exmdb: config directive "exmdb_deep_backtrace"

References: DESK-2595

Author: jengelh

doc/exmdb_provider.4gx

@@ -20,6 +20,12 @@ with exclusive locking).
 .br
 Default: \fIno\fP
 .TP
+\fBexmdb_deep_backtrace\fP
+(Developer option.) Record and report transaction problems with a multi-level
+backtrace instead of a single-level location indicator.
+.br
+Default: \fIno\fP
+.TP
 \fBexmdb_ics_log_file\fP
 Log ICS/synchronization requests (and their results) to this file.
 .br

exch/exmdb/main.cpp

@@ -36,6 +36,7 @@ using namespace exmdb;
 static std::shared_ptr<CONFIG_FILE> g_config_during_init;
 
 static constexpr cfg_directive exmdb_gromox_cfg_defaults[] = {
+	{"exmdb_deep_backtrace", "0", CFG_BOOL},
 	{"exmdb_force_write_txn", "0", CFG_BOOL},
 	{"exmdb_ics_log_file", ""},
 	CFG_TABLE_END,
@@ -111,6 +112,7 @@ static bool exmdb_provider_reload(std::shared_ptr<config_file> gxcfg = nullptr,
 	g_exmdb_search_pacing_time = pconfig->get_ll("exmdb_search_pacing_time");
 	g_exmdb_max_sqlite_spares = pconfig->get_ll("exmdb_max_sqlite_spares");
 	g_sqlite_busy_timeout_ns = pconfig->get_ll("sqlite_busy_timeout");
+	gx_sql_deep_backtrace = gxcfg->get_ll("exmdb_deep_backtrace");
 	gx_force_write_txn = gxcfg->get_ll("exmdb_force_write_txn");
 	auto s = gxcfg->get_value("exmdb_ics_log_file");
 	if (s != nullptr)

include/gromox/database.h

@@ -105,5 +105,6 @@ static inline uint64_t gx_sql_col_uint64(sqlite3_stmt *s, int c)
 }
 
 extern GX_EXPORT unsigned int gx_sqlite_debug, gx_force_write_txn;
+extern GX_EXPORT unsigned int gx_sql_deep_backtrace;
 
 }

lib/dbhelper.cpp

@@ -12,7 +12,7 @@
 
 namespace gromox {
 
-unsigned int gx_sqlite_debug, gx_force_write_txn;
+unsigned int gx_sqlite_debug, gx_force_write_txn, gx_sql_deep_backtrace;
 
 static bool write_statement(const char *q)
 {
@@ -100,7 +100,10 @@ xtransaction gx_sql_begin3(const std::string &pos, sqlite3 *db, txn_mode mode)
 		auto fn = sqlite3_db_filename(db, nullptr);
 		if (fn != nullptr && *fn != '\0') {
 			std::unique_lock lk(active_xa_lock);
-			active_xa[fn] = pos;
+			if (gx_sql_deep_backtrace)
+				active_xa[fn] = simple_backtrace();
+			else
+				active_xa[fn] = pos;
 		}
 		return xtransaction(db);
 	}
@@ -112,7 +115,7 @@ xtransaction gx_sql_begin3(const std::string &pos, sqlite3 *db, txn_mode mode)
 		auto it = active_xa.find(fn);
 		mlog(LV_ERR, "sqlite_busy on %s: held by %s, take from %s", znul(fn),
 			it != active_xa.end() ? it->second.c_str() : "unknown",
-			pos.c_str());
+			gx_sql_deep_backtrace ? simple_backtrace().c_str() : pos.c_str());
 	}
 	return xtransaction(nullptr);
 }