fixes #1372 nni_reap could be smaller

1 files changed, 31 insertions, 11 deletions

diff --git a/src/core/reap.h b/src/core/reap.h
index 40c27a5d..5f631885 100644
--- a/src/core/reap.h
+++ b/src/core/reap.h
@@ -1,5 +1,5 @@
 //
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -14,19 +14,35 @@
 #include "core/defs.h"
 #include "core/list.h"
 
-// nni_reap_item is defined here so that it can be inlined into
-// structures.  Callers must access its members directly.
-typedef struct nni_reap_item {
-	nni_list_node r_link;
-	void *        r_ptr;
-	nni_cb        r_func;
-} nni_reap_item;
+// nni_reap_node is to be inserted inline into structures
+// for subsystems that wish to support deferred reaping.
+// It should be zeroed at object initialization, but apart
+// from that it must not be touched directly except by the
+// reap subsystem.
+typedef struct nni_reap_node nni_reap_node;
+struct nni_reap_node {
+	nni_reap_node *rn_next;
+};
+
+// nni_reap_list is for subsystems to define their own reap lists.
+// This allows for the reap linkage to be restricted to a single
+// pointer.  Subsystems should initialize rl_offset and rl_func,
+// and leave the rest zeroed.  The intention is that this is a global
+// static member for each subsystem.
+typedef struct nni_reap_list nni_reap_list;
+struct nni_reap_list {
+	nni_reap_list *rl_next;   // linkage in global reap list
+	nni_reap_node *rl_nodes;  // list of nodes to reap
+	size_t         rl_offset; // offset of reap_node within member.
+	nni_cb         rl_func;   // function called to reap the item
+	bool           rl_inited; // initialized means it is linked in the list
+};
 
 // nni_reap performs an asynchronous reap of an item.  This allows functions
 // it calls to acquire locks or resources without worrying about deadlocks
 // (such as from a completion callback.)  The called function should avoid
 // blocking for too long if possible, since only one reap thread is present
-// in the system.  The intended usage is for an nni_reap_item to be a member
+// in the system.  The intended usage is for an nni_reap_node to be a member
 // of the structure to be reaped, and and then this function is called to
 // finalize it.
 //
@@ -35,10 +51,14 @@ typedef struct nni_reap_item {
 // is busy.  These will be queued at the end of the reap list.  This will
 // allow a dependency to defer reaping until its dependents have first been
 // reaped.  HOWEVER, it is important that the item in question actually be
-// part of a fully reapable graph; otherwise this can lead to an infinite
+// part of a fully reap-able graph; otherwise this can lead to an infinite
 // loop in the reap thread.
-extern void nni_reap(nni_reap_item *, nni_cb, void *);
+
+extern void nni_reap(nni_reap_list *, void *);
+
+// nni_reap_drain waits for the reap queue to be drained.
 extern void nni_reap_drain(void);
+
 extern int  nni_reap_sys_init(void);
 extern void nni_reap_sys_fini(void);