ns_iter.c

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/* -*- C -*- */
/*
 * Copyright (c) 2012-2020 Seagate Technology LLC and/or its Affiliates
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * For any questions about this software or licensing,
 * please email opensource@seagate.com or cortx-questions@seagate.com.
 *
 */


#include "lib/memory.h"
#include "lib/misc.h"  /* SET0 */
#include "lib/errno.h"
#include "cob/ns_iter.h"
#define M0_TRACE_SUBSYSTEM M0_TRACE_SUBSYS_COB
#include "lib/trace.h"
#

static bool ns_iter_invariant(const struct m0_cob_fid_ns_iter *iter)
{
        return iter != NULL &&
               iter->cni_cdom != NULL && m0_fid_is_set(&iter->cni_last_fid);
}

M0_INTERNAL int m0_cob_ns_iter_init(struct m0_cob_fid_ns_iter *iter,
                                    struct m0_fid *gfid,
                                    struct m0_cob_domain *cdom)
{
        M0_PRE(iter != NULL);

        M0_SET0(iter);

        iter->cni_cdom     =  cdom;
        iter->cni_last_fid = *gfid;

        M0_POST(ns_iter_invariant(iter));

        return 0;
}

M0_INTERNAL int m0_cob_ns_rec_of(struct m0_be_btree *cob_namespace,
                                 const struct m0_fid *key_gfid,
                                 struct m0_fid *next_gfid,
                                 struct m0_cob_nsrec **nsrec)
{
        struct m0_cob_nskey       *key = NULL;
        struct m0_buf              kbuf;
        struct m0_buf              nbuf;
        struct m0_be_btree_cursor  it;
        uint32_t                   cob_idx = 0;
        char                       nskey_bs[UINT32_STR_LEN];
        uint32_t                   nskey_bs_len;
        int                        rc;

        m0_be_btree_cursor_init(&it, cob_namespace);
        M0_SET0(&nskey_bs);
        snprintf(nskey_bs, UINT32_STR_LEN, "%u", cob_idx);
        nskey_bs_len = strlen(nskey_bs);

        rc = m0_cob_nskey_make(&key, key_gfid, nskey_bs,
                               nskey_bs_len);
        if (rc != 0)
                return M0_RC(rc);

        m0_buf_init(&kbuf, key, m0_cob_nskey_size(key) + UINT32_STR_LEN);
        rc = m0_be_btree_cursor_get_sync(&it, &kbuf, true);
        if (rc == 0) {
                /*
                 * Assign the fetched value to gfid, which is treated as
                 * iterator output.
                 */
                struct m0_cob_nskey* k;

                m0_be_btree_cursor_kv_get(&it, &kbuf, &nbuf);
                k = (struct m0_cob_nskey *)kbuf.b_addr;
                *nsrec = (struct m0_cob_nsrec *)nbuf.b_addr;
                *next_gfid = k->cnk_pfid;
        }
        m0_free(key);
        m0_be_btree_cursor_fini(&it);

        return M0_RC(rc);
}

M0_INTERNAL int m0_cob_ns_iter_next(struct m0_cob_fid_ns_iter *iter,
                                    struct m0_fid *gfid,
                                    struct m0_cob_nsrec **nsrec)
{
        int           rc;
        struct m0_fid key_fid;

        M0_PRE(ns_iter_invariant(iter));
        M0_PRE(gfid != NULL);

        key_fid = iter->cni_last_fid;
        rc = m0_cob_ns_rec_of(&iter->cni_cdom->cd_namespace, &key_fid, gfid,
                              nsrec);
        if (rc == 0) {
                /* Container (f_container) value remains same, typically 0. */
                iter->cni_last_fid.f_container = gfid->f_container;
                /* Increment the f_key by 1, to exploit cursor_get() property.*/
                iter->cni_last_fid.f_key = gfid->f_key + 1;
        }

        return M0_RC(rc);
}

M0_INTERNAL void m0_cob_ns_iter_fini(struct m0_cob_fid_ns_iter *iter)
{
        M0_PRE(ns_iter_invariant(iter));
        M0_SET0(iter);
}

#undef M0_TRACE_SUBSYSTEM

/*
 *  Local variables:
 *  c-indentation-style: "K&R"
 *  c-basic-offset: 8
 *  tab-width: 8
 *  fill-column: 80
 *  scroll-step: 1
 *  End:
 */