From: Alberto Leiva Popper <ydahhrk@gmail.com>
Date: Thu, 16 May 2019 18:40:45 +0000 (-0500)
Subject: Fix atomic reference counter TODO
X-Git-Tag: v0.0.2~32
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=739e61c56e0a462cf4e75cb340bc6ce5677161a0;p=thirdparty%2FFORT-validator.git

Fix atomic reference counter TODO

I couldn't find a viable way to multithreadedly manage deltas
without reference counters, and sig_atomic_t doesn't look portable
to me. So I decided to use C11 atomic types.

Upgrades the language standard from gnu99 to gnu11.
---

diff --git a/src/Makefile.am b/src/Makefile.am
index a41a1bfa..40a8d9b1 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -96,7 +96,7 @@ fort_SOURCES += slurm/slurm_parser.c slurm/slurm_parser.h
 fort_CFLAGS  = -Wall
 # Feel free to temporarily remove this one if you're not using gcc 7.3.0.
 #fort_CFLAGS += $(GCC_WARNS)
-fort_CFLAGS += -std=gnu99 -O0 -g $(CFLAGS_DEBUG)
+fort_CFLAGS += -std=gnu11 -O0 -g $(CFLAGS_DEBUG)
 fort_LDFLAGS = $(LDFLAGS_DEBUG)
 fort_LDADD   = ${JANSSON_LIBS}
 
diff --git a/src/abbreviations.txt b/src/abbreviations.txt
index 92263bc1..6cab74cd 100644
--- a/src/abbreviations.txt
+++ b/src/abbreviations.txt
@@ -20,6 +20,8 @@ msg: message
 pdu: Protocol Data Unit (RFC 6810)
 pr: print
 ptr: pointer
+refget: reference get (+1 to reference counter)
+refput: reference put (-1 to reference counter)
 str: string
 tmp: temporal
 uint: unsigned int
diff --git a/src/rtr/db/delta.c b/src/rtr/db/delta.c
index 3bcc1c5d..7ffe0790 100644
--- a/src/rtr/db/delta.c
+++ b/src/rtr/db/delta.c
@@ -1,5 +1,6 @@
 #include "rtr/db/delta.h"
 
+#include <stdatomic.h>
 #include "data_structure/array_list.h"
 
 struct delta_v4 {
@@ -27,8 +28,7 @@ struct deltas {
 		struct deltas_v6 removes;
 	} v6;
 
-	/* TODO (now) atomic */
-	unsigned int references;
+	atomic_uint references;
 };
 
 int
@@ -44,23 +44,26 @@ deltas_create(struct deltas **_result)
 	deltas_v4_init(&result->v4.removes);
 	deltas_v6_init(&result->v6.adds);
 	deltas_v6_init(&result->v6.removes);
-	result->references = 1;
+	atomic_init(&result->references, 1);
 
 	*_result = result;
 	return 0;
 }
 
 void
-deltas_get(struct deltas *deltas)
+deltas_refget(struct deltas *deltas)
 {
-	deltas->references++;
+	atomic_fetch_add(&deltas->references, 1);
 }
 
 void
-deltas_put(struct deltas *deltas)
+deltas_refput(struct deltas *deltas)
 {
-	deltas->references--;
-	if (deltas->references == 0) {
+	/*
+	 * Reminder: atomic_fetch_sub() returns the previous value, not the
+	 * resulting one.
+	 */
+	if (atomic_fetch_sub(&deltas->references, 1) == 1) {
 		deltas_v4_cleanup(&deltas->v4.adds, NULL);
 		deltas_v4_cleanup(&deltas->v4.removes, NULL);
 		deltas_v6_cleanup(&deltas->v6.adds, NULL);
diff --git a/src/rtr/db/delta.h b/src/rtr/db/delta.h
index 1d2a0701..a3d66ae6 100644
--- a/src/rtr/db/delta.h
+++ b/src/rtr/db/delta.h
@@ -7,8 +7,8 @@
 struct deltas;
 
 int deltas_create(struct deltas **);
-void deltas_get(struct deltas *);
-void deltas_put(struct deltas *);
+void deltas_refget(struct deltas *);
+void deltas_refput(struct deltas *);
 
 int deltas_add_roa_v4(struct deltas *, uint32_t, struct v4_address *, int);
 int deltas_add_roa_v6(struct deltas *, uint32_t, struct v6_address *, int);
diff --git a/src/rtr/db/roa_table.c b/src/rtr/db/roa_table.c
index bf4c012d..5e7df96b 100644
--- a/src/rtr/db/roa_table.c
+++ b/src/rtr/db/roa_table.c
@@ -269,6 +269,6 @@ compute_deltas(struct roa_table *old, struct roa_table *new,
 	return 0;
 
 fail:
-	deltas_put(deltas);
+	deltas_refput(deltas);
 	return error;
 }
diff --git a/src/rtr/db/vrps.c b/src/rtr/db/vrps.c
index 7a290b62..b32296c2 100644
--- a/src/rtr/db/vrps.c
+++ b/src/rtr/db/vrps.c
@@ -48,7 +48,7 @@ static pthread_rwlock_t lock;
 void
 deltagroup_cleanup(struct delta_group *group)
 {
-	deltas_put(group->deltas);
+	deltas_refput(group->deltas);
 }
 
 int
@@ -173,7 +173,7 @@ resize_deltas_db(struct deltas_db *db, struct delta_group *start)
 	memcpy(tmp, start, db->len * sizeof(struct delta_group));
 	/* Release memory allocated */
 	for (ptr = db->array; ptr < start; ptr++)
-		deltas_put(ptr->deltas);
+		deltas_refput(ptr->deltas);
 	free(db->array);
 	db->array = tmp;
 }
@@ -187,12 +187,12 @@ vrps_purge(void)
 
 	min_serial = clients_get_min_serial();
 
-	/** Assume is ordered by serial, so get the new initial pointer */
+	/* Assume is ordered by serial, so get the new initial pointer */
 	ARRAYLIST_FOREACH(&state.deltas, group, i)
 		if (group->serial >= min_serial)
 			break;
 
-	/** Is the first element or reached end, nothing to purge */
+	/* Is the first element or reached end, nothing to purge */
 	if (group == state.deltas.array ||
 	    (group - state.deltas.array) == state.deltas.len)
 		return;
@@ -251,7 +251,7 @@ vrps_update(bool *changed)
 		 */
 		old_base = state.base;
 
-		/** Remove unnecessary deltas */
+		/* Remove unnecessary deltas */
 		vrps_purge();
 
 	} else {
@@ -287,7 +287,7 @@ vrps_update(bool *changed)
 	return 0;
 
 revert_deltas:
-	deltas_put(deltas);
+	deltas_refput(deltas);
 revert_base:
 	roa_table_destroy(new_base);
 	return error;
@@ -369,7 +369,7 @@ vrps_get_deltas_from(serial_t from, serial_t *to, struct deltas_db *result)
 			return error;
 		}
 
-		deltas_get(group->deltas);
+		deltas_refget(group->deltas);
 		*to = group->serial;
 	}