zebra: add lock and busy counter for zclients

Add a mutex used to manage the list of zclients. Add a busy
counter to the zapi client session, so that we can use a
client session from another pthread.

Signed-off-by: Mark Stapp <mjs@voltanet.io>

1 files changed, 30 insertions, 1 deletions

diff --git a/zebra/zserv.h b/zebra/zserv.h
index 9d442899f..b943c246c 100644
--- a/zebra/zserv.h
+++ b/zebra/zserv.h
@@ -96,6 +96,14 @@ struct zserv {
 	/* Client file descriptor. */
 	int sock;
 
+	/* Attributes used to permit access to zapi clients from
+	 * other pthreads: the client has a busy counter, and a
+	 * 'closed' flag. These attributes are managed using a
+	 * lock, via the acquire_client() and release_client() apis.
+	 */
+	int busy_count;
+	bool is_closed;
+
 	/* Input/output buffer to the client. */
 	pthread_mutex_t ibuf_mtx;
 	struct stream_fifo *ibuf_fifo;
@@ -116,7 +124,7 @@ struct zserv {
 	/* Event for message processing, for the main pthread */
 	struct thread *t_process;
 
-	/* Threads for the main pthread */
+	/* Event for the main pthread */
 	struct thread *t_cleanup;
 
 	/* This client's redistribute flag. */
@@ -306,6 +314,27 @@ struct zserv *zserv_find_client_session(uint8_t proto, unsigned short instance,
 					uint32_t session_id);
 
 /*
+ * Retrieve a client object by the complete tuple of
+ * {protocol, instance, session}. This version supports use
+ * from a different pthread: the object will be returned marked
+ * in-use. The caller *must* release the client object with the
+ * release_client() api, to ensure that the in-use marker is cleared properly.
+ *
+ * Returns:
+ *    The Zebra API client.
+ */
+extern struct zserv *zserv_acquire_client(uint8_t proto,
+					  unsigned short instance,
+					  uint32_t session_id);
+
+/*
+ * Release a client object that was acquired with the acquire_client() api.
+ * After this has been called, the pointer must not be used - it may be freed
+ * in another pthread if the client has closed.
+ */
+extern void zserv_release_client(struct zserv *client);
+
+/*
  * Close a client.
  *
  * Kills a client's thread, removes the client from the client list and cleans