1 files changed, 68 insertions, 0 deletions
diff --git a/examples/redis-unstable/src/connhelpers.h b/examples/redis-unstable/src/connhelpers.h
new file mode 100644
index 0000000..8d6f4b9
--- /dev/null
+++ b/examples/redis-unstable/src/connhelpers.h
@@ -0,0 +1,68 @@
+
+/*
+ * Copyright (c) 2019-Present, Redis Ltd.
+ * All rights reserved.
+ *
+ * Licensed under your choice of (a) the Redis Source Available License 2.0
+ * (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the
+ * GNU Affero General Public License v3 (AGPLv3).
+ */
+
+#ifndef __REDIS_CONNHELPERS_H
+#define __REDIS_CONNHELPERS_H
+
+#include "connection.h"
+
+/* These are helper functions that are common to different connection
+ * implementations (currently sockets in connection.c and TLS in tls.c).
+ *
+ * Currently helpers implement the mechanisms for invoking connection
+ * handlers and tracking connection references, to allow safe destruction
+ * of connections from within a handler.
+ */
+
+/* Increment connection references.
+ *
+ * Inside a connection handler, we guarantee refs >= 1 so it is always
+ * safe to connClose().
+ *
+ * In other cases where we don't want to prematurely lose the connection,
+ * it can go beyond 1 as well; currently it is only done by connAccept().
+ */
+static inline void connIncrRefs(connection *conn) {
+    conn->refs++;
+}
+
+/* Decrement connection references.
+ *
+ * Note that this is not intended to provide any automatic free logic!
+ * callHandler() takes care of that for the common flows, and anywhere an
+ * explicit connIncrRefs() is used, the caller is expected to take care of
+ * that.
+ */
+
+static inline void connDecrRefs(connection *conn) {
+    conn->refs--;
+}
+
+static inline int connHasRefs(connection *conn) {
+    return conn->refs;
+}
+
+/* Helper for connection implementations to call handlers:
+ * 1. Increment refs to protect the connection.
+ * 2. Execute the handler (if set).
+ * 3. Decrement refs and perform deferred close, if refs==0.
+ */
+static inline int callHandler(connection *conn, ConnectionCallbackFunc handler) {
+    connIncrRefs(conn);
+    if (handler) handler(conn);
+    connDecrRefs(conn);
+    if (conn->flags & CONN_FLAG_CLOSE_SCHEDULED) {
+        if (!connHasRefs(conn)) connClose(conn);
+        return 0;
+    }
+    return 1;
+}
+
+#endif  /* __REDIS_CONNHELPERS_H */