/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
#ident "$Id$"
/*======
This file is part of PerconaFT.


Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.

    PerconaFT is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2,
    as published by the Free Software Foundation.

    PerconaFT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.

----------------------------------------

    PerconaFT is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License, version 3,
    as published by the Free Software Foundation.

    PerconaFT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
======= */

#ident "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."

#pragma once

#include <toku_list.h>
#include <toku_pthread.h>

// The work struct is the base class for work to be done by some threads
struct work {
    struct toku_list next;
};

// The workset struct contains the set of work to be done by some threads
struct workset {
    toku_mutex_t lock;
    struct toku_list worklist;           // a list of work
    int refs;                            // number of workers that have a reference on the workset
    toku_cond_t worker_wait;     // a condition variable used to wait for all of the worker to release their reference on the workset
};

static inline void 
workset_init(struct workset *ws) {
    toku_mutex_init(&ws->lock, NULL);
    toku_list_init(&ws->worklist);
    ws->refs = 1;      // the calling thread gets a reference
    toku_cond_init(&ws->worker_wait, NULL);
}

static inline void 
workset_destroy(struct workset *ws) {
    invariant(toku_list_empty(&ws->worklist));
    toku_cond_destroy(&ws->worker_wait);
    toku_mutex_destroy(&ws->lock);
}

static inline void 
workset_lock(struct workset *ws) {
    toku_mutex_lock(&ws->lock);
}
        
static inline void 
workset_unlock(struct workset *ws) {
    toku_mutex_unlock(&ws->lock);
}

// Put work in the workset.  Assume the workset is already locked.
static inline void 
workset_put_locked(struct workset *ws, struct work *w) {
    toku_list_push(&ws->worklist, &w->next);
}

// Put work in the workset 
static inline void 
workset_put(struct workset *ws, struct work *w) {
    workset_lock(ws);
    workset_put_locked(ws, w);
    workset_unlock(ws);
}

// Get work from the workset
static inline struct work *
workset_get(struct workset *ws) {
    workset_lock(ws);
    struct work *w = NULL;
    if (!toku_list_empty(&ws->worklist)) {
        struct toku_list *l = toku_list_pop_head(&ws->worklist);
        w = toku_list_struct(l, struct work, next);
    }
    workset_unlock(ws);
    return w;
}

// Add references to the workset
static inline void 
workset_add_ref(struct workset *ws, int refs) {
    workset_lock(ws);
    ws->refs += refs;
    workset_unlock(ws);
}

// Release a reference on the workset
static inline void 
workset_release_ref(struct workset *ws) {
    workset_lock(ws);
    if (--ws->refs == 0) {
        toku_cond_broadcast(&ws->worker_wait);
    }
    workset_unlock(ws);
}

// Wait until all of the worker threads have released their reference on the workset
static inline void 
workset_join(struct workset *ws) {
    workset_lock(ws);
    while (ws->refs != 0) {
        toku_cond_wait(&ws->worker_wait, &ws->lock);
    }
    workset_unlock(ws);
}