On Wed, May 11, 2011 at 10:15 PM, ajg <[email protected]> wrote: > - is there any other structure in v8 that can be better used for a
hashmap (e.g. that would support Object as key)? > v8 only offers the JS-defined types, so Object is all there is unless you create your own class which can use object keys (which would presumably require some sort of custom hashing routine). > - what is maximum number of keys it can hold? > If it can hold 500k keys/values then it can probably hold any number it can allocate. Certainly they wouldn't say "oh, let's cap it out at 501k," seeing as 500k is already an absolutely _absurd_ amount of keys/values for a single object. The amount of memory required for such an object is _huge_. There are storage-based hashtables out there which can support these sizes, have average O(1) performance, and constant (low) memory costs. > - assuming that I expect an object to be large, any way to make object > large in advance to avoid copying around? > There is no JS API to reserve memory within an object's lookup table (and i say "lookup table" because the exact implementation is unspecified). It might not be practical/possible to reserve slots in the underlying structure. You can reserve space in an array with the ctor taking an integer, but IIRC someone reported a bug that numbers larger than some point caused an error to be thrown (i think it was 30000 or so, but i don't recall exactly, and that was a couple years ago, so that may no longer be an issue). -- ----- stephan beal http://wanderinghorse.net/home/stephan/ -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users
