Added batch address/scripthash POST call

[gr0kchain]

Added a batch POST call. This is similar to the address and scripthash get calls, but allows retrieving more than one address at a time instead of having to flood the elects server with get requests for each address.

[shesek]

Thanks for the PR!

I've been thinking to implement this with a more generic POST /batch endpoint that lets you batch requests to any GET endpoint, by specifying an array of URI paths. For example:

$ curl -X POST https://blockstream.info/api/batch \
       -d '["/address/<address1>/stats","/address/<address1>/txs","/address/<address2>/stats","/address/<address2>/txs"]'

This could be accomplished by emulating HTTP calls via handle_request(), without sending actual HTTP requests.

But I can see this being useful even if only available for the /address/:address/stats endpoint. I would change the endpoint to accept a JSON array of addresses instead of a comma-separated list, though.

What do you think @greenaddress?

[gr0kchain]

Invoking the existing single object calls through some batch wrapper does seem feasible. I'd however avoid having to pass through the amount of overhead in the request. The repetitiveness of the the URL templates seem to add unnecessary bloat to the payload.

[shesek]

Gzipping the request would make the url template repetitiveness much less of an issue, at least bandwidth wise.

[gr0kchain]

That would, but gzipping it without the repetitiveness would be even better. Either way, I think the shortest path to getting this working is as you've suggested. Perhaps a reduction could be as follows, where the patterns for the requests are parsed and batched by path and array of elements.

curl -X POST https://blockstream.info/api/batch \
       -d 
'[{
"/address/stats" : [<address1>, <address2>],
"/address/txs" : [<address1>, <address2>]
}]'

[tiero]

Any update on this? Super valuable feature

[junderw]

Sorry, I pushed something to my personal fork and for some reason it took the PR references from the mempool repo and converted them to this repo and made a mention, bumping the issue. Looks like a bug with GitHub.