Hi Jakob and v8-users,
I have following observations on printing logs in v8 and date.now call
trace.
1. *Logs in v8:*
*printf* and *std::cout* were not outputting any logs in adb logcat. I
tried redirecting stdio logs to logcat by following commands -
$ adb shell stop$ adb shell setprop log.redirect-stdio true$ adb shell start
But still logs were not getting displayed in adb logcat. So I used
android log library. Following is the procedure
- Import header file:
#if defined(V8_OS_ANDROID)
#include <android/log.h>
#endif
- Print log:
#if defined(V8_OS_ANDROID)
__android_log_print(ANDROID_LOG_INFO, "<TAG>", "<MESSAGE>");
#endif
2. Date.now() final system call:
Date.now() calls *V8Platform::CurrentClockTimeMillis()* from*
src/gin/v8_platform.cc *---> *Time::Now() *from *src/base/time/time.cc*
---> *getTimeofDay() *rather than *base::OS::TimeCurrentMillis. *Can
anyone explain this behaviour?
Regards,
K Abhishek
On Mon, Jun 18, 2018 at 7:07 PM Jakob Kummerow <jkumme...@chromium.org>
wrote:
> Sure, just use printf or std::cout << "print\n". I don't know whether adb
> logcat has any special requirements.
>
> On Mon, Jun 18, 2018 at 3:48 PM Abhishek Kanike <
> kai.dranzer32...@gmail.com> wrote:
>
>> Jakob,
>> Thanks for quick reply.
>> That's a good point, should have tried with gdb. Will check with that.
>> Is there a way to add logs in v8 source code, it will be lot faster to
>> debug.
>> In cc (compositor), i used *LOG(INFO)<<"print";* from *base/logging.h *(of
>> main chromium *src*)
>>
>> On Mon, Jun 18, 2018 at 5:12 PM Jakob Kummerow <jkumme...@chromium.org>
>> wrote:
>>
>>> Yes, it is.
>>>
>>> Have you tried using a debugger? You can set a breakpoint in
>>> the BUILTIN(DateNow) function here:
>>>
>>>
>>> https://cs.chromium.org/chromium/src/v8/src/builtins/builtins-date.cc?q=builtins-date.cc&sq=package:chromium&dr&l=282
>>>
>>> and step through the code from there.
>>>
>>> On Mon, Jun 18, 2018 at 2:39 PM Abhishek Kanike <
>>> kai.dranzer32...@gmail.com> wrote:
>>>
>>>> Hi,
>>>> For confirmation i am using a simple Date.now() call on button click
>>>> [Attached].
>>>> I have added a print log in Time::NOW() at
>>>> https://cs.chromium.org/chromium/src/v8/src/base/platform/time.cc?type=cs&sq=package:chromium&g=0&l=402
>>>> as printf("v8:DEBUG::TIME:NOW called").
>>>> I am not getting this log in adb logcat. So is this the correct place
>>>> from where Date.now() is getting called?
>>>>
>>>> Regards,
>>>> K Abhishek
>>>>
>>>> On Mon, May 21, 2018 at 6:51 PM Abhishek Kanike <
>>>> kai.dranzer32...@gmail.com> wrote:
>>>>
>>>>> Sorry JaKob
>>>>>
>>>>> On Mon, May 21, 2018, 6:51 PM Abhishek Kanike <
>>>>> kai.dranzer32...@gmail.com> wrote:
>>>>>
>>>>>> Cool.. I see it. Thanks a lot Jacob.
>>>>>>
>>>>>> On Mon, May 21, 2018, 5:40 PM Jakob Kummerow <jkumme...@chromium.org>
>>>>>> wrote:
>>>>>>
>>>>>>> The time always has to be retrieved from the kernel. V8's
>>>>>>> implementation is in base::OS::TimeCurrentMillis, implemented in
>>>>>>> src/base/platform/platform-{win32,posix}.cc.
>>>>>>>
>>>>>>> On Mon, May 21, 2018 at 3:22 PM Abhishek Kanike <
>>>>>>> kai.dranzer32...@gmail.com> wrote:
>>>>>>>
>>>>>>>> Hi,
>>>>>>>> I want to know how the date.now() function is called in javascript
>>>>>>>> (or how it returns the value). I believe that javascript uses
>>>>>>>> date.now() by
>>>>>>>> system call. I want to in chrome source code how it is being set.
>>>>>>>> This is useful for one of the performance benchmark that I am
>>>>>>>> working on.
>>>>>>>> Can someone please guide me to know how this happens in v8 engine.
>>>>>>>>
>>>>>>>> Thanks in advance.
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>> K Abhishek
>>>>>>>>
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>>>> Cheers,
>>>> K Abhishek
>>>>
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>>
>>
>> --
>> Cheers,
>> K Abhishek
>>
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Cheers,
K Abhishek
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