Stream Meter

Stream Meter is a... uh, meter for streams.

It is a streams2 Transform stream that passes through content, but counts the number of bytes it forwards.

However, give it a size in bytes and it will abort as soon as that threshold is passed. This is useful for capping your hyperquest or http/https clients or servers content size.

npm install stream-meter

Examples:

1var meter = require("stream-meter")
2
3// make an un-capped meter
4var m = meter()
5process.stdin.pipe(m).pipe(process.stdout)
6setTimeout(function () {
7  // Log how much we saw in a couple seconds.
8  console.log(m.bytes)
9}, 2000)
10
11// this will abort (with an Error) in the frame where 1024 bytes is reached
12process.stdin.pipe(meter(1024)).pipe(process.stdout)
13
14// create a 1024 byte-capped meter
15var m = meter(1024)
16m.on("error", function (e) {
17  // log the error but don't kill the process
18  console.log(e.message)
19})
20process.stdin.pipe(m).pipe(process.stdout)
21

1var hyperquest = require("hyperquest")
2
3var req = hyperquest("https://raw.github.com/mranney/node_redis/master/index.js")
4
5var meter = require("stream-meter")(1024)
6meter.on("error", function (e) {
7  console.log(e.message)
8  console.log("Read %s bytes", meter.bytes)
9})
10
11
12req.pipe(meter).pipe(process.stderr)

1$ node hypermeter.js 2> /dev/null
2Stream exceeded specified max of 1024 bytes.
3Read 7377 bytes

Usage

1var meter = require("stream-meter")
2
3var stream = meter(size)
4stream.on("error", function (e) {
5  // handle the meter aborting the stream
6})
7
8// read the bytes processed by the meter and passed through to any subsequent streams.
9var size = stream.bytes

See test/index.js for additional examples.

Options

size

Size (in bytes) to trigger the stream to abort. It will complete whatever frame it aborted in, so the size streamed will still be >= size but no more than size + highWaterMark

Properties

bytes

Number of bytes handled and passed through the meter.

LICENSE

MIT