname);
+ if (m_ndbtab) {
+ // Successfully loaded table
+ return;
+ }
+ // Expect error to be set
+ assert(m_ndberror.code != 0);
+
+ if (m_ndberror.status != NdbError::TemporaryError) {
+ // Not an error that should be retried
+ return;
+ }
+
+ attempt++;
+ ndb_retry_sleep(50);
+
+ } while (attempt < retries);
+
+ // Failed to load table
+ assert(m_ndbtab == nullptr && m_ndberror.code != 0);
+ }
+
+ void open_table_from_NDB(const char *dbname, const char *tabname) {
+ DBUG_TRACE;
+ assert(m_ndbtab == nullptr);
+
  // Change to the database where the table should be found
  Ndb_dbname_guard dbname_guard(m_ndb, dbname);
  if (dbname_guard.change_database_failed()) {