1 |
On Thu, 26 Nov 2009 08:33:03 -0800 |
2 |
Brian Harring <ferringb@×××××.com> wrote: |
3 |
> > "Provide proof that all existing and future caches that would rely |
4 |
> > upon this validation mechanism are functions purely and exclusively |
5 |
> > dependent upon the VDB content, and I shall be happy to make the |
6 |
> > change." |
7 |
> |
8 |
> First I've seen this question actually or at least this particular |
9 |
> interesting phrasing. That said, "no" comes to mind, since the |
10 |
> requirement you set is daft. |
11 |
|
12 |
It's clipboarded from the bug. |
13 |
|
14 |
> The timestamp updating is for whenever the vdb content (addition of a |
15 |
> pkg, pkgmoves being applied, removal of a pkg, modification of |
16 |
> metadata, etc) is changed. That's all that timestamp is for. Vdb |
17 |
> content. |
18 |
> |
19 |
> In light of what the timestamp is, your demand for proof is pretty |
20 |
> off the mark. If you still consider it to be a valid question, |
21 |
> please rephrase it and clarify why exactly proof must be provided |
22 |
> that people reading that timestamp (which is for vdb content only) |
23 |
> will only be using that timestamp for vdb content. |
24 |
> |
25 |
> Your request is akin to demanding proof that a hammer only be used as |
26 |
> a hammer. It's a fricking hammer- it has one use, one way of being |
27 |
> used. If someone goes out of their way to be an idiot, they're an |
28 |
> idiot, not the specs problem. |
29 |
> |
30 |
> Seriously, if you're actually worrying about some specific usage |
31 |
> case, state it- on the face of it, your request for proof right now |
32 |
> makes zero sense. Kindly provide a scenario or elucidation. |
33 |
|
34 |
You're asking for a cache validation mechanism that's based not upon |
35 |
what it logically invalidates, but upon something you assume to be |
36 |
equivalent. Specifically, you assume that "VDB has changed" and "the |
37 |
installed packages have changed" are exactly the same thing, and you're |
38 |
wanting to build a cache based upon that highly questionable |
39 |
assumption. There are at least two logically different sets of |
40 |
'changes' that might apply to VDB (metadata changes, and package |
41 |
version changes), and you're attempting to confuse the two, along with |
42 |
any others that people come up with later on. |
43 |
|
44 |
What's wrong with, instead, having cache files for "something has |
45 |
changed", "the set of installed packages has potentially changed", "the |
46 |
metadata for installed packages has potentially changed" and "the set of |
47 |
installable packages has potentially changed"? That way you can write |
48 |
your cache checks to depend explicitly upon the thing upon which they |
49 |
depend (along with a global catch-all to make future new validation |
50 |
mechanisms easier), not upon something you assume is equivalent but |
51 |
probably isn't. |
52 |
|
53 |
-- |
54 |
Ciaran McCreesh |