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PhabricatorFactsUpdateIterator.php
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Created
Sun, Aug 25, 12:14
Size
2 KB
Mime Type
text/x-php
Expires
Tue, Aug 27, 12:14 (1 d, 21 h)
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blob
Format
Raw Data
Handle
20166305
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rPH Phabricator
PhabricatorFactsUpdateIterator.php
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<?php
/*
* Copyright 2012 Facebook, Inc.
*
* 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.
*/
/**
* Iterate over objects by update time in a stable way. This iterator only works
* for "normal" Lisk objects: objects with an autoincrement ID and a
* dateModified column.
*/
final
class
PhabricatorFactsUpdateIterator
extends
PhutilBufferedIterator
{
private
$cursor
;
private
$object
;
private
$start
;
private
$ignoreUpdatesDuration
=
15
;
public
function
__construct
(
LiskDAO
$object
,
$start
=
null
)
{
if
(
$start
===
null
)
{
$start
=
'0:0'
;
}
$this
->
object
=
$object
;
$this
->
start
=
$start
;
}
protected
function
didRewind
()
{
$this
->
cursor
=
$this
->
start
;
}
protected
function
getCursorFromObject
(
$object
)
{
return
$object
->
getDateModified
().
':'
.
$object
->
getID
();
}
public
function
key
()
{
return
$this
->
getCursorFromObject
(
$this
->
current
());
}
protected
function
loadPage
()
{
list
(
$after_epoch
,
$after_id
)
=
explode
(
':'
,
$this
->
cursor
);
// NOTE: We ignore recent updates because once we process an update we'll
// never process rows behind it again. We need to read only rows which
// we're sure no new rows will be inserted behind. If we read a row that
// was updated on the current second, another update later on in this second
// could affect an object with a lower ID, and we'd skip that update. To
// avoid this, just ignore any rows which have been updated in the last few
// seconds. This also reduces the amount of work we need to do if an object
// is repeatedly updated; we will just look at the end state without
// processing the intermediate states. Finally, this gives us reasonable
// protections against clock skew between the machine the daemon is running
// on and any machines performing writes.
$page
=
$this
->
object
->
loadAllWhere
(
'((dateModified > %d) OR (dateModified = %d AND id > %d))
AND (dateModified < %d - %d)
ORDER BY dateModified ASC, id ASC LIMIT %d'
,
$after_epoch
,
$after_epoch
,
$after_id
,
time
(),
$this
->
ignoreUpdatesDuration
,
$this
->
getPageSize
());
if
(
$page
)
{
$this
->
cursor
=
$this
->
getCursorFromObject
(
end
(
$page
));
}
return
$page
;
}
}
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