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564 rader
16 KiB
564 rader
16 KiB
#include <stdio.h>
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#include <unistd.h>
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#include "erl_nif.h"
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#include "cq_nif.h"
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/* #ifndef ERL_NIF_DIRTY_SCHEDULER_SUPPORT
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# error Requires dirty schedulers
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#endif */
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ERL_NIF_TERM
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mk_atom(ErlNifEnv* env, const char* atom)
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{
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ERL_NIF_TERM ret;
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if(!enif_make_existing_atom(env, atom, &ret, ERL_NIF_LATIN1))
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return enif_make_atom(env, atom);
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return ret;
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}
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ERL_NIF_TERM
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mk_error(ErlNifEnv* env, const char* mesg)
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{
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return enif_make_tuple2(env, mk_atom(env, "error"), mk_atom(env, mesg));
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}
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static ERL_NIF_TERM
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queue_new(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
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{
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cq_t *q = enif_alloc_resource(CQ_RESOURCE, sizeof(cq_t));
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if (q == NULL)
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return mk_error(env, "priv_alloc_error");
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ERL_NIF_TERM ret = enif_make_resource(env, q);
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/* enif_release_resource(ret); */
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uint32_t queue_id = 0;
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uint32_t queue_size = 0;
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uint32_t overflow_size = 0;
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if (!enif_get_uint(env, argv[0], &queue_id) ||
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!enif_get_uint(env, argv[1], &queue_size) ||
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!enif_get_uint(env, argv[2], &overflow_size))
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return mk_error(env, "badarg");
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if (queue_id > 8)
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return mk_error(env, "bad_queue_id");
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/* TODO: Check that queue_size is power of 2 */
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if (QUEUES[queue_id] != NULL)
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return mk_error(env, "queue_id_already_exists");
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q->id = queue_id;
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q->queue_size = queue_size;
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q->overflow_size = overflow_size;
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q->tail = 0;
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q->head = 0;
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q->slots_states = calloc(q->queue_size, CACHE_LINE_SIZE);
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q->slots_terms = calloc(q->queue_size, CACHE_LINE_SIZE);
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q->slots_envs = calloc(q->queue_size, CACHE_LINE_SIZE);
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q->overflow_terms = calloc(q->overflow_size, CACHE_LINE_SIZE);
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q->overflow_envs = calloc(q->queue_size, CACHE_LINE_SIZE);
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q->push_queue = new_queue();
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q->pop_queue = new_queue();
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/* TODO: Check calloc return */
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for (int i = 0; i < q->queue_size; i++) {
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ErlNifEnv *slot_env = enif_alloc_env();
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q->slots_envs[i*CACHE_LINE_SIZE] = slot_env;
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//q->overflow_envs[i*CACHE_LINE_SIZE] = (ErlNifEnv *) enif_alloc_env();
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}
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QUEUES[q->id] = q;
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return enif_make_tuple2(env, mk_atom(env, "ok"), ret);
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}
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static ERL_NIF_TERM
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queue_free(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
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{
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uint32_t queue_id = 0;
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if (!enif_get_uint(env, argv[0], &queue_id))
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return mk_error(env, "badarg");
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if (queue_id > 8)
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return mk_error(env, "badarg");
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cq_t *q = QUEUES[queue_id];
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if (q == NULL)
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return mk_error(env, "bad_queue_id");
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/* TODO: Free all the things! */
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QUEUES[queue_id] = NULL;
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return enif_make_atom(env, "ok");
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}
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/* Push to the head of the queue. */
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static ERL_NIF_TERM
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queue_push(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
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{
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uint32_t queue_id = 0;
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if (!enif_get_uint(env, argv[0], &queue_id))
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return mk_error(env, "badarg");
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if (queue_id > 8)
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return mk_error(env, "badarg");
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/* Load the queue */
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cq_t *q = QUEUES[queue_id];
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if (q == NULL)
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return mk_error(env, "bad_queue_id");
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if (q->id != queue_id)
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return mk_error(env, "not_identical_queue_id");
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for (int i = 0; i < q->queue_size; i++) {
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fprintf(stderr, "queue slot %d, index %d, state %d\n",
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i, i*CACHE_LINE_SIZE, q->slots_states[i*CACHE_LINE_SIZE]);
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}
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/* If there's consumers waiting, the queue must be empty and we
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should directly pick a consumer to notify. */
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ErlNifPid *waiting_consumer;
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int dequeue_ret = dequeue(q->pop_queue, &waiting_consumer);
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if (dequeue_ret) {
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ErlNifEnv *msg_env = enif_alloc_env();
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ERL_NIF_TERM copy = enif_make_copy(msg_env, argv[1]);
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ERL_NIF_TERM tuple = enif_make_tuple2(msg_env, mk_atom(env, "pop"), copy);
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if (enif_send(env, waiting_consumer, msg_env, tuple)) {
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enif_free_env(msg_env);
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return mk_atom(env, "ok");
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} else {
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return mk_error(env, "notify_failed");
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}
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}
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/* Increment head and attempt to claim the slot by marking it as
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busy. This ensures no other thread will attempt to modify this
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slot. If we cannot lock it, another thread must have */
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uint64_t head = __sync_add_and_fetch(&q->head, 1);
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size_t size = q->queue_size;
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while (1) {
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uint64_t index = SLOT_INDEX(head, size);
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uint64_t ret = __sync_val_compare_and_swap(&q->slots_states[index],
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STATE_EMPTY,
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STATE_WRITE);
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switch (ret) {
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case STATE_EMPTY:
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head = __sync_add_and_fetch(&q->head, 1);
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case STATE_WRITE:
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/* We acquired the write lock, go ahead with the write. */
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break;
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case STATE_FULL:
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/* We have caught up with the tail and the buffer is
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full. Block the producer until a consumer reads the
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item. */
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return mk_error(env, "full_not_implemented");
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}
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}
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/* If head catches up with tail, the queue is full. Add to
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overflow instead */
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/* Copy term to slot-specific temporary process env. */
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ERL_NIF_TERM copy = enif_make_copy(q->slots_envs[SLOT_INDEX(head, size)], argv[1]);
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q->slots_terms[SLOT_INDEX(head, size)] = copy;
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__sync_synchronize(); /* Or compiler memory barrier? */
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/* TODO: Do we need to collect garbage? */
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/* Mark the slot ready to be consumed */
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if (__sync_bool_compare_and_swap(&q->slots_states[SLOT_INDEX(head, size)],
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STATE_WRITE,
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STATE_FULL)) {
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return mk_atom(env, "ok");
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} else {
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return mk_error(env, "could_not_update_slots_after_insert");
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}
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}
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static ERL_NIF_TERM
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queue_async_pop(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
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{
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/* Load queue */
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uint32_t queue_id = 0;
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if (!enif_get_uint(env, argv[0], &queue_id))
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return mk_error(env, "badarg");
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if (queue_id > 8)
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return mk_error(env, "badarg");
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cq_t *q = QUEUES[queue_id];
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if (q == NULL)
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return mk_error(env, "bad_queue_id");
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if (q->id != queue_id)
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return mk_error(env, "not_identical_queue_id");
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uint64_t qsize = q->queue_size;
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uint64_t tail = q->tail;
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uint64_t num_busy = 0;
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/* Walk the buffer starting the tail position until we are either
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able to consume a term or find an empty slot. */
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while (1) {
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uint64_t index = SLOT_INDEX(tail, qsize);
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uint64_t ret = __sync_val_compare_and_swap(&q->slots_states[index],
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STATE_FULL,
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STATE_READ);
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if (ret == STATE_READ) {
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/* We were able to mark the term as read in progress. We
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now have an exclusive lock. */
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break;
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} else if (ret == STATE_WRITE) {
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/* We found an item with a write in progress. If that
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thread progresses, it will eventually mark the slot as
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full. We can spin until that happens.
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This can take an arbitrary amount of time and multiple
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reading threads will compete for the same slot.
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Instead we add the caller to the queue of blocking
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consumers. When the next producer comes it will "help"
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this thread by calling enif_send on the current
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in-progress term *and* handle it's own terms. If
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there's no new push to the queue, this will block
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forever. */
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return mk_atom(env, "write_in_progress_not_implemented");
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} else if (ret == STATE_EMPTY) {
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/* We found an empty item. Queue must be empty. Add
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calling Erlang consumer process to queue of waiting
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processes. When the next producer comes along, it first
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checks the waiting consumers and calls enif_send
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instead of writing to the slots. */
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ErlNifPid *pid = enif_alloc(sizeof(ErlNifPid));
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pid = enif_self(env, pid);
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enqueue(q->pop_queue, pid);
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return mk_atom(env, "wait_for_msg");
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} else {
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tail = __sync_add_and_fetch(&q->tail, 1);
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}
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}
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/* Copy term into calling process env. The NIF env can now be
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gargbage collected. */
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ERL_NIF_TERM copy = enif_make_copy(env, q->slots_terms[SLOT_INDEX(tail, qsize)]);
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/* Mark the slot as free. Note: We don't increment the tail
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position here, as another thread also walking the buffer might
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have incremented it multiple times */
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q->slots_terms[SLOT_INDEX(tail, qsize)] = 0;
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if (__sync_bool_compare_and_swap(&q->slots_states[SLOT_INDEX(tail, qsize)],
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STATE_READ,
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STATE_EMPTY)) {
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return enif_make_tuple2(env, mk_atom(env, "ok"), copy);
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} else {
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return mk_error(env, "could_not_update_slots_after_pop");
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}
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}
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static ERL_NIF_TERM
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queue_debug(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
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{
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uint32_t queue_id = 0;
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if (!enif_get_uint(env, argv[0], &queue_id))
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return mk_error(env, "badarg");
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if (queue_id > 8)
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return mk_error(env, "badarg");
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cq_t *q = QUEUES[queue_id];
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if (q == NULL)
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return mk_error(env, "bad_queue_id");
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ERL_NIF_TERM *slots_states = enif_alloc(sizeof(ERL_NIF_TERM) * q->queue_size);
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ERL_NIF_TERM *slots_terms = enif_alloc(sizeof(ERL_NIF_TERM) * q->queue_size);
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for (int i = 0; i < q->queue_size; i++) {
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slots_states[i] = enif_make_int(env, q->slots_states[i * CACHE_LINE_SIZE]);
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if (q->slots_terms[i * CACHE_LINE_SIZE] == 0) {
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slots_terms[i] = mk_atom(env, "null");
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} else {
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slots_terms[i] = enif_make_copy(env, q->slots_terms[i * CACHE_LINE_SIZE]);
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}
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}
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return enif_make_tuple4(env,
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enif_make_uint64(env, q->tail),
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enif_make_uint64(env, q->head),
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enif_make_list_from_array(env, slots_states, q->queue_size),
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enif_make_list_from_array(env, slots_terms, q->queue_size));
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}
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static ERL_NIF_TERM
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queue_debug_poppers(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
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{
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uint32_t queue_id = 0;
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if (!enif_get_uint(env, argv[0], &queue_id))
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return mk_error(env, "badarg");
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if (queue_id > 8)
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return mk_error(env, "badarg");
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cq_t *q = QUEUES[queue_id];
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if (q == NULL)
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return mk_error(env, "bad_queue_id");
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uint64_t pop_queue_size = 0;
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cq_node_t *node = q->pop_queue->head;
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if (node->value == NULL) {
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node = node->next;
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node = Q_PTR(node);
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}
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while (node != NULL) {
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pop_queue_size++;
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node = node->next;
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node = Q_PTR(node);
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}
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ERL_NIF_TERM *pop_queue_pids = enif_alloc(sizeof(ERL_NIF_TERM) * pop_queue_size);
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node = q->pop_queue->head;
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node = Q_PTR(node);
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if (node->value == NULL) {
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node = node->next;
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node = Q_PTR(node);
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}
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uint64_t i = 0;
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while (node != NULL) {
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if (node->value == 0) {
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pop_queue_pids[i] = mk_atom(env, "null");
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}
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else {
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pop_queue_pids[i] = enif_make_pid(env, node->value);
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}
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i++;
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node = node->next;
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node = Q_PTR(node);
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}
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ERL_NIF_TERM list = enif_make_list_from_array(env, pop_queue_pids, pop_queue_size);
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enif_free(pop_queue_pids);
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return list;
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}
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static ERL_NIF_TERM
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print_bits(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
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{
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uint64_t *p1 = malloc(8);
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*p1 = 0;
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for (int bit = 63; bit >= 0; bit--) {
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uint64_t power = 1 << bit;
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//uint64_t byte = *p1;
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uint64_t byte = p1;
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fprintf(stderr, "%d", (byte & power) >> bit);
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}
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fprintf(stderr, "\n");
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//enif_free(p1);
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return mk_atom(env, "ok");
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}
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void free_resource(ErlNifEnv* env, void* arg)
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{
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//cq_t *cq = (cq_t *) arg;
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fprintf(stderr, "free_resource\n");
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}
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cq_queue_t * new_queue()
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{
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cq_queue_t *queue = enif_alloc(sizeof(cq_queue_t));
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cq_node_t *node = enif_alloc(sizeof(cq_node_t));
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node->next = NULL;
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//node->env = NULL;
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node->value = NULL;
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queue->head = node;
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queue->tail = node;
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return queue;
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}
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void enqueue(cq_queue_t *queue, ErlNifPid *pid)
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{
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cq_node_t *node = enif_alloc(sizeof(cq_node_t));
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//node->env = enif_alloc_env();
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//node->term = enif_make_copy(node->env, term);
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node->value = pid;
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node->next = NULL;
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fprintf(stderr, "node %lu\n", node);
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cq_node_t *tail = NULL;
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uint64_t tail_count = 0;
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while (1) {
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tail = queue->tail;
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cq_node_t *tail_ptr = Q_PTR(tail);
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tail_count = Q_COUNT(tail);
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cq_node_t *next = tail->next;
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cq_node_t *next_ptr = Q_PTR(next);
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uint64_t next_count = Q_COUNT(next);
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if (tail == queue->tail) {
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fprintf(stderr, "tail == queue->tail\n");
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if (next_ptr == NULL) {
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fprintf(stderr, "next_ptr == NULL\n");
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if (__sync_bool_compare_and_swap(&tail_ptr->next,
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next,
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Q_SET_COUNT(node, next_count+1)))
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fprintf(stderr, "CAS(tail_ptr->next, next, (node, next_count+1)) -> true\n");
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break;
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} else {
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__sync_bool_compare_and_swap(&queue->tail,
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tail,
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Q_SET_COUNT(next_ptr, next_count+1));
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fprintf(stderr, "CAS(queue->tail, tail, (next_ptr, next_count+1))\n");
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}
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}
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}
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cq_node_t *node_with_count = Q_SET_COUNT(node, tail_count+1);
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int ret = __sync_bool_compare_and_swap(&queue->tail,
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tail,
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node_with_count);
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fprintf(stderr, "CAS(queue->tail, tail, %lu) -> %d\n", node_with_count, ret);
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}
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int dequeue(cq_queue_t *queue, ErlNifPid **pid)
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{
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fprintf(stderr, "dequeue\n");
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cq_node_t *head, *head_ptr, *tail, *tail_ptr, *next, *next_ptr;
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while (1) {
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head = queue->head;
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head_ptr = Q_PTR(head);
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tail = queue->tail;
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tail_ptr = Q_PTR(tail);
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next = head->next;
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next_ptr = Q_PTR(next);
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fprintf(stderr, "head %lu, tail %lu, next %lu\n", head, tail, next);
|
|
|
|
if (head == queue->head) {
|
|
if (head_ptr == tail_ptr) {
|
|
if (next_ptr == NULL) {
|
|
return 0; /* Queue is empty */
|
|
}
|
|
fprintf(stderr, "CAS(queue->tail, tail, (next_ptr, tail+1))\n");
|
|
__sync_bool_compare_and_swap(&queue->tail,
|
|
tail,
|
|
Q_SET_COUNT(next_ptr, Q_COUNT(tail)+1));
|
|
} else {
|
|
fprintf(stderr, "next->value %lu\n", next_ptr->value);
|
|
*pid = next_ptr->value;
|
|
fprintf(stderr, "CAS(queue->head, head, (next_ptr, head+1))\n");
|
|
if (__sync_bool_compare_and_swap(&queue->head,
|
|
head,
|
|
Q_SET_COUNT(next_ptr, Q_COUNT(head)+1)))
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
// free pid
|
|
//enif_free(Q_PTR(head));
|
|
return 1;
|
|
}
|
|
|
|
|
|
|
|
|
|
int load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info) {
|
|
/* Initialize global array mapping id to cq_t ptr */
|
|
QUEUES = (cq_t **) calloc(8, sizeof(cq_t **));
|
|
if (QUEUES == NULL)
|
|
return -1;
|
|
|
|
|
|
ErlNifResourceFlags flags = (ErlNifResourceFlags)(ERL_NIF_RT_CREATE | ERL_NIF_RT_TAKEOVER);
|
|
CQ_RESOURCE = enif_open_resource_type(env, "cq", "cq",
|
|
&free_resource, flags, NULL);
|
|
|
|
if (CQ_RESOURCE == NULL)
|
|
return -1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
static ErlNifFunc nif_funcs[] = {
|
|
{"new" , 3, queue_new},
|
|
{"free" , 1, queue_free},
|
|
{"push" , 2, queue_push},
|
|
{"async_pop", 1, queue_async_pop},
|
|
{"debug" , 1, queue_debug},
|
|
{"debug_poppers", 1, queue_debug_poppers},
|
|
{"print_bits", 0, print_bits}
|
|
};
|
|
|
|
ERL_NIF_INIT(cq, nif_funcs, load, NULL, NULL, NULL);
|