/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2017 Intel Corporation
 */

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>

#include <rte_string_fns.h>
#include <rte_branch_prediction.h>
#include <rte_debug.h>
#include <rte_lcore.h>
#include <rte_log.h>
#include <rte_malloc.h>
#include <rte_memcpy.h>
#include <rte_memory.h>
#include <rte_memzone.h>
#include <rte_atomic.h>

#include "opdl_ring.h"
#include "opdl_log.h"

#define LIB_NAME "opdl_ring"

#define OPDL_NAME_SIZE 64


#define OPDL_EVENT_MASK  (0x00000000000FFFFFULL)
#define OPDL_FLOWID_MASK (0xFFFFF)
#define OPDL_OPA_MASK    (0xFF)
#define OPDL_OPA_OFFSET  (0x38)

/* Types of dependency between stages */
enum dep_type {
        DEP_NONE = 0,  /* no dependency */
        DEP_DIRECT,  /* stage has direct dependency */
        DEP_INDIRECT,  /* in-direct dependency through other stage(s) */
        DEP_SELF,  /* stage dependency on itself, used to detect loops */
};

/* Shared section of stage state.
 * Care is needed when accessing and the layout is important, especially to
 * limit the adjacent cache-line HW prefetcher from impacting performance.
 */
struct shared_state {
        /* Last known minimum sequence number of dependencies, used for multi
         * thread operation
         */
        uint32_t available_seq;
        char _pad1[RTE_CACHE_LINE_SIZE * 3];
        uint32_t head;  /* Head sequence number (for multi thread operation) */
        char _pad2[RTE_CACHE_LINE_SIZE * 3];
        struct opdl_stage *stage;  /* back pointer */
        uint32_t tail;  /* Tail sequence number */
        char _pad3[RTE_CACHE_LINE_SIZE * 2];
} __rte_cache_aligned;

/* A structure to keep track of "unfinished" claims. This is only used for
 * stages that are threadsafe. Each lcore accesses its own instance of this
 * structure to record the entries it has claimed. This allows one lcore to make
 * multiple claims without being blocked by another. When disclaiming it moves
 * forward the shared tail when the shared tail matches the tail value recorded
 * here.
 */
struct claim_manager {
        uint32_t num_to_disclaim;
        uint32_t num_claimed;
        uint32_t mgr_head;
        uint32_t mgr_tail;
        struct {
                uint32_t head;
                uint32_t tail;
        } claims[OPDL_DISCLAIMS_PER_LCORE];
} __rte_cache_aligned;

/* Context for each stage of opdl_ring.
 * Calculations on sequence numbers need to be done with other uint32_t values
 * so that results are modulus 2^32, and not undefined.
 */
struct opdl_stage {
        struct opdl_ring *t;  /* back pointer, set at init */
        uint32_t num_slots;  /* Number of slots for entries, set at init */
        uint32_t index;  /* ID for this stage, set at init */
        bool threadsafe;  /* Set to 1 if this stage supports threadsafe use */
        /* Last known min seq number of dependencies for used for single thread
         * operation
         */
        uint32_t available_seq;
        uint32_t head;  /* Current head for single-thread operation */
        uint32_t nb_instance;  /* Number of instances */
        uint32_t instance_id;  /* ID of this stage instance */
        uint16_t num_claimed;  /* Number of slots claimed */
        uint16_t num_event;             /* Number of events */
        uint32_t seq;                   /* sequence number  */
        uint32_t num_deps;  /* Number of direct dependencies */
        /* Keep track of all dependencies, used during init only */
        enum dep_type *dep_tracking;
        /* Direct dependencies of this stage */
        struct shared_state **deps;
        /* Other stages read this! */
        struct shared_state shared __rte_cache_aligned;
        /* For managing disclaims in multi-threaded processing stages */
        struct claim_manager pending_disclaims[RTE_MAX_LCORE]
                                               __rte_cache_aligned;
        uint32_t shadow_head;  /* Shadow head for single-thread operation */
        uint32_t queue_id;     /* ID of Queue which is assigned to this stage */
        uint32_t pos;           /* Atomic scan position */
} __rte_cache_aligned;

/* Context for opdl_ring */
struct opdl_ring {
        char name[OPDL_NAME_SIZE];  /* OPDL queue instance name */
        int socket;  /* NUMA socket that memory is allocated on */
        uint32_t num_slots;  /* Number of slots for entries */
        uint32_t mask;  /* Mask for sequence numbers (num_slots - 1) */
        uint32_t slot_size;  /* Size of each slot in bytes */
        uint32_t num_stages;  /* Number of stages that have been added */
        uint32_t max_num_stages;  /* Max number of stages */
        /* Stages indexed by ID */
        struct opdl_stage *stages;
        /* Memory for storing slot data */
        uint8_t slots[0] __rte_cache_aligned;
};


/* Return input stage of a opdl_ring */
static __rte_always_inline struct opdl_stage *
input_stage(const struct opdl_ring *t)
{
        return &t->stages[0];
}

/* Check if a stage is the input stage */
static __rte_always_inline bool
is_input_stage(const struct opdl_stage *s)
{
        return s->index == 0;
}

/* Get slot pointer from sequence number */
static __rte_always_inline void *
get_slot(const struct opdl_ring *t, uint32_t n)
{
        return (void *)(uintptr_t)&t->slots[(n & t->mask) * t->slot_size];
}

/* Find how many entries are available for processing */
static __rte_always_inline uint32_t
available(const struct opdl_stage *s)
{
        if (s->threadsafe == true) {
                uint32_t n = __atomic_load_n(&s->shared.available_seq,
                                __ATOMIC_ACQUIRE) -
                                __atomic_load_n(&s->shared.head,
                                __ATOMIC_ACQUIRE);

                /* Return 0 if available_seq needs to be updated */
                return (n <= s->num_slots) ? n : 0;
        }

        /* Single threaded */
        return s->available_seq - s->head;
}

/* Read sequence number of dependencies and find minimum */
static __rte_always_inline void
update_available_seq(struct opdl_stage *s)
{
        uint32_t i;
        uint32_t this_tail = s->shared.tail;
        uint32_t min_seq = __atomic_load_n(&s->deps[0]->tail, __ATOMIC_ACQUIRE);
        /* Input stage sequence numbers are greater than the sequence numbers of
         * its dependencies so an offset of t->num_slots is needed when
         * calculating available slots and also the condition which is used to
         * determine the dependencies minimum sequence number must be reverted.
         */
        uint32_t wrap;

        if (is_input_stage(s)) {
                wrap = s->num_slots;
                for (i = 1; i < s->num_deps; i++) {
                        uint32_t seq = __atomic_load_n(&s->deps[i]->tail,
                                        __ATOMIC_ACQUIRE);
                        if ((this_tail - seq) > (this_tail - min_seq))
                                min_seq = seq;
                }
        } else {
                wrap = 0;
                for (i = 1; i < s->num_deps; i++) {
                        uint32_t seq = __atomic_load_n(&s->deps[i]->tail,
                                        __ATOMIC_ACQUIRE);
                        if ((seq - this_tail) < (min_seq - this_tail))
                                min_seq = seq;
                }
        }

        if (s->threadsafe == false)
                s->available_seq = min_seq + wrap;
        else
                __atomic_store_n(&s->shared.available_seq, min_seq + wrap,
                                __ATOMIC_RELEASE);
}

/* Wait until the number of available slots reaches number requested */
static __rte_always_inline void
wait_for_available(struct opdl_stage *s, uint32_t n)
{
        while (available(s) < n) {
                rte_pause();
                update_available_seq(s);
        }
}

/* Return number of slots to process based on number requested and mode */
static __rte_always_inline uint32_t
num_to_process(struct opdl_stage *s, uint32_t n, bool block)
{
        /* Don't read tail sequences of dependencies if not needed */
        if (available(s) >= n)
                return n;

        update_available_seq(s);

        if (block == false) {
                uint32_t avail = available(s);

                if (avail == 0) {
                        rte_pause();
                        return 0;
                }
                return (avail <= n) ? avail : n;
        }

        if (unlikely(n > s->num_slots)) {
                PMD_DRV_LOG(ERR, "%u entries is more than max (%u)",
                                n, s->num_slots);
                return 0;  /* Avoid infinite loop */
        }
        /* blocking */
        wait_for_available(s, n);
        return n;
}

/* Copy entries in to slots with wrap-around */
static __rte_always_inline void
copy_entries_in(struct opdl_ring *t, uint32_t start, const void *entries,
                uint32_t num_entries)
{
        uint32_t slot_size = t->slot_size;
        uint32_t slot_index = start & t->mask;

        if (slot_index + num_entries <= t->num_slots) {
                rte_memcpy(get_slot(t, start), entries,
                                num_entries * slot_size);
        } else {
                uint32_t split = t->num_slots - slot_index;

                rte_memcpy(get_slot(t, start), entries, split * slot_size);
                rte_memcpy(get_slot(t, 0),
                                RTE_PTR_ADD(entries, split * slot_size),
                                (num_entries - split) * slot_size);
        }
}

/* Copy entries out from slots with wrap-around */
static __rte_always_inline void
copy_entries_out(struct opdl_ring *t, uint32_t start, void *entries,
                uint32_t num_entries)
{
        uint32_t slot_size = t->slot_size;
        uint32_t slot_index = start & t->mask;

        if (slot_index + num_entries <= t->num_slots) {
                rte_memcpy(entries, get_slot(t, start),
                                num_entries * slot_size);
        } else {
                uint32_t split = t->num_slots - slot_index;

                rte_memcpy(entries, get_slot(t, start), split * slot_size);
                rte_memcpy(RTE_PTR_ADD(entries, split * slot_size),
                                get_slot(t, 0),
                                (num_entries - split) * slot_size);
        }
}

/* Input function optimised for single thread */
static __rte_always_inline uint32_t
opdl_ring_input_singlethread(struct opdl_ring *t, const void *entries,
                uint32_t num_entries, bool block)
{
        struct opdl_stage *s = input_stage(t);
        uint32_t head = s->head;

        num_entries = num_to_process(s, num_entries, block);
        if (num_entries == 0)
                return 0;

        copy_entries_in(t, head, entries, num_entries);

        s->head += num_entries;
        __atomic_store_n(&s->shared.tail, s->head, __ATOMIC_RELEASE);

        return num_entries;
}

/* Convert head and tail of claim_manager into valid index */
static __rte_always_inline uint32_t
claim_mgr_index(uint32_t n)
{
        return n & (OPDL_DISCLAIMS_PER_LCORE - 1);
}

/* Check if there are available slots in claim_manager */
static __rte_always_inline bool
claim_mgr_available(struct claim_manager *mgr)
{
        return (mgr->mgr_head < (mgr->mgr_tail + OPDL_DISCLAIMS_PER_LCORE)) ?
                        true : false;
}

/* Record a new claim. Only use after first checking an entry is available */
static __rte_always_inline void
claim_mgr_add(struct claim_manager *mgr, uint32_t tail, uint32_t head)
{
        if ((mgr->mgr_head != mgr->mgr_tail) &&
                        (mgr->claims[claim_mgr_index(mgr->mgr_head - 1)].head ==
                        tail)) {
                /* Combine with previous claim */
                mgr->claims[claim_mgr_index(mgr->mgr_head - 1)].head = head;
        } else {
                mgr->claims[claim_mgr_index(mgr->mgr_head)].head = head;
                mgr->claims[claim_mgr_index(mgr->mgr_head)].tail = tail;
                mgr->mgr_head++;
        }

        mgr->num_claimed += (head - tail);
}

/* Read the oldest recorded claim */
static __rte_always_inline bool
claim_mgr_read(struct claim_manager *mgr, uint32_t *tail, uint32_t *head)
{
        if (mgr->mgr_head == mgr->mgr_tail)
                return false;

        *head = mgr->claims[claim_mgr_index(mgr->mgr_tail)].head;
        *tail = mgr->claims[claim_mgr_index(mgr->mgr_tail)].tail;
        return true;
}

/* Remove the oldest recorded claim. Only use after first reading the entry */
static __rte_always_inline void
claim_mgr_remove(struct claim_manager *mgr)
{
        mgr->num_claimed -= (mgr->claims[claim_mgr_index(mgr->mgr_tail)].head -
                        mgr->claims[claim_mgr_index(mgr->mgr_tail)].tail);
        mgr->mgr_tail++;
}

/* Update tail in the oldest claim. Only use after first reading the entry */
static __rte_always_inline void
claim_mgr_move_tail(struct claim_manager *mgr, uint32_t num_entries)
{
        mgr->num_claimed -= num_entries;
        mgr->claims[claim_mgr_index(mgr->mgr_tail)].tail += num_entries;
}

static __rte_always_inline void
opdl_stage_disclaim_multithread_n(struct opdl_stage *s,
                uint32_t num_entries, bool block)
{
        struct claim_manager *disclaims = &s->pending_disclaims[rte_lcore_id()];
        uint32_t head;
        uint32_t tail;

        while (num_entries) {
                bool ret = claim_mgr_read(disclaims, &tail, &head);

                if (ret == false)
                        break;  /* nothing is claimed */
                /* There should be no race condition here. If shared.tail
                 * matches, no other core can update it until this one does.
                 */
                if (__atomic_load_n(&s->shared.tail, __ATOMIC_ACQUIRE) ==
                                tail) {
                        if (num_entries >= (head - tail)) {
                                claim_mgr_remove(disclaims);
                                __atomic_store_n(&s->shared.tail, head,
                                                __ATOMIC_RELEASE);
                                num_entries -= (head - tail);
                        } else {
                                claim_mgr_move_tail(disclaims, num_entries);
                                __atomic_store_n(&s->shared.tail,
                                                num_entries + tail,
                                                __ATOMIC_RELEASE);
                                num_entries = 0;
                        }
                } else if (block == false)
                        break;  /* blocked by other thread */
                /* Keep going until num_entries are disclaimed. */
                rte_pause();
        }

        disclaims->num_to_disclaim = num_entries;
}

/* Move head atomically, returning number of entries available to process and
 * the original value of head. For non-input stages, the claim is recorded
 * so that the tail can be updated later by opdl_stage_disclaim().
 */
static __rte_always_inline void
move_head_atomically(struct opdl_stage *s, uint32_t *num_entries,
                uint32_t *old_head, bool block, bool claim_func)
{
        uint32_t orig_num_entries = *num_entries;
        uint32_t ret;
        struct claim_manager *disclaims = &s->pending_disclaims[rte_lcore_id()];

        /* Attempt to disclaim any outstanding claims */
        opdl_stage_disclaim_multithread_n(s, disclaims->num_to_disclaim,
                        false);

        *old_head = __atomic_load_n(&s->shared.head, __ATOMIC_ACQUIRE);
        while (true) {
                bool success;
                /* If called by opdl_ring_input(), claim does not need to be
                 * recorded, as there will be no disclaim.
                 */
                if (claim_func) {
                        /* Check that the claim can be recorded */
                        ret = claim_mgr_available(disclaims);
                        if (ret == false) {
                                /* exit out if claim can't be recorded */
                                *num_entries = 0;
                                return;
                        }
                }

                *num_entries = num_to_process(s, orig_num_entries, block);
                if (*num_entries == 0)
                        return;

                success = __atomic_compare_exchange_n(&s->shared.head, old_head,
                                *old_head + *num_entries,
                                true,  /* may fail spuriously */
                                __ATOMIC_RELEASE,  /* memory order on success */
                                __ATOMIC_ACQUIRE);  /* memory order on fail */
                if (likely(success))
                        break;
                rte_pause();
        }

        if (claim_func)
                /* Store the claim record */
                claim_mgr_add(disclaims, *old_head, *old_head + *num_entries);
}

/* Input function that supports multiple threads */
static __rte_always_inline uint32_t
opdl_ring_input_multithread(struct opdl_ring *t, const void *entries,
                uint32_t num_entries, bool block)
{
        struct opdl_stage *s = input_stage(t);
        uint32_t old_head;

        move_head_atomically(s, &num_entries, &old_head, block, false);
        if (num_entries == 0)
                return 0;

        copy_entries_in(t, old_head, entries, num_entries);

        /* If another thread started inputting before this one, but hasn't
         * finished, we need to wait for it to complete to update the tail.
         */
        rte_wait_until_equal_32(&s->shared.tail, old_head, __ATOMIC_ACQUIRE);

        __atomic_store_n(&s->shared.tail, old_head + num_entries,
                        __ATOMIC_RELEASE);

        return num_entries;
}

static __rte_always_inline uint32_t
opdl_first_entry_id(uint32_t start_seq, uint8_t nb_p_lcores,
                uint8_t this_lcore)
{
        return ((nb_p_lcores <= 1) ? 0 :
                        (nb_p_lcores - (start_seq % nb_p_lcores) + this_lcore) %
                        nb_p_lcores);
}

/* Claim slots to process, optimised for single-thread operation */
static __rte_always_inline uint32_t
opdl_stage_claim_singlethread(struct opdl_stage *s, void *entries,
                uint32_t num_entries, uint32_t *seq, bool block, bool atomic)
{
        uint32_t i = 0, j = 0,  offset;
        uint32_t opa_id   = 0;
        uint32_t flow_id  = 0;
        uint64_t event    = 0;
        void *get_slots;
        struct rte_event *ev;
        RTE_SET_USED(seq);
        struct opdl_ring *t = s->t;
        uint8_t *entries_offset = (uint8_t *)entries;

        if (!atomic) {

                offset = opdl_first_entry_id(s->seq, s->nb_instance,
                                s->instance_id);

                num_entries = s->nb_instance * num_entries;

                num_entries = num_to_process(s, num_entries, block);

                for (; offset < num_entries; offset += s->nb_instance) {
                        get_slots = get_slot(t, s->head + offset);
                        memcpy(entries_offset, get_slots, t->slot_size);
                        entries_offset += t->slot_size;
                        i++;
                }
        } else {
                num_entries = num_to_process(s, num_entries, block);

                for (j = 0; j < num_entries; j++) {
                        ev = (struct rte_event *)get_slot(t, s->head+j);

                        event  = __atomic_load_n(&(ev->event),
                                        __ATOMIC_ACQUIRE);

                        opa_id = OPDL_OPA_MASK & (event >> OPDL_OPA_OFFSET);
                        flow_id  = OPDL_FLOWID_MASK & event;

                        if (opa_id >= s->queue_id)
                                continue;

                        if ((flow_id % s->nb_instance) == s->instance_id) {
                                memcpy(entries_offset, ev, t->slot_size);
                                entries_offset += t->slot_size;
                                i++;
                        }
                }
        }
        s->shadow_head = s->head;
        s->head += num_entries;
        s->num_claimed = num_entries;
        s->num_event = i;
        s->pos = 0;

        /* automatically disclaim entries if number of rte_events is zero */
        if (unlikely(i == 0))
                opdl_stage_disclaim(s, 0, false);

        return i;
}

/* Thread-safe version of function to claim slots for processing */
static __rte_always_inline uint32_t
opdl_stage_claim_multithread(struct opdl_stage *s, void *entries,
                uint32_t num_entries, uint32_t *seq, bool block)
{
        uint32_t old_head;
        struct opdl_ring *t = s->t;
        uint32_t i = 0, offset;
        uint8_t *entries_offset = (uint8_t *)entries;

        if (seq == NULL) {
                PMD_DRV_LOG(ERR, "Invalid seq PTR");
                return 0;
        }
        offset = opdl_first_entry_id(*seq, s->nb_instance, s->instance_id);
        num_entries = offset + (s->nb_instance * num_entries);

        move_head_atomically(s, &num_entries, &old_head, block, true);

        for (; offset < num_entries; offset += s->nb_instance) {
                memcpy(entries_offset, get_slot(t, s->head + offset),
                        t->slot_size);
                entries_offset += t->slot_size;
                i++;
        }

        *seq = old_head;

        return i;
}

/* Claim and copy slot pointers, optimised for single-thread operation */
static __rte_always_inline uint32_t
opdl_stage_claim_copy_singlethread(struct opdl_stage *s, void *entries,
                uint32_t num_entries, uint32_t *seq, bool block)
{
        num_entries = num_to_process(s, num_entries, block);
        if (num_entries == 0)
                return 0;
        copy_entries_out(s->t, s->head, entries, num_entries);
        if (seq != NULL)
                *seq = s->head;
        s->head += num_entries;
        return num_entries;
}

/* Thread-safe version of function to claim and copy pointers to slots */
static __rte_always_inline uint32_t
opdl_stage_claim_copy_multithread(struct opdl_stage *s, void *entries,
                uint32_t num_entries, uint32_t *seq, bool block)
{
        uint32_t old_head;

        move_head_atomically(s, &num_entries, &old_head, block, true);
        if (num_entries == 0)
                return 0;
        copy_entries_out(s->t, old_head, entries, num_entries);
        if (seq != NULL)
                *seq = old_head;
        return num_entries;
}

static __rte_always_inline void
opdl_stage_disclaim_singlethread_n(struct opdl_stage *s,
                uint32_t num_entries)
{
        uint32_t old_tail = s->shared.tail;

        if (unlikely(num_entries > (s->head - old_tail))) {
                PMD_DRV_LOG(WARNING, "Attempt to disclaim (%u) more than claimed (%u)",
                                num_entries, s->head - old_tail);
                num_entries = s->head - old_tail;
        }
        __atomic_store_n(&s->shared.tail, num_entries + old_tail,
                        __ATOMIC_RELEASE);
}

uint32_t
opdl_ring_input(struct opdl_ring *t, const void *entries, uint32_t num_entries,
                bool block)
{
        if (input_stage(t)->threadsafe == false)
                return opdl_ring_input_singlethread(t, entries, num_entries,
                                block);
        else
                return opdl_ring_input_multithread(t, entries, num_entries,
                                block);
}

uint32_t
opdl_ring_copy_from_burst(struct opdl_ring *t, struct opdl_stage *s,
                const void *entries, uint32_t num_entries, bool block)
{
        uint32_t head = s->head;

        num_entries = num_to_process(s, num_entries, block);

        if (num_entries == 0)
                return 0;

        copy_entries_in(t, head, entries, num_entries);

        s->head += num_entries;
        __atomic_store_n(&s->shared.tail, s->head, __ATOMIC_RELEASE);

        return num_entries;

}

uint32_t
opdl_ring_copy_to_burst(struct opdl_ring *t, struct opdl_stage *s,
                void *entries, uint32_t num_entries, bool block)
{
        uint32_t head = s->head;

        num_entries = num_to_process(s, num_entries, block);
        if (num_entries == 0)
                return 0;

        copy_entries_out(t, head, entries, num_entries);

        s->head += num_entries;
        __atomic_store_n(&s->shared.tail, s->head, __ATOMIC_RELEASE);

        return num_entries;
}

uint32_t
opdl_stage_find_num_available(struct opdl_stage *s, uint32_t num_entries)
{
        /* return (num_to_process(s, num_entries, false)); */

        if (available(s) >= num_entries)
                return num_entries;

        update_available_seq(s);

        uint32_t avail = available(s);

        if (avail == 0) {
                rte_pause();
                return 0;
        }
        return (avail <= num_entries) ? avail : num_entries;
}

uint32_t
opdl_stage_claim(struct opdl_stage *s, void *entries,
                uint32_t num_entries, uint32_t *seq, bool block, bool atomic)
{
        if (s->threadsafe == false)
                return opdl_stage_claim_singlethread(s, entries, num_entries,
                                seq, block, atomic);
        else
                return opdl_stage_claim_multithread(s, entries, num_entries,
                                seq, block);
}

uint32_t
opdl_stage_claim_copy(struct opdl_stage *s, void *entries,
                uint32_t num_entries, uint32_t *seq, bool block)
{
        if (s->threadsafe == false)
                return opdl_stage_claim_copy_singlethread(s, entries,
                                num_entries, seq, block);
        else
                return opdl_stage_claim_copy_multithread(s, entries,
                                num_entries, seq, block);
}

void
opdl_stage_disclaim_n(struct opdl_stage *s, uint32_t num_entries,
                bool block)
{

        if (s->threadsafe == false) {
                opdl_stage_disclaim_singlethread_n(s, s->num_claimed);
        } else {
                struct claim_manager *disclaims =
                        &s->pending_disclaims[rte_lcore_id()];

                if (unlikely(num_entries > s->num_slots)) {
                        PMD_DRV_LOG(WARNING, "Attempt to disclaim (%u) more than claimed (%u)",
                                        num_entries, disclaims->num_claimed);
                        num_entries = disclaims->num_claimed;
                }

                num_entries = RTE_MIN(num_entries + disclaims->num_to_disclaim,
                                disclaims->num_claimed);
                opdl_stage_disclaim_multithread_n(s, num_entries, block);
        }
}

int
opdl_stage_disclaim(struct opdl_stage *s, uint32_t num_entries, bool block)
{
        if (num_entries != s->num_event) {
                rte_errno = EINVAL;
                return 0;
        }
        if (s->threadsafe == false) {
                __atomic_store_n(&s->shared.tail, s->head, __ATOMIC_RELEASE);
                s->seq += s->num_claimed;
                s->shadow_head = s->head;
                s->num_claimed = 0;
        } else {
                struct claim_manager *disclaims =
                                &s->pending_disclaims[rte_lcore_id()];
                opdl_stage_disclaim_multithread_n(s, disclaims->num_claimed,
                                block);
        }
        return num_entries;
}

uint32_t
opdl_ring_available(struct opdl_ring *t)
{
        return opdl_stage_available(&t->stages[0]);
}

uint32_t
opdl_stage_available(struct opdl_stage *s)
{
        update_available_seq(s);
        return available(s);
}

void
opdl_ring_flush(struct opdl_ring *t)
{
        struct opdl_stage *s = input_stage(t);

        wait_for_available(s, s->num_slots);
}

/******************** Non performance sensitive functions ********************/

/* Initial setup of a new stage's context */
static int
init_stage(struct opdl_ring *t, struct opdl_stage *s, bool threadsafe,
                bool is_input)
{
        uint32_t available = (is_input) ? t->num_slots : 0;

        s->t = t;
        s->num_slots = t->num_slots;
        s->index = t->num_stages;
        s->threadsafe = threadsafe;
        s->shared.stage = s;

        /* Alloc memory for deps */
        s->dep_tracking = rte_zmalloc_socket(LIB_NAME,
                        t->max_num_stages * sizeof(enum dep_type),
                        0, t->socket);
        if (s->dep_tracking == NULL)
                return -ENOMEM;

        s->deps = rte_zmalloc_socket(LIB_NAME,
                        t->max_num_stages * sizeof(struct shared_state *),
                        0, t->socket);
        if (s->deps == NULL) {
                rte_free(s->dep_tracking);
                return -ENOMEM;
        }

        s->dep_tracking[s->index] = DEP_SELF;

        if (threadsafe == true)
                s->shared.available_seq = available;
        else
                s->available_seq = available;

        return 0;
}

/* Add direct or indirect dependencies between stages */
static int
add_dep(struct opdl_stage *dependent, const struct opdl_stage *dependency,
                enum dep_type type)
{
        struct opdl_ring *t = dependent->t;
        uint32_t i;

        /* Add new direct dependency */
        if ((type == DEP_DIRECT) &&
                        (dependent->dep_tracking[dependency->index] ==
                                        DEP_NONE)) {
                PMD_DRV_LOG(DEBUG, "%s:%u direct dependency on %u",
                                t->name, dependent->index, dependency->index);
                dependent->dep_tracking[dependency->index] = DEP_DIRECT;
        }

        /* Add new indirect dependency or change direct to indirect */
        if ((type == DEP_INDIRECT) &&
                        ((dependent->dep_tracking[dependency->index] ==
                        DEP_NONE) ||
                        (dependent->dep_tracking[dependency->index] ==
                        DEP_DIRECT))) {
                PMD_DRV_LOG(DEBUG, "%s:%u indirect dependency on %u",
                                t->name, dependent->index, dependency->index);
                dependent->dep_tracking[dependency->index] = DEP_INDIRECT;
        }

        /* Shouldn't happen... */
        if ((dependent->dep_tracking[dependency->index] == DEP_SELF) &&
                        (dependent != input_stage(t))) {
                PMD_DRV_LOG(ERR, "Loop in dependency graph %s:%u",
                                t->name, dependent->index);
                return -EINVAL;
        }

        /* Keep going to dependencies of the dependency, until input stage */
        if (dependency != input_stage(t))
                for (i = 0; i < dependency->num_deps; i++) {
                        int ret = add_dep(dependent, dependency->deps[i]->stage,
                                        DEP_INDIRECT);

                        if (ret < 0)
                                return ret;
                }

        /* Make list of sequence numbers for direct dependencies only */
        if (type == DEP_DIRECT)
                for (i = 0, dependent->num_deps = 0; i < t->num_stages; i++)
                        if (dependent->dep_tracking[i] == DEP_DIRECT) {
                                if ((i == 0) && (dependent->num_deps > 1))
                                        rte_panic("%s:%u depends on > input",
                                                        t->name,
                                                        dependent->index);
                                dependent->deps[dependent->num_deps++] =
                                                &t->stages[i].shared;
                        }

        return 0;
}

struct opdl_ring *
opdl_ring_create(const char *name, uint32_t num_slots, uint32_t slot_size,
                uint32_t max_num_stages, int socket)
{
        struct opdl_ring *t;
        char mz_name[RTE_MEMZONE_NAMESIZE];
        int mz_flags = 0;
        struct opdl_stage *st = NULL;
        const struct rte_memzone *mz = NULL;
        size_t alloc_size = RTE_CACHE_LINE_ROUNDUP(sizeof(*t) +
                        (num_slots * slot_size));

        /* Compile time checking */
        RTE_BUILD_BUG_ON((sizeof(struct shared_state) & RTE_CACHE_LINE_MASK) !=
                        0);
        RTE_BUILD_BUG_ON((offsetof(struct opdl_stage, shared) &
                        RTE_CACHE_LINE_MASK) != 0);
        RTE_BUILD_BUG_ON((offsetof(struct opdl_ring, slots) &
                        RTE_CACHE_LINE_MASK) != 0);
        RTE_BUILD_BUG_ON(!rte_is_power_of_2(OPDL_DISCLAIMS_PER_LCORE));

        /* Parameter checking */
        if (name == NULL) {
                PMD_DRV_LOG(ERR, "name param is NULL");
                return NULL;
        }
        if (!rte_is_power_of_2(num_slots)) {
                PMD_DRV_LOG(ERR, "num_slots (%u) for %s is not power of 2",
                                num_slots, name);
                return NULL;
        }

        /* Alloc memory for stages */
        st = rte_zmalloc_socket(LIB_NAME,
                max_num_stages * sizeof(struct opdl_stage),
                RTE_CACHE_LINE_SIZE, socket);
        if (st == NULL)
                goto exit_fail;

        snprintf(mz_name, sizeof(mz_name), "%s%s", LIB_NAME, name);

        /* Alloc memory for memzone */
        mz = rte_memzone_reserve(mz_name, alloc_size, socket, mz_flags);
        if (mz == NULL)
                goto exit_fail;

        t = mz->addr;

        /* Initialise opdl_ring queue */
        memset(t, 0, sizeof(*t));
        strlcpy(t->name, name, sizeof(t->name));
        t->socket = socket;
        t->num_slots = num_slots;
        t->mask = num_slots - 1;
        t->slot_size = slot_size;
        t->max_num_stages = max_num_stages;
        t->stages = st;

        PMD_DRV_LOG(DEBUG, "Created %s at %p (num_slots=%u,socket=%i,slot_size=%u)",
                        t->name, t, num_slots, socket, slot_size);

        return t;

exit_fail:
        PMD_DRV_LOG(ERR, "Cannot reserve memory");
        rte_free(st);
        rte_memzone_free(mz);

        return NULL;
}

void *
opdl_ring_get_slot(const struct opdl_ring *t, uint32_t index)
{
        return get_slot(t, index);
}

bool
opdl_ring_cas_slot(struct opdl_stage *s, const struct rte_event *ev,
                uint32_t index, bool atomic)
{
        uint32_t i = 0, offset;
        struct opdl_ring *t = s->t;
        struct rte_event *ev_orig = NULL;
        bool ev_updated = false;
        uint64_t ev_temp    = 0;
        uint64_t ev_update  = 0;

        uint32_t opa_id   = 0;
        uint32_t flow_id  = 0;
        uint64_t event    = 0;

        if (index > s->num_event) {
                PMD_DRV_LOG(ERR, "index is overflow");
                return ev_updated;
        }

        ev_temp = ev->event & OPDL_EVENT_MASK;

        if (!atomic) {
                offset = opdl_first_entry_id(s->seq, s->nb_instance,
                                s->instance_id);
                offset += index*s->nb_instance;
                ev_orig = get_slot(t, s->shadow_head+offset);
                if ((ev_orig->event&OPDL_EVENT_MASK) != ev_temp) {
                        ev_orig->event = ev->event;
                        ev_updated = true;

                }
                if (ev_orig->u64 != ev->u64) {
                        ev_orig->u64 = ev->u64;
                        ev_updated = true;
                }

        } else {
                for (i = s->pos; i < s->num_claimed; i++) {
                        ev_orig = (struct rte_event *)
                                get_slot(t, s->shadow_head+i);

                        event  = __atomic_load_n(&(ev_orig->event),
                                        __ATOMIC_ACQUIRE);

                        opa_id = OPDL_OPA_MASK & (event >> OPDL_OPA_OFFSET);
                        flow_id  = OPDL_FLOWID_MASK & event;

                        if (opa_id >= s->queue_id)
                                continue;

                        if ((flow_id % s->nb_instance) == s->instance_id) {
                                ev_update = s->queue_id;
                                ev_update = (ev_update << OPDL_OPA_OFFSET)
                                        | ev->event;

                                s->pos = i + 1;

                                if ((event & OPDL_EVENT_MASK) !=
                                                ev_temp) {
                                        __atomic_store_n(&(ev_orig->event),
                                                        ev_update,
                                                        __ATOMIC_RELEASE);
                                        ev_updated = true;
                                }
                                if (ev_orig->u64 != ev->u64) {
                                        ev_orig->u64 = ev->u64;
                                        ev_updated = true;
                                }

                                break;
                        }
                }

        }

        return ev_updated;
}

int
opdl_ring_get_socket(const struct opdl_ring *t)
{
        return t->socket;
}

uint32_t
opdl_ring_get_num_slots(const struct opdl_ring *t)
{
        return t->num_slots;
}

const char *
opdl_ring_get_name(const struct opdl_ring *t)
{
        return t->name;
}

/* Check dependency list is valid for a given opdl_ring */
static int
check_deps(struct opdl_ring *t, struct opdl_stage *deps[],
                uint32_t num_deps)
{
        unsigned int i;

        for (i = 0; i < num_deps; ++i) {
                if (!deps[i]) {
                        PMD_DRV_LOG(ERR, "deps[%u] is NULL", i);
                        return -EINVAL;
                }
                if (t != deps[i]->t) {
                        PMD_DRV_LOG(ERR, "deps[%u] is in opdl_ring %s, not %s",
                                        i, deps[i]->t->name, t->name);
                        return -EINVAL;
                }
        }

        return 0;
}

struct opdl_stage *
opdl_stage_add(struct opdl_ring *t, bool threadsafe, bool is_input)
{
        struct opdl_stage *s;

        /* Parameter checking */
        if (!t) {
                PMD_DRV_LOG(ERR, "opdl_ring is NULL");
                return NULL;
        }
        if (t->num_stages == t->max_num_stages) {
                PMD_DRV_LOG(ERR, "%s has max number of stages (%u)",
                                t->name, t->max_num_stages);
                return NULL;
        }

        s = &t->stages[t->num_stages];

        if (((uintptr_t)&s->shared & RTE_CACHE_LINE_MASK) != 0)
                PMD_DRV_LOG(WARNING, "Tail seq num (%p) of %s stage not cache aligned",
                                &s->shared, t->name);

        if (init_stage(t, s, threadsafe, is_input) < 0) {
                PMD_DRV_LOG(ERR, "Cannot reserve memory");
                return NULL;
        }
        t->num_stages++;

        return s;
}

uint32_t
opdl_stage_deps_add(struct opdl_ring *t, struct opdl_stage *s,
                uint32_t nb_instance, uint32_t instance_id,
                struct opdl_stage *deps[],
                uint32_t num_deps)
{
        uint32_t i;
        int ret = 0;

        if ((num_deps > 0) && (!deps)) {
                PMD_DRV_LOG(ERR, "%s stage has NULL dependencies", t->name);
                return -1;
        }
        ret = check_deps(t, deps, num_deps);
        if (ret < 0)
                return ret;

        for (i = 0; i < num_deps; i++) {
                ret = add_dep(s, deps[i], DEP_DIRECT);
                if (ret < 0)
                        return ret;
        }

        s->nb_instance = nb_instance;
        s->instance_id = instance_id;

        return ret;
}

struct opdl_stage *
opdl_ring_get_input_stage(const struct opdl_ring *t)
{
        return input_stage(t);
}

int
opdl_stage_set_deps(struct opdl_stage *s, struct opdl_stage *deps[],
                uint32_t num_deps)
{
        unsigned int i;
        int ret;

        if ((num_deps == 0) || (!deps)) {
                PMD_DRV_LOG(ERR, "cannot set NULL dependencies");
                return -EINVAL;
        }

        ret = check_deps(s->t, deps, num_deps);
        if (ret < 0)
                return ret;

        /* Update deps */
        for (i = 0; i < num_deps; i++)
                s->deps[i] = &deps[i]->shared;
        s->num_deps = num_deps;

        return 0;
}

struct opdl_ring *
opdl_stage_get_opdl_ring(const struct opdl_stage *s)
{
        return s->t;
}

void
opdl_stage_set_queue_id(struct opdl_stage *s,
                uint32_t queue_id)
{
        s->queue_id = queue_id;
}

void
opdl_ring_dump(const struct opdl_ring *t, FILE *f)
{
        uint32_t i;

        if (t == NULL) {
                fprintf(f, "NULL OPDL!\n");
                return;
        }
        fprintf(f, "OPDL \"%s\": num_slots=%u; mask=%#x; slot_size=%u; num_stages=%u; socket=%i\n",
                        t->name, t->num_slots, t->mask, t->slot_size,
                        t->num_stages, t->socket);
        for (i = 0; i < t->num_stages; i++) {
                uint32_t j;
                const struct opdl_stage *s = &t->stages[i];

                fprintf(f, "  %s[%u]: threadsafe=%s; head=%u; available_seq=%u; tail=%u; deps=%u",
                                t->name, i, (s->threadsafe) ? "true" : "false",
                                (s->threadsafe) ? s->shared.head : s->head,
                                (s->threadsafe) ? s->shared.available_seq :
                                s->available_seq,
                                s->shared.tail, (s->num_deps > 0) ?
                                s->deps[0]->stage->index : 0);
                for (j = 1; j < s->num_deps; j++)
                        fprintf(f, ",%u", s->deps[j]->stage->index);
                fprintf(f, "\n");
        }
        fflush(f);
}

void
opdl_ring_free(struct opdl_ring *t)
{
        uint32_t i;
        const struct rte_memzone *mz;
        char mz_name[RTE_MEMZONE_NAMESIZE];

        if (t == NULL) {
                PMD_DRV_LOG(DEBUG, "Freeing NULL OPDL Ring!");
                return;
        }

        PMD_DRV_LOG(DEBUG, "Freeing %s opdl_ring at %p", t->name, t);

        for (i = 0; i < t->num_stages; ++i) {
                rte_free(t->stages[i].deps);
                rte_free(t->stages[i].dep_tracking);
        }

        rte_free(t->stages);

        snprintf(mz_name, sizeof(mz_name), "%s%s", LIB_NAME, t->name);
        mz = rte_memzone_lookup(mz_name);
        if (rte_memzone_free(mz) != 0)
                PMD_DRV_LOG(ERR, "Cannot free memzone for %s", t->name);
}

/* search a opdl_ring from its name */
struct opdl_ring *
opdl_ring_lookup(const char *name)
{
        const struct rte_memzone *mz;
        char mz_name[RTE_MEMZONE_NAMESIZE];

        snprintf(mz_name, sizeof(mz_name), "%s%s", LIB_NAME, name);

        mz = rte_memzone_lookup(mz_name);
        if (mz == NULL)
                return NULL;

        return mz->addr;
}

void
opdl_ring_set_stage_threadsafe(struct opdl_stage *s, bool threadsafe)
{
        s->threadsafe = threadsafe;
}