#include "moar.h"

/* Turns finalization on or off for a type. */

void MVM_gc_finalize_set(MVMThreadContext *tc, MVMObject *type, MVMint64 finalize) {

    MVMSTable *st        = STABLE(type);

    MVMint64   new_flags = st->mode_flags & (~MVM_FINALIZE_TYPE);

    if (finalize)

        new_flags |= MVM_FINALIZE_TYPE;

    st->mode_flags = new_flags;

    MVM_SC_WB_ST(tc, st);

}

/* Adds an object we've just allocated to the queue of those with finalizers

 * that will need calling upon collection. */

void MVM_gc_finalize_add_to_queue(MVMThreadContext *tc, MVMObject *obj) {

    MVM_ASSERT_NOT_FROMSPACE(tc, obj);

    if (tc->num_finalize == tc->alloc_finalize) {

        if (tc->alloc_finalize)

            tc->alloc_finalize *= 2;

        else

            tc->alloc_finalize = 64;

        tc->finalize = MVM_realloc(tc->finalize,

            sizeof(MVMCollectable **) * tc->alloc_finalize);

    }

    tc->finalize[tc->num_finalize] = obj;

    tc->num_finalize++;

}

/* Sets the passed thread context's thread up so that we'll run a finalize

 * handler on it in the near future. */

static void finalize_handler_caller(MVMThreadContext *tc, void *sr_data) {

    MVMObject *handler = MVM_hll_current(tc)->finalize_handler;

    if (handler) {

        MVMCallsite *inv_arg_callsite = MVM_callsite_get_common(tc, MVM_CALLSITE_ID_INV_ARG);

        /* Drain the finalizing queue to an array. */

        MVMObject *drain = MVM_repr_alloc_init(tc, tc->instance->boot_types.BOOTArray);

        while (tc->num_finalizing > 0)

            MVM_repr_push_o(tc, drain, tc->finalizing[--tc->num_finalizing]);

        /* Invoke the handler. */

        handler = MVM_frame_find_invokee(tc, handler, NULL);

        MVM_args_setup_thunk(tc, NULL, MVM_RETURN_VOID, inv_arg_callsite);

        tc->cur_frame->args[0].o = drain;

        STABLE(handler)->invoke(tc, handler, inv_arg_callsite, tc->cur_frame->args);

    }

}

static void setup_finalize_handler_call(MVMThreadContext *tc) {

    MVMFrame *install_on = tc->cur_frame;

    while (install_on) {

        if (!install_on->extra || !install_on->extra->special_return)

            if (install_on->static_info->body.cu->body.hll_config)

                break;

        install_on = install_on->caller;

    }

    if (install_on)

        MVM_frame_special_return(tc, install_on, finalize_handler_caller, NULL,

            NULL, NULL);

}

/* Walks through the per-thread finalize queues, identifying objects that

 * should be finalized, pushing them onto a finalize list, and then marking

 * that list entry. Assumes the world is stopped. */

static void add_to_finalizing(MVMThreadContext *tc, MVMObject *obj) {

    if (tc->num_finalizing == tc->alloc_finalizing) {

        if (tc->alloc_finalizing)

            tc->alloc_finalizing *= 2;

        else

            tc->alloc_finalizing = 64;

        tc->finalizing = MVM_realloc(tc->finalizing,

            sizeof(MVMCollectable **) * tc->alloc_finalizing);

    }

    tc->finalizing[tc->num_finalizing] = obj;

    tc->num_finalizing++;

}

static void walk_thread_finalize_queue(MVMThreadContext *tc, MVMuint8 gen) {

    MVMuint32 collapse_pos = 0;

    MVMuint32 i;

    for (i = 0; i < tc->num_finalize; i++) {

        /* See if it's dead, taking which generation we've marked into

         * account. */

        MVMuint32 flags   = tc->finalize[i]->header.flags;

        MVMuint32 in_gen2 = flags & MVM_CF_SECOND_GEN;

        if (gen == MVMGCGenerations_Both || !in_gen2) {

            MVMuint32 live = flags & (MVM_CF_GEN2_LIVE | MVM_CF_FORWARDER_VALID);

            if (live) {

                /* Alive, so just leave it in finalized queue, taking updated

                 * address if needed. */

                tc->finalize[collapse_pos++] = flags & MVM_CF_FORWARDER_VALID

                    ? (MVMObject *)tc->finalize[i]->header.sc_forward_u.forwarder

                    : tc->finalize[i];

            }

            else {

                /* Dead; needs finalizing, so pop it on the finalizing list. */

                add_to_finalizing(tc, tc->finalize[i]);

            }

        }

    }

    tc->num_finalize = collapse_pos;

}

void MVM_finalize_walk_queues(MVMThreadContext *tc, MVMuint8 gen) {

    MVMThread *cur_thread = (MVMThread *)MVM_load(&tc->instance->threads);

    while (cur_thread) {

        if (cur_thread->body.tc) {

            walk_thread_finalize_queue(cur_thread->body.tc, gen);

            if (cur_thread->body.tc->num_finalizing > 0) {

                MVM_gc_collect(cur_thread->body.tc, MVMGCWhatToDo_Finalizing, gen);

                setup_finalize_handler_call(cur_thread->body.tc);

            }

        }

        cur_thread = cur_thread->body.next;

    }

}