From 469294502e8ba99fd36feacd5e704b833b882ba9 Mon Sep 17 00:00:00 2001
From: Tomasz Sowa <t.sowa@ttmath.org>
Date: Fri, 29 Apr 2022 05:56:02 +0200
Subject: [PATCH] allow specify how many times we can try to connect to the
 database

---
 src/postgresqlconnector.cpp | 54 ++++++++++++++++++++++++++++++++-----
 src/postgresqlconnector.h   | 28 +++++++++++++------
 2 files changed, 67 insertions(+), 15 deletions(-)

diff --git a/src/postgresqlconnector.cpp b/src/postgresqlconnector.cpp
index 62a7a18..6cc26ee 100644
--- a/src/postgresqlconnector.cpp
+++ b/src/postgresqlconnector.cpp
@@ -101,7 +101,7 @@ bool PostgreSQLConnector::do_query(const char * query_str, PostgreSQLQueryResult
 		{
 			if( PQstatus(pg_conn) != CONNECTION_OK )
 			{
-				assert_connection();
+				assert_connection_is_working();
 				psql_result->psql_result = PQexec(pg_conn, query_str);
 			}
 		}
@@ -431,6 +431,8 @@ void PostgreSQLConnector::set_conn_param(const std::wstring & database_name, con
 }
 
 
+
+
 void PostgreSQLConnector::overwrite(pt::TextStream & stream)
 {
 	pt::TextStream::iterator i = stream.begin();
@@ -511,6 +513,17 @@ void PostgreSQLConnector::connect()
 //
 //
 
+void PostgreSQLConnector::log_no_connection(size_t attempts)
+{
+	if( log )
+	{
+		(*log) << pt::Log::log2 << "Morm: connection to the database cannot be established";
+		(*log) << pt::Log::log3 << ", (" << attempts << " attempt(s))" << pt::Log::logend;
+		(*log) << pt::Log::logsave;
+	}
+}
+
+
 void PostgreSQLConnector::log_connection_socket()
 {
 	if( pg_conn && log )
@@ -521,8 +534,18 @@ void PostgreSQLConnector::log_connection_socket()
 	}
 }
 
-void PostgreSQLConnector::wait_for_connection()
+
+bool PostgreSQLConnector::wait_for_connection(size_t attempts_max, size_t attempt_delay)
 {
+	size_t attempts = 0;
+	bool attempts_exceeded = false;
+
+	if( attempt_delay == 0 )
+		attempt_delay = 1;
+
+	if( attempt_delay > 120 )
+		attempt_delay = 120;
+
 	if( !pg_conn || PQstatus(pg_conn) != CONNECTION_OK )
 	{
 		if( log )
@@ -530,24 +553,41 @@ void PostgreSQLConnector::wait_for_connection()
 			(*log) << pt::Log::log3 << "Morm: waiting for the db to be ready...." << pt::Log::logend << pt::Log::logsave;
 		}
 
-		while( !assert_connection(false) )
+		while( !attempts_exceeded && !assert_connection_is_working(false) )
 		{
-			sleep(5);
-		}
+			if( attempts_max != 0 )
+			{
+				attempts += 1;
+				attempts_exceeded = (attempts >= attempts_max);
+			}
 
+			if( !attempts_exceeded )
+			{
+				sleep(attempt_delay);
+			}
+		}
+	}
+
+	if( attempts_exceeded )
+	{
+		log_no_connection(attempts);
+	}
+	else
+	{
 		log_connection_socket();
 	}
+
+	return !attempts_exceeded;
 }
 
 
 
 
 // IMPROVE ME what about the exception now?
-bool PostgreSQLConnector::assert_connection(bool put_log)
+bool PostgreSQLConnector::assert_connection_is_working(bool put_log)
 {
 bool was_connection = true;
 
-
 	if( !pg_conn )
 	{
 		was_connection = false;
diff --git a/src/postgresqlconnector.h b/src/postgresqlconnector.h
index 7755075..d5b99ae 100644
--- a/src/postgresqlconnector.h
+++ b/src/postgresqlconnector.h
@@ -104,17 +104,23 @@ public:
 	virtual void set_conn_param(const std::wstring & database_host, const std::wstring & database_hostaddr, const std::wstring & database_port,
 								const std::wstring & database, const std::wstring & user, const std::wstring & pass);
 
-
 	virtual void set_conn_param(const std::wstring & database, const std::wstring & user, const std::wstring & pass);
 
-	virtual void connect();
-	virtual void wait_for_connection();
-	virtual void close();
-	//virtual bool assert_connection(bool put_log = true, bool throw_if_no_connection = true);
-	virtual bool assert_connection(bool put_log = true);
-	virtual void set_db_parameters();
-	virtual void log_connection_socket();
 
+	/*
+	 * waiting for a valid connection to the database
+	 *
+	 * attempts_max - how many connection attempts are allowed (0 - infinite)
+	 * attempt_delay - delay between each attempt (in seconds)
+	 *
+	 */
+	virtual bool wait_for_connection(size_t attempts_max = 0, size_t attempt_delay = 5);
+
+
+	/*
+	 * close the connection with the database if it was open
+	 */
+	virtual void close();
 
 
 
@@ -132,6 +138,12 @@ protected:
 	std::wstring db_user;
 	std::wstring db_pass;
 
+	virtual void set_db_parameters();
+	virtual void log_no_connection(size_t attempts);
+	virtual void log_connection_socket();
+	virtual bool assert_connection_is_working(bool put_log = true);
+	virtual void connect();
+
 	virtual bool do_query(const char * query_str, PostgreSQLQueryResult * psql_result);
 	virtual void allocate_default_expression();
 	virtual void overwrite(pt::TextStream & stream);