in_tail: new 'db.wal' option

Signed-off-by: Eduardo Silva <edsiper@gmail.com>

Author: edsiper

plugins/in_tail/tail.c

@@ -604,6 +604,13 @@ static struct flb_config_map config_map[] = {
      "set exclusive locking mode, increase performance but don't allow "
      "external connections to the database file."
     },
+    {
+     FLB_CONFIG_MAP_BOOL, "db.wal", "on",
+     0, FLB_TRUE, offsetof(struct flb_tail_config, db_wal),
+     "enable or disable Work Ahead Logging mechanism (WAL). Enabling WAL "
+     "provides higher performance. Note that WAL is not compatible with "
+     "shared network file systems."
+    },
 #endif
 
     /* Multiline Options */

plugins/in_tail/tail_config.h

@@ -86,6 +86,7 @@ struct flb_tail_config {
     struct flb_sqldb *db;
     int db_sync;
     int db_locking;
+    int db_wal;
     sqlite3_stmt *stmt_get_file;
     sqlite3_stmt *stmt_insert_file;
     sqlite3_stmt *stmt_delete_file;

plugins/in_tail/tail_db.c

@@ -67,13 +67,6 @@ struct flb_sqldb *flb_tail_db_open(const char *path,
         }
     }
 
-    ret = flb_sqldb_query(db, SQL_PRAGMA_JOURNAL_MODE, NULL, NULL);
-    if (ret != FLB_OK) {
-        flb_plg_error(ctx->ins, "db: could not set pragma 'journal_mode'");
-        flb_sqldb_close(db);
-        return NULL;
-    }
-
     if (ctx->db_locking == FLB_TRUE) {
         ret = flb_sqldb_query(db, SQL_PRAGMA_LOCKING_MODE, NULL, NULL);
         if (ret != FLB_OK) {
@@ -83,6 +76,15 @@ struct flb_sqldb *flb_tail_db_open(const char *path,
         }
     }
 
+    if (ctx->db_wal) {
+        ret = flb_sqldb_query(db, SQL_PRAGMA_JOURNAL_MODE, NULL, NULL);
+        if (ret != FLB_OK) {
+            flb_plg_error(ctx->ins, "db: could not set pragma 'journal_mode'");
+            flb_sqldb_close(db);
+            return NULL;
+        }
+    }
+
     return db;
 }