// validate.cpp

/**
 *    Copyright (C) 2013 10gen 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.
 */

#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kCommand

#include "mongo/platform/basic.h"

#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/collection_catalog_entry.h"
#include "mongo/db/client.h"
#include "mongo/db/commands.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/query/internal_plans.h"
#include "mongo/db/storage/record_store.h"
#include "mongo/util/fail_point_service.h"
#include "mongo/util/log.h"
#include "mongo/util/scopeguard.h"

namespace mongo {

using std::endl;
using std::string;
using std::stringstream;

MONGO_FP_DECLARE(validateCmdCollectionNotValid);

namespace {

// Protects `_validationQueue`
stdx::mutex _validationMutex;

// Wakes up `_validationQueue`
stdx::condition_variable _validationNotifier;

// Holds the set of full `database.collections` namespace strings in progress.
std::set<std::string> _validationsInProgress;
}  // namespace

class ValidateCmd : public BasicCommand {
public:
    ValidateCmd() : BasicCommand("validate") {}

    AllowedOnSecondary secondaryAllowed(ServiceContext*) const override {
        return AllowedOnSecondary::kAlways;
    }

    std::string help() const override {
        return "Validate contents of a namespace by scanning its data structures for correctness.  "
               "Slow.\n"
               "Add full:true option to do a more thorough check\n"
               "Add scandata:false to skip the scan of the collection data without skipping scans "
               "of any indexes";
    }

    virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
        return false;
    }
    virtual void addRequiredPrivileges(const std::string& dbname,
                                       const BSONObj& cmdObj,
                                       std::vector<Privilege>* out) const {
        ActionSet actions;
        actions.addAction(ActionType::validate);
        out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
    }
    //{ validate: "collectionnamewithoutthedbpart" [, scandata: <bool>] [, full: <bool> } */

    bool run(OperationContext* opCtx,
             const string& dbname,
             const BSONObj& cmdObj,
             BSONObjBuilder& result) {
        if (MONGO_FAIL_POINT(validateCmdCollectionNotValid)) {
            result.appendBool("valid", false);
            return true;
        }

        const NamespaceString nss(CommandHelpers::parseNsCollectionRequired(dbname, cmdObj));

        const bool full = cmdObj["full"].trueValue();
        const bool scanData = cmdObj["scandata"].trueValue();

        ValidateCmdLevel level = kValidateIndex;

        if (full) {
            level = kValidateFull;
        } else if (scanData) {
            level = kValidateRecordStore;
        }

        if (!nss.isNormal() && full) {
            uasserted(ErrorCodes::CommandFailed,
                      "Can only run full validate on a regular collection");
        }

        if (!serverGlobalParams.quiet.load()) {
            LOG(0) << "CMD: validate " << nss.ns();
        }

        AutoGetDb ctx(opCtx, nss.db(), MODE_IX);
        auto collLk = stdx::make_unique<Lock::CollectionLock>(opCtx->lockState(), nss.ns(), MODE_X);
        Collection* collection = ctx.getDb() ? ctx.getDb()->getCollection(opCtx, nss) : NULL;
        if (!collection) {
            if (ctx.getDb() && ctx.getDb()->getViewCatalog()->lookup(opCtx, nss.ns())) {
                uasserted(ErrorCodes::CommandNotSupportedOnView, "Cannot validate a view");
            }

            uasserted(ErrorCodes::NamespaceNotFound, "ns not found");
        }

        // Omit background validation logic until it is fully implemented and vetted.
        const bool background = false;
        /*
        bool isInRecordIdOrder = collection->getRecordStore()->isInRecordIdOrder();
        if (isInRecordIdOrder && !full) {
            background = true;
        }

        if (cmdObj.hasElement("background")) {
            background = cmdObj["background"].trueValue();
        }

        if (!isInRecordIdOrder && background) {
            uasserted(ErrorCodes::CommandFailed,
                      "This storage engine does not support the background option, use "
                      "background:false");
            return false;
        }

        if (full && background) {
            uasserted(ErrorCodes::CommandFailed,
                      "A full validate cannot run in the background, use full:false");
        }
        */

        result.append("ns", nss.ns());

        // Only one validation per collection can be in progress, the rest wait in order.
        {
            stdx::unique_lock<stdx::mutex> lock(_validationMutex);
            try {
                while (_validationsInProgress.find(nss.ns()) != _validationsInProgress.end()) {
                    opCtx->waitForConditionOrInterrupt(_validationNotifier, lock);
                }
            } catch (AssertionException& e) {
                CommandHelpers::appendCommandStatusNoThrow(
                    result,
                    {ErrorCodes::CommandFailed,
                     str::stream() << "Exception during validation: " << e.toString()});
                return false;
            }

            _validationsInProgress.insert(nss.ns());
        }

        ON_BLOCK_EXIT([&] {
            stdx::lock_guard<stdx::mutex> lock(_validationMutex);
            _validationsInProgress.erase(nss.ns());
            _validationNotifier.notify_all();
        });

        ValidateResults results;
        Status status =
            collection->validate(opCtx, level, background, std::move(collLk), &results, &result);
        if (!status.isOK()) {
            return CommandHelpers::appendCommandStatusNoThrow(result, status);
        }

        CollectionCatalogEntry* catalogEntry = collection->getCatalogEntry();
        CollectionOptions opts = catalogEntry->getCollectionOptions(opCtx);

        // Skip checking UUID on system.indexes and system.namespaces until SERVER-30095 and
        // SERVER-29926 are resolved.
        bool skipUUIDCheck = nss.coll() == "system.indexes" || nss.coll() == "system.namespaces";

        if (!skipUUIDCheck) {
            // All collections must have a UUID.
            if (!opts.uuid) {
                results.errors.push_back(str::stream() << "UUID missing on collection " << nss.ns()
                                                       << " but SchemaVersion=3.6");
                results.valid = false;
            }
        }

        if (!full) {
            results.warnings.push_back(
                "Some checks omitted for speed. use {full:true} option to do more thorough scan.");
        }

        result.appendBool("valid", results.valid);
        result.append("warnings", results.warnings);
        result.append("errors", results.errors);

        if (!results.valid) {
            result.append("advice",
                          "A corrupt namespace has been detected. See "
                          "http://dochub.mongodb.org/core/data-recovery for recovery steps.");
        }

        return true;
    }

} validateCmd;
}