Receive features list from a real provider (#266)

* Receive features list from a real provider

* Prevent statement caching if the provider doesn't support it

* Changes requested by Dmitry Yemanov

doc/sql.extensions/README.isc_info_xxx

@@ -45,6 +45,17 @@ New items for isc_database_info
 	isc_dpb_addr_flag_conn_encrypted - connection is encrypted;
    fb_info_wire_crypt - name of connection encryption plugin.
 
+6. fb_info_provider_features:
+	return list of features supported by current connection's provider.
+	Each byte in returned array shall be one of following info_provider_features:
+
+	fb_feature_multi_statements - multiple prepared statements in single attachment
+	fb_feature_multi_transactions - multiple concurrent transactions in single attachment
+	fb_feature_named_parameters - query parameters can be named
+	fb_feature_session_reset - ALTER SESSION RESET is supported
+	fb_feature_read_consistency - read consistency TIL is supported
+	fb_feature_statement_timeout - statement timeout is supported
+
 
 New items for isc_transaction_info:
 

src/include/firebird/impl/inf_pub.h

@@ -162,6 +162,9 @@ enum db_info_types
 
 	fb_info_wire_crypt = 140,
 
+	// Return list of features supported by provider of current connection
+	fb_info_provider_features = 141,
+
 	isc_info_db_last_value   /* Leave this LAST! */
 };
 
@@ -171,6 +174,19 @@ enum db_info_crypt			/* flags set in fb_info_crypt_state */
 	fb_info_crypt_process = 0x02
 };
 
+enum info_provider_features // response to fb_info_provider_features
+{
+	fb_feature_multi_statements 	= 1,    // Multiple prepared statements in single attachment
+	fb_feature_multi_transactions	= 2,	// Multiple concurrent transaction in single attachment
+	fb_feature_named_parameters		= 3,	// Query parameters can be named
+	fb_feature_session_reset		= 4,	// ALTER SESSION RESET is supported
+	fb_feature_read_consistency		= 5,	// Read consistency TIL is supported
+	fb_feature_statement_timeout	= 6,	// Statement timeout is supported
+	fb_feature_statement_long_life  = 7,    // Prepared statement can survive transaction end
+
+	info_provider_features_max      // Not really a feature. Keep this last.
+};
+
 #define isc_info_version isc_info_isc_version
 
 

src/jrd/constants.h

@@ -466,6 +466,14 @@ const int OPT_STATIC_ITEMS = 64;
 #define CURRENT_ENGINE "Engine13"
 #define EMBEDDED_PROVIDERS "Providers=" CURRENT_ENGINE
 
+// Feature mask for current version of engine provider
+#define ENGINE_FEATURES {fb_feature_multi_statements, \
+						 fb_feature_multi_transactions, \
+						 fb_feature_session_reset, \
+						 fb_feature_read_consistency, \
+						 fb_feature_statement_timeout, \
+						 fb_feature_statement_long_life}
+
 const int WITH_GRANT_OPTION = 1;
 const int WITH_ADMIN_OPTION = 2;
 

src/jrd/extds/ExtDS.cpp

@@ -524,7 +524,7 @@ Connection::Connection(Provider& prov) :
 	m_sqlDialect(0),
 	m_wrapErrors(true),
 	m_broken(false),
-	m_features(0)
+	m_features{}
 {
 }
 
@@ -639,7 +639,7 @@ void Connection::releaseStatement(Jrd::thread_db* tdbb, Statement* stmt)
 {
 	fb_assert(stmt && !stmt->isActive());
 
-	if (stmt->isAllocated() && m_free_stmts < MAX_CACHED_STMTS)
+	if (stmt->isAllocated() && testFeature(fb_feature_statement_long_life) && m_free_stmts < MAX_CACHED_STMTS)
 	{
 		stmt->m_nextFree = m_freeStatements;
 		m_freeStatements = stmt;
@@ -1753,7 +1753,7 @@ void Statement::prepare(thread_db* tdbb, Transaction* tran, const string& sql, b
 	string sql2(getPool());
 	const string* readySql = &sql;
 
-	if (named && !(m_provider.getFlags() & prvNamedParams))
+	if (named && !m_connection.testFeature(fb_feature_named_parameters))
 	{
 		preprocess(sql, sql2);
 		readySql = &sql2;
@@ -1772,7 +1772,7 @@ void Statement::setTimeout(thread_db* tdbb, unsigned int timeout)
 }
 
 void Statement::execute(thread_db* tdbb, Transaction* tran,
-	const MetaName* const* in_names, const ValueListNode* in_params, const ParamNumbers* in_excess, 
+	const MetaName* const* in_names, const ValueListNode* in_params, const ParamNumbers* in_excess,
 	const ValueListNode* out_params)
 {
 	fb_assert(isAllocated() && !m_stmt_selectable);
@@ -1787,7 +1787,7 @@ void Statement::execute(thread_db* tdbb, Transaction* tran,
 }
 
 void Statement::open(thread_db* tdbb, Transaction* tran,
-	const MetaName* const* in_names, const ValueListNode* in_params, const ParamNumbers* in_excess, 
+	const MetaName* const* in_names, const ValueListNode* in_params, const ParamNumbers* in_excess,
 	bool singleton)
 {
 	fb_assert(isAllocated() && m_stmt_selectable);

src/jrd/extds/ExtDS.h

@@ -197,10 +197,7 @@ protected:
 };
 
 // Provider flags
-const int prvMultyStmts		= 0x0001;	// supports many active statements per connection
-const int prvMultyTrans		= 0x0002;	// supports many active transactions per connection
-const int prvNamedParams	= 0x0004;	// supports named parameters
-const int prvTrustedAuth	= 0x0008;	// supports trusted authentication
+const int prvTrustedAuth	= 0x0001;	// supports trusted authentication
 
 
 class ConnectionsPool
@@ -494,12 +491,12 @@ public:
 
 	virtual Blob* createBlob() = 0;
 
-	// Test specified flags, return true if all bits present
-	bool testFeature(ULONG value) const { return m_features & value; }
-	// Set specified flags, return new value
-	ULONG setFeature(ULONG value) { return m_features |= value; }
-	// Clear specified flags, return new value
-	ULONG clearFeature(ULONG value) { return m_features &= ~value; }
+	// Test specified feature flag
+	bool testFeature(info_provider_features value) const { return m_features[value]; }
+	// Set specified flag
+	void setFeature(info_provider_features value) { m_features[value] = true; }
+	// Clear specified flag
+	void clearFeature(info_provider_features value) { m_features[value] = false; }
 
 protected:
 	virtual Transaction* doCreateTransaction() = 0;
@@ -531,17 +528,9 @@ protected:
 	int m_sqlDialect;	// must be filled in attach call
 	bool m_wrapErrors;
 	bool m_broken;
-	ULONG m_features;	// bitmask
+	bool m_features[info_provider_features_max];
 };
 
-// Connection features flags
-const ULONG conFtrSessionReset		= 0x01;		// supports ALTER SESSION RESET
-const ULONG conFtrReadConsistency	= 0x02;		// supports READ COMMITTED READ CONSISTENCY
-const ULONG conFtrStatementTimeout	= 0x04;		// supports statements timeout
-
-// Features of Firebird 4
-const ULONG conFtrFB4 = conFtrSessionReset | conFtrReadConsistency | conFtrStatementTimeout;
-
 class Transaction : public Firebird::PermanentStorage
 {
 protected:
@@ -618,7 +607,7 @@ public:
 		const Firebird::MetaName* const* in_names, const Jrd::ValueListNode* in_params,
 		const ParamNumbers* in_excess, const Jrd::ValueListNode* out_params);
 	void open(Jrd::thread_db* tdbb, Transaction* tran,
-		const Firebird::MetaName* const* in_names, const Jrd::ValueListNode* in_params, 
+		const Firebird::MetaName* const* in_names, const Jrd::ValueListNode* in_params,
 		const ParamNumbers* in_excess, bool singleton);
 	bool fetch(Jrd::thread_db* tdbb, const Jrd::ValueListNode* out_params);
 	void close(Jrd::thread_db* tdbb, bool invalidTran = false);

src/jrd/extds/InternalDS.cpp

@@ -188,7 +188,10 @@ void InternalConnection::attach(thread_db* tdbb)
 	m_sqlDialect = (attachment->att_database->dbb_flags & DBB_DB_SQL_dialect_3) ?
 					SQL_DIALECT_V6 : SQL_DIALECT_V5;
 
-	m_features = conFtrFB4;
+	memset(m_features, false, sizeof(m_features));
+	static const info_provider_features features[] = ENGINE_FEATURES;
+	for (int i = 0; i < sizeof(features); i++)
+		setFeature(features[i]);
 }
 
 void InternalConnection::doDetach(thread_db* tdbb)

src/jrd/extds/InternalDS.h

@@ -34,7 +34,6 @@ public:
 	explicit InternalProvider(const char* prvName) :
 		Provider(prvName)
 	{
-		m_flags = (prvMultyStmts | prvMultyTrans);
 	}
 
 	~InternalProvider()

src/jrd/extds/IscDS.cpp

@@ -144,17 +144,20 @@ void IscConnection::attach(thread_db* tdbb)
 		}
 	}
 
-	char buff[16];
+	char buff[BUFFER_TINY];
 	{
 		EngineCallbackGuard guard(tdbb, *this, FB_FUNCTION);
 
-		const char info[] = {isc_info_db_sql_dialect, isc_info_end};
+		const unsigned char info[] = {isc_info_db_sql_dialect, fb_info_provider_features, isc_info_end};
 		m_iscProvider.isc_database_info(&status, &m_handle, sizeof(info), info, sizeof(buff), buff);
 	}
 	if (status->getState() & IStatus::STATE_ERRORS) {
 		raise(&status, tdbb, "isc_database_info");
 	}
 
+	memset(m_features, false, sizeof(m_features));
+	m_sqlDialect = 1;
+
 	const char* p = buff, *end = buff + sizeof(buff);
 	while (p < end)
 	{
@@ -168,22 +171,42 @@ void IscConnection::attach(thread_db* tdbb)
 				m_sqlDialect = m_iscProvider.isc_vax_integer(p, len);
 				break;
 
+			case fb_info_provider_features:
+			    for (int i = 0; i < len; i++)
+                {
+                    if (p[i] == 0)
+                    {
+                        ERR_post(Arg::Gds(isc_random) << Arg::Str("Bad provider feature value"));
+                    }
+
+                    if (p[i] < info_provider_features_max)
+                    {
+                        setFeature(static_cast<info_provider_features>(p[i]));
+                    }
+                    // else this provider supports unknown feature, ignore it.
+                }
+				break;
+
 			case isc_info_error:
-				if (*p == isc_info_db_sql_dialect)
-				{
-					const ULONG err = m_iscProvider.isc_vax_integer(p + 1, len - 1);
-					if (err == isc_infunk)
-					{
-						// Remote server don't understand isc_info_db_sql_dialect.
-						// Consider it as pre-IB6 server and use SQL dialect 1 to work with it.
-						m_sqlDialect = 1;
-						break;
-					}
-				}
-				// fall thru
+			    {
+                    const ULONG err = m_iscProvider.isc_vax_integer(p + 1, len - 1);
+                    if (err == isc_infunk)
+                    {
+                        if (*p == fb_info_provider_features)
+                        {
+                            // Used provider follow Firebird error reporting conventions but is not aware of
+                            // this info item. Assume Firebird 3 or earlier.
+                            m_features[fb_feature_multi_statements] = true;
+                            m_features[fb_feature_multi_transactions] = true;
+                            m_features[fb_feature_statement_long_life] = true;
+                        }
+                        break;
+                    }
+                    ERR_post(Arg::Gds(isc_random) << Arg::Str("Unexpected error in isc_database_info"));
+			    }
 
 			case isc_info_truncated:
-				ERR_post(Arg::Gds(isc_random) << Arg::Str("Unexpected error in isc_database_info"));
+				ERR_post(Arg::Gds(isc_random) << Arg::Str("Result truncation in isc_database_info"));
 
 			case isc_info_end:
 				p = end;
@@ -192,7 +215,6 @@ void IscConnection::attach(thread_db* tdbb)
 		p += len;
 	}
 
-	m_features = conFtrFB4;	// Exact feature set will be detected at first usage
 }
 
 void IscConnection::doDetach(thread_db* tdbb)
@@ -240,7 +262,7 @@ bool IscConnection::resetSession()
 	if (!m_handle)
 		return false;
 
-	if (!testFeature(conFtrSessionReset))
+	if (!testFeature(fb_feature_session_reset))
 		return true;
 
 	FbLocalStatus status;
@@ -252,7 +274,7 @@ bool IscConnection::resetSession()
 
 	if (status->getErrors()[1] == isc_dsql_error)
 	{
-		clearFeature(conFtrSessionReset);
+		clearFeature(fb_feature_session_reset);
 		return true;
 	}
 
@@ -267,11 +289,10 @@ bool IscConnection::resetSession()
 //    transactions
 bool IscConnection::isAvailable(thread_db* tdbb, TraScope traScope) const
 {
-	const int flags = m_provider.getFlags();
-	if (m_used_stmts && !(flags & prvMultyStmts))
+	if (m_used_stmts && !testFeature(fb_feature_multi_statements))
 		return false;
 
-	if (m_transactions.getCount() && !(flags & prvMultyTrans) && !findTransaction(tdbb, traScope))
+	if (m_transactions.getCount() && !testFeature(fb_feature_multi_transactions) && !findTransaction(tdbb, traScope))
 	{
 		return false;
 	}
@@ -288,7 +309,7 @@ bool IscConnection::validate(Jrd::thread_db* tdbb)
 
 	EngineCallbackGuard guard(tdbb, *this, FB_FUNCTION);
 
-	char info[] = {isc_info_attachment_id, isc_info_end};
+	const unsigned char info[] = {isc_info_attachment_id, isc_info_end};
 	char buff[32];
 
 	return m_iscProvider.isc_database_info(&status, &m_handle,
@@ -315,7 +336,7 @@ Statement* IscConnection::doCreateStatement()
 void IscTransaction::generateTPB(thread_db* tdbb, ClumpletWriter& tpb,
 	TraModes traMode, bool readOnly, bool wait, int lockTimeout) const
 {
-	if (traMode == traReadCommitedReadConsistency && !m_connection.testFeature(conFtrReadConsistency))
+	if (traMode == traReadCommitedReadConsistency && !m_connection.testFeature(fb_feature_read_consistency))
 		traMode = traConcurrency;
 
 	Transaction::generateTPB(tdbb, tpb, traMode, readOnly, wait, lockTimeout);
@@ -335,7 +356,7 @@ void IscTransaction::doStart(FbStatusVector* status, thread_db* tdbb, Firebird::
 	if ((status->getState() & IStatus::STATE_ERRORS) &&
 		(status->getErrors()[1] == isc_bad_tpb_form) &&
 		tpb.find(isc_tpb_read_consistency) &&
-		m_connection.testFeature(conFtrReadConsistency))
+		m_connection.testFeature(fb_feature_read_consistency))
 	{
 		tpb.deleteWithTag(isc_tpb_read_committed);
 		tpb.deleteWithTag(isc_tpb_read_consistency);
@@ -348,7 +369,7 @@ void IscTransaction::doStart(FbStatusVector* status, thread_db* tdbb, Firebird::
 		}
 
 		if (!(status->getState() & IStatus::STATE_ERRORS))
-			m_connection.clearFeature(conFtrReadConsistency);
+			m_connection.clearFeature(fb_feature_read_consistency);
 	}
 }
 
@@ -562,7 +583,7 @@ void IscStatement::doPrepare(thread_db* tdbb, const string& sql)
 
 void IscStatement::doSetTimeout(thread_db* tdbb, unsigned int timeout)
 {
-	if (!m_connection.testFeature(conFtrStatementTimeout))
+	if (!m_connection.testFeature(fb_feature_statement_timeout))
 		return;
 
 	FbLocalStatus status;
@@ -578,7 +599,7 @@ void IscStatement::doSetTimeout(thread_db* tdbb, unsigned int timeout)
 		// or loaded client library
 		if (status[0] == isc_arg_gds && (status[1] == isc_wish_list || status[1] == isc_unavailable))
 		{
-			m_connection.clearFeature(conFtrStatementTimeout);
+			m_connection.clearFeature(fb_feature_statement_timeout);
 			return;
 		}
 
@@ -1047,7 +1068,7 @@ ISC_STATUS ISC_EXPORT IscProvider::isc_create_database(FbStatusVector* user_stat
 ISC_STATUS ISC_EXPORT IscProvider::isc_database_info(FbStatusVector* user_status,
 									isc_db_handle* db_handle,
 									short info_len,
-									const char* info,
+									const unsigned char* info,
 									short res_len,
 									char* res)
 {
@@ -1055,7 +1076,7 @@ ISC_STATUS ISC_EXPORT IscProvider::isc_database_info(FbStatusVector* user_status
 		return notImplemented(user_status);
 
 	return (*m_api.database_info) (IscStatus(user_status), db_handle,
-			info_len, info, res_len, res);
+			info_len, reinterpret_cast<const ISC_SCHAR*>(info), res_len, res);
 }
 
 void ISC_EXPORT IscProvider::isc_decode_date(const ISC_QUAD*,

src/jrd/extds/IscDS.h

@@ -186,7 +186,7 @@ public:
 	virtual ISC_STATUS ISC_EXPORT isc_database_info(Jrd::FbStatusVector*,
 										isc_db_handle*,
 										short,
-										const char*,
+										const unsigned char*,
 										short,
 										char*);
 
@@ -497,7 +497,8 @@ public:
 	explicit FBProvider(const char* prvName) :
 		IscProvider(prvName)
 	{
-		m_flags = (prvMultyStmts | prvMultyTrans | prvTrustedAuth);
+	    // Assume that winsspi auth plugin is enabled in configuration
+		m_flags = prvTrustedAuth;
 	}
 
 protected:

src/jrd/inf.cpp

@@ -855,6 +855,14 @@ void INF_database_info(thread_db* tdbb,
 			length = INF_convert(att->getActualIdleTimeout(), buffer);
 			break;
 
+		case fb_info_provider_features:
+		    {
+                static const unsigned char features[] = ENGINE_FEATURES;
+                length = sizeof(features);
+                memcpy(buffer, features, length);
+                break;
+		    }
+
 		default:
 			buffer[0] = item;
 			item = isc_info_error;