[Kimchi-devel] [PATCH] [Wok 1/3] Issue #158: Move AsyncTask information to memory

[Aline Manera]

On 08/24/2016 04:36 PM, pvital at linux.vnet.ibm.com wrote:
> From: Paulo Vital <pvital at linux.vnet.ibm.com>
>
> This patch moves all infrastructure of AsyncTask to store and read
> the tasks' information (id, status, messages and target_uri) from
> objectstore to memory, by the implementation of a dictionary of
> AsyncTasks objects.
>
> It also removes the tasks cleanup process from objectstore.
>
> Signed-off-by: Paulo Vital <pvital at linux.vnet.ibm.com>
> ---
>   src/wok/asynctask.py   | 25 ++++---------------------
>   src/wok/i18n.py        |  2 --
>   src/wok/objectstore.py |  6 ------
>   src/wok/utils.py       | 31 ++++++++++++++++++++++++-------
>   4 files changed, 28 insertions(+), 36 deletions(-)
>
> diff --git a/src/wok/asynctask.py b/src/wok/asynctask.py
> index fb614a2..2008c18 100644
> --- a/src/wok/asynctask.py
> +++ b/src/wok/asynctask.py
> @@ -21,24 +21,18 @@
>
>   import cherrypy
>   import threading
> +import time
>   import traceback
>
>
> -from wok.exception import OperationFailed
> -
> -
>   class AsyncTask(object):
> -    def __init__(self, id, target_uri, fn, objstore, opaque=None):
> -        if objstore is None:
> -            raise OperationFailed("WOKASYNC0001E")
> -
> +    def __init__(self, id, target_uri, fn, opaque=None):
>           self.id = str(id)
>           self.target_uri = target_uri
>           self.fn = fn
> -        self.objstore = objstore
>           self.status = 'running'
> -        self.message = 'OK'
> -        self._save_helper()

> +        self.message = 'Starting AsyncTask'

The 'message' is used on UI and the user is not aware about AsyncTask.
So my suggestion is to have a more generic message ("Processing 
started"/"Processing request") or keep it in blank.

> +        self.timestamp = time.time()
>           self._cp_request = cherrypy.serving.request
>           self.thread = threading.Thread(target=self._run_helper,
>                                          args=(opaque, self._status_cb))
> @@ -51,17 +45,6 @@ class AsyncTask(object):
>
>           if message.strip():
>               self.message = message
> -            self._save_helper()
> -
> -    def _save_helper(self):
> -        obj = {}
> -        for attr in ('id', 'target_uri', 'message', 'status'):
> -            obj[attr] = getattr(self, attr)
> -        try:
> -            with self.objstore as session:
> -                session.store('task', self.id, obj)
> -        except Exception as e:
> -            raise OperationFailed('WOKASYNC0002E', {'err': e.message})
>
>       def _run_helper(self, opaque, cb):
>           cherrypy.serving.request = self._cp_request
> diff --git a/src/wok/i18n.py b/src/wok/i18n.py
> index 33107ee..1a0446b 100644
> --- a/src/wok/i18n.py
> +++ b/src/wok/i18n.py
> @@ -33,8 +33,6 @@ messages = {
>       "WOKAPI0008E": _("Parameters does not match requirement in schema: %(err)s"),
>       "WOKAPI0009E": _("You don't have permission to perform this operation."),
>
> -    "WOKASYNC0001E": _("Datastore is not initiated in the model object."),
> -    "WOKASYNC0002E": _("Unable to start task due error: %(err)s"),
>       "WOKASYNC0003E": _("Timeout of %(seconds)s seconds expired while running task '%(task)s."),
>
>       "WOKAUTH0001E": _("Authentication failed for user '%(username)s'. [Error code: %(code)s]"),
> diff --git a/src/wok/objectstore.py b/src/wok/objectstore.py
> index 59354f3..817f60c 100644
> --- a/src/wok/objectstore.py
> +++ b/src/wok/objectstore.py
> @@ -107,8 +107,6 @@ class ObjectStore(object):
>           c.execute('''SELECT * FROM sqlite_master WHERE type='table' AND
>                        tbl_name='objects'; ''')
>           res = c.fetchall()
> -        # Because the tasks are regarded as temporary resource, the task states
> -        # are purged every time the daemon startup
>           if len(res) == 0:
>               c.execute('''CREATE TABLE objects
>                         (id TEXT, type TEXT, json TEXT, version TEXT,
> @@ -116,10 +114,6 @@ class ObjectStore(object):
>               conn.commit()
>               return
>
> -        # Clear out expired objects from a previous session
> -        c.execute('''DELETE FROM objects WHERE type = 'task'; ''')
> -        conn.commit()
> -
>       def _get_conn(self):
>           ident = threading.currentThread().ident
>           try:
> diff --git a/src/wok/utils.py b/src/wok/utils.py
> index 4c132a1..8c13c70 100644
> --- a/src/wok/utils.py
> +++ b/src/wok/utils.py
> @@ -31,6 +31,7 @@ import re
>   import sqlite3
>   import subprocess
>   import sys
> +import time
>   import traceback
>   import xml.etree.ElementTree as ET
>
> @@ -47,6 +48,7 @@ from wok.stringutils import decode_value
>
>   wok_log = cherrypy.log.error_log
>   task_id = 0
> +tasks_queue = {}
>
>
>   def get_next_task_id():
> @@ -55,17 +57,32 @@ def get_next_task_id():
>       return task_id
>
>
> -def get_task_id():
> -    global task_id
> -    return task_id
> -
> -
>   def add_task(target_uri, fn, objstore, opaque=None):
> -    id = get_next_task_id()
> -    AsyncTask(id, target_uri, fn, objstore, opaque)
> +    # let's prevent memory leak
> +    clean_old_tasks()
> +    id = str(get_next_task_id())
> +    tasks_queue[id] = AsyncTask(id, target_uri, fn, opaque)
>       return id
>
>
> +def remove_task(id):
> +    try:
> +        del tasks_queue[id]
> +    except KeyError:
> +        cherrypy.log.error_log.error("There's no task_id %s in tasks_queue."
> +                                     " Nothing changed." % id)
> +
> +

> +def clean_old_tasks():
> +    """
> +    Check for all tasks in tasks_queue and remove those if timestamp < than
> +    10 minutes ago.
> +    """
> +    for id, task in tasks_queue.items():
> +        if task.timestamp < (time.time()-600):
> +            remove_task(id)
> +
> +

I like that idea to remove old entries but I think 10 minutes is not a 
good number.
Some tasks take long to finish, ie, in 10 minutes they may be running. 
Even if you check the Task status to be finished you may clean up an 
entry that would be used to update the UI.

Said that, I'd say to increase that value to 12h/24h (yeah, a big amount 
of time) to be safer.

What do you think about it?

>   def is_digit(value):
>       if isinstance(value, int):
>           return True