Hello,
Is it valid to change the update hook from the update hook itself?
The reason for this question is the following: when a notified database change
makes it useless to perform further observation, one may want to remove the
update hook alltogether. Can it be done from the update hook itself?
Here is a quick and dirty sample code, for the context: it installs an update
hook that tracks any modification to the "players" table, and attempts to
remove the update hook as soon as the "players" table is modified:
typedef struct {
sqlite3 *conn;
int players_table_was_modified;
} info;
void update_hook(info *info, int change, char const *db, char const *table,
sqlite3_int64 rowed) {
if (strcmp(table, "players") == 0) {
info->players_table_was_modified = 1;
// Is it valid?
sqlite3_update_hook(info->conn, NULL, NULL);
}
}
sqlite3 *conn = ...;
info info = { conn, 0 };
sqlite3_update_hook(conn, update_hook, &info);
Quoting https://sqlite.org/c3ref/update_hook.html:
> The update hook implementation must not do anything that will modify the
> database connection that invoked the update hook. Any actions to modify the
> database connection must be deferred until after the completion of the
> sqlite3_step() call that triggered the update hook. Note that
> sqlite3_prepare_v2() and sqlite3_step() both modify their database
> connections for the meaning of "modify" in this paragraph.
According to this documentation, I'm note sure if sqlite3_update_hook itself
modifies the database connection for the meaning of "modify" in the quoted
documentation paragraph, and is thus forbidden, or not.
Can anyone lift this doubt?
Thanks in advance,
Gwendal Roué
_______________________________________________
sqlite-users mailing list
[email protected]
http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
