Resolve 'database is locked' problem when opening a new connection

The schema and static tables should only be initialized on the first
connection; ensuring the database is in WAL mode and setting up a
connection busy handler also should have been done immediately upon
connection rather than at the end of the connection process

README.md

@@ -47,6 +47,7 @@ git clone https://github.com/djp952/external-sqlite -b sqlite-3.17.0 --depth=1
 git clone https://github.com/djp952/prebuilt-libcurl -b libcurl-7.52.1 --depth=1
 git clone https://github.com/djp952/prebuilt-libssl -b libssl-1.0.2k --depth=1
 git clone https://github.com/djp952/prebuilt-libuuid -b libuuid-1.0.3 --depth=1
+git clone https://github.com/djp952/prebuilt-libz -b libz-1.2.8 --depth=1
 git clone https://github.com/djp952/pvr.hdhomerundvr -b Jarvis
 cd pvr.hdhomerundvr
 msbuild msbuild.proj

pvr.hdhomerundvr/changelog.txt

@@ -1,3 +1,8 @@
+v1.0.3
+- Add "SD Channels" channel group
+- Use IPv4 specific backend discovery URLs (ipv4.my.hdhomerun.com)
+- Resolve issue with SQLite database being locked during initialization of a new connection
+
 v1.0.2
 - Add option to enable discovery of extended (8 hour) Electronic Program Guide data
 - Update SQLite database engine to v3.17.0

src/database.cpp

@@ -172,9 +172,9 @@ connectionpool::connectionpool(char const* connstring, int flags) : m_connstr((c
 
 	if(connstring == nullptr) throw std::invalid_argument("connstring");
 
-	// Create and pool an initial connection now to give the caller an opportunity
-	// to catch any exceptions during construction of the connection pool 
-	handle = open_database(m_connstr.c_str(), m_flags);
+	// Create and pool the initial connection now to give the caller an opportunity
+	// to catch any exceptions during initialization of the database
+	handle = open_database(m_connstr.c_str(), m_flags, true);
 	m_connections.push_back(handle);
 	m_queue.push(handle);
 }
@@ -205,9 +205,8 @@ sqlite3* connectionpool::acquire(void)
 
 	if(m_queue.empty()) {
 
-		// No connections are available, open a new one using the same connection data
-		// and add it to the vector<> of all active connection objects
-		handle = open_database(m_connstr.c_str(), m_flags);
+		// No connections are available, open a new one using the same flags
+		handle = open_database(m_connstr.c_str(), m_flags, false);
 		m_connections.push_back(handle);
 	}
 
@@ -2523,18 +2522,43 @@ void modify_recordingrule(sqlite3* instance, struct recordingrule const& recordi
 //	flags			- Database open flags (see sqlite3_open_v2)
 
 sqlite3* open_database(char const* connstring, int flags)
+{
+	return open_database(connstring, flags, false);
+}
+
+//---------------------------------------------------------------------------
+// open_database
+//
+// Opens the SQLite database instance
+//
+// Arguments:
+//
+//	connstring		- Database connection string
+//	flags			- Database open flags (see sqlite3_open_v2)
+//	initialize		- Flag indicating database schema should be (re)initialized
+
+sqlite3* open_database(char const* connstring, int flags, bool initialize)
 {
 	sqlite3*			instance = nullptr;			// SQLite database instance
 
 	// Create the SQLite database using the provided connection string
 	int result = sqlite3_open_v2(connstring, &instance, flags, nullptr);
 	if(result != SQLITE_OK) throw sqlite_exception(result);
 
-	// Set the connection to report extended error codes
+	// set the connection to report extended error codes
+	//
 	sqlite3_extended_result_codes(instance, -1);
 
+	// set a busy_timeout handler for this connection
+	//
+	sqlite3_busy_timeout(instance, 30000);
+
 	try {
 
+		// switch the database to write-ahead logging
+		//
+		execute_non_query(instance, "pragma journal_mode=wal");
+
 		// scalar function: decode_channel_id
 		//
 		result = sqlite3_create_function_v2(instance, "decode_channel_id", 1, SQLITE_UTF8, nullptr, decode_channel_id, nullptr, nullptr, nullptr);
@@ -2580,70 +2604,68 @@ sqlite3* open_database(char const* connstring, int flags)
 		result = sqlite3_create_function_v2(instance, "url_encode", 1, SQLITE_UTF8, nullptr, url_encode, nullptr, nullptr, nullptr);
 		if(result != SQLITE_OK) throw sqlite_exception(result);
 
-		// table: client
+		// Only execute schema creation steps if the database is being initialized; the caller needs
+		// to ensure that this is set for only one connection otherwise locking issues can occur
 		//
-		// clientid(pk)
-		execute_non_query(instance, "create table if not exists client(clientid text primary key not null)");
-
-		// table: device
-		// 
-		// deviceid(pk) | type | data
-		execute_non_query(instance, "create table if not exists device(deviceid text primary key not null, type text, data text)");
-
-		// table: lineup
-		//
-		// deviceid(pk) | data
-		execute_non_query(instance, "create table if not exists lineup(deviceid text primary key not null, data text)");
-
-		// table: recording
-		//
-		// deviceid(pk) | data
-		execute_non_query(instance, "create table if not exists recording(deviceid text primary key not null, data text)");
-
-		// table: guide
-		//
-		// channelid(pk) | channelname | iconurl | data
-		execute_non_query(instance, "create table if not exists guide(channelid integer primary key not null, channelname text, iconurl text, data text)");
-
-		// table: recordingrule
-		//
-		// recordingruleid(pk) | data
-		execute_non_query(instance, "create table if not exists recordingrule(recordingruleid text primary key not null, seriesid text not null, data text)");
-
-		// table: episode
-		//
-		// seriesid(pk) | data
-		execute_non_query(instance, "create table if not exists episode(seriesid text primary key not null, data text)");
-
-		// table: genremap
-		//
-		// filter(pk) | genretype
-		execute_non_query(instance, "create table if not exists genremap(filter text primary key not null, genretype integer)");
-
-		// (re)generate the clientid
-		//
-		execute_non_query(instance, "delete from client");
-		execute_non_query(instance, "insert into client values(generate_uuid())");
-
-		// (re)build the genremap table
-		//
-		sqlite3_exec(instance, "replace into genremap values('Movies', 0x10)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_MOVIEDRAMA 
-		sqlite3_exec(instance, "replace into genremap values('News', 0x20)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_NEWSCURRENTAFFAIRS
-		sqlite3_exec(instance, "replace into genremap values('Comedy', 0x30)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_SHOW
-		sqlite3_exec(instance, "replace into genremap values('Drama', 0x30)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_SHOW 
-		sqlite3_exec(instance, "replace into genremap values('Game Show', 0x30)", nullptr, nullptr, nullptr);	// EPG_EVENT_CONTENTMASK_SHOW
-		sqlite3_exec(instance, "replace into genremap values('Talk Show', 0x30)", nullptr, nullptr, nullptr);	// EPG_EVENT_CONTENTMASK_SHOW
-		sqlite3_exec(instance, "replace into genremap values('Sports', 0x40)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_SPORTS
-		sqlite3_exec(instance, "replace into genremap values('Kids', 0x50)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_CHILDRENYOUTH
-		sqlite3_exec(instance, "replace into genremap values('Food', 0xA0)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_LEISUREHOBBIES
-
-		// set a busy_timeout handler for this connection
-		//
-		sqlite3_busy_timeout(instance, 30000);
-
-		// switch the database to write-ahead logging
-		//
-		execute_non_query(instance, "pragma journal_mode=wal");
+		if(initialize) {
+
+			// table: client
+			//
+			// clientid(pk)
+			execute_non_query(instance, "create table if not exists client(clientid text primary key not null)");
+
+			// table: device
+			// 
+			// deviceid(pk) | type | data
+			execute_non_query(instance, "create table if not exists device(deviceid text primary key not null, type text, data text)");
+
+			// table: lineup
+			//
+			// deviceid(pk) | data
+			execute_non_query(instance, "create table if not exists lineup(deviceid text primary key not null, data text)");
+
+			// table: recording
+			//
+			// deviceid(pk) | data
+			execute_non_query(instance, "create table if not exists recording(deviceid text primary key not null, data text)");
+
+			// table: guide
+			//
+			// channelid(pk) | channelname | iconurl | data
+			execute_non_query(instance, "create table if not exists guide(channelid integer primary key not null, channelname text, iconurl text, data text)");
+
+			// table: recordingrule
+			//
+			// recordingruleid(pk) | data
+			execute_non_query(instance, "create table if not exists recordingrule(recordingruleid text primary key not null, seriesid text not null, data text)");
+
+			// table: episode
+			//
+			// seriesid(pk) | data
+			execute_non_query(instance, "create table if not exists episode(seriesid text primary key not null, data text)");
+
+			// table: genremap
+			//
+			// filter(pk) | genretype
+			execute_non_query(instance, "create table if not exists genremap(filter text primary key not null, genretype integer)");
+
+			// (re)generate the clientid
+			//
+			execute_non_query(instance, "delete from client");
+			execute_non_query(instance, "insert into client values(generate_uuid())");
+
+			// (re)build the genremap table
+			//
+			sqlite3_exec(instance, "replace into genremap values('Movies', 0x10)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_MOVIEDRAMA 
+			sqlite3_exec(instance, "replace into genremap values('News', 0x20)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_NEWSCURRENTAFFAIRS
+			sqlite3_exec(instance, "replace into genremap values('Comedy', 0x30)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_SHOW
+			sqlite3_exec(instance, "replace into genremap values('Drama', 0x30)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_SHOW 
+			sqlite3_exec(instance, "replace into genremap values('Game Show', 0x30)", nullptr, nullptr, nullptr);	// EPG_EVENT_CONTENTMASK_SHOW
+			sqlite3_exec(instance, "replace into genremap values('Talk Show', 0x30)", nullptr, nullptr, nullptr);	// EPG_EVENT_CONTENTMASK_SHOW
+			sqlite3_exec(instance, "replace into genremap values('Sports', 0x40)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_SPORTS
+			sqlite3_exec(instance, "replace into genremap values('Kids', 0x50)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_CHILDRENYOUTH
+			sqlite3_exec(instance, "replace into genremap values('Food', 0xA0)", nullptr, nullptr, nullptr);		// EPG_EVENT_CONTENTMASK_LEISUREHOBBIES
+		}
 	}
 
 	// Close the database instance on any thrown exceptions

src/database.h

@@ -448,6 +448,7 @@ void modify_recordingrule(sqlite3* instance, struct recordingrule const& recordi
 //
 // Opens a handle to the backend SQLite database
 sqlite3* open_database(char const* connstring, int flags);
+sqlite3* open_database(char const* connstring, int flags, bool initialize);
 
 // try_execute_non_query
 //

src/sqlite_exception.cpp

@@ -32,8 +32,11 @@
 //
 //	code		- SQLite error code
 
-sqlite_exception::sqlite_exception(int code) : m_what(sqlite3_errstr(code))
+sqlite_exception::sqlite_exception(int code)
 {
+	char* what = sqlite3_mprintf("(%d) %s", code, sqlite3_errstr(code));
+	m_what.assign(what);
+	sqlite3_free(reinterpret_cast<void*>(what));
 }
 
 //-----------------------------------------------------------------------------
@@ -46,8 +49,9 @@ sqlite_exception::sqlite_exception(int code) : m_what(sqlite3_errstr(code))
 
 sqlite_exception::sqlite_exception(int code, char const* message) : m_what(sqlite3_errstr(code))
 {
-	// If a message was provided, append it to the generated error message
-	if(message) m_what += std::string(": ") + message;
+	char* what = sqlite3_mprintf("%s: (%d) %s", message, code, sqlite3_errstr(code));
+	m_what.assign(what);
+	sqlite3_free(reinterpret_cast<void*>(what));
 }
 
 //-----------------------------------------------------------------------------

src/version.ini

@@ -8,4 +8,4 @@
 Company=Michael G. Brehm
 Copyright=
 Product=zuki.pvr.hdhomerundvr
-Version=1.0.2
+Version=1.0.3