Add a poll callback to channels.

[meshlink] / src / meshlink.h

diff --git a/src/meshlink.h b/src/meshlink.h
index 17545ed289b4c464dadc9e0ba53ca7108a74348b..6a83f6c60b41772c8ea529675ed737e9f45fa6a9 100644 (file)
--- a/src/meshlink.h
+++ b/src/meshlink.h
@@ -524,6 +524,15 @@ typedef bool (*meshlink_channel_accept_cb_t)(meshlink_handle_t *mesh, meshlink_c
  */
 typedef void (*meshlink_channel_receive_cb_t)(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len);
 
+/// A callback informing the application when data can be sent on a channel.
+/** This function is called whenever there is enough free buffer space so a call to meshlink_channel_send() will succeed.
+ *
+ *  @param mesh         A handle which represents an instance of MeshLink.
+ *  @param channel      A handle for the channel.
+ *  @param len          The maximum amount of data that is guaranteed to be accepted by meshlink_channel_send().
+ */
+typedef void (*meshlink_channel_poll_cb_t)(meshlink_handle_t *mesh, meshlink_channel_t *channel, size_t len);
+
 /// Set the accept callback.
 /** This functions sets the callback that is called whenever another node sends data to the local node.
  *  The callback is run in MeshLink's own thread.
@@ -553,6 +562,20 @@ extern void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_cha
  */
 extern void meshlink_set_channel_receive_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_receive_cb_t cb);
 
+/// Set the poll callback.
+/** This functions sets the callback that is called whenever data can be sent to another node.
+ *  The callback is run in MeshLink's own thread.
+ *  It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
+ *  to pass data to or from the application's thread.
+ *  The callback should also not block itself and return as quickly as possible.
+ *
+ *  @param mesh      A handle which represents an instance of MeshLink.
+ *  @param channel   A handle for the channel.
+ *  @param cb        A pointer to the function which will be called when data can be sent to another node.
+ *                   If a NULL pointer is given, the callback will be disabled.
+ */
+extern void meshlink_set_channel_poll_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_poll_cb_t cb);
+
 /// Open a reliable stream channel to another node.
 /** This function is called whenever a remote node wants to open a channel to the local node.
  *  The application then has to decide whether to accept or reject this channel.