1 files changed, 108 insertions, 0 deletions
diff --git a/devtools/client/memory/test/browser/browser_memory_refresh_does_not_leak.js b/devtools/client/memory/test/browser/browser_memory_refresh_does_not_leak.js
new file mode 100644
index 000000000..7ab768b01
--- /dev/null
+++ b/devtools/client/memory/test/browser/browser_memory_refresh_does_not_leak.js
@@ -0,0 +1,108 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that refreshing the page with devtools open does not leak the old
+// windows from previous navigations.
+//
+// IF THIS TEST STARTS FAILING, YOU ARE LEAKING EVERY WINDOW EVER NAVIGATED TO
+// WHILE DEVTOOLS ARE OPEN! THIS IS NOT SPECIFIC TO THE MEMORY TOOL ONLY!
+
+"use strict";
+
+const HeapSnapshotFileUtils = require("devtools/shared/heapsnapshot/HeapSnapshotFileUtils");
+const { getLabelAndShallowSize } = require("devtools/shared/heapsnapshot/DominatorTreeNode");
+
+const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_empty.html";
+
+function* getWindowsInSnapshot(front) {
+  dumpn("Taking snapshot.");
+  const path = yield front.saveHeapSnapshot();
+  dumpn("Took snapshot with path = " + path);
+  const snapshot = ChromeUtils.readHeapSnapshot(path);
+  dumpn("Read snapshot into memory, taking census.");
+  const report = snapshot.takeCensus({
+    breakdown: {
+      by: "objectClass",
+      then: { by: "bucket" },
+      other: { by: "count", count: true, bytes: false },
+    }
+  });
+  dumpn("Took census, window count = " + report.Window.count);
+  return report.Window;
+}
+
+const DESCRIPTION = {
+  by: "coarseType",
+  objects: {
+    by: "objectClass",
+    then: { by: "count", count: true, bytes: false },
+    other: { by: "count", count: true, bytes: false },
+  },
+  strings: { by: "count", count: true, bytes: false },
+  scripts: {
+    by: "internalType",
+    then: { by: "count", count: true, bytes: false },
+  },
+  other: {
+    by: "internalType",
+    then: { by: "count", count: true, bytes: false },
+  }
+};
+
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
+  const heapWorker = panel.panelWin.gHeapAnalysesClient;
+  const front = panel.panelWin.gFront;
+  const store = panel.panelWin.gStore;
+  const { getState, dispatch } = store;
+  const doc = panel.panelWin.document;
+
+  const startWindows = yield getWindowsInSnapshot(front);
+  dumpn("Initial windows found = " + startWindows.map(w => "0x" + w.toString(16)).join(", "));
+  is(startWindows.length, 1);
+
+  yield refreshTab(tab);
+
+  const endWindows = yield getWindowsInSnapshot(front);
+  is(endWindows.length, 1);
+
+  if (endWindows.length === 1) {
+    return;
+  }
+
+  dumpn("Test failed, diagnosing leaking windows.");
+  dumpn("(This may fail if a moving GC has relocated the initial Window objects.)");
+
+  dumpn("Taking full runtime snapshot.");
+  const path = yield front.saveHeapSnapshot({ boundaries: { runtime: true } });
+  dumpn("Full runtime's snapshot path = " + path);
+
+  dumpn("Reading full runtime heap snapshot.");
+  const snapshot = ChromeUtils.readHeapSnapshot(path);
+  dumpn("Done reading full runtime heap snapshot.");
+
+  const dominatorTree = snapshot.computeDominatorTree();
+  const paths = snapshot.computeShortestPaths(dominatorTree.root, startWindows, 50);
+
+  for (let i = 0; i < startWindows.length; i++) {
+    dumpn("Shortest retaining paths for leaking Window 0x" + startWindows[i].toString(16) + " =========================");
+    let j = 0;
+    for (let retainingPath of paths.get(startWindows[i])) {
+      if (retainingPath.find(part => part.predecessor === startWindows[i])) {
+        // Skip paths that loop out from the target window and back to it again.
+        continue;
+      }
+
+      dumpn("    Path #" + (++j) + ": --------------------------------------------------------------------");
+      for (let part of retainingPath) {
+        const { label } = getLabelAndShallowSize(part.predecessor, snapshot, DESCRIPTION);
+        dumpn("        0x" + part.predecessor.toString(16) +
+              " (" + label.join(" > ") + ")");
+        dumpn("               |");
+        dumpn("              " + part.edge);
+        dumpn("               |");
+        dumpn("               V");
+      }
+      dumpn("        0x" + startWindows[i].toString(16) + " (objects > Window)");
+    }
+  }
+});