First, how big is the data member of the object ? Is it as big as the
actual array buffer length which I declare on JavaScript and which I can
build on top of it a typedarray ?
No, I’m just trying to understand how v8 works, I know it is a big thing
but at least how it moves then I might read the code and understand, extra
parts.
So, when a typedarray is build on top of an areaybuffer instance, how do I
get to call the arraybufferbuilder::append ?
On Mon, 10 Sep 2018 at 23:30, @soylentgraham <gra...@grahamreeves.com>
wrote:
> I'm guessing you may be a bit new to unmanaged-memory languages/systems.
>
> buffer is an object, (it's structure/layout will look a bit like it's
> class declaration, but it's a little more complex than that) that was
> allocated somewhere sometime, (you can figure out where, but really you
> don't need to, for this purpose it's just an object)
> data is a member of that object, that points to some memory (somewhere
> else, maybe allocated by a different system, in a different place)
> you have no idea (and you shouldn't need to know, or use the information)
> the "offset" from the buffer-object to the data. They are not necessarily
> related, or share the same memory space. (and in most cases, they're not
> even real memory addresses, they're more like identifiers)
>
> Simple Javascript scripts can look like C sometimes (a few variables here
> and there, a few array creations), but underneath it's doing a lot more
> moving things around.
> function x()
> {
> var a = new array(10);
> var b = new array(100);
> }
> This may look like it allocates 2 arrays, but more than likely it's doing
> something radically different with actual memory.
>
>
> > so how can i see the memory management ?
> As I said, you can't see the javascript side so easily (other than using
> the v8 debugging/inspector tools)
> But if you want to see the C-side memory (which MAY be where the data that
> buffer points at came from) you can make your own allocator that v8 can use.
> If you then breakpoint each call, you'll know when V8 is allocating some
> memory to use (which may or may not be a direct object in javascript, an
> array or typed array in javascript may not directly allocate here)
>
>
> class TV8Allocator : public v8::ArrayBuffer::Allocator
>
> {
>
> public:
>
> virtual void* Allocate(size_t length) override;
>
> virtual void* AllocateUninitialized(size_t length) override;
>
> virtual void Free(void* data, size_t length) override;
>
> };
>
>
> void* TV8Allocator::Allocate(size_t length)
>
> {
>
> auto* Bytes = new uint8_t[length];
>
> for ( auto i=0; i<length; i++ )
>
> Bytes[i] = 0;
>
> return Bytes;
>
> }
>
>
> void* TV8Allocator::AllocateUninitialized(size_t length)
>
> {
>
> auto* Bytes = new uint8_t[length];
>
> return Bytes;
>
> }
>
>
> void TV8Allocator::Free(void* data, size_t length)
>
> {
>
> auto* data8 = reinterpret_cast<uint8_t*>(data);
>
> delete[] data8;
>
> }
>
> v8::Isolate::CreateParams create_params;
>
> create_params.array_buffer_allocator = &mAllocator;
>
>
>
> > Cause i saw the code but didn't find how it handles all the possible
> javascript i might write into a script file....
>
>
> Your computer most likely has more memory than you'll ever write in a
> script :)
>
> If you're trying to work out where your script goes... arraybuffer isn't
> the right place.
>
>
> Do you NEED to know? What exactly are you trying to achieve? (take a step
> back from the code and describe what you're trying to do;
>
> are you trying to make an app? learn how memory works in c++? learn how
> memory is used in javascript? Why your app uses 1gb of memory?
>
>
>
>
> On Monday, 10 September 2018 22:10:54 UTC+1, dan Med wrote:
>>
>> How big is the offset from buffer to data ?
>> const void* Data
>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=80&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523b8F1aEDx%25252F6En%25252FkOKh2zVkvONjtDNg9gr5KG7gT9XeJk%25253D&gsn=Data&ct=xref_usages>()
>> const { return buffer_
>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=94&ct=xref_jump_to_def&gsn=buffer_>
>> ->
>> <https://cs.chromium.org/chromium/src/base/memory/scoped_refptr.h?l=218&ct=xref_jump_to_def&gsn=-%3E>
>> Data
>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer.h?l=225&ct=xref_jump_to_def&gsn=Data>();
>> }
>>
>> sorry for spamming emails, i will try to condensate more
>>
>> Il giorno lun 10 set 2018 alle ore 23:07 dan Med <litoki...@gmail.com>
>> ha scritto:
>>
>>> Cause i saw the code but didn't find how it handles all the possible
>>> javascript i might write into a script file....
>>>
>>> Il giorno lun 10 set 2018 alle ore 23:06 dan Med <litoki...@gmail.com>
>>> ha scritto:
>>>
>>>> But after using it for a little while, I have found v8 in general is
>>>> pretty simple. It provides an interface to C functions and memory. This is
>>>> kinda what it's for.
>>>>
>>>> so how can i see the memory management ?
>>>>
>>>>
>>>> Il giorno lun 10 set 2018 alle ore 23:06 dan Med <litoki...@gmail.com>
>>>> ha scritto:
>>>>
>>>>> So, the hole length of this raw memory is set to be Data ? And to use
>>>>> it i should create a view on top of it like with typedarrays?
>>>>>
>>>>>
>>>>> So to call arraybuffer::append i should first, try to make the typed
>>>>> array bigger that action will call the arraybuffer::append ? i didn't
>>>>> ask
>>>>> how memcpy work, i didn't get the Data() thing, in the class that's all.
>>>>>
>>>>> Il giorno lun 10 set 2018 alle ore 22:55 @soylentgraham <
>>>>> gra...@grahamreeves.com> ha scritto:
>>>>>
>>>>>> > How can i understand the structure in memory of an arraybuffer and how
>>>>>> > big is the data field which is pointed by this void pointerIt has no
>>>>>> > structure. It is just a series of linear bytes, raw memory, allocated
>>>>>> > by the memory allocator. (If you implement your own memory allocator
>>>>>> > you can catch when this happens)It's just the data(buffer) for an
>>>>>> > array.
>>>>>> > How are they represented in memory....It IS memory. It's nothing more
>>>>>> > (it's an array of bytes)
>>>>>> > How big is the data field ?If by "field", you mean, the data buffer...
>>>>>> > it's Capacity
>>>>>> > <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=76&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523kB%25252BJ1WxDvoDqf1c8Tz5Ol3yne4lD03cRpevK2LHMUZk%25253D&gsn=Capacity&ct=xref_usages>
>>>>>> > (capacity is how much it can fit) in length. But not how much is
>>>>>> > being used. (bytes_used)
>>>>>> If you're curious about when memory grows, reallocates, is written to,
>>>>>> accessed... it might be worth setting up your environment so you can
>>>>>> debug it by stepping through the code as it executes. You can watch
>>>>>> memory, (this would show what memcpy changes) see the values passed
>>>>>> around, track when memory gets allocated etc.
>>>>>> Your questions are a mix of very broad, ("How does v8 work") and very
>>>>>> specific programming questions (what is memcpy() doing)Broad questions
>>>>>> are very hard to answer in general. ("How does a car work")
>>>>>>
>>>>>> I agree, simply browsing the code doesn't give a good overview of say,
>>>>>> how the javascript compiler works, or how memory is utilised. (How it is
>>>>>> allocated is very simple, on the C/++ side it doesn't implement any
>>>>>> memory management, and the array buffer/view is a view of the C-side
>>>>>> memory)But after using it for a little while, I have found v8 in general
>>>>>> is pretty simple. It provides an interface to C functions and memory.
>>>>>> This is kinda what it's for.
>>>>>> But the point of v8 is that it does a lot of that for you. I don't
>>>>>> REALLY need to know how the memory is tracked on the javascript side, it
>>>>>> just works (if I'm using the API correctly)Then again, if you NEED to
>>>>>> know how it works for a specific purpose (very restricted memory, fixing
>>>>>> a bug), we can help you a lot more easily by answering a very specific
>>>>>> question. ("My car's low-oil light is blinking, where do I fill it up")
>>>>>> If you're just curious as to how the entire v8 engine works... that's a
>>>>>> massive ask. A lot of people work on it, and there is a lot of work and
>>>>>> topics involved.Your best bet is reading the (limited) documentation on
>>>>>> the wiki, and read the blog posts https://v8project.blogspot.com/ which
>>>>>> go into quite a lot of detail on each post topic.I've not seen any real
>>>>>> general overview (the wiki itself says it's out of date) so, stepping
>>>>>> through all the code as it executes is probably your best bet.
>>>>>>
>>>>>>
>>>>>> On Monday, 10 September 2018 21:25:37 UTC+1, dan Med wrote:
>>>>>>>
>>>>>>> in this snippet for example
>>>>>>>
>>>>>>> namespace WTF
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=40&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%2523WTF%252523n%252523namespace&gsn=WTF&ct=xref_usages>
>>>>>>> {// A utility class to build an ArrayBuffer instance. Validity must be
>>>>>>> checked// by isValid() before using an instance.class WTF_EXPORT
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/wtf_export.h?l=46&ct=xref_jump_to_def&gsn=WTF_EXPORT>
>>>>>>> ArrayBufferBuilder
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=44&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523ArrayBufferBuilder%25253AWTF%252523c%252523hTnYOn1mFcU%2Bkythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523NyhHD05MjDx8XOe1m%25252BLqXBLvqdjWPsLmDrRvvmR2Ywk%25253D&gsn=ArrayBufferBuilder&ct=xref_usages>
>>>>>>> final { // Disallow copying since it's expensive and we don't want
>>>>>>> code to do it by // accident. USING_FAST_MALLOC
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/allocator.h?l=146&ct=xref_jump_to_def&gsn=USING_FAST_MALLOC>(ArrayBufferBuilder
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=44&ct=xref_jump_to_def&gsn=ArrayBufferBuilder>);
>>>>>>> public: // Creates an ArrayBufferBuilder using the default capacity.
>>>>>>> ArrayBufferBuilder
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=51&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523me5JBk4wDIaIJCK86MiUpy%25252BnGYRZwEr0AvVg3KaU0pw%25253D&gsn=ArrayBufferBuilder&ct=xref_usages>();
>>>>>>> ArrayBufferBuilder
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=53&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523VW0P45Tk9IGjtOqM%25252B9dHdJ64so3WDAfcY1jNBLt0GNY%25253D&gsn=ArrayBufferBuilder&ct=xref_usages>(unsigned
>>>>>>> capacity
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=53&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523trfcCH7BPCRWiubGq1QF9bypkCRNYtWGHb2AzglMces%25253D&gsn=capacity&ct=xref_usages>)
>>>>>>> : bytes_used_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=92&ct=xref_jump_to_def&gsn=bytes_used_>(0),
>>>>>>> variable_capacity_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=93&ct=xref_jump_to_def&gsn=variable_capacity_>(true)
>>>>>>> { buffer_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=94&ct=xref_jump_to_def&gsn=buffer_>
>>>>>>> =
>>>>>>> <https://cs.chromium.org/chromium/src/base/memory/scoped_refptr.h?l=226&ct=xref_jump_to_def&gsn=%3D>
>>>>>>> ArrayBuffer
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer.h?l=42&ct=xref_jump_to_def&gsn=ArrayBuffer>::Create
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer.h?l=125&ct=xref_jump_to_def&gsn=Create>(capacity
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=53&ct=xref_jump_to_def&gsn=capacity>,
>>>>>>> 1); } bool IsValid
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=58&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523Bx72YH%25252BiA4nF5ZIPsFhA9MQpdVCDOCRHSZa0Ksg6Wp4%25253D&gsn=IsValid&ct=xref_usages>()
>>>>>>> const { return buffer_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=94&ct=xref_jump_to_def&gsn=buffer_>.get
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/base/memory/scoped_refptr.h?l=211&ct=xref_jump_to_def&gsn=get>();
>>>>>>> } // Appending empty data is not allowed. unsigned Append
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=61&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523BHKR8BlIFhr03faCJF5mu7RDXZ%25252FPtZDAlnACyKmv1XM%25253D&gsn=Append&ct=xref_usages>(const
>>>>>>> char* data
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=61&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%25233VvJP%25252BUI3abzouA4%25252FYSBHt09pw3AiNI9e9QAJGooqYI%25253D&gsn=data&ct=xref_usages>,
>>>>>>> unsigned length
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=61&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523xOZXOK9mCrzsbUtqCxdbDuLg939IJhl7gbf0EykKwnY%25253D&gsn=length&ct=xref_usages>);
>>>>>>> // Returns the accumulated data as an ArrayBuffer instance. If
>>>>>>> needed, // creates a new ArrayBuffer instance and copies contents from
>>>>>>> the internal // buffer to it. Otherwise, returns a RefPtr pointing to
>>>>>>> the internal // buffer. scoped_refptr
>>>>>>> <https://cs.chromium.org/chromium/src/base/memory/scoped_refptr.h?l=167&ct=xref_jump_to_def&gsn=scoped_refptr><ArrayBuffer
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer.h?l=42&ct=xref_jump_to_def&gsn=ArrayBuffer>>
>>>>>>> ToArrayBuffer
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=67&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523JX559OA9Zt0rALNU4DOTOkzcmtws4U5V42xhN0rrbow%25253D&gsn=ToArrayBuffer&ct=xref_usages>();
>>>>>>> // Converts the accumulated data into a String using the default
>>>>>>> encoding. String
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/text/wtf_string.h?l=64&ct=xref_jump_to_def&gsn=String>
>>>>>>> ToString
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=70&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523VMCyw7t%25252FF0UIo65pz8LTbfX5k5G4pIXrUNQbDNKDjaE%25253D&gsn=ToString&ct=xref_usages>();
>>>>>>> // Number of bytes currently accumulated. unsigned ByteLength
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=73&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523P5Klo%25252BJeJiug%25252FrSAfsaHI8wAnW8h5UBg2%25252BoJByO85kA%25253D&gsn=ByteLength&ct=xref_usages>()
>>>>>>> const { return bytes_used_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=92&ct=xref_jump_to_def&gsn=bytes_used_>;
>>>>>>> } // Number of bytes allocated. unsigned Capacity
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=76&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523kB%25252BJ1WxDvoDqf1c8Tz5Ol3yne4lD03cRpevK2LHMUZk%25253D&gsn=Capacity&ct=xref_usages>()
>>>>>>> const { return buffer_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=94&ct=xref_jump_to_def&gsn=buffer_>->
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/base/memory/scoped_refptr.h?l=218&ct=xref_jump_to_def&gsn=-%3E>ByteLength
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer.h?l=249&ct=xref_jump_to_def&gsn=ByteLength>();
>>>>>>> } void ShrinkToFit
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=78&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523WBvAUuWtgva6ffSXIiEGEkt%25252FFFbeCcQcsCz5E%25252FHCKOo%25253D&gsn=ShrinkToFit&ct=xref_usages>();
>>>>>>> const void* Data
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=80&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523b8F1aEDx%25252F6En%25252FkOKh2zVkvONjtDNg9gr5KG7gT9XeJk%25253D&gsn=Data&ct=xref_usages>()
>>>>>>> const { return buffer_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=94&ct=xref_jump_to_def&gsn=buffer_>->
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/base/memory/scoped_refptr.h?l=218&ct=xref_jump_to_def&gsn=-%3E>Data
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer.h?l=225&ct=xref_jump_to_def&gsn=Data>();
>>>>>>> } // If set to false, the capacity won't be expanded and when
>>>>>>> appended data // overflows, the overflowed part will be dropped. void
>>>>>>> SetVariableCapacity
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=84&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%25232ib6USbezkKcLs8hjPaCz4GUGrUHdD%25252BeN%25252FKenERnRLA%25253D&gsn=SetVariableCapacity&ct=xref_usages>(bool
>>>>>>> value
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=84&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523vUjrriXMW5FurGjU87jcAlZRQs3b8JSgA4Tt1xrSq7I%25253D&gsn=value&ct=xref_usages>)
>>>>>>> { variable_capacity_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=93&ct=xref_jump_to_def&gsn=variable_capacity_>
>>>>>>> = value
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=84&ct=xref_jump_to_def&gsn=value>;
>>>>>>> } private: // Expands the size of m_buffer to size + m_bytesUsed
>>>>>>> bytes. Returns true // iff successful. If reallocation is needed,
>>>>>>> copies only data in // [0, m_bytesUsed) range. bool ExpandCapacity
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=90&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523szv9AYLlP3J7qhn%25252Fm%25252BJqzPmSgWf45%25252BRVwVxvXDk3WYQ%25253D&gsn=ExpandCapacity&ct=xref_usages>(unsigned
>>>>>>> size
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=90&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523mXwymG5xtblCCeS4C9QcnmOwJxql8nYDr2HLqNZVJ8I%25253D&gsn=size&ct=xref_usages>);
>>>>>>> unsigned bytes_used_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=92&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523x95FyaH%25252BSeW1SF4BFhX9oIq7qgtHy3xzXCMmc37LcL8%25253D&gsn=bytes_used_&ct=xref_usages>;
>>>>>>> bool variable_capacity_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=93&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523FKWGJXbcZ%25252BRuy6YD7uxQ765XV8Mhciv4FM%25252FF5B3bNvU%25253D&gsn=variable_capacity_&ct=xref_usages>;
>>>>>>> scoped_refptr
>>>>>>> <https://cs.chromium.org/chromium/src/base/memory/scoped_refptr.h?l=167&ct=xref_jump_to_def&gsn=scoped_refptr><ArrayBuffer
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer.h?l=42&ct=xref_jump_to_def&gsn=ArrayBuffer>>
>>>>>>> buffer_
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=94&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523aFDjYtlmS2tmLXL2XyJ158HoigBmsAdzguhOSb6XQIw%25253D&gsn=buffer_&ct=xref_usages>;
>>>>>>> DISALLOW_COPY_AND_ASSIGN
>>>>>>> <https://cs.chromium.org/chromium/src/base/macros.h?l=33&ct=xref_jump_to_def&gsn=DISALLOW_COPY_AND_ASSIGN>(ArrayBufferBuilder
>>>>>>>
>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?l=96&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.h%2523E6nSXqAY3ipexrHDKPfjzHqWqWIsAlT3EH3KVhT57GQ%25253D&gsn=ArrayBufferBuilder&ct=xref_usages>);};}
>>>>>>> // namespace WTF
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> How can i understand the structure in memory of an arraybuffer and how
>>>>>>> big is the data field which is pointed by this void pointerHow are they
>>>>>>> represented in memory....How big is the data field ?
>>>>>>>
>>>>>>>
>>>>>>> Il giorno lun 10 set 2018 alle ore 22:19 dan Med <
>>>>>>> litoki...@gmail.com> ha scritto:
>>>>>>>
>>>>>>>> i already did that and btw it is under the WTF/webkit .
>>>>>>>> I'm interested how v8 handles javascript into every detail if u can
>>>>>>>> guide me...
>>>>>>>> Tell me which repository are being used by v8 on the related topic
>>>>>>>> that would help me really much.
>>>>>>>>
>>>>>>>> By when it is called i mean, which javascript code will enable me
>>>>>>>> to call that funciton cause if u click u can't go any further than
>>>>>>>> that,
>>>>>>>>
>>>>>>>> Il giorno lun 10 set 2018 alle ore 21:53 Jakob Kummerow <
>>>>>>>> jkum...@chromium.org> ha scritto:
>>>>>>>>
>>>>>>>>> On Mon, Sep 10, 2018 at 12:22 PM dan Med <litoki...@gmail.com>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> I don't quite see if this google group is useful or not,
>>>>>>>>>> everybody keeps answering me with superficial things,
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> You said you wanted to read the compiler's source but couldn't
>>>>>>>>> find it, so I told you that it's in src/compiler/. If that was not the
>>>>>>>>> answer you wanted, then try asking a different question?
>>>>>>>>>
>>>>>>>>> Please also keep in mind that people's time is limited. The
>>>>>>>>> easier/quicker it is to answer your question, the more likely you are
>>>>>>>>> to
>>>>>>>>> get an answer.
>>>>>>>>>
>>>>>>>>> i don't care about the trminology like tell me which allocator it
>>>>>>>>>> uses when and why or at least if there's something i can read to
>>>>>>>>>> understand.....
>>>>>>>>>> I'm surprised u don't know what a JIT page is, basically if you
>>>>>>>>>> call a function foo() let's say 100 times then v8,had enough time to
>>>>>>>>>> understand the parameters given to that specific function and how to
>>>>>>>>>> optimize it efficently based on it's prediction/observation.
>>>>>>>>>>
>>>>>>>>>> I'm not interested in the terminology of things, (that's just a
>>>>>>>>>> matter of reading the source code ) i'm more in reading how it works
>>>>>>>>>> when
>>>>>>>>>> and why..
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> It's great that you want to understand how things work.
>>>>>>>>> Terminology is an important aspect of that though, because it enables
>>>>>>>>> communication. If we use different words for the same thing, we won't
>>>>>>>>> understand each other.
>>>>>>>>> Based on your explanation, I'm guessing that by "JIT page" you
>>>>>>>>> mean "the strategy V8 uses to select functions for optimization". The
>>>>>>>>> core
>>>>>>>>> of that logic is in MarkCandidatesForOptimization in
>>>>>>>>> src/runtime-profiler.cc.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> For example when is ArrayBufferBuilder::Append called ??
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I don't know; it's not part of V8. But you can use Code Search to
>>>>>>>>> find out where anything is called, just click the function in
>>>>>>>>> question to
>>>>>>>>> get a list of call sites:
>>>>>>>>> https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.h?q=ArrayBufferBuilder&sq=package:chromium&g=0&l=61
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> And i thing i've looked at the entire v8 source code but didn't
>>>>>>>>>> find much, apart from the array.js file which describes some
>>>>>>>>>> javascript
>>>>>>>>>> function, i don't understand where's the rest....
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Il giorno lun 10 set 2018 alle ore 20:45 Jakob Kummerow <
>>>>>>>>>> jkum...@chromium.org> ha scritto:
>>>>>>>>>>
>>>>>>>>>>> On Sun, Sep 9, 2018 at 8:54 AM dan Med <litoki...@gmail.com>
>>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> Oh and one more thing, i've surfed perhaps the entire source
>>>>>>>>>>>> code of v8 at least the interesting parts, but what i came across
>>>>>>>>>>>> was just
>>>>>>>>>>>> very short code execpt for some builtins written in javascript i
>>>>>>>>>>>> believe,
>>>>>>>>>>>> can't find all of the things i've found on the documentation such
>>>>>>>>>>>> as the
>>>>>>>>>>>> interpreter
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> src/interpreter/
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> and the JIT compilers,
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> src/compiler/
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> one more thing i'd like to understand how the memory is
>>>>>>>>>>>> handeled like how can i read about the JIT pages,
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> What's a JIT page?
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> or which memory allocator does v8 use
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> It uses several allocation techniques for different purposes.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> and it's garbage collector
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> src/heap/
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Thank you !
>>>>>>>>>>>>
>>>>>>>>>>>> Il giorno dom 9 set 2018 alle ore 17:51 dan Med <
>>>>>>>>>>>> litoki...@gmail.com> ha scritto:
>>>>>>>>>>>>
>>>>>>>>>>>>> I don't have understood this part, let me explain it to you.
>>>>>>>>>>>>> This is how i get it tell me if i'm wrong at any part.
>>>>>>>>>>>>>
>>>>>>>>>>>>> I need to understand how is the structure in memory of the
>>>>>>>>>>>>> arraybuffer how is it represented and if the data of the array
>>>>>>>>>>>>> are directly
>>>>>>>>>>>>> stored at an offset accessed by buffer_ -> data().
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> before the call to expand capacity it does create an array
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> the arraybuffer in src <https://cs.chromium.org/chromium/src/>
>>>>>>>>>>>>> /third_party
>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/>/blink
>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/>/
>>>>>>>>>>>>> renderer
>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/>
>>>>>>>>>>>>> /platform
>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/>
>>>>>>>>>>>>> /wtf
>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/>
>>>>>>>>>>>>> /typed_arrays
>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/>
>>>>>>>>>>>>> /array_buffer_builder.cc
>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.cc>
>>>>>>>>>>>>> is
>>>>>>>>>>>>> called whenever the renderer (has to execute some javascript
>>>>>>>>>>>>> which defines
>>>>>>>>>>>>> arraybuffers)
>>>>>>>>>>>>> First when is arraybuffer::append called, cause i know that
>>>>>>>>>>>>> if someone need to reallocate a bigger arraybuffer then a new
>>>>>>>>>>>>> instance will
>>>>>>>>>>>>> be created and filled with the old values if the length in the
>>>>>>>>>>>>> original
>>>>>>>>>>>>> array isn't has much as the user reqeusted ?
>>>>>>>>>>>>>
>>>>>>>>>>>>> One more thing is, when this class is called, the arraybuffer
>>>>>>>>>>>>> is always set to the initial length of static const int
>>>>>>>>>>>>> kDefaultBufferCapacity
>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_builder.cc?l=38&gs=kythe%253A%252F%252Fchromium%253Flang%253Dc%25252B%25252B%253Fpath%253Dsrc%252Fthird_party%252Fblink%252Frenderer%252Fplatform%252Fwtf%252Ftyped_arrays%252Farray_buffer_builder.cc%2523YXDT7WTpXCAcuhdyTlkuCzsfCzI%25252BoHLRFAlkbCrkx4g%25253D&gsn=kDefaultBufferCapacity&ct=xref_usages>
>>>>>>>>>>>>> = 32768; if in the javascript i declare an arraybuffer of
>>>>>>>>>>>>> 20bytes will it allocate of
>>>>>>>>>>>>> 32768bytes anyway =?
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Il giorno mar 4 set 2018 alle ore 12:14 Graham Reeves <
>>>>>>>>>>>>> gra...@grahamreeves.com> ha scritto:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> > is std::numeric_limits
>>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/buildtools/third_party/libc%2B%2B/trunk/include/limits?l=442&ct=xref_jump_to_def&gsn=numeric_limits>
>>>>>>>>>>>>>> <unsigned>::max
>>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/buildtools/third_party/libc%2B%2B/trunk/include/limits?l=450&ct=xref_jump_to_def&gsn=max>();
>>>>>>>>>>>>>> referring to the max unsigned int value ? cause the source code
>>>>>>>>>>>>>> won't find
>>>>>>>>>>>>>> it
>>>>>>>>>>>>>> Yes, that's the maximum value unsigned (an unsigned int) can
>>>>>>>>>>>>>> be, but what do you mean by, the source won't find it?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Monday, 3 September 2018 19:55:48 UTC+1, dan Med wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Can someone help me out?
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Il giorno sab 1 set 2018 alle ore 15:30 <litoki...@gmail.com>
>>>>>>>>>>>>>>> ha scritto:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> array_buffer_builder.cc in src
>>>>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/>/third_party
>>>>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/>/blink
>>>>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/>/
>>>>>>>>>>>>>>>> renderer
>>>>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/>
>>>>>>>>>>>>>>>> /platform
>>>>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/>
>>>>>>>>>>>>>>>> /wtf
>>>>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/>
>>>>>>>>>>>>>>>> /
>>>>>>>>>>>>>>>> <https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/wtf/typed_arrays/>
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
--
--
v8-users mailing list
v8-users@googlegroups.com
http://groups.google.com/group/v8-users
---
You received this message because you are subscribed to the Google Groups
"v8-users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to v8-users+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
