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>

1 files changed, 154 insertions, 0 deletions

diff --git a/src/svm/message_queue.h b/src/svm/message_queue.h
new file mode 100644
index 00000000000..5ec8547016e
--- /dev/null
+++ b/src/svm/message_queue.h
@@ -0,0 +1,154 @@
+/*
+ * 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.
+ */
+/**
+ * @file
+ * @brief Unidirectional shared-memory multi-ring message queue
+ */
+
+#ifndef SRC_SVM_MESSAGE_QUEUE_H_
+#define SRC_SVM_MESSAGE_QUEUE_H_
+
+#include <vppinfra/clib.h>
+#include <svm/queue.h>
+
+typedef struct svm_msg_q_ring_
+{
+  volatile u32 cursize;			/**< current size of the ring */
+  u32 nitems;				/**< max size of the ring */
+  u32 head;				/**< current head (for dequeue) */
+  u32 tail;				/**< current tail (for enqueue) */
+  u32 elsize;				/**< size of an element */
+  u8 *data;				/**< chunk of memory for msg data */
+} svm_msg_q_ring_t;
+
+typedef struct svm_msg_q_
+{
+  svm_queue_t *q;			/**< queue for exchanging messages */
+  svm_msg_q_ring_t *rings;		/**< rings with message data*/
+} svm_msg_q_t;
+
+typedef struct svm_msg_q_ring_cfg_
+{
+  u32 nitems;
+  u32 elsize;
+  void *data;
+} svm_msg_q_ring_cfg_t;
+
+typedef struct svm_msg_q_cfg_
+{
+  int consumer_pid;			/**< pid of msg consumer */
+  u32 q_nitems;				/**< msg queue size (not rings) */
+  u32 n_rings;				/**< number of msg rings */
+  svm_msg_q_ring_cfg_t *ring_cfgs;	/**< array of ring cfgs */
+} svm_msg_q_cfg_t;
+
+typedef union
+{
+  struct
+  {
+    u32 ring_index;			/**< ring index, could be u8 */
+    u32 elt_index;			/**< index in ring */
+  };
+  u64 as_u64;
+} svm_msg_q_msg_t;
+
+/**
+ * Allocate message queue
+ *
+ * Allocates a message queue on the heap. Based on the configuration options,
+ * apart from the message queue this also allocates (one or multiple)
+ * shared-memory rings for the messages.
+ *
+ * @param cfg 		configuration options: queue len, consumer pid,
+ * 			ring configs
+ * @return		message queue
+ */
+svm_msg_q_t *svm_msg_q_alloc (svm_msg_q_cfg_t * cfg);
+
+/**
+ * Free message queue
+ *
+ * @param mq		message queue to be freed
+ */
+void svm_msg_q_free (svm_msg_q_t * mq);
+
+/**
+ * Allocate message buffer
+ *
+ * Message is allocated on the first available ring capable of holding
+ * the requested number of bytes.
+ *
+ * @param mq		message queue
+ * @param nbytes	number of bytes needed for message
+ * @return		message structure pointing to the ring and position
+ * 			allocated
+ */
+svm_msg_q_msg_t svm_msg_q_alloc_msg (svm_msg_q_t * mq, u32 nbytes);
+
+/**
+ * Free message buffer
+ *
+ * Marks message buffer on ring as free.
+ *
+ * @param mq		message queue
+ * @param msg		message to be freed
+ */
+void svm_msg_q_free_msg (svm_msg_q_t * mq, svm_msg_q_msg_t * msg);
+/**
+ * Producer enqueue one message to queue
+ *
+ * Prior to calling this, the producer should've obtained a message buffer
+ * from one of the rings by calling @ref svm_msg_q_alloc_msg.
+ *
+ * @param mq		message queue
+ * @param msg		message (pointer to ring position) to be enqueued
+ * @param nowait	flag to indicate if request is blocking or not
+ * @return		success status
+ */
+int svm_msg_q_add (svm_msg_q_t * mq, svm_msg_q_msg_t msg, int nowait);
+
+/**
+ * Consumer dequeue one message from queue
+ *
+ * This returns the message pointing to the data in the message rings.
+ * The consumer is expected to call @ref svm_msg_q_free_msg once it
+ * finishes processing/copies the message data.
+ *
+ * @param mq		message queue
+ * @param msg		pointer to structure where message is to be received
+ * @param cond		flag that indicates if request should block or not
+ * @return		success status
+ */
+int svm_msg_q_sub (svm_msg_q_t * mq, svm_msg_q_msg_t * msg,
+		   svm_q_conditional_wait_t cond, u32 time);
+
+/**
+ * Get data for message in queu
+ *
+ * @param mq		message queue
+ * @param msg		message for which the data is requested
+ * @return		pointer to data
+ */
+void *svm_msg_q_msg_data (svm_msg_q_t * mq, svm_msg_q_msg_t * msg);
+
+#endif /* SRC_SVM_MESSAGE_QUEUE_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */