MCOL-605 limit connections for I_S table

I_S.COLUMNSTORE_FILES now caches a connection per dbroot instead of
using a connection per file.

dbcon/mysql/is_columnstore_files.cpp

@@ -49,27 +49,14 @@ ST_FIELD_INFO is_columnstore_files_fields[] =
     {0, 0, MYSQL_TYPE_NULL, 0, 0, 0, 0}
 };
 
-static bool get_file_sizes(int db_root, const char *fileName, off_t *fileSize, off_t *compressedFileSize)
+static bool get_file_sizes(messageqcpp::MessageQueueClient *msgQueueClient, const char *fileName, off_t *fileSize, off_t *compressedFileSize)
 {
-    oam::Oam oam_instance;
-    messageqcpp::MessageQueueClient *msgQueueClient;
-    std::ostringstream oss;
     messageqcpp::ByteStream bs;
     messageqcpp::ByteStream::byte rc;
     std::string errMsg;
-    int pmId = 0;
 
-    oam_instance.getDbrootPmConfig(db_root, pmId);
-    oss << "pm" << pmId << "_WriteEngineServer";
     try
     {
-        msgQueueClient = new messageqcpp::MessageQueueClient(oss.str());
-    }
-    catch (...)
-    {
-        delete msgQueueClient;
-        return false;
-    }
         bs << (messageqcpp::ByteStream::byte) WriteEngine::WE_SVR_GET_FILESIZE;
         // header??
         bs << fileName;
@@ -86,12 +73,27 @@ static bool get_file_sizes(int db_root, const char *fileName, off_t *fileSize, o
         *sbs >> errMsg;
         *sbs >> *fileSize;
         *sbs >> *compressedFileSize;
-    delete msgQueueClient;
         return true;
+    }
+    catch (...)
+    {
+        return false;
+    }
 }
 
-static bool is_columnstore_files_get_entries(THD *thd, TABLE_LIST *tables, BRM::OID_t oid, std::vector<struct BRM::EMEntry> &entries)
+static void cleanup(std::map<int, messageqcpp::MessageQueueClient*> &clients)
 {
+    for(std::map<int, messageqcpp::MessageQueueClient*>::iterator itr = clients.begin(); itr != clients.end(); itr++)
+    {
+        delete itr->second;
+    }
+}
+
+
+static int is_columnstore_files_fill(THD *thd, TABLE_LIST *tables, COND *cond)
+{
+    BRM::DBRM *emp = new BRM::DBRM();
+    std::vector<struct BRM::EMEntry> entries;
     CHARSET_INFO *cs = system_charset_info;
     TABLE *table = tables->table;
 
@@ -103,7 +105,25 @@ static bool is_columnstore_files_get_entries(THD *thd, TABLE_LIST *tables, BRM::
     off_t fileSize = 0;
     off_t compressedFileSize = 0;
     we_config.initConfigCache();
+    std::map<int, messageqcpp::MessageQueueClient*> clients;
+    messageqcpp::MessageQueueClient *msgQueueClient;
+    oam::Oam oam_instance;
+    int pmId = 0;
+    std::ostringstream oss;
 
+    if (!emp || !emp->isDBRMReady())
+    {
+        return 1;
+    }
+
+    execplan::ObjectIDManager oidm;
+    BRM::OID_t MaxOID = oidm.size();
+
+    for(BRM::OID_t oid = 3000; oid <= MaxOID; oid++)
+    {
+        emp->getExtents(oid, entries, false, false, true);
+        if (entries.size() == 0)
+            continue;
 
         std::vector<struct BRM::EMEntry>::const_iterator iter = entries.begin();
         while ( iter != entries.end() ) //organize extents into files
@@ -124,8 +144,37 @@ static bool is_columnstore_files_get_entries(THD *thd, TABLE_LIST *tables, BRM::
             std::string DbRootPath = config->getConfig("SystemConfig", DbRootName.str());
             fileSize = compressedFileSize = 0;
             snprintf(fullFileName, WriteEngine::FILE_NAME_SIZE, "%s/%s", DbRootPath.c_str(), oidDirName);
-        if (!get_file_sizes(iter->dbRoot, fullFileName, &fileSize, &compressedFileSize))
+            try
             {
+                msgQueueClient = clients.at(iter->dbRoot);
+            }
+            catch (...)
+            {
+                msgQueueClient = NULL;
+            }
+            if (!msgQueueClient)
+            {
+                oam_instance.getDbrootPmConfig(iter->dbRoot, pmId);
+                oss << "pm" << pmId << "_WriteEngineServer";
+                try
+                {
+                    msgQueueClient = new messageqcpp::MessageQueueClient(oss.str());
+                }
+                catch (...)
+                {
+                    delete msgQueueClient;
+                    cleanup(clients);
+                    delete emp;
+                    return 1;
+                }
+                clients[iter->dbRoot] = msgQueueClient;
+            }
+
+
+            if (!get_file_sizes(msgQueueClient, fullFileName, &fileSize, &compressedFileSize))
+            {
+                cleanup(clients);
+                delete emp;
                 return 1;
             }
             table->field[3]->store(fullFileName, strlen(fullFileName), cs);
@@ -151,39 +200,14 @@ static bool is_columnstore_files_get_entries(THD *thd, TABLE_LIST *tables, BRM::
             }
 
             if (schema_table_store_record(thd, table))
-            return 1;
-        iter++;
-    }
-    return 0;
-}
-
-static int is_columnstore_files_fill(THD *thd, TABLE_LIST *tables, COND *cond)
-{
-    BRM::DBRM *emp = new BRM::DBRM();
-    std::vector<struct BRM::EMEntry> entries;
-
-    if (!emp || !emp->isDBRMReady())
-    {
-        return 1;
-    }
-
-    execplan::ObjectIDManager oidm;
-    BRM::OID_t MaxOID = oidm.size();
-
-    for(BRM::OID_t oid = 3000; oid <= MaxOID; oid++)
-    {
-        emp->getExtents(oid, entries, false, false, true);
-        if (entries.size() == 0)
-            continue;
-
-        if (is_columnstore_files_get_entries(thd, tables, oid, entries))
             {
+                cleanup(clients);
                 delete emp;
                 return 1;
             }
-
+            iter++;
+        }
     }
-
     delete emp;
     return 0;
 }