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Custom ("user") session handler using database (ie MySQL) instead of "files" #1279

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robocoder opened this Issue · 25 comments

3 participants

Anthon Pang Matthieu Aubry Anonymous Piwik user
Anthon Pang
Collaborator

Use Zend_Session_SaveHandler_DbTable.

see: http://zendframework.com/manual/1.10/en/zend.session.savehandler.dbtable.html

For Installation, we would store session information in a signed cookie, and delete the cookie when the installation is complete.

Pros:

  • reduce number of inodes, eliminating tmp/sessions
  • move the session handling logic out of ./index.php (to FrontController init?)
  • potentially simplifies the session handling logic
  • no longer second guessing security of user's configuration
  • works with load balanced web servers that don't share session files
  • works when user doesn't have write access to shared session folder (technically, considered to be an improperly configured web server)

Cons:

  • cookies subject to 4K limit (only applies to installer and custom dashboard layout for anonymous)
  • slower (especially with garbage collection)
  • would have to rework LanguagesManager/API.php's use of Zend_Session_Namespace in getLanguageForSession() and setLanguageForSession()

Note: Piwik still requires write access to ./tmp (i.e., templates_c, cache/tracker, latest).

While you're at it, add a systemCheck for the 'session' extension, in case php was compiled with --disable-session.

And look into handling disabled ini_set() -- used by Zend_Session.

Oh, and make sure we handle the case where session.use_cookies = 0 (ref: http://forum.piwik.org/index.php?showtopic=11381)

Anthon Pang
Collaborator

(In [2121]) refs #1279 - refactor session initialization code out of index.php

Anthon Pang
Collaborator

(In [2122]) refs #1279 - fallback to system default

Anthon Pang
Collaborator

(In [2280]) refs #1279 - test that session.save_path is also readable, otherwise
session file cleanup may fail, e.g.,

Zend_Session_Exception: Zend_Session::start() - /PATH/libs/Zend/Session.php(Line:480): Error #8 session_start(): ps_files_cleanup_dir: opendir(/var/lib/php5) failed: Permission denied

Anonymous Piwik user

I've confirmed on my fresh install that this patch fixes the exception output. Thank you.

Anthon Pang
Collaborator

Reprioritizing. On the demo server, I noticed we have 285000+ session files in piwik/tmp/sessions -- most being empty files. That's a lot of inodes, and could be a problem for some users with shared hosting accounts.

Anthon Pang
Collaborator

Nice to have:

  • eliminate dependency on libs/Zend/Session and the session extension. (No more workarounds.)
Anthon Pang
Collaborator

(In [3514]) refs #1279, refs #1910 - language preference for anonymous users is now stored in a cookie; we can't use this workaround for the dashboard layout because of cookie size limits

Anthon Pang
Collaborator

(In [3515]) refs #1279, refs #1910 - fix typo

Anthon Pang
Collaborator

Other suggestions:

  • not every request requires session data; propose not calling Zend_Session::start() in Piwik_Session; ie lazy init
  • Dashboard: set expiry for the anonymous user's non-persistent dashboard layout, eg $ns->setExpirationSeconds(1800);
Anthon Pang
Collaborator

Using a DB table should avoid the potential race condition experienced with locked session files (see #2296).

Anthon Pang
Collaborator

(In [4761]) refs #1279 - add session table

Anthon Pang
Collaborator

(In [4762]) refs #1279 - add update script and bump version

Anthon Pang
Collaborator

(In [4763]) refs #1279 - fix typo

Anthon Pang
Collaborator

(In [4764]) refs #1279 - typo

Anthon Pang
Collaborator

(In [4765]) fixes #1279

Anthon Pang
Collaborator

CI shows the update fails:

[22-May-2011 19:05:51] PHP Fatal error:  Uncaught exception 'PDOException' with message 'SQLSTATE[42S02]: Base table or view not found: 1146 Table 'piwik_qa.canoo_session' doesn't exist' in /home/www/data/root/jenkins.private/jobs/Piwik/workspace/build/libs/Zend/Db/Statement/Pdo.php:228
Stack trace:
#0 /home/www/data/root/jenkins.private/jobs/Piwik/workspace/build/libs/Zend/Db/Statement/Pdo.php(228): PDOStatement->execute(Array)
#1 /home/www/data/root/jenkins.private/jobs/Piwik/workspace/build/libs/Zend/Db/Statement.php(300): Zend_Db_Statement_Pdo->_execute(Array)
#2 /home/www/data/root/jenkins.private/jobs/Piwik/workspace/build/libs/Zend/Db/Adapter/Abstract.php(479): Zend_Db_Statement->execute(Array)
#3 /home/www/data/root/jenkins.private/jobs/Piwik/workspace/build/libs/Zend/Db/Adapter/Pdo/Abstract.php(238): Zend_Db_Adapter_Abstract->query('DESCRIBE `canoo...', Array)
#4 /home/www/data/root/jenkins.private/jobs/Piwik/workspace/build/core/Db/Adapter/Pdo/Mysql.php(211): Zend_Db_Adapter_Pdo_Abstract->query('DESCRIBE `canoo...', Array)
#5 /home/www/dat in /home/www/data/root/jenkins.private/jobs/Piwik/workspace/build/libs/Zend/Db/Statement/Pdo.php on line 234
Matthieu Aubry
Owner

Interesting!!
Questions:

  • Why move Piwik_Session::start to frontController instead of previous location in index.php?
  • Session purge: what is the default timeout after which sessions will be deleted from the DB to ensure the table doesn't grow out of control?

This is great feature because it will ensure that load balanced Piwik Reporting UI will work fine without requiring to "stick" same users to the same backend server!

Matthieu Aubry
Owner

(In [4766]) Refs #1279 Important to copy paste the table definitions in update files: this ensures that subsequent "ALTER" on these tables will work fine (otherwise, if we change table definition in myisam file in 1.8, and users upgrade from 1.4 to 1.9, the 1.5 upgrade will install the newest version of 1.8 tables which will then fail the 1.8 ALTER table on this table..)

Anthon Pang
Collaborator

I had to move the Piwik_Session::start() to front controller because the save handler needs the $db handle.

Purge: the frequency of cleanup and lifetime is defined in php.ini (e.g., session.gc_maxlifetime)

re: r4767 Good point. I'll go back and fix those cases in 0.2.10, 0.2.13, and 0.2.27, so we don't set a bad example. ;)

I'm just installing 1.0 now, and going through the auto-update to find out what's causing the problem in comment:30.

Anthon Pang
Collaborator

(In [4768]) refs #1279

Matthieu Aubry
Owner

on the update screen I see an error at the bottom, not important but if easy to hide would be nice :) (see attached file)

Matthieu Aubry
Owner

Attachment:
Piwik Update.png

Anthon Pang
Collaborator

(In [4772]) refs #1279

Anthon Pang
Collaborator

Yes, I saw the exception too. This is fixed in r4772. I'm just waiting for confirmation from Jenkins before I close this ticket.

Anthon Pang
Collaborator

Thank you, Jenkins.

Anthon Pang robocoder added this to the 1.5 - Piwik 1.5 milestone
Anthon Pang robocoder self-assigned this
This issue was closed.
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