utils strings: Add stringv_append_if_missing().

[sysdb.git] / src / include / utils / channel.h

diff --git a/src/include/utils/channel.h b/src/include/utils/channel.h
index 3eb7dc1897feab7639ec289ceb408089216f932b..49d37fdcfec6ec6d87df83697a382fa243b48575 100644 (file)
--- a/src/include/utils/channel.h
+++ b/src/include/utils/channel.h
@@ -30,6 +30,8 @@
 
 #include "core/object.h"
 
+#include <sys/time.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -89,6 +91,35 @@ sdb_channel_write(sdb_channel_t *chan, const void *data);
 int
 sdb_channel_read(sdb_channel_t *chan, void *data);
 
+/*
+ * sdb_channel_select:
+ * Wait for a channel to become "ready" for I/O. A channel is considered ready
+ * if it is possible to perform the corresponding I/O operation successfully
+ * *in some thread*. In case 'wantread' or 'read_data' is non-NULL, wait for
+ * data to be available in the channel for reading. In case 'wantwrite' or
+ * 'write_data' is non-NULL, wait for buffer space to be available for writing
+ * to the channel. If non-NULL, the value pointed to by the 'want...'
+ * arguments will be "true" iff the respective operation is ready. If the
+ * '..._data' arguments are non-NULL, the respective operation is executed
+ * atomically once the channel is ready for it. If 'timeout' is specified, the
+ * operation will time out with an error after the specified time has passed.
+ */
+int
+sdb_channel_select(sdb_channel_t *chan, int *wantread, void *read_data,
+               int *wantwrite, void *write_data, const struct timespec *timeout);
+
+/* sdb_channel_shutdown:
+ * Initiate a shutdown of the channel. Any subsequent writes will fail. Read
+ * operations will still be possible until the channel buffer is empty and
+ * then fail as well. Failing operations set errno to EBADF.
+ *
+ * Returns:
+ *  - 0 on success
+ *  - a negative value else
+ */
+int
+sdb_channel_shutdown(sdb_channel_t *chan);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif