Zachary, I agree that adding a Python dependency might not be a good idea, so 
I'll take a closer look at the network code available in lldb. Symbol format we 
are currently using is pretty simple - every artifact is identified by a type 
(elf, src, etc), an id (build id for binary or hash for source) and a path. I'm 
not sure what you mean by platform agnostic, but with this approach every 
SymbolVendor will just have to pass the appropriate type, build id and a path 
to a ArtifactManager, which will download or locate a locally cached artifact 
and return a path to it.

________________________________
From: Zachary Turner <ztur...@google.com>
Sent: Friday, August 26, 2016 8:18:54 PM
To: Taras Tsugrii; lldb-dev@lists.llvm.org
Cc: Kevin Frei
Subject: Re: [lldb-dev] Symbol Server for everyone.

Making the SymbolVendor dependent on Python is probably a non starter, and it 
would also make debugging more difficult.

We have network code for various platforms in Host already.

It would be nice to have a symbol server format that is platform agnostic. On 
the other hand, Microsoft tools already understand their own symbol server 
format , so if i ever reprioritize this, we will probably want the standard 
Microsoft symbol server format on Windows for interoperability.


On Fri, Aug 26, 2016 at 8:00 PM Taras Tsugrii via lldb-dev 
<lldb-dev@lists.llvm.org<mailto:lldb-dev@lists.llvm.org>> wrote:

Hello lldb developers,


In one of the older posts 
(http://blog.llvm.org/2015/01/lldb-is-coming-to-windows.html<https://urldefense.proofpoint.com/v2/url?u=http-3A__blog.llvm.org_2015_01_lldb-2Dis-2Dcoming-2Dto-2Dwindows.html&d=DQMFaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=jqaYv5aDYHR_MGTz1rkWPg&m=cGDliRKtgFrgnkWwFqxPh4RyRVqdfaAmOCGP-zL_LbA&s=0aQ3fWYzXJkFu8RXsNn-tueEzkRgtHCC53MVc6Mbbqw&e=>),
 symbol server support was mentioned. Most likely it was meant for Windows, but 
at FB we have our own symbol server implementation for Linux (technically it's 
completely platform agnostic), which we would like to integrate with LLDB and 
eventually open source along with the server. As such I thought I'd ask LLDB 
gurus like you, if anyone is already working on symbol server support and if 
not, I'd appreciate your thoughts on a desired architecture.


General idea.

Based on current LLDB implementation and the fact that symbol server feature is 
a cross-cutting concern, the natural place to put this logic would be inside 
SymbolVendor plugin, which on Mac is used to resolve separate dSYM bundles. In 
theory symbol server logic is completely platform-agnostic, as all we need to 
know is some sort of binary ID (could either be a real .build-id or UUID or 
some custom logic to compute a stable binary hash) and binary name. This info 
can be used to make a network request to check whether corresponding binary 
exists and if so, download it to a temporary location and call 
symbol_vendor->AddSymbolFileRepresentation with FileSpec pointing at that 
temporary location.


Implementation details.


Logic placement.

Even though symbol resolution is platform agnostic, the process of 
extracting/computing binary ID is. As such it seems like SymbolServerResolver 
can either be a part of LLDB core, or a separate directory in 
Plugins/SymbolVendor, which will then be used by SymbolVendorELF and 
SymbolVendorMacOSX. First both symbol vendors will try to resolve the symbols 
the way they currently do and only if they cannot find anything, will they try 
to use SymbolVendorSymbolServer.

Alternatively symbol server resolution logic can be placed into its own 
SymbolVendorSymbolServer, and modify SymbolVendor FindPlugin's logic such that 
it does not return the first found SymbolVendor instance and instead returns 
either the first SymbolVendor instance that managed to successfully resolve 
symbols or just last one.

Yet another alternative would be to use a delegation chain, such that any 
SymbolVendor could be wrapped into a SymbolVendorSymbolServer, which would 
first try to invoke the delegate and if it cannot find symbols, will try to 
perform its magic. This approach seems nice, but does not play nice with 
current implementation based on static factory method.


Symbol server communication.

Network communication can either be implemented natively for different 
platforms or it can be delegated to a python script invoked by 
ScriptInterpreter. Using Python seems an easier option in order to make this 
cross-platform, but it adds a dependency on Python and will require propagating 
ScriptInterpreter to SymbolVendor creation factory.


Thoughts, suggestions and comments are very welcome.


Thank you,

Taras

LLVM Project Blog: LLDB is Coming to 
Windows<https://urldefense.proofpoint.com/v2/url?u=http-3A__blog.llvm.org_2015_01_lldb-2Dis-2Dcoming-2Dto-2Dwindows.html&d=DQMFaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=jqaYv5aDYHR_MGTz1rkWPg&m=cGDliRKtgFrgnkWwFqxPh4RyRVqdfaAmOCGP-zL_LbA&s=0aQ3fWYzXJkFu8RXsNn-tueEzkRgtHCC53MVc6Mbbqw&e=>
blog.llvm.org<https://urldefense.proofpoint.com/v2/url?u=http-3A__blog.llvm.org&d=DQMFaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=jqaYv5aDYHR_MGTz1rkWPg&m=cGDliRKtgFrgnkWwFqxPh4RyRVqdfaAmOCGP-zL_LbA&s=hwDLjBupq4WCB2Tnss4NgxIrkZa-YY8Haze1be8QP9w&e=>
This preliminary bootstraping work is mostly complete, and you can use LLDB to 
debug simple executables generated with Clang on Windows today.


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