Fix #158: Add 'attempt_extraction' and 'complete_extraction' probes

* Update 'method' extra key for 'complete_extraction' event to have values of 'fathom', 'css_selectors', 'open_graph' or 'none' to distinguish between the two fallback extraction methods to Fathom: CSS Selectors or Open Graph attributes.
  * Note: Since none of our five supported sites use Open Graph attributes currently for product information, we should not expect to see any successful extraction using that method for the MVP.
* Important caveats for making conclusions using these probes as-is:
  * The coverage values that these probes will suggest will not be very accurate initially until we ensure we are extracting on only **product pages** for a supported site, rather than any page on the site (see Issues #225 and #181).
  * Successful extraction does not mean that the information extracted for the product is correct. It only means that _a_ value was extracted for each product feature (i.e. title, image and price) on the page.

docs/METRICS.md

@@ -140,7 +140,7 @@ Below is a sample ping for the `badge_toolbar_button` and `visit_supported_site`
 - `'badge_type'`: Indicates what, if any, badge was present on the browserAction toolbar button. One of 'add', 'price_alert', or 'none'. A value of 'unknown' is possible if the badge text is unrecognized.
 - `'extraction_id'`: A unique identifier to associate an extraction attempt to an extraction completion event for a given page.
 - `'is_bg_update'`: 'true' if the extraction is associated with a background price check; otherwise 'false'.
-- `method`: The extraction method that was successful, if any. One of: 'fathom', 'fallback' or 'neither'. A value of 'neither' means that extraction failed.
+- `method`: The extraction method that was successful, if any. One of: 'fathom', 'css_selectors', 'open_graph' or 'none'. A value of 'none' means that all extraction methods failed.
 - `'price'`: The price of the product in subunits (e.g. a $10.00 product would have a value of `'1000'`). For the MVP, the units here are always cents (USD currency only).
 - `'price_alert'`: 'true' if the product has an active Price Alert; otherwise 'false'.
 - `'price_last_high'`: The last high price of the product in subunits (e.g. a $10.00 product would have a value of `'1000'`). For the MVP, the units here are always cents (USD currency only).

src/extraction/index.js

@@ -8,9 +8,11 @@
  * been parsed but before all resources have been loaded.
  */
 
+import uuidv4 from 'uuid/v4';
+
 import config from 'commerce/config/content';
 import extractProductWithFathom from 'commerce/extraction/fathom';
-import extractProductWithFallback from 'commerce/extraction/selector';
+import extractProductWithCSSSelectors from 'commerce/extraction/selector';
 import extractProductWithOpenGraph from 'commerce/extraction/open_graph';
 import {shouldExtract} from 'commerce/privacy';
 import recordEvent from 'commerce/telemetry/content';
@@ -20,25 +22,39 @@ import recordEvent from 'commerce/telemetry/content';
  * return either a valid ExtractedProduct, or null if a valid product could not
  * be found.
  */
-const EXTRACTION_METHODS = [
-  extractProductWithFathom,
-  extractProductWithFallback,
-  extractProductWithOpenGraph,
-];
+const EXTRACTION_METHODS = {
+  fathom: extractProductWithFathom,
+  css_selectors: extractProductWithCSSSelectors,
+  open_graph: extractProductWithOpenGraph,
+};
 
 /**
  * Perform product extraction, trying each method from EXTRACTION_METHODS in
  * order until one of them returns a truthy result.
  * @return {ExtractedProduct|null}
  */
-function extractProduct() {
-  for (const extract of EXTRACTION_METHODS) {
+function extractProduct(isBackgroundUpdate) {
+  const baseExtra = {
+    extraction_id: uuidv4(),
+    is_bg_update: isBackgroundUpdate,
+  };
+  recordEvent('attempt_extraction', 'product_page', null, {
+    ...baseExtra,
+  });
+  for (const [method, extract] of Object.entries(EXTRACTION_METHODS)) {
     const extractedProduct = extract(window.document);
     if (extractedProduct) {
+      recordEvent('complete_extraction', 'product_page', null, {
+        ...baseExtra,
+        method,
+      });
       return extractedProduct;
     }
   }
-
+  recordEvent('complete_extraction', 'product_page', null, {
+    ...baseExtra,
+    method: 'none',
+  });
   return null;
 }
 
@@ -58,8 +74,8 @@ async function sendProductToBackground(extractedProduct, sendTelemetry) {
  * Checks to see if any product information for the page was found,
  * and if so, sends it to the background script.
  */
-async function attemptExtraction() {
-  const extractedProduct = extractProduct();
+async function attemptExtraction(isBackgroundUpdate) {
+  const extractedProduct = extractProduct(isBackgroundUpdate);
   if (extractedProduct) {
     await sendProductToBackground(extractedProduct);
   }
@@ -105,9 +121,9 @@ async function attemptExtraction() {
   }
 
   // Extract immediately, and again if the readyState changes.
-  let extractedProduct = await attemptExtraction();
+  let extractedProduct = await attemptExtraction(isBackgroundUpdate);
   document.addEventListener('readystatechange', async () => {
-    extractedProduct = await attemptExtraction();
+    extractedProduct = await attemptExtraction(isBackgroundUpdate);
   });
 
   // Messy workaround for bug 1493470: Resend product info to the background