122483 - RFE: Priority Cache

Status: RESOLVED WONTFIX

(Core :: Networking: Cache, enhancement, P2)

Description

[Dave Barrowman]

The Priority Cache feature is essentially a second disk cache.  It lives
alongside the existing disk cache.  The Priority Cache has two key features:

    * Base URLs: Associated with the Priority Cache are several "base URLs". 
Data passed to the client which falls under one of these base URLs will be
cached in the priority cache, rather than the regular disk cache.  

    * Prepopulation: In order to maximize the performance  during a user's first
visit to a web service, the Priority Cache will be prepopulated, so that much of
the required data is already present on the client side.

Services can deliver content to the Priority Cache with the client installer,
but as this content becomes stale, that content can be selectively refreshed,
just as in a the normal cache.  The advantage the Priority Cache offers over the
exisitng cache is that since membership is limited, there is a reduced chance of
content being evicted to make room for other content.


Populating and Configuring the Priority Cache
Mechanisms must be developed which allow simple configuration of the Priority
Cache, for new and exisitng profiles, at client install time, profile creation
time, and subsequently.

    * Must be able to prepopulate Priority Cache at profile creation time
    * Must be able to modify the list of Priority Cache base URLs at profile
creation time
    * Must be able to prepopulate Priority Cache of existing profile at new
client install time
    * Must be able to modify the list of Priority Cache base URLs of existing
profile at first launch of the profile following a new client install
    * Must be able to modify the list of Priority Cache base URLs via XPI to
enable changes to clients in the field; users should be notified of this and
hacve the option to block the request.

Associated with each Base URL is a size limit; this is the amount of cache space
available to that Base URL.  If content from a Base URL exceeds its size, other
content from that Base URL will be evicted from the Priority Cache.


Other features:
- user should be able to turn the Priority Cache off (and back on); if disabled,
the regular cache would be used
- the scheme for comparing the contents of the Priority Cache to the content on
the network should be the same as that chosen by the user for the regular disk
cache.


It should be a requirement that the existence of the Priority Cache should have
no measurable detrimental impact on the performance of content which does not
take advantage of it.  (I.e., do no harm.)

Comment 1

[Martin Poirier]

is this bug related to bug 81724 ?, which is about a 3rd level cache. Wouldn't
that be covered in that bug ?.

Comment 2

[gordon]

No. This is a completely different feature.

Comment 3

[gordon]

This feature will not land (or likely be defined) by Tuesday night.  Moving to 1.0.

Comment 4

[gordon]

After further discussion with Dave Barrowman, darin, gagan, and others, we've
determined that a "priority cache" would not be of great benefit to the current
cache clients.

Since this is no longer a requirement, I'm marking this bug WONTFIX.