1 files changed, 26 insertions, 2 deletions

diff --git a/src/core/iomgr/fd_posix.h b/src/core/iomgr/fd_posix.h
index be21f2b55f..cfc533b7f5 100644
--- a/src/core/iomgr/fd_posix.h
+++ b/src/core/iomgr/fd_posix.h
@@ -66,8 +66,32 @@ struct grpc_fd {
   gpr_mu set_state_mu;
   gpr_atm shutdown;
 
+  /* The watcher list.
+     
+     The following watcher related fields are protected by watcher_mu.
+     
+     An fd_watcher is an ephemeral object created when an fd wants to
+     begin polling, and destroyed after the poll.
+     
+     It denotes the fd's interest in whether to read poll or write poll
+     or both or neither on this fd.
+
+     If a watcher is asked to poll for reads or writes, the read_watcher
+     or write_watcher fields are set respectively. A watcher may be asked
+     to poll for both, in which case both fields will be set.
+
+     read_watcher and write_watcher may be NULL if no watcher has been
+     asked to poll for reads or writes.
+
+     If an fd_watcher is not asked to poll for reads or writes, it's added
+     to a linked list of inactive watchers, rooted at inactive_watcher_root.
+     If at a later time there becomes need of a poller to poll, one of
+     the inactive pollers may be kicked out of their poll loops to take
+     that responsibility. */
   gpr_mu watcher_mu;
-  grpc_fd_watcher watcher_root;
+  grpc_fd_watcher inactive_watcher_root;
+  grpc_fd_watcher *read_watcher;
+  grpc_fd_watcher *write_watcher;
 
   gpr_atm readst;
   gpr_atm writest;
@@ -103,7 +127,7 @@ gpr_uint32 grpc_fd_begin_poll(grpc_fd *fd, grpc_pollset *pollset,
                               gpr_uint32 read_mask, gpr_uint32 write_mask,
                               grpc_fd_watcher *rec);
 /* Complete polling previously started with grpc_fd_begin_poll */
-void grpc_fd_end_poll(grpc_fd_watcher *rec);
+void grpc_fd_end_poll(grpc_fd_watcher *rec, int got_read, int got_write);
 
 /* Return 1 if this fd is orphaned, 0 otherwise */
 int grpc_fd_is_orphaned(grpc_fd *fd);