multi-hypercore-index
v1.0.2
Published
build an index over a set of hypercores
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multi-hypercore-index
Build an index over a set of hypercores.
Traverses a set of hypercores (as a multi-hypercore) and calls a user indexing function to build an index.
Example
Let's build a key-value index using this and unordered-materialized-kv:
var hypercore = require('hypercore')
var multicore = require('multi-hypercore')
var indexer = require('.')
var umkv = require('unordered-materialized-kv')
var ram = require('random-access-memory')
var memdb = require('memdb')
var multi = multicore(hypercore, ram, { valueEncoding: 'json' })
var kv = umkv(memdb())
var hyperkv = indexer({
cores: multi,
map: function (node, feed, seq, next) {
var entry = {
id: feed.key.toString('hex') + '@' + seq,
key: node.key,
links: node.links
}
kv.batch([entry], next)
}
})
function append (w, data, cb) {
w.append(data, function (err) {
if (err) return cb(err)
var id = w.key.toString('hex') + '@' + (w.length - 1)
cb(null, id)
})
}
multi.writer(function (_, w) {
append(w, {
key: 'foo',
value: 'bax',
links: []
}, function (_, id1) {
console.log('id-1', id1)
append(w, {
key: 'foo',
value: 'bax',
links: [id1]
}, function (_, id2) {
console.log('id-2', id2)
hyperkv.ready(function () {
kv.get('foo', function (_, res) {
console.log(res)
})
})
})
})
})
outputs
id-1 9736a3ff7ae522ca80b7612fed5aefe8cfb40e0a43199174e47d78703abaa22f@0
id-2 9736a3ff7ae522ca80b7612fed5aefe8cfb40e0a43199174e47d78703abaa22f@1
[
'9736a3ff7ae522ca80b7612fed5aefe8cfb40e0a43199174e47d78703abaa22f@1'
]
API
var Index = require('multi-hypercore-index')
var index = Index(opts)
Required opts
include:
cores
: a multi-hypercore instancemap
: a mapping function, to be called on each node in the hypercores ofcores
. Expects params(node, feed, seq, next)
.next
should be called when you are done processing.
index.ready(cb)
Registers the callback cb()
to fire when the indexes have "caught up" to the
latest known change. The cb()
function fires exactly once. You may call
index.ready()
multiple times with different functions.
See Also
License
ISC