From 62e4f1deddd1be882d69d6f7e76c663aade11210 Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Sun, 7 Dec 2008 20:16:23 +0100
Subject: [PATCH] [MINOR] add back-references to sessions for later use by a
 dumper.

This is the first step in implementing a session dump tool.
A session dump will need restart points. It will be necessary for
it to get references to sessions which can be moved when the session
dies.

The principle is not that complex : when a session ends, it looks for
any potential back-references. If it finds any, then it moves them to
the next session in the list. The dump function will of course have
to restart from that new point.
---
 include/types/session.h | 1 +
 src/client.c            | 7 +++++++
 src/proto_uxst.c        | 7 +++++++
 src/session.c           | 7 +++++++
 4 files changed, 22 insertions(+)

diff --git a/include/types/session.h b/include/types/session.h
index eaa053fbf..7630bc30c 100644
--- a/include/types/session.h
+++ b/include/types/session.h
@@ -153,6 +153,7 @@ enum {
  */
 struct session {
 	struct list list;			/* position in global sessions list */
+	struct list back_refs;			/* list of users tracking this session */
 	struct task *task;			/* the task associated with this session */
 	/* application specific below */
 	struct listener *listener;		/* the listener by which the request arrived */
diff --git a/src/client.c b/src/client.c
index a9625dac1..4e8004e76 100644
--- a/src/client.c
+++ b/src/client.c
@@ -66,6 +66,7 @@ int event_accept(int fd) {
 	struct session *s;
 	struct http_txn *txn;
 	struct task *t;
+	struct bref *bref, *back;
 	int cfd;
 	int max_accept = global.tune.maxaccept;
 
@@ -108,6 +109,7 @@ int event_accept(int fd) {
 		}
 
 		LIST_ADDQ(&sessions, &s->list);
+		LIST_INIT(&s->back_refs);
 
 		s->flags = 0;
 		s->term_trace = 0;
@@ -464,6 +466,11 @@ int event_accept(int fd) {
  out_free_task:
 	pool_free2(pool2_task, t);
  out_free_session:
+	list_for_each_entry_safe(bref, back, &s->back_refs, users) {
+		LIST_DEL(&bref->users);
+		LIST_ADDQ(&LIST_ELEM(s->list.n, struct session *, list)->back_refs, &bref->users);
+		bref->ref = s->list.n;
+	}
 	LIST_DEL(&s->list);
 	pool_free2(pool2_session, s);
  out_close:
diff --git a/src/proto_uxst.c b/src/proto_uxst.c
index 06ec18570..25432687a 100644
--- a/src/proto_uxst.c
+++ b/src/proto_uxst.c
@@ -360,6 +360,7 @@ int uxst_event_accept(int fd) {
 	struct listener *l = fdtab[fd].owner;
 	struct session *s;
 	struct task *t;
+	struct bref *bref, *back;
 	int cfd;
 	int max_accept;
 
@@ -409,6 +410,7 @@ int uxst_event_accept(int fd) {
 		}
 
 		LIST_ADDQ(&sessions, &s->list);
+		LIST_INIT(&s->back_refs);
 
 		s->flags = 0;
 		s->term_trace = 0;
@@ -545,6 +547,11 @@ int uxst_event_accept(int fd) {
  out_free_task:
 	pool_free2(pool2_task, t);
  out_free_session:
+	list_for_each_entry_safe(bref, back, &s->back_refs, users) {
+		LIST_DEL(&bref->users);
+		LIST_ADDQ(&LIST_ELEM(s->list.n, struct session *, list)->back_refs, &bref->users);
+		bref->ref = s->list.n;
+	}
 	LIST_DEL(&s->list);
 	pool_free2(pool2_session, s);
  out_close:
diff --git a/src/session.c b/src/session.c
index a6190730d..e82bfccdf 100644
--- a/src/session.c
+++ b/src/session.c
@@ -42,6 +42,7 @@ void session_free(struct session *s)
 {
 	struct http_txn *txn = &s->txn;
 	struct proxy *fe = s->fe;
+	struct bref *bref, *back;
 
 	if (s->pend_pos)
 		pendconn_free(s->pend_pos);
@@ -82,6 +83,12 @@ void session_free(struct session *s)
 	pool_free2(pool2_requri, txn->uri);
 	pool_free2(pool2_capture, txn->cli_cookie);
 	pool_free2(pool2_capture, txn->srv_cookie);
+
+	list_for_each_entry_safe(bref, back, &s->back_refs, users) {
+		LIST_DEL(&bref->users);
+		LIST_ADDQ(&LIST_ELEM(s->list.n, struct session *, list)->back_refs, &bref->users);
+		bref->ref = s->list.n;
+	}
 	LIST_DEL(&s->list);
 	pool_free2(pool2_session, s);