rte_graph_worker.h

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(C) 2020 Marvell International Ltd.
 */

#ifndef _RTE_GRAPH_WORKER_H_
#define _RTE_GRAPH_WORKER_H_

/**
 * @file rte_graph_worker.h
 *
 * @warning
 * @b EXPERIMENTAL:
 * All functions in this file may be changed or removed without prior notice.
 *
 * This API allows a worker thread to walk over a graph and nodes to create,
 * process, enqueue and move streams of objects to the next nodes.
 */

#include <rte_common.h>
#include <rte_cycles.h>
#include <rte_prefetch.h>
#include <rte_memcpy.h>
#include <rte_memory.h>

#include "rte_graph.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @internal
 *
 * Data structure to hold graph data.
 */
struct rte_graph {
	uint32_t tail;		     /**< Tail of circular buffer. */
	uint32_t head;		     /**< Head of circular buffer. */
	uint32_t cir_mask;	     /**< Circular buffer wrap around mask. */
	rte_node_t nb_nodes;	     /**< Number of nodes in the graph. */
	rte_graph_off_t *cir_start;  /**< Pointer to circular buffer. */
	rte_graph_off_t nodes_start; /**< Offset at which node memory starts. */
	rte_graph_t id;	/**< Graph identifier. */
	int socket;	/**< Socket ID where memory is allocated. */
	char name[RTE_GRAPH_NAMESIZE];	/**< Name of the graph. */
	uint64_t fence;			/**< Fence. */
} __rte_cache_aligned;

/**
 * @internal
 *
 * Data structure to hold node data.
 */
struct rte_node {
	/* Slow path area  */
	uint64_t fence;		/**< Fence. */
	rte_graph_off_t next;	/**< Index to next node. */
	rte_node_t id;		/**< Node identifier. */
	rte_node_t parent_id;	/**< Parent Node identifier. */
	rte_edge_t nb_edges;	/**< Number of edges from this node. */
	uint32_t realloc_count;	/**< Number of times realloced. */

	char parent[RTE_NODE_NAMESIZE];	/**< Parent node name. */
	char name[RTE_NODE_NAMESIZE];	/**< Name of the node. */

	/* Fast path area  */
#define RTE_NODE_CTX_SZ 16
	uint8_t ctx[RTE_NODE_CTX_SZ] __rte_cache_aligned; /**< Node Context. */
	uint16_t size;		/**< Total number of objects available. */
	uint16_t idx;		/**< Number of objects used. */
	rte_graph_off_t off;	/**< Offset of node in the graph reel. */
	uint64_t total_cycles;	/**< Cycles spent in this node. */
	uint64_t total_calls;	/**< Calls done to this node. */
	uint64_t total_objs;	/**< Objects processed by this node. */
	RTE_STD_C11
		union {
			void **objs;	   /**< Array of object pointers. */
			uint64_t objs_u64;
		};
	RTE_STD_C11
		union {
			rte_node_process_t process; /**< Process function. */
			uint64_t process_u64;
		};
	struct rte_node *nodes[] __rte_cache_min_aligned; /**< Next nodes. */
} __rte_cache_aligned;

/**
 * @internal
 *
 * Allocate a stream of objects.
 *
 * If stream already exists then re-allocate it to a larger size.
 *
 * @param graph
 *   Pointer to the graph object.
 * @param node
 *   Pointer to the node object.
 */
__rte_experimental
void __rte_node_stream_alloc(struct rte_graph *graph, struct rte_node *node);

/**
 * @internal
 *
 * Allocate a stream with requested number of objects.
 *
 * If stream already exists then re-allocate it to a larger size.
 *
 * @param graph
 *   Pointer to the graph object.
 * @param node
 *   Pointer to the node object.
 * @param req_size
 *   Number of objects to be allocated.
 */
__rte_experimental
void __rte_node_stream_alloc_size(struct rte_graph *graph,
				  struct rte_node *node, uint16_t req_size);

/**
 * Perform graph walk on the circular buffer and invoke the process function
 * of the nodes and collect the stats.
 *
 * @param graph
 *   Graph pointer returned from rte_graph_lookup function.
 *
 * @see rte_graph_lookup()
 */
__rte_experimental
static inline void
rte_graph_walk(struct rte_graph *graph)
{
	const rte_graph_off_t *cir_start = graph->cir_start;
	const rte_node_t mask = graph->cir_mask;
	uint32_t head = graph->head;
	struct rte_node *node;
	uint64_t start;
	uint16_t rc;
	void **objs;

	/*
	 * Walk on the source node(s) ((cir_start - head) -> cir_start) and then
	 * on the pending streams (cir_start -> (cir_start + mask) -> cir_start)
	 * in a circular buffer fashion.
	 *
	 *	+-----+ <= cir_start - head [number of source nodes]
	 *	|     |
	 *	| ... | <= source nodes
	 *	|     |
	 *	+-----+ <= cir_start [head = 0] [tail = 0]
	 *	|     |
	 *	| ... | <= pending streams
	 *	|     |
	 *	+-----+ <= cir_start + mask
	 */
	while (likely(head != graph->tail)) {
		node = (struct rte_node *)RTE_PTR_ADD(graph, cir_start[(int32_t)head++]);
		RTE_ASSERT(node->fence == RTE_GRAPH_FENCE);
		objs = node->objs;
		rte_prefetch0(objs);

		if (rte_graph_has_stats_feature()) {
			start = rte_rdtsc();
			rc = node->process(graph, node, objs, node->idx);
			node->total_cycles += rte_rdtsc() - start;
			node->total_calls++;
			node->total_objs += rc;
		} else {
			node->process(graph, node, objs, node->idx);
		}
		node->idx = 0;
		head = likely((int32_t)head > 0) ? head & mask : head;
	}
	graph->tail = 0;
}

/* Fast path helper functions */

/**
 * @internal
 *
 * Enqueue a given node to the tail of the graph reel.
 *
 * @param graph
 *   Pointer Graph object.
 * @param node
 *   Pointer to node object to be enqueued.
 */
static __rte_always_inline void
__rte_node_enqueue_tail_update(struct rte_graph *graph, struct rte_node *node)
{
	uint32_t tail;

	tail = graph->tail;
	graph->cir_start[tail++] = node->off;
	graph->tail = tail & graph->cir_mask;
}

/**
 * @internal
 *
 * Enqueue sequence prologue function.
 *
 * Updates the node to tail of graph reel and resizes the number of objects
 * available in the stream as needed.
 *
 * @param graph
 *   Pointer to the graph object.
 * @param node
 *   Pointer to the node object.
 * @param idx
 *   Index at which the object enqueue starts from.
 * @param space
 *   Space required for the object enqueue.
 */
static __rte_always_inline void
__rte_node_enqueue_prologue(struct rte_graph *graph, struct rte_node *node,
			    const uint16_t idx, const uint16_t space)
{

	/* Add to the pending stream list if the node is new */
	if (idx == 0)
		__rte_node_enqueue_tail_update(graph, node);

	if (unlikely(node->size < (idx + space)))
		__rte_node_stream_alloc(graph, node);
}

/**
 * @internal
 *
 * Get the node pointer from current node edge id.
 *
 * @param node
 *   Current node pointer.
 * @param next
 *   Edge id of the required node.
 *
 * @return
 *   Pointer to the node denoted by the edge id.
 */
static __rte_always_inline struct rte_node *
__rte_node_next_node_get(struct rte_node *node, rte_edge_t next)
{
	RTE_ASSERT(next < node->nb_edges);
	RTE_ASSERT(node->fence == RTE_GRAPH_FENCE);
	node = node->nodes[next];
	RTE_ASSERT(node->fence == RTE_GRAPH_FENCE);

	return node;
}

/**
 * Enqueue the objs to next node for further processing and set
 * the next node to pending state in the circular buffer.
 *
 * @param graph
 *   Graph pointer returned from rte_graph_lookup().
 * @param node
 *   Current node pointer.
 * @param next
 *   Relative next node index to enqueue objs.
 * @param objs
 *   Objs to enqueue.
 * @param nb_objs
 *   Number of objs to enqueue.
 */
__rte_experimental
static inline void
rte_node_enqueue(struct rte_graph *graph, struct rte_node *node,
		 rte_edge_t next, void **objs, uint16_t nb_objs)
{
	node = __rte_node_next_node_get(node, next);
	const uint16_t idx = node->idx;

	__rte_node_enqueue_prologue(graph, node, idx, nb_objs);

	rte_memcpy(&node->objs[idx], objs, nb_objs * sizeof(void *));
	node->idx = idx + nb_objs;
}

/**
 * Enqueue only one obj to next node for further processing and
 * set the next node to pending state in the circular buffer.
 *
 * @param graph
 *   Graph pointer returned from rte_graph_lookup().
 * @param node
 *   Current node pointer.
 * @param next
 *   Relative next node index to enqueue objs.
 * @param obj
 *   Obj to enqueue.
 */
__rte_experimental
static inline void
rte_node_enqueue_x1(struct rte_graph *graph, struct rte_node *node,
		    rte_edge_t next, void *obj)
{
	node = __rte_node_next_node_get(node, next);
	uint16_t idx = node->idx;

	__rte_node_enqueue_prologue(graph, node, idx, 1);

	node->objs[idx++] = obj;
	node->idx = idx;
}

/**
 * Enqueue only two objs to next node for further processing and
 * set the next node to pending state in the circular buffer.
 * Same as rte_node_enqueue_x1 but enqueue two objs.
 *
 * @param graph
 *   Graph pointer returned from rte_graph_lookup().
 * @param node
 *   Current node pointer.
 * @param next
 *   Relative next node index to enqueue objs.
 * @param obj0
 *   Obj to enqueue.
 * @param obj1
 *   Obj to enqueue.
 */
__rte_experimental
static inline void
rte_node_enqueue_x2(struct rte_graph *graph, struct rte_node *node,
		    rte_edge_t next, void *obj0, void *obj1)
{
	node = __rte_node_next_node_get(node, next);
	uint16_t idx = node->idx;

	__rte_node_enqueue_prologue(graph, node, idx, 2);

	node->objs[idx++] = obj0;
	node->objs[idx++] = obj1;
	node->idx = idx;
}

/**
 * Enqueue only four objs to next node for further processing and
 * set the next node to pending state in the circular buffer.
 * Same as rte_node_enqueue_x1 but enqueue four objs.
 *
 * @param graph
 *   Graph pointer returned from rte_graph_lookup().
 * @param node
 *   Current node pointer.
 * @param next
 *   Relative next node index to enqueue objs.
 * @param obj0
 *   1st obj to enqueue.
 * @param obj1
 *   2nd obj to enqueue.
 * @param obj2
 *   3rd obj to enqueue.
 * @param obj3
 *   4th obj to enqueue.
 */
__rte_experimental
static inline void
rte_node_enqueue_x4(struct rte_graph *graph, struct rte_node *node,
		    rte_edge_t next, void *obj0, void *obj1, void *obj2,
		    void *obj3)
{
	node = __rte_node_next_node_get(node, next);
	uint16_t idx = node->idx;

	__rte_node_enqueue_prologue(graph, node, idx, 4);

	node->objs[idx++] = obj0;
	node->objs[idx++] = obj1;
	node->objs[idx++] = obj2;
	node->objs[idx++] = obj3;
	node->idx = idx;
}

/**
 * Enqueue objs to multiple next nodes for further processing and
 * set the next nodes to pending state in the circular buffer.
 * objs[i] will be enqueued to nexts[i].
 *
 * @param graph
 *   Graph pointer returned from rte_graph_lookup().
 * @param node
 *   Current node pointer.
 * @param nexts
 *   List of relative next node indices to enqueue objs.
 * @param objs
 *   List of objs to enqueue.
 * @param nb_objs
 *   Number of objs to enqueue.
 */
__rte_experimental
static inline void
rte_node_enqueue_next(struct rte_graph *graph, struct rte_node *node,
		      rte_edge_t *nexts, void **objs, uint16_t nb_objs)
{
	uint16_t i;

	for (i = 0; i < nb_objs; i++)
		rte_node_enqueue_x1(graph, node, nexts[i], objs[i]);
}

/**
 * Get the stream of next node to enqueue the objs.
 * Once done with the updating the objs, needs to call
 * rte_node_next_stream_put to put the next node to pending state.
 *
 * @param graph
 *   Graph pointer returned from rte_graph_lookup().
 * @param node
 *   Current node pointer.
 * @param next
 *   Relative next node index to get stream.
 * @param nb_objs
 *   Requested free size of the next stream.
 *
 * @return
 *   Valid next stream on success.
 *
 * @see rte_node_next_stream_put().
 */
__rte_experimental
static inline void **
rte_node_next_stream_get(struct rte_graph *graph, struct rte_node *node,
			 rte_edge_t next, uint16_t nb_objs)
{
	node = __rte_node_next_node_get(node, next);
	const uint16_t idx = node->idx;
	uint16_t free_space = node->size - idx;

	if (unlikely(free_space < nb_objs))
		__rte_node_stream_alloc_size(graph, node, nb_objs);

	return &node->objs[idx];
}

/**
 * Put the next stream to pending state in the circular buffer
 * for further processing. Should be invoked after rte_node_next_stream_get().
 *
 * @param graph
 *   Graph pointer returned from rte_graph_lookup().
 * @param node
 *   Current node pointer.
 * @param next
 *   Relative next node index..
 * @param idx
 *   Number of objs updated in the stream after getting the stream using
 *   rte_node_next_stream_get.
 *
 * @see rte_node_next_stream_get().
 */
__rte_experimental
static inline void
rte_node_next_stream_put(struct rte_graph *graph, struct rte_node *node,
			 rte_edge_t next, uint16_t idx)
{
	if (unlikely(!idx))
		return;

	node = __rte_node_next_node_get(node, next);
	if (node->idx == 0)
		__rte_node_enqueue_tail_update(graph, node);

	node->idx += idx;
}

/**
 * Home run scenario, Enqueue all the objs of current node to next
 * node in optimized way by swapping the streams of both nodes.
 * Performs good when next node is already not in pending state.
 * If next node is already in pending state then normal enqueue
 * will be used.
 *
 * @param graph
 *   Graph pointer returned from rte_graph_lookup().
 * @param src
 *   Current node pointer.
 * @param next
 *   Relative next node index.
 */
__rte_experimental
static inline void
rte_node_next_stream_move(struct rte_graph *graph, struct rte_node *src,
			  rte_edge_t next)
{
	struct rte_node *dst = __rte_node_next_node_get(src, next);

	/* Let swap the pointers if dst don't have valid objs */
	if (likely(dst->idx == 0)) {
		void **dobjs = dst->objs;
		uint16_t dsz = dst->size;
		dst->objs = src->objs;
		dst->size = src->size;
		src->objs = dobjs;
		src->size = dsz;
		dst->idx = src->idx;
		__rte_node_enqueue_tail_update(graph, dst);
	} else { /* Move the objects from src node to dst node */
		rte_node_enqueue(graph, src, next, src->objs, src->idx);
	}
}

#ifdef __cplusplus
}
#endif

#endif /* _RTE_GRAPH_WORKER_H_ */