V Tue, 14 May 2019 15:04:43 +0200
Ladislav Slezak <[email protected]> napsáno:
> Hi all,
>
> I'd like to discuss how to improve the pkg-bindings API in YaST, more
> specifically
> the Pkg.ResolvableProperties(name, kind, version) call.
>
> But if you find some other pkg-bindings API calls difficult to use just ping
> me,
> we can improve more calls.
>
>
> There are basically two problems with Pkg.ResolvableProperties() call:
>
> - You cannot use any input filters, you can only filter by name, kind or
> version.
> That's quite limited, for the other cases you need to get *all* objects and
> filter
> the returned list.
>
> - The result contains all possible attributes for each object, even those you
> do not
> need in most cases (like the package description and summary, installed
> size, RPM
> size, full RPM name, vendor, ...). That is wasting the memory space.
>
> If you call Pkg.ResolvableProperties("", :package, "") in Leap with the online
> repositories enabled you will get a huge detailed list with about 40.000 (!)
> packages. And that requires quite a lot of memory and might freeze the
> installer as
> reported in [1].
>
>
> A GraphQL Side Note
> -------------------
>
> I was interested in some existing generic solution for this problem. And I
> found a
> quite nice GraphQL project. It can not only describe the search query but also
> describe the result (which objects or attributes you need in the response).
>
> Although there is a C++ library [2] or a Ruby library [3] in the end it looks
> like an
> overkill for the internal API. But if you would need to design some big and
> complicated REST API then you could consider it. See more details in [4] or
> in the
> specification [5].
>
>
> The Proposal
> ============
>
> To not break the backward compatibility we cannot change the
> ResolvableProperties()
> call so let's create a new one:
>
> # <filter_hash> = required matching values
> # <attributes_list> = returned attributes, empty list => return all
> Yast::Pkg.Resolvables(<filter_hash>, <attributes_list>)
>
>
> # a ResolvableProperties() compatible version:
> Yast::Pkg.Resolvables({kind: :package, name: "yast2"}, []) => Array<Hash>
>
> [{
> "arch"=>"x86_64",
> "description"=>
> "This package contains scripts and data needed for SUSE Linux\n" +
> "installation with YaST2",
> "download_size"=>518308,
> "inst_size"=>2388454,
> "location"=>"yast2-4.0.87-lp150.2.9.1.x86_64.rpm",
> "locked"=>false,
> "medium_nr"=>1,
> "name"=>"yast2",
> "on_system_by_user"=>false,
> "path"=>"./rpms/x86_64/yast2-4.0.87-lp150.2.9.1.x86_64.rpm",
> "source"=>7,
> "status"=>:available,
> "summary"=>"YaST2 - Main Package",
> "transact_by"=>:solver,
> "vendor"=>"openSUSE",
> "version"=>"4.0.87-lp150.2.9.1",
> "version_epoch"=>nil,
> "version_release"=>"lp150.2.9.1",
> "version_version"=>"4.0.87"
> }]
>
>
> # new functionality: more search criteria and limiting the result:
> Yast::Pkg.Resolvables({kind: :package, status: :available, name: "yast2"},
> [:name, :version]) => Array<Hash>
>
> [{
> "name"=>"yast2",
> "version"=>"4.0.87-lp150.2.9.1",
> }]
>
>
> Quite often we just need to know whether an object with some attributes exists
> without need to know the specific details, like a package is installed:
>
> Yast::Pkg.AnyResolvable(name: "foo", kind: :package, status: :installed) =>
> Boolean
>
> That would be basically the same as Pkg.Resolvables, just returning a simple
> Boolean
> as the result instead of the details. (And it could be faster, it can return
> after
> finding the first matching item, it does not need to iterate over all
> objects.)
>
>
> Ruby Wrapper
> ------------
>
> Unfortunately the C++ Pkg-bindings API does not allow specifying optional
> parameters
> (that's a limitation of the YaST component system)
In fact there is a way, just not so easy.
see e.g.
https://github.com/yast/yast-core/blob/master/libycp/src/YCPBuiltinPath.cc#L155
so you need to define it multiple times there. ( just note that I do not test
it enough with ruby, as it is used now only in builtins which is already
defined in ruby itself.
I do not test it, but maybe also in ruby you can have something like:
publish function: :test, signature: "string (string)"
publish function: :test, signature: "string (string, string)"
You can try it and maybe it will work. If not, I can check a bit more code as
in general component system should allow it, just ycp does not allow it.
Josef
> and cannot provide an
> object-oriented API so probably having a small Ruby wrapper would be nice:
>
> Yast::Resolvable.find(<filter_hash>) => Array<Resolvable>)
>
> Where the Resolvable would be an object wrapper for the pkg-bindings Hash.
>
> Examples:
>
> Yast::Resolvable.find(kind: :package, status: :selected)
> Yast::Resolvable.find(name: "package", kind: :package, status: :installed)
>
> Similarly for the existence check (just for completeness):
>
> Yast::Resolvable.any?(kind: :package, status: :selected)
>
>
> I'll propose some code snippets at GitHub, I think it will be better to
> discuss some
> details in a draft pull request with some real code...
>
>
>
> [1] https://bugzilla.suse.com/show_bug.cgi?id=1132650
> [2] https://github.com/graphql/libgraphqlparser
> [3] https://graphql-ruby.org/
> [4] https://graphql.org/
> [5] https://graphql.github.io/graphql-spec/
>
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