[erlang-questions] Erlang C NIF access to process struct

[Dmytro Lytovchenko]

You might enjoy reading this one
http://beam-wisdoms.clau.se/en/latest/indepth-memory-layout.html
And also this one https://github.com/happi/theBeamBook

2017-11-06 4:55 GMT+01:00 Boshan Sun <sunboshan@REDACTED>:

> Does your fix also fix the variable alignment issue as well? The variable
> is in the beginning of the next row now, and should be in the end of same
> row. Also can you fix hipe_bifs:show_estack/1, hipe_bifs:show_nstack/1,
> hipe_bifs:show_pcb/1? They all suffer the "off" issue.
>
> BTW, I just read your paper *A Staged Tag Scheme for Erlang* and it
> explains Erlang's tag scheme pretty well. Thanks for that. The paper was
> written in 2000 for R6B/R7A, just wondering do you guys have some updated
> paper regarding for current state of Erlang/OTP's tag scheme?
>
> Thanks!
>
> 2017-11-05 1:34 GMT-08:00 Mikael Pettersson <mikpelinux@REDACTED>:
>
>> The "off" table is due to a glitch in the output routine.  The too short
>> "H  E A P" banner is indeed a 32-vs-64 bit bug.  I fixed both in
>> https://github.com/erlang/otp/pull/1619.
>>
>> WRT accessing the current "struct process", I haven't looked in detail,
>> but in general the NIF interface wants to abstract away representational
>> details and replace them function calls (actual runtime function calls, not
>> just function-like macros).  I don't see direct accesses to "struct
>> process" fitting into that.
>>
>> On Sun, Nov 5, 2017 at 4:39 AM, Boshan Sun <sunboshan@REDACTED> wrote:
>>
>>> Hi all,
>>>
>>> In Erlang, you can use `hipe_bifs:show_heap(self()).` to debug the
>>> process's heap.
>>>
>>> From: 0x000000001ee5c6e0 to 0x000000001ee5c748
>>>  |         H E A P         |
>>>  |            Address |           Contents |
>>>  |--------------------|--------------------|
>>> 4 | 0x000000001ee5c6e0 | 0x000000000000004f |
>>> [] | 0x000000001ee5c6e8 | 0xfffffffffffffffb |
>>> 3 | 0x000000001ee5c6f0 | 0x000000000000003f |
>>> [4] | 0x000000001ee5c6f8 | 0x000000001ee5c6e1 |
>>>  |--------------------|--------------------|
>>>
>>> However the implementation is for 32-bits machine, and the table is kind
>>> of off for a 64-bits erlang.
>>>
>>> I want to write a C NIF to print similar heap information. What I need
>>> is the address of `process -> heap` and the heap size so I can get the
>>> heap's information.
>>>
>>> My question is, is there a way to get a pointer to the given process via
>>> pid in C NIF?
>>>
>>> In NIF doc there's enif_get_local_pid
>>> <http://erlang.org/doc/man/erl_nif.html#enif_get_local_pid> , how does
>>> this pid translate to the process pointer?
>>>
>>> Thanks!
>>>
>>> Boshan
>>>
>>>
>>> _______________________________________________
>>> erlang-questions mailing list
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>>>
>>>
>>
>
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