osmo_io: avoid OSMO_ASSERT one each API call

There's only one way to set the osmo_iofd_ops, which is by environment
variable during the constructor time at shared library load time.

There's hence no point in doing OSMO_ASSERT() on each and every call to
osmo_iofd_notify_connected() at runtime.  We can move those kind of
asserts to the one-time load-time constructor instead.

At the same time, we can extend those asserts to all the mandatory
call-backs to be provided by the backend.

Change-Id: Id9005ac6bb260236c88670373816bf7ee6a627f1
---
M src/core/osmo_io.c
1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/core/osmo_io.c b/src/core/osmo_io.c
index 8b53aa6..d52d601 100644
--- a/src/core/osmo_io.c
+++ b/src/core/osmo_io.c
@@ -105,6 +105,13 @@
 		exit(1);
 	}
 
+	OSMO_ASSERT(osmo_iofd_ops.close);
+	OSMO_ASSERT(osmo_iofd_ops.write_enable);
+	OSMO_ASSERT(osmo_iofd_ops.write_disable);
+	OSMO_ASSERT(osmo_iofd_ops.read_enable);
+	OSMO_ASSERT(osmo_iofd_ops.read_disable);
+	OSMO_ASSERT(osmo_iofd_ops.notify_connected);
+
 	osmo_iofd_init();
 }
 
@@ -787,7 +794,6 @@
 
 	iofd->pending = NULL;
 
-	OSMO_ASSERT(osmo_iofd_ops.close);
 	rc = osmo_iofd_ops.close(iofd);
 	iofd->fd = -1;
 	return rc;
@@ -927,7 +933,6 @@
 {
 	OSMO_ASSERT(iofd->mode == OSMO_IO_FD_MODE_READ_WRITE ||
 		    iofd->mode == OSMO_IO_FD_MODE_RECVMSG_SENDMSG);
-	OSMO_ASSERT(osmo_iofd_ops.notify_connected);
 	osmo_iofd_ops.notify_connected(iofd);
 }
 

