From b3f374cb5589a52900ea207fa9f977ff6e5e39c6 Mon Sep 17 00:00:00 2001
From: Samy Al Bahra <sbahra@repnop.org>
Date: Wed, 5 Nov 2014 18:30:31 -0500
Subject: [PATCH] ck_epoch: Allow for deferral from callbacks.

This makes things much easier in cases where deferral is mixed
with other reclamation mechanisms such as reference counters.
---
 regressions/ck_epoch/validate/Makefile        |  5 +-
 regressions/ck_epoch/validate/ck_epoch_call.c | 64 +++++++++++++++++++
 src/ck_epoch.c                                |  9 ++-
 3 files changed, 74 insertions(+), 4 deletions(-)
 create mode 100644 regressions/ck_epoch/validate/ck_epoch_call.c

diff --git a/regressions/ck_epoch/validate/Makefile b/regressions/ck_epoch/validate/Makefile
index 73f8e5d..c053d22 100644
--- a/regressions/ck_epoch/validate/Makefile
+++ b/regressions/ck_epoch/validate/Makefile
@@ -1,6 +1,6 @@
 .PHONY: check clean distribution
 
-OBJECTS=ck_stack ck_epoch_synchronize ck_epoch_poll
+OBJECTS=ck_stack ck_epoch_synchronize ck_epoch_poll ck_epoch_call
 HALF=`expr $(CORES) / 2`
 
 all: $(OBJECTS)
@@ -16,6 +16,9 @@ ck_epoch_synchronize: ck_epoch_synchronize.c ../../../include/ck_stack.h ../../.
 ck_epoch_poll: ck_epoch_poll.c ../../../include/ck_stack.h ../../../include/ck_epoch.h ../../../src/ck_epoch.c
 	$(CC) $(CFLAGS) -o ck_epoch_poll ck_epoch_poll.c ../../../src/ck_epoch.c
 
+ck_epoch_call: ck_epoch_call.c ../../../include/ck_stack.h ../../../include/ck_epoch.h ../../../src/ck_epoch.c
+	$(CC) $(CFLAGS) -o ck_epoch_call ck_epoch_call.c ../../../src/ck_epoch.c
+
 ck_stack: ck_stack.c ../../../include/ck_stack.h ../../../include/ck_epoch.h ../../../src/ck_epoch.c
 	$(CC) $(CFLAGS) -o ck_stack ck_stack.c ../../../src/ck_epoch.c
 
diff --git a/regressions/ck_epoch/validate/ck_epoch_call.c b/regressions/ck_epoch/validate/ck_epoch_call.c
new file mode 100644
index 0000000..9219ddd
--- /dev/null
+++ b/regressions/ck_epoch/validate/ck_epoch_call.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2014 Samy Al Bahra.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <ck_epoch.h>
+
+#include "../../common.h"
+
+static ck_epoch_t epoch;
+static unsigned int counter;
+static ck_epoch_record_t record[2];
+
+static void
+cb(ck_epoch_entry_t *p)
+{
+
+	if (counter == 0)
+		ck_epoch_call(&epoch, &record[1], p, cb);
+
+	printf("Counter value: %u -> %u\n",
+	    counter, counter + 1);
+	counter++;
+	return;
+}
+
+int
+main(void)
+{
+	static ck_epoch_entry_t entry;
+
+	ck_epoch_register(&epoch, &record[0]);
+	ck_epoch_register(&epoch, &record[1]);
+
+	ck_epoch_call(&epoch, &record[1], &entry, cb);
+	ck_epoch_barrier(&epoch, &record[1]);
+	ck_epoch_barrier(&epoch, &record[1]);
+	if (counter != 2)
+		ck_error("Expected counter value 2, read %u.\n", counter);
+
+	return 0;
+}
diff --git a/src/ck_epoch.c b/src/ck_epoch.c
index 1a51059..01320ee 100644
--- a/src/ck_epoch.c
+++ b/src/ck_epoch.c
@@ -257,12 +257,16 @@ static void
 ck_epoch_dispatch(struct ck_epoch_record *record, unsigned int e)
 {
 	unsigned int epoch = e & (CK_EPOCH_LENGTH - 1);
-	ck_stack_entry_t *next, *cursor;
+	ck_stack_entry_t *head, *next, *cursor;
 	unsigned int i = 0;
 
-	CK_STACK_FOREACH_SAFE(&record->pending[epoch], cursor, next) {
+	head = CK_STACK_FIRST(&record->pending[epoch]);
+	ck_stack_init(&record->pending[epoch]);
+
+	for (cursor = head; cursor != NULL; cursor = next) {
 		struct ck_epoch_entry *entry = ck_epoch_entry_container(cursor);
 
+		next = CK_STACK_NEXT(cursor);
 		entry->function(entry);
 		i++;
 	}
@@ -272,7 +276,6 @@ ck_epoch_dispatch(struct ck_epoch_record *record, unsigned int e)
 
 	record->n_dispatch += i;
 	record->n_pending -= i;
-	ck_stack_init(&record->pending[epoch]);
 	return;
 }