// @file cpuprofile.cpp

/**
*    Copyright (C) 2012 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.
*/

/**
 * This module provides commands for starting and stopping the Google perftools
 * cpu profiler linked into mongod.
 *
 * The following command enables the not-currently-enabled profiler, and writes
 * the profile data to the specified "profileFilename."
 *     { _cpuProfilerStart: { profileFilename: '/path/on/mongod-host.prof' } }
 *
 * The following command disables the already-enabled profiler:
 *     { _cpuProfilerStop: 1}
 *
 * The commands defined here, and profiling, are only available when enabled at
 * build-time with the "--use-cpu-profiler" argument to scons.
 *
 * Example SCons command line:
 *
 *     scons --release --use-cpu-profiler
 */

#include "gperftools/profiler.h"

#include <string>
#include <vector>

#include "mongo/db/auth/action_set.h"
#include "mongo/db/auth/action_type.h"
#include "mongo/db/auth/authorization_manager.h"
#include "mongo/db/auth/privilege.h"
#include "mongo/db/client.h"
#include "mongo/db/commands.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/jsobj.h"

namespace mongo {

namespace {

/**
 * Common code for the implementation of cpu profiler commands.
 */
class CpuProfilerCommand : public ErrmsgCommandDeprecated {
public:
    CpuProfilerCommand(char const* name) : ErrmsgCommandDeprecated(name) {}
    virtual bool slaveOk() const {
        return true;
    }
    virtual bool adminOnly() const {
        return true;
    }
    virtual bool localHostOnlyIfNoAuth() {
        return true;
    }
    virtual void addRequiredPrivileges(const std::string& dbname,
                                       const BSONObj& cmdObj,
                                       std::vector<Privilege>* out) {
        ActionSet actions;
        actions.addAction(ActionType::cpuProfiler);
        out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
    }

    // This is an abuse of the global dbmutex.  We only really need to
    // ensure that only one cpuprofiler command runs at once; it would
    // be fine for it to run concurrently with other operations.
    virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
        return false;
    }
};

/**
 * Class providing implementation of the _cpuProfilerStart command.
 */
class CpuProfilerStartCommand : public CpuProfilerCommand {
public:
    CpuProfilerStartCommand() : CpuProfilerCommand(commandName) {}

    virtual bool errmsgRun(OperationContext* opCtx,
                           std::string const& db,
                           const BSONObj& cmdObj,
                           std::string& errmsg,
                           BSONObjBuilder& result);

    static char const* const commandName;
} cpuProfilerStartCommandInstance;

/**
 * Class providing implementation of the _cpuProfilerStop command.
 */
class CpuProfilerStopCommand : public CpuProfilerCommand {
public:
    CpuProfilerStopCommand() : CpuProfilerCommand(commandName) {}

    virtual bool errmsgRun(OperationContext* opCtx,
                           std::string const& db,
                           const BSONObj& cmdObj,
                           std::string& errmsg,
                           BSONObjBuilder& result);

    static char const* const commandName;
} cpuProfilerStopCommandInstance;

char const* const CpuProfilerStartCommand::commandName = "_cpuProfilerStart";
char const* const CpuProfilerStopCommand::commandName = "_cpuProfilerStop";

bool CpuProfilerStartCommand::errmsgRun(OperationContext* opCtx,
                                        std::string const& db,
                                        const BSONObj& cmdObj,
                                        std::string& errmsg,
                                        BSONObjBuilder& result) {
    // The DB lock here is just so we have IX on the global lock in order to prevent shutdown
    Lock::DBLock dbXLock(opCtx, db, MODE_X);
    OldClientContext ctx(opCtx, db, false /* no shard version checking */);

    std::string profileFilename = cmdObj[commandName]["profileFilename"].String();
    if (!::ProfilerStart(profileFilename.c_str())) {
        errmsg = "Failed to start profiler";
        return false;
    }
    return true;
}

bool CpuProfilerStopCommand::errmsgRun(OperationContext* opCtx,
                                       std::string const& db,
                                       const BSONObj& cmdObj,
                                       std::string& errmsg,
                                       BSONObjBuilder& result) {
    // The DB lock here is just so we have IX on the global lock in order to prevent shutdown
    Lock::DBLock dbXLock(opCtx, db, MODE_X);
    OldClientContext ctx(opCtx, db, false /* no shard version checking */);

    ::ProfilerStop();
    return true;
}

}  // namespace

}  // namespace mongo