wlock_helper.c

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/* -*- C -*- */
/*
 * Copyright (c) 2017-2020 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.
 *
 */


#define M0_TRACE_SUBSYSTEM M0_TRACE_SUBSYS_RM
#include "lib/trace.h"
#include "lib/string.h"
#include "rm/rm.h"
#include "rm/rm_rwlock.h"
#include "rpc/rpclib.h"

struct wlock_ctx {
        struct m0_rpc_machine     *wlc_rmach;     
        struct m0_rpc_conn         wlc_conn;      
        struct m0_rpc_session      wlc_sess;      
        char                      *wlc_rm_addr;   
        struct m0_fid              wlc_rm_fid;    
        struct m0_rw_lockable      wlc_rwlock;    
        struct m0_rm_owner         wlc_owner;     
        struct m0_fid              wlc_owner_fid; 
        struct m0_rm_remote        wlc_creditor;  
        struct m0_rm_incoming      wlc_req;       
        struct m0_semaphore        wlc_sem;
        struct m0_rm_domain        wlc_dom;
        struct m0_rm_resource_type wlc_rt;
        int32_t                    wlc_rc;
} wlx;

static void write_lock_complete(struct m0_rm_incoming *in,
                                int32_t                rc)
{
        M0_ENTRY("incoming %p, rc %d", in, rc);
        wlx.wlc_rc = rc;
        m0_semaphore_up(&wlx.wlc_sem);
        M0_LEAVE();
}

static void write_lock_conflict(struct m0_rm_incoming *in)
{
        /* Do nothing */
}

static struct m0_rm_incoming_ops ri_ops = {
        .rio_complete = write_lock_complete,
        .rio_conflict = write_lock_conflict,
};

static int wlock_ctx_create(struct m0_rpc_machine *rpc_mach, const char *rm_ep)
{
        int rc;

        wlx.wlc_rmach = rpc_mach;
        m0_rwlockable_domain_type_init(&wlx.wlc_dom, &wlx.wlc_rt);
        m0_rw_lockable_init(&wlx.wlc_rwlock, &M0_RWLOCK_FID, &wlx.wlc_dom);
        m0_fid_tgenerate(&wlx.wlc_owner_fid, M0_RM_OWNER_FT);
        m0_rm_rwlock_owner_init(&wlx.wlc_owner, &wlx.wlc_owner_fid,
                                &wlx.wlc_rwlock, NULL);
        wlx.wlc_rm_addr = m0_strdup(rm_ep);
        rc = m0_semaphore_init(&wlx.wlc_sem, 0);
        return M0_RC(rc);
}

static int wlock_ctx_connect(struct wlock_ctx *wlx)
{
        enum { MAX_RPCS_IN_FLIGHT = 15 };

        M0_PRE(wlx != NULL);
        return m0_rpc_client_connect(&wlx->wlc_conn, &wlx->wlc_sess,
                                     wlx->wlc_rmach, wlx->wlc_rm_addr, NULL,
                                     MAX_RPCS_IN_FLIGHT, M0_TIME_NEVER);
}

static void wlock_ctx_creditor_setup(struct wlock_ctx *wlx)
{
        M0_ENTRY("wlx=%p", wlx);
        M0_PRE(wlx != NULL);
        m0_rm_remote_init(&wlx->wlc_creditor, wlx->wlc_owner.ro_resource);
        wlx->wlc_creditor.rem_session = &wlx->wlc_sess;
        m0_rm_owner_creditor_reset(&wlx->wlc_owner, &wlx->wlc_creditor);
        M0_LEAVE();
}

static void _write_lock_get(struct wlock_ctx *wlx)
{
        M0_ENTRY("wlx=%p", wlx);
        M0_PRE(wlx != NULL);
        m0_rm_rwlock_req_init(&wlx->wlc_req, &wlx->wlc_owner, &ri_ops,
                              RIF_MAY_BORROW | RIF_MAY_REVOKE | RIF_LOCAL_WAIT |
                              RIF_RESERVE, RM_RWLOCK_WRITE);
        m0_rm_credit_get(&wlx->wlc_req);
        M0_LEAVE();
}

static void wlock_ctx_destroy(struct wlock_ctx *wlx)
{
        M0_ENTRY("wlx=%p", wlx);
        M0_PRE(wlx != NULL);
        M0_LOG(M0_DEBUG, "owner wound up");
        m0_rm_rwlock_owner_fini(&wlx->wlc_owner);
        m0_rw_lockable_fini(&wlx->wlc_rwlock);
        m0_rwlockable_domain_type_fini(&wlx->wlc_dom, &wlx->wlc_rt);
        M0_LEAVE();
}

static void wlock_ctx_disconnect(struct wlock_ctx *wlx)
{
        int rc;

        M0_ENTRY("wlx=%p", wlx);
        M0_PRE(_0C(wlx != NULL) && _0C(!M0_IS0(&wlx->wlc_sess)));
        rc = m0_rpc_session_destroy(&wlx->wlc_sess, M0_TIME_NEVER);
        if (rc != 0)
                M0_LOG(M0_ERROR, "Failed to destroy wlock session");
        rc = m0_rpc_conn_destroy(&wlx->wlc_conn, M0_TIME_NEVER);
        if (rc != 0)
                M0_LOG(M0_ERROR, "Failed to destroy wlock connection");
        M0_LEAVE();

}

static void wlock_ctx_owner_windup(struct wlock_ctx *wlx)
{
        int rc;

        M0_ENTRY("wlx=%p", wlx);
        m0_rm_owner_windup(&wlx->wlc_owner);
        rc = m0_rm_owner_timedwait(&wlx->wlc_owner,
                                   M0_BITS(ROS_FINAL, ROS_INSOLVENT),
                                   M0_TIME_NEVER);
        M0_ASSERT(rc == 0);
        M0_LEAVE();
}

static void wlock_ctx_creditor_unset(struct wlock_ctx *wlx)
{
        M0_ENTRY("wlx=%p", wlx);
        M0_PRE(wlx != NULL);
        m0_rm_remote_fini(&wlx->wlc_creditor);
        M0_SET0(&wlx->wlc_creditor);
        wlx->wlc_owner.ro_creditor = NULL;
        M0_LEAVE();
}

static void _write_lock_put(struct wlock_ctx *wlx)
{
        struct m0_rm_incoming *req;

        M0_ENTRY("wlx=%p", wlx);
        M0_PRE(wlx != NULL);
        req = &wlx->wlc_req;
        m0_rm_credit_put(req);
        m0_rm_incoming_fini(req);
        wlock_ctx_owner_windup(wlx);
        wlock_ctx_creditor_unset(wlx);
        M0_LEAVE();
}

M0_INTERNAL void rm_write_lock_put()
{
        _write_lock_put(&wlx);
        wlock_ctx_destroy(&wlx);
        wlock_ctx_disconnect(&wlx);
        m0_free0(&wlx.wlc_rm_addr);
        M0_LEAVE();
}

M0_INTERNAL int rm_write_lock_get(struct m0_rpc_machine *rpc_mach,
                                  const char *rm_ep)
{
        int rc;

        rc = wlock_ctx_create(rpc_mach, rm_ep);
        if (rc != 0) {
                M0_ERR(rc);
                goto fail;
        }
        rc = wlock_ctx_connect(&wlx);
        if (rc != 0) {
                M0_ERR_INFO(rc, "ep=%s", rm_ep);
                goto ctx_free;
        }
        wlock_ctx_creditor_setup(&wlx);
        _write_lock_get(&wlx);
        m0_semaphore_down(&wlx.wlc_sem);
        rc = wlx.wlc_rc;
        if (rc != 0) {
                M0_ERR(rc);
                goto ctx_destroy;
        }
        return M0_RC(rc);
ctx_destroy:
        wlock_ctx_owner_windup(&wlx);
        wlock_ctx_creditor_unset(&wlx);
        wlock_ctx_destroy(&wlx);
        wlock_ctx_disconnect(&wlx);
ctx_free:
        m0_free0(&wlx.wlc_rm_addr);
fail:
        return M0_ERR(rc);
}

#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:
 */