Re: [Libguestfs] [PATCH 2/9] Refactor plugin_* functions into a backend struct.

Introduce the concept of a backend. Currently the only type of backend is a plugin, and there can only be one of them. Instead of calling functions like ‘plugin_pwrite’ you call the backend method ‘backend->pwrite (backend, ...)’. The change is largely mechanical. I was able to remove ‘assert (dl)’ statements throughout since we can now prove they will never be called. Note this does not lift the restriction of one plugin per server, and it can *never* do that because plugins can use global variables. --- src/connections.c | 40 +++-- src/internal.h | 55 +++--- src/locks.c | 8 +- src/main.c | 31 ++-- src/plugins.c | 529 ++++++++++++++++++++++++++++++------------------------ 5 files changed, 368 insertions(+), 295 deletions(-)

- if (plugin_thread_model () < NBDKIT_THREAD_MODEL_PARALLEL || nworkers == 1) + if (backend->thread_model (backend) < NBDKIT_THREAD_MODEL_PARALLEL || + nworkers == 1)

+++ b/src/plugins.c

+static int +plugin_zero (struct backend *b, struct connection *conn, uint32_t count, uint64_t offset, int may_trim) { - assert (dl); - assert (connection_get_handle (conn)); + struct backend_plugin *p = container_of (b, struct backend_plugin, backend); char *buf; uint32_t limit; int result; int err = 0; + assert (connection_get_handle (conn)); + debug ("zero count=%" PRIu32 " offset=%" PRIu64 " may_trim=%d", count, offset, may_trim); if (!count) return 0; - if (plugin.zero) { + if (p->plugin.zero) { errno = 0; - result = plugin.zero (connection_get_handle (conn), count, offset, may_trim); + result = p->plugin.zero (connection_get_handle (conn), + count, offset, may_trim); if (result == -1) { err = threadlocal_get_error (); - if (!err && plugin_errno_is_preserved ()) + if (!err && plugin_errno_is_preserved (b)) err = errno; } if (result == 0 || err != EOPNOTSUPP) return result; } - assert (plugin.pwrite); + assert (p->plugin.pwrite); threadlocal_set_error (0); limit = count < MAX_REQUEST_SIZE ? count : MAX_REQUEST_SIZE; buf = calloc (limit, 1); @@ -525,7 +446,8 @@ plugin_zero (struct connection *conn, } while (count) { - result = plugin.pwrite (connection_get_handle (conn), buf, limit, offset); + result = p->plugin.pwrite (connection_get_handle (conn), + buf, limit, offset);