Support local files in the sync client

Summary:
The async client doesn't support local files (used for LOAD DATA LOCAL INFILE) as the response from the server is telling the client to start sending the file and the code has never been written to handle this correctly in a background thread.

However, the sync client can support it.  Add the code to query the client for whether it can be supported when initializing the connection.

Reviewed By: abal147

Differential Revision: D33781238

fbshipit-source-id: da8c2ee3f635682a82ef4fa5144ccbbd69ed0302

Author: jkedgar

squangle/mysql_client/AsyncMysqlClient.h

@@ -189,6 +189,11 @@ class AsyncMysqlClient : public MysqlClientBase {
     return ret;
   }
 
+  bool supportsLocalFiles() override {
+    // The async client does not yet support local files for LOAD DATA
+    return false;
+  }
+
  protected:
   AsyncMysqlClient(
       std::unique_ptr<db::SquangleLoggerBase> db_logger,

squangle/mysql_client/Connection.cpp

@@ -43,7 +43,9 @@ void Connection::initMysqlOnly() {
   CHECK_THROW(mysql_connection_ == nullptr, db::InvalidConnectionException);
   mysql_connection_ = std::make_unique<MysqlConnectionHolder>(
       mysql_client_, mysql_init(nullptr), conn_key_);
-  mysql_connection_->mysql()->options.client_flag &= ~CLIENT_LOCAL_FILES;
+  if (!mysql_client_->supportsLocalFiles()) {
+    mysql_connection_->mysql()->options.client_flag &= ~CLIENT_LOCAL_FILES;
+  }
   // Turn off SSL by default for tests that rely on this.
   enum mysql_ssl_mode ssl_mode = SSL_MODE_DISABLED;
   mysql_options(mysql_connection_->mysql(), MYSQL_OPT_SSL_MODE, &ssl_mode);

squangle/mysql_client/MysqlClientBase.h

@@ -120,6 +120,8 @@ class MysqlClientBase {
     return 0.0;
   }
 
+  virtual bool supportsLocalFiles() = 0;
+
  protected:
   friend class Connection;
   friend class Operation;

squangle/mysql_client/SyncMysqlClient.h

@@ -58,6 +58,10 @@ class SyncMysqlClient : public MysqlClientBase {
 
   void drain(bool /*unused*/) {}
 
+  bool supportsLocalFiles() override {
+    return true;
+  }
+
  protected:
   // Private methods, primarily used by Operations and its subclasses.
   friend class AsyncConnectionPool;