Bug 941685 - Ping metrics server with snippets impression data. r=bnicholson

mobile/android/app/mobile.js

@@ -800,5 +800,8 @@ pref("browser.snippets.updateInterval", 86400);
 // URL used to check for user's country code
 pref("browser.snippets.geoUrl", "https://geo.mozilla.org/country.json");
 
+// URL used to ping metrics with stats about which snippets have been shown
+pref("browser.snippets.statsUrl", "https://snippets-stats.mozilla.org/mobile");
+
 // This pref requires a restart to take effect.
 pref("browser.snippets.enabled", false);

mobile/android/components/Snippets.js

@@ -9,6 +9,7 @@ Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "Home", "resource://gre/modules/Home.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "OS", "resource://gre/modules/osfile.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "Task", "resource://gre/modules/Task.jsm");
 
 XPCOMUtils.defineLazyGetter(this, "gEncoder", function() { return new gChromeWin.TextEncoder(); });
 XPCOMUtils.defineLazyGetter(this, "gDecoder", function() { return new gChromeWin.TextDecoder(); });
@@ -18,6 +19,9 @@ const SNIPPETS_ENABLED = Services.prefs.getBoolPref("browser.snippets.enabled");
 // URL to fetch snippets, in the urlFormatter service format.
 const SNIPPETS_UPDATE_URL_PREF = "browser.snippets.updateUrl";
 
+// URL to send stats data to metrics.
+const SNIPPETS_STATS_URL_PREF = "browser.snippets.statsUrl";
+
 // URL to fetch country code, a value that's cached and refreshed once per month.
 const SNIPPETS_GEO_URL_PREF = "browser.snippets.geoUrl";
 
@@ -38,6 +42,20 @@ XPCOMUtils.defineLazyGetter(this, "gSnippetsURL", function() {
   return Services.urlFormatter.formatURL(updateURL);
 });
 
+// Where we cache snippets data
+XPCOMUtils.defineLazyGetter(this, "gSnippetsPath", function() {
+  return OS.Path.join(OS.Constants.Path.profileDir, "snippets.json");
+});
+
+XPCOMUtils.defineLazyGetter(this, "gStatsURL", function() {
+  return Services.prefs.getCharPref(SNIPPETS_STATS_URL_PREF);
+});
+
+// Where we store stats about which snippets have been shown
+XPCOMUtils.defineLazyGetter(this, "gStatsPath", function() {
+  return OS.Path.join(OS.Constants.Path.profileDir, "snippets-stats.txt");
+});
+
 XPCOMUtils.defineLazyGetter(this, "gGeoURL", function() {
   return Services.prefs.getCharPref(SNIPPETS_GEO_URL_PREF);
 });
@@ -109,9 +127,8 @@ function updateSnippets() {
  * @param response responseText returned from snippets server
  */
 function cacheSnippets(response) {
-  let path = OS.Path.join(OS.Constants.Path.profileDir, "snippets.json");
   let data = gEncoder.encode(response);
-  let promise = OS.File.writeAtomic(path, data, { tmpPath: path + ".tmp" });
+  let promise = OS.File.writeAtomic(gSnippetsPath, data, { tmpPath: gSnippetsPath + ".tmp" });
   promise.then(null, e => Cu.reportError("Error caching snippets: " + e));
 }
 
@@ -119,8 +136,7 @@ function cacheSnippets(response) {
  * Loads snippets from cached `snippets.json`.
  */
 function loadSnippetsFromCache() {
-  let path = OS.Path.join(OS.Constants.Path.profileDir, "snippets.json");
-  let promise = OS.File.read(path);
+  let promise = OS.File.read(gSnippetsPath);
   promise.then(array => updateBanner(gDecoder.decode(array)), e => {
     // If snippets.json doesn't exist, update data from the server.
     if (e instanceof OS.File.Error && e.becauseNoSuchFile) {
@@ -167,7 +183,10 @@ function updateBanner(response) {
         gChromeWin.BrowserApp.addTab(message.url);
       },
       onshown: function() {
-        // XXX: 10% of the time, let the metrics server know which message was shown (bug 937373)
+        // 10% of the time, record the snippet id and a timestamp
+        if (Math.random() < .1) {
+          writeStat(message.id, new Date().toISOString());
+        }
       }
     });
     // Keep track of the message we added so that we can remove it later.
@@ -175,6 +194,76 @@ function updateBanner(response) {
   });
 }
 
+/**
+ * Appends snippet id and timestamp to the end of `snippets-stats.txt`.
+ *
+ * @param snippetId unique id for snippet, sent from snippets server
+ * @param timestamp in ISO8601
+ */
+function writeStat(snippetId, timestamp) {
+  let data = gEncoder.encode(snippetId + "," + timestamp + ";");
+
+  Task.spawn(function() {
+    try {
+      let file = yield OS.File.open(gStatsPath, { append: true, write: true });
+      try {
+        yield file.write(data);
+      } finally {
+        yield file.close();
+      }
+    } catch (ex if ex instanceof OS.File.Error && ex.becauseNoSuchFile) {
+      // If the file doesn't exist yet, create it.
+      yield OS.File.writeAtomic(gStatsPath, data, { tmpPath: gStatsPath + ".tmp" });
+    }
+  }).then(null, e => Cu.reportError("Error writing snippets stats: " + e));
+}
+
+/**
+ * Reads snippets stats data from `snippets-stats.txt` and sends the data to metrics.
+ */
+function sendStats() {
+  let promise = OS.File.read(gStatsPath);
+  promise.then(array => sendStatsRequest(gDecoder.decode(array)), e => {
+    if (e instanceof OS.File.Error && e.becauseNoSuchFile) {
+      // If the file doesn't exist, there aren't any stats to send.
+    } else {
+      Cu.reportError("Error eading snippets stats: " + e);
+    }
+  });
+}
+
+/**
+ * Sends stats to metrics about which snippets have been shown.
+ * Appends snippet ids and timestamps as parameters to a GET request.
+ * e.g. https://snippets-stats.mozilla.org/mobile?s1=3825&t1=2013-11-17T18:27Z&s2=6326&t2=2013-11-18T18:27Z
+ *
+ * @param data contents of stats data file
+ */
+function sendStatsRequest(data) {
+  let params = [];
+  let stats = data.split(";");
+
+  // The last item in the array will be an empty string, so stop before then.
+  for (let i = 0; i < stats.length - 1; i++) {
+    let stat = stats[i].split(",");
+    params.push("s" + i + "=" + encodeURIComponent(stat[0]));
+    params.push("t" + i + "=" + encodeURIComponent(stat[1]));
+  }
+
+  let url = gStatsURL + "?" + params.join("&");
+
+  // Remove the file after succesfully sending the data.
+  _httpGetRequest(url, removeStats);
+}
+
+/**
+ * Removes text file where we store snippets stats.
+ */
+function removeStats() {
+  let promise = OS.File.remove(gStatsPath);
+  promise.then(null, e => Cu.reportError("Error removing snippets stats: " + e));
+}
+
 /**
  * Helper function to make HTTP GET requests.
  *
@@ -227,6 +316,7 @@ Snippets.prototype = {
       return;
     }
     update();
+    sendStats();
   }
 };