s3: Implement tevent_barrier

This will help notify torture tests: A tevent barrier can be waited on with
tevent_barrier_wait_send/recv. The barrier is initialized with a number of
requests that it will accept waiting. When that number is reached, all those
requests will be released and their callback will be called. The barrier will
be free for re-use again.

2 files changed, 234 insertions, 0 deletions

diff --git a/source3/lib/tevent_barrier.c b/source3/lib/tevent_barrier.c
new file mode 100644
index 0000000000..d699b5fda9
--- /dev/null
+++ b/source3/lib/tevent_barrier.c
@@ -0,0 +1,197 @@
+/*
+   Unix SMB/CIFS implementation.
+   Implement a barrier
+   Copyright (C) Volker Lendecke 2012
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "tevent_barrier.h"
+#include "lib/util/tevent_unix.h"
+
+struct tevent_barrier_waiter {
+	struct tevent_immediate *im;
+	struct tevent_context *ev;
+	struct tevent_req *req;
+};
+
+struct tevent_barrier {
+	unsigned count;
+	struct tevent_barrier_waiter *waiters;
+	void (*trigger_cb)(void *private_data);
+	void *private_data;
+};
+
+static int tevent_barrier_destructor(struct tevent_barrier *b);
+static void tevent_barrier_release(struct tevent_barrier *b);
+static void tevent_barrier_release_one(struct tevent_context *ctx,
+				       struct tevent_immediate *im,
+				       void *private_data);
+static void tevent_barrier_release_trigger(struct tevent_context *ctx,
+					   struct tevent_immediate *im,
+					   void *private_data);
+
+struct tevent_barrier *tevent_barrier_init(
+	TALLOC_CTX *mem_ctx, unsigned count,
+	void (*trigger_cb)(void *private_data), void *private_data)
+{
+	struct tevent_barrier *b;
+	unsigned i;
+
+	if (count == 0) {
+		return NULL;
+	}
+
+	b = talloc(mem_ctx, struct tevent_barrier);
+	if (b == NULL) {
+		return NULL;
+	}
+	b->count = 0;
+	b->trigger_cb = trigger_cb;
+	b->private_data = private_data;
+
+	b->waiters = talloc_array(b, struct tevent_barrier_waiter, count);
+	if (b->waiters == NULL) {
+		goto fail;
+	}
+	for (i=0; i<count; i++) {
+		struct tevent_barrier_waiter *w = &b->waiters[i];
+
+		w->im = tevent_create_immediate(b->waiters);
+		if (w->im == NULL) {
+			goto fail;
+		}
+		w->req = NULL;
+	}
+	talloc_set_destructor(b, tevent_barrier_destructor);
+	return b;
+fail:
+	TALLOC_FREE(b);
+	return NULL;
+}
+
+static int tevent_barrier_destructor(struct tevent_barrier *b)
+{
+	tevent_barrier_release(b);
+	return 0;
+}
+
+struct tevent_barrier_wait_state {
+	struct tevent_barrier *b;
+	int index;
+};
+
+static void tevent_barrier_release(struct tevent_barrier *b)
+{
+	unsigned i;
+
+	for (i=0; i<b->count; i++) {
+		struct tevent_barrier_waiter *w = &b->waiters[i];
+		struct tevent_barrier_wait_state *state;
+
+		if (w->req == NULL) {
+			continue;
+		}
+		tevent_schedule_immediate(
+			w->im, w->ev, tevent_barrier_release_one, w->req);
+
+		state = tevent_req_data(
+			w->req, struct tevent_barrier_wait_state);
+		talloc_set_destructor(state, NULL);
+
+		w->req = NULL;
+		w->ev = NULL;
+	}
+	b->count = 0;
+	if (b->trigger_cb != NULL) {
+		b->trigger_cb(b->private_data);
+	}
+}
+
+static void tevent_barrier_release_one(struct tevent_context *ctx,
+				       struct tevent_immediate *im,
+				       void *private_data)
+{
+	struct tevent_req *req = talloc_get_type_abort(
+		private_data, struct tevent_req);
+	tevent_req_done(req);
+}
+
+static int tevent_barrier_wait_state_destructor(
+	struct tevent_barrier_wait_state *s);
+
+struct tevent_req *tevent_barrier_wait_send(TALLOC_CTX *mem_ctx,
+					    struct tevent_context *ev,
+					    struct tevent_barrier *b)
+{
+	struct tevent_req *req;
+	struct tevent_barrier_wait_state *state;
+	struct tevent_barrier_waiter *w;
+	struct tevent_immediate *im;
+
+	req = tevent_req_create(mem_ctx, &state,
+				struct tevent_barrier_wait_state);
+	if (req == NULL) {
+		return NULL;
+	}
+	state->b = b;
+	state->index = b->count;
+
+	w = &b->waiters[b->count];
+	w->ev = ev;
+	w->req = req;
+	b->count += 1;
+
+	talloc_set_destructor(state, tevent_barrier_wait_state_destructor);
+
+	if (b->count < talloc_array_length(b->waiters)) {
+		return req;
+	}
+
+	im = tevent_create_immediate(req);
+	if (tevent_req_nomem(im, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_schedule_immediate(im, ev, tevent_barrier_release_trigger, b);
+	return req;
+}
+
+static int tevent_barrier_wait_state_destructor(
+	struct tevent_barrier_wait_state *s)
+{
+	struct tevent_barrier *b = s->b;
+	b->waiters[s->index].req = b->waiters[b->count-1].req;
+	b->count -= 1;
+	return 0;
+}
+
+static void tevent_barrier_release_trigger(struct tevent_context *ctx,
+					   struct tevent_immediate *im,
+					   void *private_data)
+{
+	struct tevent_barrier *b = talloc_get_type_abort(
+		private_data, struct tevent_barrier);
+	tevent_barrier_release(b);
+}
+
+int tevent_barrier_wait_recv(struct tevent_req *req)
+{
+	int err;
+
+	if (tevent_req_is_unix_error(req, &err)) {
+		return err;
+	}
+	return 0;
+}
diff --git a/source3/lib/tevent_barrier.h b/source3/lib/tevent_barrier.h
new file mode 100644
index 0000000000..2b358522d9
--- /dev/null
+++ b/source3/lib/tevent_barrier.h
@@ -0,0 +1,37 @@
+/*
+   Unix SMB/CIFS implementation.
+   Implement a barrier
+   Copyright (C) Volker Lendecke 2012
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _TEVENT_BARRIER_H
+#define _TEVENT_BARRIER_H
+
+#include "talloc.h"
+#include "tevent.h"
+
+struct tevent_barrier;
+
+struct tevent_barrier *tevent_barrier_init(
+	TALLOC_CTX *mem_ctx, unsigned count,
+	void (*trigger_cb)(void *private_data), void *private_data);
+
+struct tevent_req *tevent_barrier_wait_send(TALLOC_CTX *mem_ctx,
+					    struct tevent_context *ev,
+					    struct tevent_barrier *b);
+int tevent_barrier_wait_recv(struct tevent_req *req);
+
+#endif /* _TEVENT_BARRIER_H */