one/include/VirtualMachine.h

/* -------------------------------------------------------------------------- */
/* Copyright 2002-2012, OpenNebula Project Leads (OpenNebula.org)             */
/*                                                                            */
/* 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.                                             */
/* -------------------------------------------------------------------------- */

#ifndef VIRTUAL_MACHINE_H_
#define VIRTUAL_MACHINE_H_

#include "VirtualMachineTemplate.h"
#include "PoolSQL.h"
#include "History.h"
#include "Log.h"
#include "NebulaLog.h"

#include <time.h>
#include <set>
#include <sstream>

using namespace std;

class AuthRequest;

/* -------------------------------------------------------------------------- */
/* -------------------------------------------------------------------------- */

/**
 *  The Virtual Machine class. It represents a VM...
 */
class VirtualMachine : public PoolObjectSQL
{
public:
    // -------------------------------------------------------------------------
    // VM States
    // -------------------------------------------------------------------------

    /**
     *  Global Virtual Machine state
     */
    enum VmState
    {
        INIT      = 0,
        PENDING   = 1,
        HOLD      = 2,
        ACTIVE    = 3,
        STOPPED   = 4,
        SUSPENDED = 5,
        DONE      = 6,
        FAILED    = 7,
        POWEROFF  = 8
    };

    /**
     *  Virtual Machine state associated to the Life-cycle Manager
     */
    enum LcmState
    {
        LCM_INIT       = 0,
        PROLOG         = 1,
        BOOT           = 2,
        RUNNING        = 3,
        MIGRATE        = 4,
        SAVE_STOP      = 5,
        SAVE_SUSPEND   = 6,
        SAVE_MIGRATE   = 7,
        PROLOG_MIGRATE = 8,
        PROLOG_RESUME  = 9,
        EPILOG_STOP    = 10,
        EPILOG         = 11,
        SHUTDOWN       = 12,
        CANCEL         = 13,
        FAILURE        = 14,
        CLEANUP        = 15,
        UNKNOWN        = 16,
        HOTPLUG        = 17,
        SHUTDOWN_POWEROFF = 18
    };

    // -------------------------------------------------------------------------
    // Log & Print
    // -------------------------------------------------------------------------

    /**
     *  writes a log message in vm.log. The class lock should be locked and
     *  the VM MUST BE obtained through the VirtualMachinePool get() method.
     */
    void log(
        const char *            module,
        const Log::MessageType  type,
        const ostringstream&    message) const
    {
        if (_log != 0)
        {
            _log->log(module,type,message.str().c_str());
        }
    };

    /**
     *  writes a log message in vm.log. The class lock should be locked and
     *  the VM MUST BE obtained through the VirtualMachinePool get() method.
     */
    void log(
        const char *            module,
        const Log::MessageType  type,
        const char *            message) const
    {
        if (_log != 0)
        {
            _log->log(module,type,message);
        }
    };

    /**
     * Function to print the VirtualMachine object into a string in
     * XML format
     *  @param xml the resulting XML string
     *  @return a reference to the generated string
     */
    string& to_xml(string& xml) const
    {
        return to_xml_extended(xml, 1);
    }

    /**
     * Function to print the VirtualMachine object into a string in
     * XML format, with extended information (full history records)
     *  @param xml the resulting XML string
     *  @return a reference to the generated string
     */
    string& to_xml_extended(string& xml) const
    {
        return to_xml_extended(xml, 2);
    }

    /**
     *  Rebuilds the object from an xml formatted string
     *    @param xml_str The xml-formatted string
     *
     *    @return 0 on success, -1 otherwise
     */
    int from_xml(const string &xml_str);

    // ------------------------------------------------------------------------
    // Dynamic Info
    // ------------------------------------------------------------------------

    /**
     *  Updates VM dynamic information (id).
     *   @param _deploy_id the VMM driver specific id
     */
    void update_info(
        const string& _deploy_id)
    {
        deploy_id = _deploy_id;
    };

    /**
     *  Updates VM dynamic information (usage counters).
     *   @param _memory Kilobytes used by the VM (total)
     *   @param _cpu used by the VM (rate)
     *   @param _net_tx transmitted bytes (total)
     *   @param _net_tx received bytes (total)
     */
    void update_info(
        const int _memory,
        const int _cpu,
        const int _net_tx,
        const int _net_rx)
    {
        if (_memory != -1)
        {
            memory = _memory;
        }

        if (_cpu != -1)
        {
            cpu    = _cpu;
        }

        if (_net_tx != -1)
        {
            net_tx = _net_tx;
        }

        if (_net_rx != -1)
        {
            net_rx = _net_rx;
        }
    };

    /**
     *  Returns the deployment ID
     *    @return the VMM driver specific ID
     */
    const string& get_deploy_id() const
    {
        return deploy_id;
    };

    /**
     *  Sets the VM exit time
     *    @param _et VM exit time (when it arrived DONE/FAILED states)
     */
    void set_exit_time(time_t et)
    {
        etime = et;
    };

    // ------------------------------------------------------------------------
    // Access to VM locations
    // ------------------------------------------------------------------------
    /**
     *  Returns the remote VM directory. The VM remote dir is in the form:
     *  $DATASTORE_LOCATION/$SYSTEM_DS_ID/$VM_ID. The remote system_dir stores
     *  disks for a running VM in the target host.
     *    @return the remote system directory for the VM
     */
    const string& get_remote_system_dir() const
    {
        return history->rsystem_dir;
    }

    /**
     *  Returns the local VM directory. The VM local dir is in the form:
     *  $SYSTEM_DS_BASE_PATH/$VM_ID. Temporary stores VM disks.
     *    @return the system directory for the VM
     */
    string get_system_dir() const;

    // ------------------------------------------------------------------------
    // History
    // ------------------------------------------------------------------------
    /**
     *  Adds a new history record an writes it in the database.
     */
    void add_history(
        int     hid,
        const string& hostname,
        const string& vmm_mad,
        const string& vnm_mad,
        const string& tm_mad,
        const string& ds_location,
        int           ds_id);

    /**
     *  Duplicates the last history record. Only the host related fields are
     *  affected (i.e. no counter is copied nor initialized).
     *    @param reason explaining the new addition.
     */
    void cp_history();

    /**
     *  Duplicates the previous history record. Only the host related fields are
     *  affected (i.e. no counter is copied nor initialized).
     *    @param reason explaining the new addition.
     */
    void cp_previous_history();

    /**
     *  Checks if the VM has a valid history record. This function
     *  MUST be called before using any history related function.
     *    @return true if the VM has a record
     */
    bool hasHistory() const
    {
        return (history!=0);
    };

    /**
     *  Checks if the VM has a valid previous history record. This function
     *  MUST be called before using any previous_history related function.
     *    @return true if the VM has a previous record
     */
    bool hasPreviousHistory() const
    {
        return (previous_history!=0);
    };

    /**
     *  Returns the VMM driver name for the current host. The hasHistory()
     *  function MUST be called before this one.
     *    @return the VMM mad name
     */
    const string & get_vmm_mad() const
    {
        return history->vmm_mad_name;
    };

    /**
     *  Returns the VMM driver name for the previous host. The hasPreviousHistory()
     *  function MUST be called before this one.
     *    @return the VMM mad name
     */
    const string & get_previous_vmm_mad() const
    {
        return previous_history->vmm_mad_name;
    };

    /**
     *  Returns the VNM driver name for the current host. The hasHistory()
     *  function MUST be called before this one.
     *    @return the VNM mad name
     */
    const string & get_vnm_mad() const
    {
        return history->vnm_mad_name;
    };

    /**
     *  Returns the VNM driver name for the previous host. The hasPreviousHistory()
     *  function MUST be called before this one.
     *    @return the VNM mad name
     */
    const string & get_previous_vnm_mad() const
    {
        return previous_history->vnm_mad_name;
    };


    /**
     *  Returns the datastore ID of the system DS for the host. The hasHistory()
     *  function MUST be called before this one.
     *    @return the ds id
     */
    string get_ds_id() const
    {
        ostringstream oss;

        oss << history->ds_id;

        return oss.str();
    };

    /**
     *  Returns the datastore ID of the system DS for the previous host.
     *  The hasPreviousHistory() function MUST be called before this one.
     *    @return the TM mad name
     */
    string get_previous_ds_id() const
    {
        ostringstream oss;

        oss << previous_history->ds_id;

        return oss.str();
    };

    /**
     *  Returns the TM driver name for the current host. The hasHistory()
     *  function MUST be called before this one.
     *    @return the TM mad name
     */
    const string & get_tm_mad() const
    {
        return history->tm_mad_name;
    };

    /**
     *  Returns the TM driver name for the previous host. The
     *  hasPreviousHistory() function MUST be called before this one.
     *    @return the TM mad name
     */
    const string & get_previous_tm_mad() const
    {
        return previous_history->tm_mad_name;
    };

    /**
     *  Returns the transfer filename. The transfer file is in the form:
     *          $ONE_LOCATION/var/$VM_ID/transfer.$SEQ
     *  or, in case that OpenNebula is installed in root
     *          /var/lib/one/$VM_ID/transfer.$SEQ
     *  The hasHistory() function MUST be called before this one.
     *    @return the transfer filename
     */
    const string & get_transfer_file() const
    {
        return history->transfer_file;
    };

    /**
     *  Returns the deployment filename. The deployment file is in the form:
     *          $ONE_LOCATION/var/$VM_ID/deployment.$SEQ
     *  or, in case that OpenNebula is installed in root
     *          /var/lib/one/$VM_ID/deployment.$SEQ
     *  The hasHistory() function MUST be called before this one.
     *    @return the deployment filename
     */
    const string & get_deployment_file() const
    {
        return history->deployment_file;
    };

    /**
     *  Returns the context filename. The context file is in the form:
     *          $ONE_LOCATION/var/$VM_ID/context.sh
     *  or, in case that OpenNebula is installed in root
     *          /var/lib/one/$VM_ID/context.sh
     *  The hasHistory() function MUST be called before this one.
     *    @return the deployment filename
     */
    const string & get_context_file() const
    {
        return history->context_file;
    }

    /**
     *  Returns the remote deployment filename. The file is in the form:
     *          $VM_DIR/$VM_ID/images/deployment.$SEQ
     *  The hasHistory() function MUST be called before this one.
     *    @return the deployment filename
     */
    const string & get_remote_deployment_file() const
    {
        return history->rdeployment_file;
    };

    /**
     *  Returns the checkpoint filename for the current host. The checkpoint file
     *  is in the form:
     *          $VM_DIR/$VM_ID/images/checkpoint
     *  The hasHistory() function MUST be called before this one.
     *    @return the checkpoint filename
     */
    const string & get_checkpoint_file() const
    {
        return history->checkpoint_file;
    };

    /**
     *  Returns the hostname for the current host. The hasHistory()
     *  function MUST be called before this one.
     *    @return the hostname
     */
    const string & get_hostname() const
    {
        return history->hostname;
    };

    /**
     *  Returns the hostname for the previous host. The hasPreviousHistory()
     *  function MUST be called before this one.
     *    @return the hostname
     */
    const string & get_previous_hostname() const
    {
        return previous_history->hostname;
    };

    /**
     *  Returns the reason that originated the VM migration in the previous host
     *    @return the migration reason to leave this host
     */
    const History::MigrationReason get_previous_reason() const
    {
        return previous_history->reason;
    };

    /**
     *  Get host id where the VM is or is going to execute. The hasHistory()
     *  function MUST be called before this one.
     */
    int get_hid()
    {
        return history->hid;
    }

    /**
     *  Get host id where the VM was executing. The hasPreviousHistory()
     *  function MUST be called before this one.
     */
    int get_previous_hid()
    {
        return previous_history->hid;
    }

    /**
     *  Sets start time of a VM.
     *    @param _stime time when the VM started
     */
    void set_stime(time_t _stime)
    {
        history->stime=_stime;
    };

    /**
     *  Sets VM info (with monitoring info) in the history record
     */
    void set_vm_info()
    {
        to_xml_extended(history->vm_info, 0);
    };

    /**
     *  Sets VM info (with monitoring info) in the previous history record
     */
    void set_previous_vm_info()
    {
        to_xml_extended(previous_history->vm_info, 0);
    };

    /**
     *  Sets end time of a VM.
     *    @param _etime time when the VM finished
     */
    void set_etime(time_t _etime)
    {
        history->etime=_etime;
    };

    /**
     *  Sets end time of a VM in the previous Host.
     *    @param _etime time when the VM finished
     */
    void set_previous_etime(time_t _etime)
    {
        previous_history->etime=_etime;
    };

    /**
     *  Sets start time of VM prolog.
     *    @param _stime time when the prolog started
     */
    void set_prolog_stime(time_t _stime)
    {
        history->prolog_stime=_stime;
    };

    /**
     *  Sets end time of VM prolog.
     *    @param _etime time when the prolog finished
     */
    void set_prolog_etime(time_t _etime)
    {
        history->prolog_etime=_etime;
    };

    /**
     *  Sets start time of VM running state.
     *    @param _stime time when the running state started
     */
    void set_running_stime(time_t _stime)
    {
        history->running_stime=_stime;
    };

    /**
     *  Sets end time of VM running state.
     *    @param _etime time when the running state finished
     */
    void set_running_etime(time_t _etime)
    {
        history->running_etime=_etime;
    };

    /**
     *  Sets end time of VM running state in the previous host.
     *    @param _etime time when the running state finished
     */
    void set_previous_running_etime(time_t _etime)
    {
        previous_history->running_etime=_etime;
    };

    /**
     *  Sets start time of VM epilog.
     *    @param _stime time when the epilog started
     */
    void set_epilog_stime(time_t _stime)
    {
        history->epilog_stime=_stime;
    };

    /**
     *  Sets end time of VM epilog.
     *    @param _etime time when the epilog finished
     */
    void set_epilog_etime(time_t _etime)
    {
        history->epilog_etime=_etime;
    };

    /**
     *  Sets the reason that originated the VM migration
     *    @param _reason migration reason to leave this host
     */
    void set_reason(History::MigrationReason _reason)
    {
        history->reason=_reason;
    };

    /**
     *  Sets the reason that originated the VM migration in the previous host
     *    @param _reason migration reason to leave this host
     */
    void set_previous_reason(History::MigrationReason _reason)
    {
        previous_history->reason=_reason;
    };

    // ------------------------------------------------------------------------
    // Template
    // ------------------------------------------------------------------------
    /**
     *  Parse a string and substitute variables (e.g. $NAME) using the VM
     *  template values:
     *    @param attribute, the string to be parsed
     *    @param parsed, the resulting parsed string
     *    @return 0 on success.
     */
    int  parse_template_attribute(const string& attribute, string& parsed);

    /**
     *  Factory method for virtual machine templates
     */
    Template * get_new_template() const
    {
        return new VirtualMachineTemplate;
    }

    /**
     *  Returns a copy of the VirtualMachineTemplate
     *    @return A copy of the VirtualMachineTemplate
     */
    VirtualMachineTemplate * clone_template() const
    {
        return new VirtualMachineTemplate(
                *(static_cast<VirtualMachineTemplate *>(obj_template)));
    };


    // ------------------------------------------------------------------------
    // States
    // ------------------------------------------------------------------------
    /**
     *  Returns the VM state (Dispatch Manager)
     *    @return the VM state
     */
    VmState get_state() const
    {
        return state;
    };

    /**
     *  Returns the VM state (life-cycle Manager)
     *    @return the VM state
     */
    LcmState get_lcm_state() const
    {
        return lcm_state;
    };

    /**
     *  Sets VM state
     *    @param s state
     */
    void set_state(VmState s)
    {
        state = s;
    };

    /**
     *  Sets VM LCM state
     *    @param s state
     */
    void set_state(LcmState s)
    {
        lcm_state = s;
    };

    /**
     *  Sets the re-scheduling flag
     *    @param set or unset the re-schedule flag
     */
    void set_resched(bool do_sched)
    {
        if ( do_sched == true )
        {
            resched = 1;
        }
        else
        {
            resched = 0;
        }
    };

    // ------------------------------------------------------------------------
    // Timers
    // ------------------------------------------------------------------------
    /**
     *  Gets time from last information polling.
     *    @return time of last poll (epoch) or 0 if never polled
     */
    time_t get_last_poll() const
    {
        return last_poll;
    };

    /**
     *  Sets time of last information polling.
     *    @param poll time in epoch, normally time(0)
     */
    void set_last_poll(time_t poll)
    {
        last_poll = poll;
    };

    /**
     *  Get the VM physical requirements for the host.
     *    @param cpu
     *    @param memory
     *    @param disk
     */
    void get_requirements (int& cpu, int& memory, int& disk);

    // ------------------------------------------------------------------------
    // Network Leases & Disk Images
    // ------------------------------------------------------------------------
    /**
     *  Get all network leases for this Virtual Machine
     *  @return 0 if success
     */
    int get_network_leases(string &error_str);

    /**
     *  Releases all network leases taken by this Virtual Machine
     */
    void release_network_leases();

    /**
     *  Get all disk images for this Virtual Machine
     *  @param error_str Returns the error reason, if any
     *  @return 0 if success
     */
    int get_disk_images(string &error_str);

    /**
     *  Releases all disk images taken by this Virtual Machine
     */
    void release_disk_images();

    // ------------------------------------------------------------------------
    // Context related functions
    // ------------------------------------------------------------------------
    /**
     *  Writes the context file for this VM, and gets the paths to be included
     *  in the context block device (CBD)
     *    @param  files space separated list of paths to be included in the CBD
     *    @return 0 if success
     */
    int  generate_context(string &files);

    // ------------------------------------------------------------------------
    // Datastore related functions
    // ------------------------------------------------------------------------
    /**
     *  Set the SAVE_AS attribute for the "disk_id"th disk.
     *    @param  disk_id Index of the disk to save
     *    @param  source to save the disk (SAVE_AS_SOURCE)
     *    @param  img_id ID of the image this disk will be saved to (SAVE_AS).
     *    @return 0 if success
     */
    int save_disk(const string& disk_id,
                  const string& source,
                  int img_id);

    /**
     * Get the original image id of the disk. It also checks that the disk can
     * be saved_as.
     *    @param  disk_id Index of the disk to save
     *    @param  error_str describes the error
     *    @return -1 if failure
     */
    int get_image_from_disk(int disk_id, string& error_str);

    // ------------------------------------------------------------------------
    // Authorization related functions
    // ------------------------------------------------------------------------
    /**
     *  Sets an authorization request for a VirtualMachine template based on
     *  the images and networks used
     *    @param  uid for template owner
     *    @param  ar the AuthRequest object
     *    @param  tmpl the virtual machine template
     */
    static void set_auth_request(int uid,
                                 AuthRequest& ar,
                                 VirtualMachineTemplate *tmpl);

    // ------------------------------------------------------------------------
    // Hotplug related functions
    // ------------------------------------------------------------------------

    /**
     *  Collects information about VM DISKS
     *    @param num_disks of the VM
     *    @param used_targets by the DISKS of the VM
     */
    void get_disk_info(int& num_disks, set<string>& used_targets);

    /**
     * Generate a DISK attributed to be attached to the VM.
     *   @param tmpl Template containing a single DISK vector attribute.
     *   @param used_targets targets in use by current DISKS
     *   @param num_disks of the VM
     *   @param uid of the VM owner
     *   @param image_id returns the id of the aquired image
     *   @param error_str describes the error
     *
     *   @return a new vectorattribute with the DISK (should be freed if not
     *   added to the template), 0 in case of error;
     */
    static VectorAttribute * set_up_attach_disk(
                            VirtualMachineTemplate * tmpl,
                            set<string>&             used_targets,
                            int                      num_disks,
                            int                      uid,
                            int&                     image_id,
                            string&                  error_str);
    /**
     * Returns the disk that is waiting for an attachment action
     *
     * @return the disk waiting for an attachment action, or 0
     */
    VectorAttribute* get_attach_disk();

    /**
     * Cleans the ATTACH = YES attribute from the disks
     */
    void clear_attach_disk();

    /**
     * Deletes the DISK that was in the process of being attached
     *
     * @return the DISK or 0 if no disk was deleted
     */
    VectorAttribute * delete_attach_disk();

    /**
     *  Adds a new disk to the virtual machine template. The disk should be
     *  generated by the build_attach_disk
     *    @param new_disk must be allocated in the heap
     */
    void set_attach_disk(VectorAttribute * new_disk)
    {
        new_disk->replace("ATTACH", "YES");

        obj_template->set(new_disk);
    }

    /**
     *  Sets the attach attribute to the given disk
     *    @param disk_id of the DISK
     *    @return 0 if the disk_id was found -1 otherwise
     */
    int set_attach_disk(int disk_id);

    /**
     * Cleans the ATTACH = YES attribute from the disks
     *
     * @return 0 on success, -1 otherwise
     */
    int detach_success();

    /**
     * Cleans the ATTACH = YES attribute from the disks
     *
     * @return 0 on success, -1 otherwise
     */
    int detach_failure();

private:

    // -------------------------------------------------------------------------
    // Friends
    // -------------------------------------------------------------------------
    friend class VirtualMachinePool;

    // *************************************************************************
    // Virtual Machine Attributes
    // *************************************************************************

    // -------------------------------------------------------------------------
    // VM Scheduling & Managing Information
    // -------------------------------------------------------------------------
    /**
     *  Last time (in epoch) that the VM was polled to get its status
     */
    time_t      last_poll;

    // -------------------------------------------------------------------------
    // Virtual Machine Description
    // -------------------------------------------------------------------------
    /**
     *  The state of the virtual machine.
     */
    VmState     state;

    /**
     *  The state of the virtual machine (in the Life-cycle Manager).
     */
    LcmState    lcm_state;

    /**
     *  Marks the VM as to be re-scheduled
     */
    int         resched;

    /**
     *  Start time, the VM enter the nebula system (in epoch)
     */
    time_t      stime;

    /**
     *  Exit time, the VM leave the nebula system (in epoch)
     */
    time_t      etime;

    /**
     *  Deployment specific identification string, as returned by the VM driver
     */
    string      deploy_id;

    /**
     *  Memory in Kilobytes used by the VM
     */
    int         memory;

    /**
     *  CPU usage (percent)
     */
    int         cpu;

    /**
     *  Network usage, transmitted bytes
     */
    int         net_tx;

    /**
     *  Network usage, received bytes
     */
    int         net_rx;

    /**
     *  History record, for the current host
     */
    History *   history;

    /**
     *  History record, for the previous host
     */
    History *   previous_history;

    /**
     *  Complete set of history records for the VM
     */
    vector<History *> history_records;

    // -------------------------------------------------------------------------
    // Logging & Dirs
    // -------------------------------------------------------------------------

    /**
     *  Log class for the virtual machine, it writes log messages in
     *          $ONE_LOCATION/var/$VID/vm.log
     *  or, in case that OpenNebula is installed in root
     *          /var/log/one/$VM_ID.log
     */
    FileLog * _log;

    // *************************************************************************
    // DataBase implementation (Private)
    // *************************************************************************

    /**
     *  Bootstraps the database table(s) associated to the VirtualMachine
     *    @return 0 on success
     */
    static int bootstrap(SqlDB * db)
    {
        int rc;

        ostringstream oss_vm(VirtualMachine::db_bootstrap);
        ostringstream oss_monit(VirtualMachine::monit_db_bootstrap);
        ostringstream oss_hist(History::db_bootstrap);

        rc =  db->exec(oss_vm);
        rc += db->exec(oss_monit);
        rc += db->exec(oss_hist);

        return rc;
    };

    /**
     *  Callback function to unmarshall a VirtualMachine object
     *  (VirtualMachine::select)
     *    @param num the number of columns read from the DB
     *    @param names the column names
     *    @param vaues the column values
     *    @return 0 on success
     */
    int select_cb(void *nil, int num, char **names, char ** values);

    /**
     *  Execute an INSERT or REPLACE Sql query.
     *    @param db The SQL DB
     *    @param replace Execute an INSERT or a REPLACE
     *    @param error_str Returns the error reason, if any
     *    @return 0 one success
     */
    int insert_replace(SqlDB *db, bool replace, string& error_str);

    /**
     *  Updates the VM history record
     *    @param db pointer to the db
     *    @return 0 on success
     */
    int update_history(SqlDB * db)
    {
        if ( history != 0 )
        {
            return history->update(db);
        }
        else
            return -1;
    };

    /**
     *  Updates the previous history record
     *    @param db pointer to the db
     *    @return 0 on success
     */
    int update_previous_history(SqlDB * db)
    {
        if ( previous_history != 0 )
        {
            return previous_history->update(db);
        }
        else
            return -1;
    };

    /**
     * Inserts the last monitoring, and deletes old monitoring entries.
     *
     * @param db pointer to the db
     * @return 0 on success
     */
    int update_monitoring(SqlDB * db);

    // -------------------------------------------------------------------------
    // Attribute Parser
    // -------------------------------------------------------------------------

    /**
     * Mutex to perform just one attribute parse at a time
     */
    static pthread_mutex_t lex_mutex;

    /**
     *  Parse the "CONTEXT" attribute of the template by substituting
     *  $VARIABLE, $VARIABLE[ATTR] and $VARIABLE[ATTR, ATTR = VALUE]
     *    @param error_str Returns the error reason, if any
     *    @return 0 on success
     */
    int parse_context(string& error_str);

    /**
     *  Parse the "REQUIREMENTS" attribute of the template by substituting
     *  $VARIABLE, $VARIABLE[ATTR] and $VARIABLE[ATTR, ATTR = VALUE]
     *    @param error_str Returns the error reason, if any
     *    @return 0 on success
     */
    int parse_requirements(string& error_str);

    /**
     * Adds automatic placement requirements: Datastore and Cluster
     *
     *    @param error_str Returns the error reason, if any
     *    @return 0 on success
     */
    int automatic_requirements(string& error_str);

    /**
     *  Parse the "GRAPHICS" attribute and generates a default PORT if not
     *  defined
     */
    void parse_graphics();

    /**
     *  Function that renders the VM in XML format optinally including
     *  extended information (all history records)
     *  @param xml the resulting XML string
     *  @param n_history Number of history records to include:
     *      0: none
     *      1: the last one
     *      2: all
     *  @return a reference to the generated string
     */
    string& to_xml_extended(string& xml, int n_history) const;

protected:

    //**************************************************************************
    // Constructor
    //**************************************************************************

    VirtualMachine(int id,
                   int uid,
                   int gid,
                   const string& uname,
                   const string& gname,
                   VirtualMachineTemplate * _vm_template);

    virtual ~VirtualMachine();

    // *************************************************************************
    // DataBase implementation
    // *************************************************************************

    static const char * table;

    static const char * db_names;

    static const char * db_bootstrap;

    static const char * monit_table;

    static const char * monit_db_names;

    static const char * monit_db_bootstrap;

    /**
     *  Reads the Virtual Machine (identified with its OID) from the database.
     *    @param db pointer to the db
     *    @return 0 on success
     */
    int select(SqlDB * db);

    /**
     *  Writes the Virtual Machine and its associated template in the database.
     *    @param db pointer to the db
     *    @return 0 on success
     */
    int insert(SqlDB * db, string& error_str);

    /**
     *  Writes/updates the Virtual Machine data fields in the database.
     *    @param db pointer to the db
     *    @return 0 on success
     */
    int update(SqlDB * db)
    {
        string error_str;
        return insert_replace(db, true, error_str);
    }

    /**
     * Deletes a VM from the database and all its associated information
     *   @param db pointer to the db
     *   @return -1
     */
    int drop(SqlDB * db)
    {
        NebulaLog::log("ONE",Log::ERROR, "VM Drop not implemented!");
        return -1;
    }
};

#endif /*VIRTUAL_MACHINE_H_*/