svm: add unidirectional message queue
Meant for single reader/writer message exchanges. Supports multiple
message rings.
Change-Id: I925de9a6ae19226c5c39a63caff76424ed123a13
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/svm/message_queue.c b/src/svm/message_queue.c
new file mode 100644
index 0000000..dc0f625
--- /dev/null
+++ b/src/svm/message_queue.c
@@ -0,0 +1,159 @@
+/*
+ * Copyright (c) 2018 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <svm/message_queue.h>
+#include <vppinfra/mem.h>
+
+svm_msg_q_t *
+svm_msg_q_alloc (svm_msg_q_cfg_t * cfg)
+{
+ svm_msg_q_ring_t *ring;
+ svm_msg_q_t *mq;
+ int i;
+
+ if (!cfg)
+ return 0;
+
+ mq = clib_mem_alloc_aligned (sizeof (svm_msg_q_t), CLIB_CACHE_LINE_BYTES);
+ memset (mq, 0, sizeof (*mq));
+ mq->q = svm_queue_init (cfg->q_nitems, sizeof (svm_msg_q_msg_t),
+ cfg->consumer_pid, 0);
+ vec_validate (mq->rings, cfg->n_rings - 1);
+ for (i = 0; i < cfg->n_rings; i++)
+ {
+ ring = &mq->rings[i];
+ ring->elsize = cfg->ring_cfgs[i].elsize;
+ ring->nitems = cfg->ring_cfgs[i].nitems;
+ if (cfg->ring_cfgs[i].data)
+ ring->data = cfg->ring_cfgs[i].data;
+ else
+ ring->data = clib_mem_alloc_aligned (ring->nitems * ring->elsize,
+ CLIB_CACHE_LINE_BYTES);
+ }
+
+ return mq;
+}
+
+void
+svm_msg_q_free (svm_msg_q_t * mq)
+{
+ svm_msg_q_ring_t *ring;
+
+ vec_foreach (ring, mq->rings)
+ {
+ clib_mem_free (ring->data);
+ }
+ vec_free (mq->rings);
+ clib_mem_free (mq);
+}
+
+svm_msg_q_msg_t
+svm_msg_q_alloc_msg (svm_msg_q_t * mq, u32 nbytes)
+{
+ svm_msg_q_msg_t msg = {.as_u64 = ~0 };
+ svm_msg_q_ring_t *ring;
+
+ vec_foreach (ring, mq->rings)
+ {
+ if (ring->elsize < nbytes || ring->cursize == ring->nitems)
+ continue;
+ msg.ring_index = ring - mq->rings;
+ msg.elt_index = ring->tail;
+ ring->tail = (ring->tail + 1) % ring->nitems;
+ __sync_fetch_and_add (&ring->cursize, 1);
+ break;
+ }
+ return msg;
+}
+
+static inline svm_msg_q_ring_t *
+svm_msg_q_get_ring (svm_msg_q_t * mq, u32 ring_index)
+{
+ return vec_elt_at_index (mq->rings, ring_index);
+}
+
+static inline void *
+svm_msg_q_ring_data (svm_msg_q_ring_t * ring, u32 elt_index)
+{
+ ASSERT (elt_index < ring->nitems);
+ return (ring->data + elt_index * ring->elsize);
+}
+
+void *
+svm_msg_q_msg_data (svm_msg_q_t * mq, svm_msg_q_msg_t * msg)
+{
+ svm_msg_q_ring_t *ring = svm_msg_q_get_ring (mq, msg->ring_index);
+ return svm_msg_q_ring_data (ring, msg->elt_index);
+}
+
+void
+svm_msg_q_free_msg (svm_msg_q_t * mq, svm_msg_q_msg_t * msg)
+{
+ svm_msg_q_ring_t *ring;
+
+ if (vec_len (mq->rings) <= msg->ring_index)
+ return;
+ ring = &mq->rings[msg->ring_index];
+ if (msg->elt_index == ring->head)
+ {
+ ring->head = (ring->head + 1) % ring->nitems;
+ }
+ else
+ {
+ /* for now, expect messages to be processed in order */
+ ASSERT (0);
+ }
+ __sync_fetch_and_sub (&ring->cursize, 1);
+}
+
+static int
+svm_msq_q_msg_is_valid (svm_msg_q_t * mq, svm_msg_q_msg_t * msg)
+{
+ svm_msg_q_ring_t *ring;
+ u32 dist1, dist2;
+
+ if (vec_len (mq->rings) <= msg->ring_index)
+ return 0;
+ ring = &mq->rings[msg->ring_index];
+
+ dist1 = ((ring->nitems + msg->ring_index) - ring->head) % ring->nitems;
+ if (ring->tail == ring->head)
+ dist2 = (ring->cursize == 0) ? 0 : ring->nitems;
+ else
+ dist2 = ((ring->nitems + ring->tail) - ring->head) % ring->nitems;
+ return (dist1 < dist2);
+}
+
+int
+svm_msg_q_add (svm_msg_q_t * mq, svm_msg_q_msg_t msg, int nowait)
+{
+ ASSERT (svm_msq_q_msg_is_valid (mq, &msg));
+ return svm_queue_add (mq->q, (u8 *) & msg, nowait);
+}
+
+int
+svm_msg_q_sub (svm_msg_q_t * mq, svm_msg_q_msg_t * msg,
+ svm_q_conditional_wait_t cond, u32 time)
+{
+ return svm_queue_sub (mq->q, (u8 *) msg, cond, time);
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */