/**
 *    Copyright (C) 2013 MongoDB Inc.
 *
 *    This program 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.
 *
 *    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#include "mongo/db/exec/working_set.h"

#include "mongo/db/index/index_descriptor.h"
#include "mongo/db/storage/record_fetcher.h"

namespace mongo {

    using std::string;

    WorkingSet::MemberHolder::MemberHolder() : member(NULL) { }
    WorkingSet::MemberHolder::~MemberHolder() {}

    WorkingSet::WorkingSet() : _freeList(INVALID_ID) { }

    WorkingSet::~WorkingSet() {
        for (size_t i = 0; i < _data.size(); i++) {
            delete _data[i].member;
        }
    }

    WorkingSetID WorkingSet::allocate() {
        if (_freeList == INVALID_ID) {
            // The free list is empty so we need to make a single new WSM to return. This relies on
            // vector::resize being amortized O(1) for efficient allocation. Note that the free list
            // remains empty until something is returned by a call to free().
            WorkingSetID id = _data.size();
            _data.resize(_data.size() + 1);
            _data.back().nextFreeOrSelf = id;
            _data.back().member = new WorkingSetMember();
            return id;
        }

        // Pop the head off the free list and return it.
        WorkingSetID id = _freeList;
        _freeList = _data[id].nextFreeOrSelf;
        _data[id].nextFreeOrSelf = id; // set to self to mark as in-use
        return id;
    }

    void WorkingSet::free(const WorkingSetID& i) {
        MemberHolder& holder = _data[i];
        verify(i < _data.size()); // ID has been allocated.
        verify(holder.nextFreeOrSelf == i); // ID currently in use.

        // Free resources and push this WSM to the head of the freelist.
        holder.member->clear();
        holder.nextFreeOrSelf = _freeList;
        _freeList = i;
    }

    void WorkingSet::flagForReview(const WorkingSetID& i) {
        WorkingSetMember* member = get(i);
        verify(WorkingSetMember::OWNED_OBJ == member->state);
        _flagged.insert(i);
    }

    const unordered_set<WorkingSetID>& WorkingSet::getFlagged() const {
        return _flagged;
    }

    bool WorkingSet::isFlagged(WorkingSetID id) const {
        invariant(id < _data.size());
        return _flagged.end() != _flagged.find(id);
    }

    void WorkingSet::clear() {
        for (size_t i = 0; i < _data.size(); i++) {
            delete _data[i].member;
        }
        _data.clear();

        // Since working set is now empty, the free list pointer should
        // point to nothing.
        _freeList = INVALID_ID;

        _flagged.clear();
    }

    //
    // Iteration
    //

    WorkingSet::iterator::iterator(WorkingSet* ws, size_t index)
        : _ws(ws),
          _index(index) {
        // If we're currently not pointing at an allocated member, then we have
        // to advance to the first one, unless we're already at the end.
        if (_index < _ws->_data.size() && isFree()) {
            advance();
        }
    }

    void WorkingSet::iterator::advance() {
        // Move forward at least once in the data list.
        _index++;

        // While we haven't hit the end and the current member is not in use. (Skips ahead until
        // we find the next allocated member.)
        while (_index < _ws->_data.size() && isFree()) {
            _index++;
        }
    }

    bool WorkingSet::iterator::isFree() const {
        return _ws->_data[_index].nextFreeOrSelf != _index;
    }

    void WorkingSet::iterator::free() {
        dassert(!isFree());
        _ws->free(_index);
    }

    void WorkingSet::iterator::operator++() {
        dassert(_index < _ws->_data.size());
        advance();
    }

    bool WorkingSet::iterator::operator==(const WorkingSet::iterator& other) const {
        return (_index == other._index);
    }

    bool WorkingSet::iterator::operator!=(const WorkingSet::iterator& other) const {
        return (_index != other._index);
    }

    WorkingSetMember& WorkingSet::iterator::operator*() {
        dassert(_index < _ws->_data.size() && !isFree());
        return *_ws->_data[_index].member;
    }

    WorkingSetMember* WorkingSet::iterator::operator->() {
        dassert(_index < _ws->_data.size() && !isFree());
        return _ws->_data[_index].member;
    }

    WorkingSet::iterator WorkingSet::begin() {
        return WorkingSet::iterator(this, 0);
    }

    WorkingSet::iterator WorkingSet::end() {
        return WorkingSet::iterator(this, _data.size());
    }

    //
    // WorkingSetMember
    //

    WorkingSetMember::WorkingSetMember() : state(WorkingSetMember::INVALID), isSuspicious(false) { }

    WorkingSetMember::~WorkingSetMember() { }

    void WorkingSetMember::clear() {
        for (size_t i = 0; i < WSM_COMPUTED_NUM_TYPES; i++) {
            _computed[i].reset();
        }

        keyData.clear();
        obj.reset();
        state = WorkingSetMember::INVALID;
    }

    bool WorkingSetMember::hasLoc() const {
        return state == LOC_AND_IDX || state == LOC_AND_UNOWNED_OBJ || state == LOC_AND_OWNED_OBJ;
    }

    bool WorkingSetMember::hasObj() const {
        return hasOwnedObj() || hasUnownedObj();
    }

    bool WorkingSetMember::hasOwnedObj() const {
        return state == OWNED_OBJ || state == LOC_AND_OWNED_OBJ;
    }

    bool WorkingSetMember::hasUnownedObj() const {
        return state == LOC_AND_UNOWNED_OBJ;
    }

    bool WorkingSetMember::hasComputed(const WorkingSetComputedDataType type) const {
        return _computed[type].get();
    }

    const WorkingSetComputedData* WorkingSetMember::getComputed(const WorkingSetComputedDataType type) const {
        verify(_computed[type]);
        return _computed[type].get();
    }

    void WorkingSetMember::addComputed(WorkingSetComputedData* data) {
        verify(!hasComputed(data->type()));
        _computed[data->type()].reset(data);
    }

    void WorkingSetMember::setFetcher(RecordFetcher* fetcher) {
        _fetcher.reset(fetcher);
    }

    RecordFetcher* WorkingSetMember::releaseFetcher() {
        return _fetcher.release();
    }

    bool WorkingSetMember::hasFetcher() const {
        return NULL != _fetcher.get();
    }

    bool WorkingSetMember::getFieldDotted(const string& field, BSONElement* out) const {
        // If our state is such that we have an object, use it.
        if (hasObj()) {
            *out = obj.value().getFieldDotted(field);
            return true;
        }

        // Our state should be such that we have index data/are covered.
        for (size_t i = 0; i < keyData.size(); ++i) {
            BSONObjIterator keyPatternIt(keyData[i].indexKeyPattern);
            BSONObjIterator keyDataIt(keyData[i].keyData);

            while (keyPatternIt.more()) {
                BSONElement keyPatternElt = keyPatternIt.next();
                verify(keyDataIt.more());
                BSONElement keyDataElt = keyDataIt.next();

                if (field == keyPatternElt.fieldName()) {
                    *out = keyDataElt;
                    return true;
                }
            }
        }

        return false;
    }

    size_t WorkingSetMember::getMemUsage() const {
        size_t memUsage = 0;

        if (hasLoc()) {
            memUsage += sizeof(RecordId);
        }

        // XXX: Unowned objects count towards current size.
        //      See SERVER-12579
        if (hasObj()) {
            memUsage += obj.value().objsize();
        }

        for (size_t i = 0; i < keyData.size(); ++i) {
            const IndexKeyDatum& keyDatum = keyData[i];
            memUsage += keyDatum.keyData.objsize();
        }

        return memUsage;
    }

}  // namespace mongo