[Qemu-devel] Re: [PATCH 18/28] migration: convert current_migration from pointer to struct

[Juan Quintela]

Anthony Liguori <address@hidden> wrote:
> On 02/23/2011 03:47 PM, Juan Quintela wrote:
>> This cleans up a lot the code as we don't have to check anymore if
>> the variable is NULL or not.
>>
>> Signed-off-by: Juan Quintela<address@hidden>
>>    
>
> Yeah, but now you have to check for MIG_STATE_NONE.  I don't think
> this is an improvement.

We can:
a- remove max_throttle global (now we always have this variable to have
   fields in).
b- transitioning to ACTIVE state is a normal transition (if you look,
   you will see that it is the only case where  we call the migration
   notifier without an explicit change in state.
c- We remove all the cases of:
   if (current_migration)
      foo(current_migration)

Notice that we don't check against MIG_STATE_NONE in the whole patch.

Later, Juan.

> Regards,
>
> Anthony Liguori
>
>> ---
>>   migration.c |  121 
>> ++++++++++++++++++++++++-----------------------------------
>>   1 files changed, 49 insertions(+), 72 deletions(-)
>>
>> diff --git a/migration.c b/migration.c
>> index 593adee..f8c6d09 100644
>> --- a/migration.c
>> +++ b/migration.c
>> @@ -34,7 +34,9 @@
>>   /* Migration speed throttling */
>>   static int64_t max_throttle = (32<<  20);
>>
>> -static MigrationState *current_migration;
>> +static MigrationState current_migration = {
>> +    .state = MIG_STATE_NONE,
>> +};
>>
>>   static NotifierList migration_state_notifiers =
>>       NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
>> @@ -135,37 +137,34 @@ void do_info_migrate(Monitor *mon, QObject **ret_data)
>>   {
>>       QDict *qdict;
>>
>> -    if (current_migration) {
>> -
>> -        switch (current_migration->state) {
>> -        case MIG_STATE_NONE:
>> -            /* no migration has happened ever */
>> -            break;
>> -        case MIG_STATE_ACTIVE:
>> -            qdict = qdict_new();
>> -            qdict_put(qdict, "status", qstring_from_str("active"));
>> -
>> -            migrate_put_status(qdict, "ram", ram_bytes_transferred(),
>> -                               ram_bytes_remaining(), ram_bytes_total());
>> -
>> -            if (blk_mig_active()) {
>> -                migrate_put_status(qdict, "disk", 
>> blk_mig_bytes_transferred(),
>> -                                   blk_mig_bytes_remaining(),
>> -                                   blk_mig_bytes_total());
>> -            }
>> -
>> -            *ret_data = QOBJECT(qdict);
>> -            break;
>> -        case MIG_STATE_COMPLETED:
>> -            *ret_data = qobject_from_jsonf("{ 'status': 'completed' }");
>> -            break;
>> -        case MIG_STATE_ERROR:
>> -            *ret_data = qobject_from_jsonf("{ 'status': 'failed' }");
>> -            break;
>> -        case MIG_STATE_CANCELLED:
>> -            *ret_data = qobject_from_jsonf("{ 'status': 'cancelled' }");
>> -            break;
>> +    switch (current_migration.state) {
>> +    case MIG_STATE_NONE:
>> +        /* no migration has happened ever */
>> +        break;
>> +    case MIG_STATE_ACTIVE:
>> +        qdict = qdict_new();
>> +        qdict_put(qdict, "status", qstring_from_str("active"));
>> +
>> +        migrate_put_status(qdict, "ram", ram_bytes_transferred(),
>> +                           ram_bytes_remaining(), ram_bytes_total());
>> +
>> +        if (blk_mig_active()) {
>> +            migrate_put_status(qdict, "disk", blk_mig_bytes_transferred(),
>> +                               blk_mig_bytes_remaining(),
>> +                               blk_mig_bytes_total());
>>           }
>> +
>> +        *ret_data = QOBJECT(qdict);
>> +        break;
>> +    case MIG_STATE_COMPLETED:
>> +        *ret_data = qobject_from_jsonf("{ 'status': 'completed' }");
>> +        break;
>> +    case MIG_STATE_ERROR:
>> +        *ret_data = qobject_from_jsonf("{ 'status': 'failed' }");
>> +        break;
>> +    case MIG_STATE_CANCELLED:
>> +        *ret_data = qobject_from_jsonf("{ 'status': 'cancelled' }");
>> +        break;
>>       }
>>   }
>>
>> @@ -344,11 +343,7 @@ void remove_migration_state_change_notifier(Notifier 
>> *notify)
>>
>>   int get_migration_state(void)
>>   {
>> -    if (current_migration) {
>> -        return current_migration->state;
>> -    } else {
>> -        return MIG_STATE_ERROR;
>> -    }
>> +    return current_migration.state;
>>   }
>>
>>   void migrate_fd_connect(MigrationState *s)
>> @@ -374,28 +369,22 @@ void migrate_fd_connect(MigrationState *s)
>>       migrate_fd_put_ready(s);
>>   }
>>
>> -static MigrationState *migrate_create_state(Monitor *mon,
>> -                                            int64_t bandwidth_limit,
>> -                                            int detach, int blk, int inc)
>> +static void migrate_init_state(Monitor *mon, int64_t bandwidth_limit,
>> +                               int detach, int blk, int inc)
>>   {
>> -    MigrationState *s = qemu_mallocz(sizeof(*s));
>> -
>> -    s->blk = blk;
>> -    s->shared = inc;
>> -    s->mon = NULL;
>> -    s->bandwidth_limit = bandwidth_limit;
>> -    s->state = MIG_STATE_NONE;
>> +    current_migration.blk = blk;
>> +    current_migration.shared = inc;
>> +    current_migration.mon = NULL;
>> +    current_migration.bandwidth_limit = bandwidth_limit;
>> +    current_migration.state = MIG_STATE_NONE;
>>
>>       if (!detach) {
>> -        migrate_fd_monitor_suspend(s, mon);
>> +        migrate_fd_monitor_suspend(&current_migration, mon);
>>       }
>> -
>> -    return s;
>>   }
>>
>>   int do_migrate(Monitor *mon, const QDict *qdict, QObject **ret_data)
>>   {
>> -    MigrationState *s = NULL;
>>       const char *p;
>>       int detach = qdict_get_try_bool(qdict, "detach", 0);
>>       int blk = qdict_get_try_bool(qdict, "blk", 0);
>> @@ -403,8 +392,7 @@ int do_migrate(Monitor *mon, const QDict *qdict, QObject 
>> **ret_data)
>>       const char *uri = qdict_get_str(qdict, "uri");
>>       int ret;
>>
>> -    if (current_migration&&
>> -        current_migration->state == MIG_STATE_ACTIVE) {
>> +    if (current_migration.state == MIG_STATE_ACTIVE) {
>>           monitor_printf(mon, "migration already in progress\n");
>>           return -1;
>>       }
>> @@ -413,43 +401,35 @@ int do_migrate(Monitor *mon, const QDict *qdict, 
>> QObject **ret_data)
>>           return -1;
>>       }
>>
>> -    s = migrate_create_state(mon, max_throttle, detach, blk, inc);
>> +    migrate_init_state(mon, max_throttle, detach, blk, inc);
>>
>>       if (strstart(uri, "tcp:",&p)) {
>> -        ret = tcp_start_outgoing_migration(s, p);
>> +        ret = tcp_start_outgoing_migration(&current_migration, p);
>>   #if !defined(WIN32)
>>       } else if (strstart(uri, "exec:",&p)) {
>> -        ret = exec_start_outgoing_migration(s, p);
>> +        ret = exec_start_outgoing_migration(&current_migration, p);
>>       } else if (strstart(uri, "unix:",&p)) {
>> -        ret = unix_start_outgoing_migration(s, p);
>> +        ret = unix_start_outgoing_migration(&current_migration, p);
>>       } else if (strstart(uri, "fd:",&p)) {
>> -        ret = fd_start_outgoing_migration(s, p);
>> +        ret = fd_start_outgoing_migration(&current_migration, p);
>>   #endif
>>       } else {
>>           monitor_printf(mon, "unknown migration protocol: %s\n", uri);
>> -        ret  = -EINVAL;
>> -        goto free_migrate_state;
>> +        return -EINVAL;
>>       }
>>
>>       if (ret<  0) {
>>           monitor_printf(mon, "migration failed\n");
>> -        goto free_migrate_state;
>> +        return ret;
>>       }
>>
>> -    qemu_free(current_migration);
>> -    current_migration = s;
>>       notifier_list_notify(&migration_state_notifiers);
>>       return 0;
>> -free_migrate_state:
>> -    qemu_free(s);
>> -    return -1;
>>   }
>>
>>   int do_migrate_cancel(Monitor *mon, const QDict *qdict, QObject **ret_data)
>>   {
>> -    if (current_migration) {
>> -        migrate_fd_cancel(current_migration);
>> -    }
>> +    migrate_fd_cancel(&current_migration);
>>       return 0;
>>   }
>>
>> @@ -463,10 +443,7 @@ int do_migrate_set_speed(Monitor *mon, const QDict 
>> *qdict, QObject **ret_data)
>>       }
>>       max_throttle = d;
>>
>> -    if (current_migration) {
>> -        qemu_file_set_rate_limit(current_migration->file, max_throttle);
>> -    }
>> -
>> +    qemu_file_set_rate_limit(current_migration.file, max_throttle);
>>       return 0;
>>   }
>>
>>