Collect proxy telemetries from addon

[ncloudioj]

We wanted to collect some pings for the proxy related metrics. It needs following steps:

• sort out the target metrics @jaredkerim
• client side ping collecting and notification @sarracini
• server side telemetry processing and persistence @ncloudioj

[sarracini]

Based on #680 we want to collect:

{
    source: "TOP_FRECENT_SITES_RESPONSE",  // which SQL query produced this list of URLs
    count: 17, // the total number of URLs returned by the SQL query
    cacheHit: 13, // the number found in our local simple storage cache
    cacheMiss: 4, // the number we failed to find and will request from embedly-proxy
    success: true, // was the call to embedly-proxy successful
    urlsRequested: 4, // how many URLs did we send to the proxy
    urlsReceived: 2, // how many URLs did we get back
    requestLatency: 13.4, // how long did it take for the call to complete
}

from the client's side

[ncloudioj]

Ah, great. A couple of suggestions:

• each ping from addon has a required field action, here we can use action: "activity_stream_proxy"
• let's stick with the snake case, e.g. "cacheHit" -> "cache_hit", just be consistent with other pings.
• use integer "millisecond" for the "requestLatency" rather than float point, e.g "13.4" -> "13400"

[jaredlockhart]

To correlate multiple pings, we will use an eventID which will be shared across multiple pings which correspond to the same 'event', or in this case, a single invocation of a method.

We can use the addon SDK's uuid method found here:

https://developer.mozilla.org/en-US/Add-ons/SDK/Low-Level_APIs/util_uuid

getEvent(eventData) {
    // eventData can contain additional data to send to the payload
    return Object.assign({}, eventData, {eventID: uuid()});
}

Tracking a performance ping will have 3 parameters:

event : Event
eventName : str  ex "previewCacheHit"
value : int

We would like to track the following messages in the following places

https://github.com/mozilla/activity-stream/blob/master/lib/ActivityStreams.js#L154-L159

const event = tracker.getEvent({source: responseType});

track(event, 'previewCacheRequest', responseType, links.length)

track(event, 'previewCacheHits', responseType, result.length)

track(event, 'previewCacheMisses', responseType, links.length - result.length)

activity-stream/lib/PreviewProvider.js

Line 288 in 7c51cd6

_asyncFetchAndCache: Task.async(function*(newLinks, updateAccessTime = true) {

track(event, 'embedlyProxyRequestSentCount', newLinks.length)

track(event, 'embedlyProxyRequestTime', <duration of request in milliseconds>)

track(event, 'embedlyProxyRequestSuccess', 1) if request is successful ie 200

track(event, 'embedlyProxyRequestFailure', 1) if request is failure ie !200

track(event, 'embedlyProxyRequestReceivedCount', responseJson.urls.length)

Redacted:

track(event, 'embedlyProxyRequestError', 1) if response.error is not null

A single performance ping should contain:

(timestamp: unix timestamp, userID: str, eventName: str, eventID: str, value: int)