Add m-esr52 at 52.6.0

1 files changed, 865 insertions, 0 deletions

diff --git a/devtools/client/memory/actions/snapshot.js b/devtools/client/memory/actions/snapshot.js
new file mode 100644
index 000000000..adb24977e
--- /dev/null
+++ b/devtools/client/memory/actions/snapshot.js
@@ -0,0 +1,865 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+const { Preferences } = require("resource://gre/modules/Preferences.jsm");
+const { assert, reportException, isSet } = require("devtools/shared/DevToolsUtils");
+const {
+  censusIsUpToDate,
+  getSnapshot,
+  createSnapshot,
+  dominatorTreeIsComputed,
+} = require("../utils");
+const {
+  actions,
+  snapshotState: states,
+  viewState,
+  censusState,
+  treeMapState,
+  dominatorTreeState,
+  individualsState,
+} = require("../constants");
+const telemetry = require("../telemetry");
+const view = require("./view");
+const refresh = require("./refresh");
+const diffing = require("./diffing");
+const TaskCache = require("./task-cache");
+
+/**
+ * A series of actions are fired from this task to save, read and generate the
+ * initial census from a snapshot.
+ *
+ * @param {MemoryFront}
+ * @param {HeapAnalysesClient}
+ * @param {Object}
+ */
+const takeSnapshotAndCensus = exports.takeSnapshotAndCensus = function (front, heapWorker) {
+  return function* (dispatch, getState) {
+    const id = yield dispatch(takeSnapshot(front));
+    if (id === null) {
+      return;
+    }
+
+    yield dispatch(readSnapshot(heapWorker, id));
+    if (getSnapshot(getState(), id).state !== states.READ) {
+      return;
+    }
+
+    yield dispatch(computeSnapshotData(heapWorker, id));
+  };
+};
+
+/**
+ * Create the census for the snapshot with the provided snapshot id. If the
+ * current view is the DOMINATOR_TREE view, create the dominator tree for this
+ * snapshot as well.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ * @param {snapshotId} id
+ */
+const computeSnapshotData = exports.computeSnapshotData = function (heapWorker, id) {
+  return function* (dispatch, getState) {
+    if (getSnapshot(getState(), id).state !== states.READ) {
+      return;
+    }
+
+    // Decide which type of census to take.
+    const censusTaker = getCurrentCensusTaker(getState().view.state);
+    yield dispatch(censusTaker(heapWorker, id));
+
+    if (getState().view.state === viewState.DOMINATOR_TREE &&
+        !getSnapshot(getState(), id).dominatorTree) {
+      yield dispatch(computeAndFetchDominatorTree(heapWorker, id));
+    }
+  };
+};
+
+/**
+ * Selects a snapshot and if the snapshot's census is using a different
+ * display, take a new census.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ * @param {snapshotId} id
+ */
+const selectSnapshotAndRefresh = exports.selectSnapshotAndRefresh = function (heapWorker, id) {
+  return function* (dispatch, getState) {
+    if (getState().diffing || getState().individuals) {
+      dispatch(view.changeView(viewState.CENSUS));
+    }
+
+    dispatch(selectSnapshot(id));
+    yield dispatch(refresh.refresh(heapWorker));
+  };
+};
+
+/**
+ * Take a snapshot and return its id on success, or null on failure.
+ *
+ * @param {MemoryFront} front
+ * @returns {Number|null}
+ */
+const takeSnapshot = exports.takeSnapshot = function (front) {
+  return function* (dispatch, getState) {
+    telemetry.countTakeSnapshot();
+
+    if (getState().diffing || getState().individuals) {
+      dispatch(view.changeView(viewState.CENSUS));
+    }
+
+    const snapshot = createSnapshot(getState());
+    const id = snapshot.id;
+    dispatch({ type: actions.TAKE_SNAPSHOT_START, snapshot });
+    dispatch(selectSnapshot(id));
+
+    let path;
+    try {
+      path = yield front.saveHeapSnapshot();
+    } catch (error) {
+      reportException("takeSnapshot", error);
+      dispatch({ type: actions.SNAPSHOT_ERROR, id, error });
+      return null;
+    }
+
+    dispatch({ type: actions.TAKE_SNAPSHOT_END, id, path });
+    return snapshot.id;
+  };
+};
+
+/**
+ * Reads a snapshot into memory; necessary to do before taking
+ * a census on the snapshot. May only be called once per snapshot.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ * @param {snapshotId} id
+ */
+const readSnapshot = exports.readSnapshot =
+TaskCache.declareCacheableTask({
+  getCacheKey(_, id) {
+    return id;
+  },
+
+  task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
+    const snapshot = getSnapshot(getState(), id);
+    assert([states.SAVED, states.IMPORTING].includes(snapshot.state),
+           `Should only read a snapshot once. Found snapshot in state ${snapshot.state}`);
+
+    let creationTime;
+
+    dispatch({ type: actions.READ_SNAPSHOT_START, id });
+    try {
+      yield heapWorker.readHeapSnapshot(snapshot.path);
+      creationTime = yield heapWorker.getCreationTime(snapshot.path);
+    } catch (error) {
+      removeFromCache();
+      reportException("readSnapshot", error);
+      dispatch({ type: actions.SNAPSHOT_ERROR, id, error });
+      return;
+    }
+
+    removeFromCache();
+    dispatch({ type: actions.READ_SNAPSHOT_END, id, creationTime });
+  }
+});
+
+let takeCensusTaskCounter = 0;
+
+/**
+ * Census and tree maps both require snapshots. This function shares the logic
+ * of creating snapshots, but is configurable with specific actions for the
+ * individual census types.
+ *
+ * @param {getDisplay} Get the display object from the state.
+ * @param {getCensus} Get the census from the snapshot.
+ * @param {beginAction} Action to send at the beginning of a heap snapshot.
+ * @param {endAction} Action to send at the end of a heap snapshot.
+ * @param {errorAction} Action to send if a snapshot has an error.
+ */
+function makeTakeCensusTask({ getDisplay, getFilter, getCensus, beginAction,
+                              endAction, errorAction, canTakeCensus }) {
+  /**
+   * @param {HeapAnalysesClient} heapWorker
+   * @param {snapshotId} id
+   *
+   * @see {Snapshot} model defined in devtools/client/memory/models.js
+   * @see `devtools/shared/heapsnapshot/HeapAnalysesClient.js`
+   * @see `js/src/doc/Debugger/Debugger.Memory.md` for breakdown details
+   */
+  let thisTakeCensusTaskId = ++takeCensusTaskCounter;
+  return TaskCache.declareCacheableTask({
+    getCacheKey(_, id) {
+      return `take-census-task-${thisTakeCensusTaskId}-${id}`;
+    },
+
+    task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
+      const snapshot = getSnapshot(getState(), id);
+      if (!snapshot) {
+        removeFromCache();
+        return;
+      }
+
+      // Assert that snapshot is in a valid state
+      assert(canTakeCensus(snapshot),
+             `Attempting to take a census when the snapshot is not in a ready state. snapshot.state = ${snapshot.state}, census.state = ${(getCensus(snapshot) || { state: null }).state}`);
+
+      let report, parentMap;
+      let display = getDisplay(getState());
+      let filter = getFilter(getState());
+
+      // If display, filter and inversion haven't changed, don't do anything.
+      if (censusIsUpToDate(filter, display, getCensus(snapshot))) {
+        removeFromCache();
+        return;
+      }
+
+      // Keep taking a census if the display changes while our request is in
+      // flight. Recheck that the display used for the census is the same as the
+      // state's display.
+      do {
+        display = getDisplay(getState());
+        filter = getState().filter;
+
+        dispatch({
+          type: beginAction,
+          id,
+          filter,
+          display
+        });
+
+        let opts = display.inverted
+          ? { asInvertedTreeNode: true }
+          : { asTreeNode: true };
+
+        opts.filter = filter || null;
+
+        try {
+          ({ report, parentMap } = yield heapWorker.takeCensus(
+            snapshot.path,
+            { breakdown: display.breakdown },
+            opts));
+        } catch (error) {
+          removeFromCache();
+          reportException("takeCensus", error);
+          dispatch({ type: errorAction, id, error });
+          return;
+        }
+      }
+      while (filter !== getState().filter ||
+             display !== getDisplay(getState()));
+
+      removeFromCache();
+      dispatch({
+        type: endAction,
+        id,
+        display,
+        filter,
+        report,
+        parentMap
+      });
+
+      telemetry.countCensus({ filter, display });
+    }
+  });
+}
+
+/**
+ * Take a census.
+ */
+const takeCensus = exports.takeCensus = makeTakeCensusTask({
+  getDisplay: (state) => state.censusDisplay,
+  getFilter: (state) => state.filter,
+  getCensus: (snapshot) => snapshot.census,
+  beginAction: actions.TAKE_CENSUS_START,
+  endAction: actions.TAKE_CENSUS_END,
+  errorAction: actions.TAKE_CENSUS_ERROR,
+  canTakeCensus: snapshot =>
+    snapshot.state === states.READ &&
+    (!snapshot.census || snapshot.census.state === censusState.SAVED),
+});
+
+/**
+ * Take a census for the treemap.
+ */
+const takeTreeMap = exports.takeTreeMap = makeTakeCensusTask({
+  getDisplay: (state) => state.treeMapDisplay,
+  getFilter: () => null,
+  getCensus: (snapshot) => snapshot.treeMap,
+  beginAction: actions.TAKE_TREE_MAP_START,
+  endAction: actions.TAKE_TREE_MAP_END,
+  errorAction: actions.TAKE_TREE_MAP_ERROR,
+  canTakeCensus: snapshot =>
+    snapshot.state === states.READ &&
+    (!snapshot.treeMap || snapshot.treeMap.state === treeMapState.SAVED),
+});
+
+/**
+ * Define what should be the default mode for taking a census based on the
+ * default view of the tool.
+ */
+const defaultCensusTaker = takeTreeMap;
+
+/**
+ * Pick the default census taker when taking a snapshot. This should be
+ * determined by the current view. If the view doesn't include a census, then
+ * use the default one defined above. Some census information is always needed
+ * to display some basic information about a snapshot.
+ *
+ * @param {string} value from viewState
+ */
+const getCurrentCensusTaker = exports.getCurrentCensusTaker = function (currentView) {
+  switch (currentView) {
+    case viewState.TREE_MAP:
+      return takeTreeMap;
+    case viewState.CENSUS:
+      return takeCensus;
+    default:
+      return defaultCensusTaker;
+  }
+};
+
+/**
+ * Focus the given node in the individuals view.
+ *
+ * @param {DominatorTreeNode} node.
+ */
+const focusIndividual = exports.focusIndividual = function (node) {
+  return {
+    type: actions.FOCUS_INDIVIDUAL,
+    node,
+  };
+};
+
+/**
+ * Fetch the individual `DominatorTreeNodes` for the census group specified by
+ * `censusBreakdown` and `reportLeafIndex`.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ * @param {SnapshotId} id
+ * @param {Object} censusBreakdown
+ * @param {Set<Number> | Number} reportLeafIndex
+ */
+const fetchIndividuals = exports.fetchIndividuals =
+function (heapWorker, id, censusBreakdown, reportLeafIndex) {
+  return function* (dispatch, getState) {
+    if (getState().view.state !== viewState.INDIVIDUALS) {
+      dispatch(view.changeView(viewState.INDIVIDUALS));
+    }
+
+    const snapshot = getSnapshot(getState(), id);
+    assert(snapshot && snapshot.state === states.READ,
+           "The snapshot should already be read into memory");
+
+    if (!dominatorTreeIsComputed(snapshot)) {
+      yield dispatch(computeAndFetchDominatorTree(heapWorker, id));
+    }
+
+    const snapshot_ = getSnapshot(getState(), id);
+    assert(snapshot_.dominatorTree && snapshot_.dominatorTree.root,
+           "Should have a dominator tree with a root.");
+
+    const dominatorTreeId = snapshot_.dominatorTree.dominatorTreeId;
+
+    const indices = isSet(reportLeafIndex)
+      ? reportLeafIndex
+      : new Set([reportLeafIndex]);
+
+    let labelDisplay;
+    let nodes;
+    do {
+      labelDisplay = getState().labelDisplay;
+      assert(labelDisplay && labelDisplay.breakdown && labelDisplay.breakdown.by,
+             `Should have a breakdown to label nodes with, got: ${uneval(labelDisplay)}`);
+
+      if (getState().view.state !== viewState.INDIVIDUALS) {
+        // We switched views while in the process of fetching individuals -- any
+        // further work is useless.
+        return;
+      }
+
+      dispatch({ type: actions.FETCH_INDIVIDUALS_START });
+
+      try {
+        ({ nodes } = yield heapWorker.getCensusIndividuals({
+          dominatorTreeId,
+          indices,
+          censusBreakdown,
+          labelBreakdown: labelDisplay.breakdown,
+          maxRetainingPaths: Preferences.get("devtools.memory.max-retaining-paths"),
+          maxIndividuals: Preferences.get("devtools.memory.max-individuals"),
+        }));
+      } catch (error) {
+        reportException("actions/snapshot/fetchIndividuals", error);
+        dispatch({ type: actions.INDIVIDUALS_ERROR, error });
+        return;
+      }
+    }
+    while (labelDisplay !== getState().labelDisplay);
+
+    dispatch({
+      type: actions.FETCH_INDIVIDUALS_END,
+      id,
+      censusBreakdown,
+      indices,
+      labelDisplay,
+      nodes,
+      dominatorTree: snapshot_.dominatorTree,
+    });
+  };
+};
+
+/**
+ * Refresh the current individuals view.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ */
+const refreshIndividuals = exports.refreshIndividuals = function (heapWorker) {
+  return function* (dispatch, getState) {
+    assert(getState().view.state === viewState.INDIVIDUALS,
+           "Should be in INDIVIDUALS view.");
+
+    const { individuals } = getState();
+
+    switch (individuals.state) {
+      case individualsState.COMPUTING_DOMINATOR_TREE:
+      case individualsState.FETCHING:
+        // Nothing to do here.
+        return;
+
+      case individualsState.FETCHED:
+        if (getState().individuals.labelDisplay === getState().labelDisplay) {
+          return;
+        }
+        break;
+
+      case individualsState.ERROR:
+        // Doesn't hurt to retry: maybe we won't get an error this time around?
+        break;
+
+      default:
+        assert(false, `Unexpected individuals state: ${individuals.state}`);
+        return;
+    }
+
+    yield dispatch(fetchIndividuals(heapWorker,
+                                    individuals.id,
+                                    individuals.censusBreakdown,
+                                    individuals.indices));
+  };
+};
+
+/**
+ * Refresh the selected snapshot's census data, if need be (for example,
+ * display configuration changed).
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ */
+const refreshSelectedCensus = exports.refreshSelectedCensus = function (heapWorker) {
+  return function* (dispatch, getState) {
+    let snapshot = getState().snapshots.find(s => s.selected);
+    if (!snapshot || snapshot.state !== states.READ) {
+      return;
+    }
+
+    // Intermediate snapshot states will get handled by the task action that is
+    // orchestrating them. For example, if the snapshot census's state is
+    // SAVING, then the takeCensus action will keep taking a census until
+    // the inverted property matches the inverted state. If the snapshot is
+    // still in the process of being saved or read, the takeSnapshotAndCensus
+    // task action will follow through and ensure that a census is taken.
+    if ((snapshot.census && snapshot.census.state === censusState.SAVED) ||
+        !snapshot.census) {
+      yield dispatch(takeCensus(heapWorker, snapshot.id));
+    }
+  };
+};
+
+/**
+ * Refresh the selected snapshot's tree map data, if need be (for example,
+ * display configuration changed).
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ */
+const refreshSelectedTreeMap = exports.refreshSelectedTreeMap = function (heapWorker) {
+  return function* (dispatch, getState) {
+    let snapshot = getState().snapshots.find(s => s.selected);
+    if (!snapshot || snapshot.state !== states.READ) {
+      return;
+    }
+
+    // Intermediate snapshot states will get handled by the task action that is
+    // orchestrating them. For example, if the snapshot census's state is
+    // SAVING, then the takeCensus action will keep taking a census until
+    // the inverted property matches the inverted state. If the snapshot is
+    // still in the process of being saved or read, the takeSnapshotAndCensus
+    // task action will follow through and ensure that a census is taken.
+    if ((snapshot.treeMap && snapshot.treeMap.state === treeMapState.SAVED) ||
+        !snapshot.treeMap) {
+      yield dispatch(takeTreeMap(heapWorker, snapshot.id));
+    }
+  };
+};
+
+/**
+ * Request that the `HeapAnalysesWorker` compute the dominator tree for the
+ * snapshot with the given `id`.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ * @param {SnapshotId} id
+ *
+ * @returns {Promise<DominatorTreeId>}
+ */
+const computeDominatorTree = exports.computeDominatorTree =
+TaskCache.declareCacheableTask({
+  getCacheKey(_, id) {
+    return id;
+  },
+
+  task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
+    const snapshot = getSnapshot(getState(), id);
+    assert(!(snapshot.dominatorTree && snapshot.dominatorTree.dominatorTreeId),
+           "Should not re-compute dominator trees");
+
+    dispatch({ type: actions.COMPUTE_DOMINATOR_TREE_START, id });
+
+    let dominatorTreeId;
+    try {
+      dominatorTreeId = yield heapWorker.computeDominatorTree(snapshot.path);
+    } catch (error) {
+      removeFromCache();
+      reportException("actions/snapshot/computeDominatorTree", error);
+      dispatch({ type: actions.DOMINATOR_TREE_ERROR, id, error });
+      return null;
+    }
+
+    removeFromCache();
+    dispatch({ type: actions.COMPUTE_DOMINATOR_TREE_END, id, dominatorTreeId });
+    return dominatorTreeId;
+  }
+});
+
+/**
+ * Get the partial subtree, starting from the root, of the
+ * snapshot-with-the-given-id's dominator tree.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ * @param {SnapshotId} id
+ *
+ * @returns {Promise<DominatorTreeNode>}
+ */
+const fetchDominatorTree = exports.fetchDominatorTree =
+TaskCache.declareCacheableTask({
+  getCacheKey(_, id) {
+    return id;
+  },
+
+  task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
+    const snapshot = getSnapshot(getState(), id);
+    assert(dominatorTreeIsComputed(snapshot),
+           "Should have dominator tree model and it should be computed");
+
+    let display;
+    let root;
+    do {
+      display = getState().labelDisplay;
+      assert(display && display.breakdown,
+             `Should have a breakdown to describe nodes with, got: ${uneval(display)}`);
+
+      dispatch({ type: actions.FETCH_DOMINATOR_TREE_START, id, display });
+
+      try {
+        root = yield heapWorker.getDominatorTree({
+          dominatorTreeId: snapshot.dominatorTree.dominatorTreeId,
+          breakdown: display.breakdown,
+          maxRetainingPaths: Preferences.get("devtools.memory.max-retaining-paths"),
+        });
+      } catch (error) {
+        removeFromCache();
+        reportException("actions/snapshot/fetchDominatorTree", error);
+        dispatch({ type: actions.DOMINATOR_TREE_ERROR, id, error });
+        return null;
+      }
+    }
+    while (display !== getState().labelDisplay);
+
+    removeFromCache();
+    dispatch({ type: actions.FETCH_DOMINATOR_TREE_END, id, root });
+    telemetry.countDominatorTree({ display });
+    return root;
+  }
+});
+
+/**
+ * Fetch the immediately dominated children represented by the placeholder
+ * `lazyChildren` from snapshot-with-the-given-id's dominator tree.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ * @param {SnapshotId} id
+ * @param {DominatorTreeLazyChildren} lazyChildren
+ */
+const fetchImmediatelyDominated = exports.fetchImmediatelyDominated =
+TaskCache.declareCacheableTask({
+  getCacheKey(_, id, lazyChildren) {
+    return `${id}-${lazyChildren.key()}`;
+  },
+
+  task: function* (heapWorker, id, lazyChildren, removeFromCache, dispatch, getState) {
+    const snapshot = getSnapshot(getState(), id);
+    assert(snapshot.dominatorTree, "Should have dominator tree model");
+    assert(snapshot.dominatorTree.state === dominatorTreeState.LOADED ||
+           snapshot.dominatorTree.state === dominatorTreeState.INCREMENTAL_FETCHING,
+           "Cannot fetch immediately dominated nodes in a dominator tree unless " +
+           " the dominator tree has already been computed");
+
+    let display;
+    let response;
+    do {
+      display = getState().labelDisplay;
+      assert(display, "Should have a display to describe nodes with.");
+
+      dispatch({ type: actions.FETCH_IMMEDIATELY_DOMINATED_START, id });
+
+      try {
+        response = yield heapWorker.getImmediatelyDominated({
+          dominatorTreeId: snapshot.dominatorTree.dominatorTreeId,
+          breakdown: display.breakdown,
+          nodeId: lazyChildren.parentNodeId(),
+          startIndex: lazyChildren.siblingIndex(),
+          maxRetainingPaths: Preferences.get("devtools.memory.max-retaining-paths"),
+        });
+      } catch (error) {
+        removeFromCache();
+        reportException("actions/snapshot/fetchImmediatelyDominated", error);
+        dispatch({ type: actions.DOMINATOR_TREE_ERROR, id, error });
+        return null;
+      }
+    }
+    while (display !== getState().labelDisplay);
+
+    removeFromCache();
+    dispatch({
+      type: actions.FETCH_IMMEDIATELY_DOMINATED_END,
+      id,
+      path: response.path,
+      nodes: response.nodes,
+      moreChildrenAvailable: response.moreChildrenAvailable,
+    });
+  }
+});
+
+/**
+ * Compute and then fetch the dominator tree of the snapshot with the given
+ * `id`.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ * @param {SnapshotId} id
+ *
+ * @returns {Promise<DominatorTreeNode>}
+ */
+const computeAndFetchDominatorTree = exports.computeAndFetchDominatorTree =
+TaskCache.declareCacheableTask({
+  getCacheKey(_, id) {
+    return id;
+  },
+
+  task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
+    const dominatorTreeId = yield dispatch(computeDominatorTree(heapWorker, id));
+    if (dominatorTreeId === null) {
+      removeFromCache();
+      return null;
+    }
+
+    const root = yield dispatch(fetchDominatorTree(heapWorker, id));
+    removeFromCache();
+
+    if (!root) {
+      return null;
+    }
+
+    return root;
+  }
+});
+
+/**
+ * Update the currently selected snapshot's dominator tree.
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ */
+const refreshSelectedDominatorTree = exports.refreshSelectedDominatorTree = function (heapWorker) {
+  return function* (dispatch, getState) {
+    let snapshot = getState().snapshots.find(s => s.selected);
+    if (!snapshot) {
+      return;
+    }
+
+    if (snapshot.dominatorTree &&
+        !(snapshot.dominatorTree.state === dominatorTreeState.COMPUTED ||
+          snapshot.dominatorTree.state === dominatorTreeState.LOADED ||
+          snapshot.dominatorTree.state === dominatorTreeState.INCREMENTAL_FETCHING)) {
+      return;
+    }
+
+    if (snapshot.state === states.READ) {
+      if (snapshot.dominatorTree) {
+        yield dispatch(fetchDominatorTree(heapWorker, snapshot.id));
+      } else {
+        yield dispatch(computeAndFetchDominatorTree(heapWorker, snapshot.id));
+      }
+    } else {
+        // If there was an error, we can't continue. If we are still saving or
+        // reading the snapshot, then takeSnapshotAndCensus will finish the job
+        // for us.
+      return;
+    }
+  };
+};
+
+/**
+ * Select the snapshot with the given id.
+ *
+ * @param {snapshotId} id
+ * @see {Snapshot} model defined in devtools/client/memory/models.js
+ */
+const selectSnapshot = exports.selectSnapshot = function (id) {
+  return {
+    type: actions.SELECT_SNAPSHOT,
+    id
+  };
+};
+
+/**
+ * Delete all snapshots that are in the READ or ERROR state
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ */
+const clearSnapshots = exports.clearSnapshots = function (heapWorker) {
+  return function* (dispatch, getState) {
+    let snapshots = getState().snapshots.filter(s => {
+      let snapshotReady = s.state === states.READ || s.state === states.ERROR;
+      let censusReady = (s.treeMap && s.treeMap.state === treeMapState.SAVED) ||
+                        (s.census && s.census.state === censusState.SAVED);
+
+      return snapshotReady && censusReady;
+    });
+
+    let ids = snapshots.map(s => s.id);
+
+    dispatch({ type: actions.DELETE_SNAPSHOTS_START, ids });
+
+    if (getState().diffing) {
+      dispatch(diffing.toggleDiffing());
+    }
+    if (getState().individuals) {
+      dispatch(view.popView());
+    }
+
+    yield Promise.all(snapshots.map(snapshot => {
+      return heapWorker.deleteHeapSnapshot(snapshot.path).catch(error => {
+        reportException("clearSnapshots", error);
+        dispatch({ type: actions.SNAPSHOT_ERROR, id: snapshot.id, error });
+      });
+    }));
+
+    dispatch({ type: actions.DELETE_SNAPSHOTS_END, ids });
+  };
+};
+
+/**
+ * Delete a snapshot
+ *
+ * @param {HeapAnalysesClient} heapWorker
+ * @param {snapshotModel} snapshot
+ */
+const deleteSnapshot = exports.deleteSnapshot = function (heapWorker, snapshot) {
+  return function* (dispatch, getState) {
+    dispatch({ type: actions.DELETE_SNAPSHOTS_START, ids: [snapshot.id] });
+
+    try {
+      yield heapWorker.deleteHeapSnapshot(snapshot.path);
+    } catch (error) {
+      reportException("deleteSnapshot", error);
+      dispatch({ type: actions.SNAPSHOT_ERROR, id: snapshot.id, error });
+    }
+
+    dispatch({ type: actions.DELETE_SNAPSHOTS_END, ids: [snapshot.id] });
+  };
+};
+
+/**
+ * Expand the given node in the snapshot's census report.
+ *
+ * @param {CensusTreeNode} node
+ */
+const expandCensusNode = exports.expandCensusNode = function (id, node) {
+  return {
+    type: actions.EXPAND_CENSUS_NODE,
+    id,
+    node,
+  };
+};
+
+/**
+ * Collapse the given node in the snapshot's census report.
+ *
+ * @param {CensusTreeNode} node
+ */
+const collapseCensusNode = exports.collapseCensusNode = function (id, node) {
+  return {
+    type: actions.COLLAPSE_CENSUS_NODE,
+    id,
+    node,
+  };
+};
+
+/**
+ * Focus the given node in the snapshot's census's report.
+ *
+ * @param {SnapshotId} id
+ * @param {DominatorTreeNode} node
+ */
+const focusCensusNode = exports.focusCensusNode = function (id, node) {
+  return {
+    type: actions.FOCUS_CENSUS_NODE,
+    id,
+    node,
+  };
+};
+
+/**
+ * Expand the given node in the snapshot's dominator tree.
+ *
+ * @param {DominatorTreeTreeNode} node
+ */
+const expandDominatorTreeNode = exports.expandDominatorTreeNode = function (id, node) {
+  return {
+    type: actions.EXPAND_DOMINATOR_TREE_NODE,
+    id,
+    node,
+  };
+};
+
+/**
+ * Collapse the given node in the snapshot's dominator tree.
+ *
+ * @param {DominatorTreeTreeNode} node
+ */
+const collapseDominatorTreeNode = exports.collapseDominatorTreeNode = function (id, node) {
+  return {
+    type: actions.COLLAPSE_DOMINATOR_TREE_NODE,
+    id,
+    node,
+  };
+};
+
+/**
+ * Focus the given node in the snapshot's dominator tree.
+ *
+ * @param {SnapshotId} id
+ * @param {DominatorTreeNode} node
+ */
+const focusDominatorTreeNode = exports.focusDominatorTreeNode = function (id, node) {
+  return {
+    type: actions.FOCUS_DOMINATOR_TREE_NODE,
+    id,
+    node,
+  };
+};