add support for an optional handler for each pin log

great for analyzing which files are most in need of optimization

lib/pins.js

@@ -28,7 +28,8 @@ var createLineHandler = Pins.createLineHandler = function (ref, errorHandler) {
     // it's a weird API but it's faster than unpinning manually
     var pins = ref.pins = {};
     ref.index = 0;
-    ref.latest = 0;
+    ref.latest = 0; // the latest message (timestamp in ms)
+    ref.surplus = 0; // how many lines exist behind a reset
     return function (line) {
         ref.index++;
         if (!Boolean(line)) { return; }
@@ -52,6 +53,7 @@ var createLineHandler = Pins.createLineHandler = function (ref, errorHandler) {
             case 'RESET': {
                 pins = ref.pins = {};
                 if (l[1] && l[1].length) { l[1].forEach((x) => { ref.pins[x] = 1; }); }
+                ref.surplus = ref.index;
                 //jshint -W086
                 // fallthrough
             }
@@ -90,9 +92,14 @@ Pins.calculateFromLog = function (pinFile, fileName) {
     pins/A+/A+hyhrQLrgYixOomZYxpuEhwfiVzKk1bBp+arH-zbgo=.ndjson
 */
 
+const getSafeKeyFromPath = function (path) {
+    return path.replace(/^.*\//, '').replace(/\.ndjson/, '');
+}
+
 Pins.list = function (done, config) {
     const pinPath = config.pinPath || './data/pins';
-    const plan = Plan(5);
+    const plan = Plan(config.workers || 5);
+    const handler = config.handler || function () {};
 
     // TODO externalize this via optional handlers?
     const stats = {
@@ -106,8 +113,12 @@ Pins.list = function (done, config) {
         console.log(label, info);
     };
 
+    const pinned = {};
+
     // TODO replace this with lib-readline?
     const streamFile = function (path, cb) {
+        const id = getSafeKeyFromPath(path);
+
         return void Fs.readFile(path, 'utf8', function (err, body) {
             if (err) { return void cb(err); }
             const ref = {};
@@ -115,6 +126,7 @@ Pins.list = function (done, config) {
             var lines = body.split('\n');
             stats.lines += lines.length;
             lines.forEach(pinHandler);
+            handler(ref, id, pinned);
             cb(void 0, ref);
         });
     };
@@ -130,8 +142,6 @@ Pins.list = function (done, config) {
         });
     };
 
-    const pinned = {};
-
     scanDirectory(pinPath, function (err, paths) {
         if (err) { return; } // XXX
         paths.forEach(function (path) {