(core) New API to collect timing information from formula evaluation.

Summary:
- /timing/start endpoint to start collecting information
- /timing/stop endpoint to stop collecting
- /timing to retrive data gatherd so far

Timings are collected for all columns (including hidden/helpers/system)

Test Plan: Added new

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D4230

app/client/components/DocComm.ts

@@ -48,6 +48,8 @@ export class DocComm extends Disposable implements ActiveDocAPI {
   public getUsersForViewAs = this._wrapMethod("getUsersForViewAs");
   public getAccessToken = this._wrapMethod("getAccessToken");
   public getShare = this._wrapMethod("getShare");
+  public startTiming = this._wrapMethod("startTiming");
+  public stopTiming = this._wrapMethod("stopTiming");
 
   public changeUrlIdEmitter = this.autoDispose(new Emitter());
 

app/common/ActiveDocAPI.ts

@@ -288,6 +288,48 @@ export interface RemoteShareInfo {
   key: string;
 }
 
+/**
+ * Metrics gathered during formula calculations.
+ */
+export interface TimingInfo {
+  /**
+   * Total time spend evaluating a formula.
+   */
+  total: number;
+  /**
+   * Number of times the formula was evaluated (for all rows).
+   */
+  count: number;
+  average: number;
+  max: number;
+}
+
+/**
+ * Metrics attached to a particular column in a table. Contains also marks if they were gathered.
+ * Currently we only mark the `OrderError` exception (so when formula calculation was restarted due to
+ * order dependency).
+ */
+export interface FormulaTimingInfo extends TimingInfo {
+  tableId: string;
+  colId: string;
+  marks?: Array<TimingInfo & {name: string}>;
+}
+
+/*
+ * Status of timing info collection. Contains intermediate results if engine is not busy at the moment.
+ */
+export interface TimingStatus {
+  /**
+   * If true, timing info is being collected.
+   */
+  status: boolean;
+  /**
+   * Will be undefined if we can't get the timing info (e.g. if the document is locked by other call).
+   * Otherwise, contains the intermediate results gathered so far.
+   */
+  timing?: FormulaTimingInfo[];
+}
+
 export interface ActiveDocAPI {
   /**
    * Closes a document, and unsubscribes from its userAction events.
@@ -449,5 +491,18 @@ export interface ActiveDocAPI {
    */
   getUsersForViewAs(): Promise<PermissionDataWithExtraUsers>;
 
-  getShare(linkId: string): Promise<RemoteShareInfo>;
+  /**
+   * Get a share info associated with the document.
+   */
+  getShare(linkId: string): Promise<RemoteShareInfo|null>;
+
+  /**
+   * Starts collecting timing information from formula evaluations.
+   */
+  startTiming(): Promise<void>;
+
+  /**
+   * Stops collecting timing information and returns the collected data.
+   */
+  stopTiming(): Promise<TimingInfo[]>;
 }

app/common/UserAPI.ts

@@ -507,6 +507,16 @@ export interface DocAPI {
   flushWebhook(webhookId: string): Promise<void>;
 
   getAssistance(params: AssistanceRequest): Promise<AssistanceResponse>;
+  /**
+   * Check if the document is currently in timing mode.
+   */
+  timing(): Promise<{status: boolean}>;
+  /**
+   * Starts recording timing information for the document. Throws exception if timing is already
+   * in progress or you don't have permission to start timing.
+   */
+  startTiming(): Promise<void>;
+  stopTiming(): Promise<void>;
 }
 
 // Operations that are supported by a doc worker.
@@ -1121,6 +1131,18 @@ export class DocAPIImpl extends BaseAPI implements DocAPI {
     });
   }
 
+  public async timing(): Promise<{status: boolean}> {
+    return this.requestJson(`${this._url}/timing`);
+  }
+
+  public async startTiming(): Promise<void> {
+    await this.request(`${this._url}/timing/start`, {method: 'POST'});
+  }
+
+  public async stopTiming(): Promise<void> {
+    await this.request(`${this._url}/timing/stop`, {method: 'POST'});
+  }
+
   private _getRecords(tableId: string, endpoint: 'data' | 'records', options?: GetRowsParams): Promise<any> {
     const url = new URL(`${this._url}/tables/${tableId}/${endpoint}`);
     if (options?.filters) {

app/gen-server/lib/DocApiForwarder.ts

@@ -70,6 +70,9 @@ export class DocApiForwarder {
     app.use('/api/docs/:docId/webhooks', withDoc);
     app.use('/api/docs/:docId/assistant', withDoc);
     app.use('/api/docs/:docId/sql', withDoc);
+    app.use('/api/docs/:docId/timing', withDoc);
+    app.use('/api/docs/:docId/timing/start', withDoc);
+    app.use('/api/docs/:docId/timing/stop', withDoc);
     app.use('/api/docs/:docId/forms/:vsId', withDoc);
     app.use('^/api/docs$', withoutDoc);
   }

app/server/lib/ActiveDoc.ts

@@ -22,6 +22,7 @@ import {
   ApplyUAResult,
   DataSourceTransformed,
   ForkResult,
+  FormulaTimingInfo,
   ImportOptions,
   ImportResult,
   ISuggestionWithValue,
@@ -220,6 +221,7 @@ export class ActiveDoc extends EventEmitter {
   public docData: DocData|null = null;
   // Used by DocApi to only allow one webhook-related endpoint to run at a time.
   public readonly triggersLock: Mutex = new Mutex();
+  public isTimingOn = false;
 
   protected _actionHistory: ActionHistory;
   protected _docManager: DocManager;
@@ -1366,6 +1368,7 @@ export class ActiveDoc extends EventEmitter {
    */
   public async reloadDoc(docSession?: DocSession) {
     this._log.debug(docSession || null, 'ActiveDoc.reloadDoc starting shutdown');
+    this._docManager.restoreTimingOn(this.docName, this.isTimingOn);
     return this.shutdown();
   }
 
@@ -1870,6 +1873,40 @@ export class ActiveDoc extends EventEmitter {
     return await this._getHomeDbManagerOrFail().getShareByLinkId(this.docName, linkId);
   }
 
+  public async startTiming(): Promise<void> {
+    // Set the flag to indicate that timing is on.
+    this.isTimingOn = true;
+
+    try {
+      // Call the data engine to start timing.
+      await this._doStartTiming();
+    } catch (e) {
+      this.isTimingOn = false;
+      throw e;
+    }
+
+    // Mark self as in timing mode, in case we get reloaded.
+    this._docManager.restoreTimingOn(this.docName, true);
+  }
+
+  public async stopTiming(): Promise<FormulaTimingInfo[]> {
+    // First call the data engine to stop timing, and gather results.
+    const timingResults = await this._pyCall('stop_timing');
+
+    // Toggle the flag and clear the reminder.
+    this.isTimingOn = false;
+    this._docManager.restoreTimingOn(this.docName, false);
+
+    return timingResults;
+  }
+
+  public async getTimings(): Promise<FormulaTimingInfo[]|void>  {
+    if (this._modificationLock.isLocked()) {
+      return;
+    }
+    return await this._pyCall('get_timings');
+  }
+
   /**
    * Loads an open document from DocStorage.  Returns a list of the tables it contains.
    */
@@ -2377,6 +2414,10 @@ export class ActiveDoc extends EventEmitter {
         });
         await this._pyCall('initialize', this._options?.docUrl);
 
+        if (this.isTimingOn) {
+          await this._doStartTiming();
+        }
+
         // Calculations are not associated specifically with the user opening the document.
         // TODO: be careful with which users can create formulas.
         await this._applyUserActions(makeExceptionalDocSession('system'), [['Calculate']]);
@@ -2686,7 +2727,9 @@ export class ActiveDoc extends EventEmitter {
   }
 
   private async _getEngine(): Promise<ISandbox> {
-    if (this._shuttingDown) { throw new Error('shutting down, data engine unavailable'); }
+    if (this._shuttingDown) {
+      throw new Error('shutting down, data engine unavailable');
+    }
     if (this._dataEngine) { return this._dataEngine; }
 
     this._dataEngine = this._isSnapshot ? this._makeNullEngine() : this._makeEngine();
@@ -2830,6 +2873,10 @@ export class ActiveDoc extends EventEmitter {
     return dbManager;
   }
 
+  private _doStartTiming() {
+    return  this._pyCall('start_timing');
+  }
+
 }
 
 // Helper to initialize a sandbox action bundle with no values.

app/server/lib/DocApi.ts

@@ -1556,6 +1556,40 @@ export class DocWorkerApi {
         });
       })
     );
+
+    // GET /api/docs/:docId/timings
+    // Checks if timing is on for the document.
+    this._app.get('/api/docs/:docId/timing', isOwner, withDoc(async (activeDoc, req, res) => {
+      if (!activeDoc.isTimingOn) {
+        res.json({status: 'disabled'});
+      } else {
+        const timing =  await activeDoc.getTimings();
+        const status = timing ? 'active' : 'pending';
+        res.json({status, timing});
+      }
+    }));
+
+    // POST /api/docs/:docId/timings/start
+    // Start a timing for the document.
+    this._app.post('/api/docs/:docId/timing/start', isOwner, withDoc(async (activeDoc, req, res) => {
+      if (activeDoc.isTimingOn) {
+        res.status(400).json({error:`Timing already started for ${activeDoc.docName}`});
+        return;
+      }
+      // isTimingOn flag is switched synchronously.
+      await activeDoc.startTiming();
+      res.sendStatus(200);
+    }));
+
+    // POST /api/docs/:docId/timings/stop
+    // Stop a timing for the document.
+    this._app.post('/api/docs/:docId/timing/stop', isOwner, withDoc(async (activeDoc, req, res) => {
+      if (!activeDoc.isTimingOn) {
+        res.status(400).json({error:`Timing not started for ${activeDoc.docName}`});
+        return;
+      }
+      res.json(await activeDoc.stopTiming());
+    }));
   }
 
   /**

app/server/lib/DocManager.ts

@@ -43,7 +43,10 @@ export const DEFAULT_CACHE_TTL = 10000;
 
 // How long to remember that a document has been explicitly set in a
 // recovery mode.
-export const RECOVERY_CACHE_TTL = 30000;
+export const RECOVERY_CACHE_TTL = 30000; // 30 seconds
+
+// How long to remember the timing mode of a document.
+export const TIMING_ON_CACHE_TTL = 30000; // 30 seconds
 
 /**
  * DocManager keeps track of "active" Grist documents, i.e. those loaded
@@ -56,6 +59,9 @@ export class DocManager extends EventEmitter {
   // Remember recovery mode of documents.
   private _inRecovery = new MapWithTTL<string, boolean>(RECOVERY_CACHE_TTL);
 
+  // Remember timing mode of documents, when document is recreated it is put in the same mode.
+  private _inTimingOn = new MapWithTTL<string, boolean>(TIMING_ON_CACHE_TTL);
+
   constructor(
     public readonly storageManager: IDocStorageManager,
     public readonly pluginManager: PluginManager|null,
@@ -69,6 +75,13 @@ export class DocManager extends EventEmitter {
     this._inRecovery.set(docId, recovery);
   }
 
+  /**
+   * Will restore timing on a document when it is reloaded.
+   */
+  public restoreTimingOn(docId: string, timingOn: boolean) {
+    this._inTimingOn.set(docId, timingOn);
+  }
+
   // attach a home database to the DocManager.  During some tests, it
   // is awkward to have this set up at the point of construction.
   public testSetHomeDbManager(dbManager: HomeDBManager) {
@@ -437,6 +450,10 @@ export class DocManager extends EventEmitter {
       log.error('DocManager had problem shutting down storage: %s', err.message);
     }
 
+    // Clear any timeouts we might have.
+    this._inRecovery.clear();
+    this._inTimingOn.clear();
+
     // Clear the setInterval that the pidusage module sets up internally.
     pidusage.clear();
   }
@@ -601,7 +618,10 @@ export class DocManager extends EventEmitter {
     const doc = await this._getDoc(docSession, docName);
     // Get URL for document for use with SELF_HYPERLINK().
     const docUrls = doc && await this._getDocUrls(doc);
-    return new ActiveDoc(this, docName, {...docUrls, safeMode, doc});
+    const activeDoc = new ActiveDoc(this, docName, {...docUrls, safeMode, doc});
+    // Restore the timing mode of the document.
+    activeDoc.isTimingOn = this._inTimingOn.get(docName) || false;
+    return activeDoc;
   }
 
   /**

app/server/lib/DocWorker.ts

@@ -132,6 +132,8 @@ export class DocWorker {
       getUsersForViewAs:        activeDocMethod.bind(null, 'viewers', 'getUsersForViewAs'),
       getAccessToken:           activeDocMethod.bind(null, 'viewers', 'getAccessToken'),
       getShare:                 activeDocMethod.bind(null, 'owners', 'getShare'),
+      startTiming:              activeDocMethod.bind(null, 'owners', 'startTiming'),
+      stopTiming:               activeDocMethod.bind(null, 'owners', 'stopTiming'),
     });
   }
 

sandbox/grist/engine.py

@@ -36,6 +36,7 @@ import sandbox
 import schema
 from schema import RecalcWhen
 import table as table_module
+from timing import DummyTiming
 from user import User # pylint:disable=wrong-import-order
 import useractions
 import column
@@ -263,6 +264,8 @@ class Engine(object):
     # make multiple different requests without needing to keep all the responses in memory.
     self._cached_request_keys = set()
 
+    self._timing = DummyTiming()
+
   @property
   def autocomplete_context(self):
     # See the comment on _autocomplete_context in __init__ above.
@@ -969,6 +972,7 @@ class Engine(object):
       assert not cycle
       record = AttributeRecorder(record, "rec", record_attributes)
     value = None
+    with self._timing.measure(col.node):
       try:
         if cycle:
           raise depend.CircularRefError("Circular Reference")
@@ -1004,6 +1008,7 @@ class Engine(object):
         # Now we can raise the order error, if there was one.  Cell evaluation will be reordered
         # in response.
         if order_error:
+          self._timing.mark("order_error")
           self._cell_required_error = None
           raise order_error  # pylint: disable=raising-bad-type
 

sandbox/grist/main.py

@@ -5,6 +5,8 @@ and starts the grist sandbox. See engine.py for the API documentation.
 import os
 import random
 import sys
+
+from timing import DummyTiming, Timing
 sys.path.append('thirdparty')
 # pylint: disable=wrong-import-position
 
@@ -158,6 +160,20 @@ def run(sandbox):
   def evaluate_formula(table_id, col_id, row_id):
     return formula_prompt.evaluate_formula(eng, table_id, col_id, row_id)
 
+  @export
+  def start_timing():
+    eng._timing = Timing()
+
+  @export
+  def stop_timing():
+    stats = eng._timing.get()
+    eng._timing = DummyTiming()
+    return stats
+
+  @export
+  def get_timings():
+    return eng._timing.get()
+
   export(parse_acl_formula)
   export(eng.load_empty)
   export(eng.load_done)

sandbox/grist/timing.py

@@ -0,0 +1,115 @@
+import contextlib
+import time
+import six
+
+
+class Timing(object):
+  def __init__(self):
+    self._items = {}
+    self._marks_stack = []
+
+  @contextlib.contextmanager
+  def measure(self, key):
+    start = time.time()
+    stack_start_len = len(self._marks_stack)
+    try:
+      yield
+    finally:
+      end = time.time()
+      self._record_time(key, end - start)
+
+      # Handle the marks added while in this invocation.
+      n = len(self._marks_stack) - stack_start_len
+      if n > 0:
+        next_mark = ("end", end)
+        while n > 0:
+          mark = self._marks_stack.pop()
+          self._record_time("{}@{}={}:{}".format(key, n, mark[0], next_mark[0]),
+              next_mark[1] - mark[1])
+          next_mark = mark
+          n -= 1
+        self._record_time("{}@{}={}:{}".format(key, n, "start", next_mark[0]), next_mark[1] - start)
+
+  def mark(self, mark_name):
+    self._marks_stack.append((mark_name, time.time()))
+
+  def get(self, clear = True):
+    # Copy it and clear immediately if requested.
+    timing_log = self._items.copy()
+    if clear:
+      self.clear()
+    # Stats will contain a json like structure with table_id, col_id, sum, count, average, max
+    # and optionally a array of marks (in similar format)
+    stats = []
+    for key, t in sorted(timing_log.items(), key=lambda x: str(x[0])):
+      # Key can be either a node (tuple with table_id and col_id) or a string with a mark.
+      # The list is sorted so, we always first get the stats for the node and then the marks.
+      # We will add marks to the last node.
+      if isinstance(key, tuple):
+        stats.append({"tableId": key[0], "colId": key[1], "sum": t.sum, "count": t.count,
+                      "average": t.average, "max": t.max})
+      else:
+        # Create a marks array for the last node or append to the existing one.
+        if stats:
+          prev = stats[-1].get("marks", [])
+          stats[-1]["marks"] = prev + [{
+            "name": key, "sum": t.sum,
+            "count": t.count, "average": t.average,
+            "max": t.max
+          }]
+    return stats
+
+  def dump(self):
+    out = []
+    for key, t in sorted(self._items.items(), key=lambda x: str(x[0])):
+      out.append("%6d, %10f, %10f, %10f, %s" % (t.count, t.average, t.max, t.sum, key))
+    print("Timing\n" + "\n".join(out))
+    self.clear()
+
+  def _record_time(self, key, time_sec):
+    t = self._items.get(key)
+    if not t:
+      t = self._items[key] = TimingStats()
+    t.add(time_sec)
+
+  def clear(self):
+    self._items.clear()
+
+
+
+# An implementation that adds minimal overhead.
+class DummyTiming(object):
+  # pylint: disable=no-self-use,unused-argument,no-member
+  def measure(self, key):
+    if six.PY2:
+      return contextlib.nested()
+    return contextlib.nullcontext()
+
+  def mark(self, mark_name):
+    pass
+
+  def dump(self):
+    pass
+
+  def get(self, clear = True):
+    return []
+
+  def clear(self):
+    pass
+
+
+class TimingStats(object):
+  def __init__(self):
+    self.count = 0
+    self.sum = 0
+    self.max = 0
+
+  @property
+  def average(self):
+    return self.sum / self.count if self.count > 0 else 0
+
+  def add(self, value):
+    self.count += 1
+    self.sum += value
+    if value > self.max:
+      self.max = value

test/server/lib/DocApi2.ts

@@ -9,11 +9,12 @@ import {openClient} from 'test/server/gristClient';
 import * as testUtils from 'test/server/testUtils';
 
 const chimpy = configForUser('Chimpy');
+const kiwi = configForUser('Kiwi');
 
 describe('DocApi2', function() {
   this.timeout(40000);
   let server: TestServer;
-  let serverUrl: string;
+  let homeUrl: string;
   let owner: UserAPI;
   let wsId: number;
   testUtils.setTmpLogLevel('error');
@@ -30,7 +31,7 @@ describe('DocApi2', function() {
     }
 
     server = new TestServer(this);
-    serverUrl = await server.start(['home', 'docs']);
+    homeUrl = await server.start(['home', 'docs']);
     const api = await server.createHomeApi('chimpy', 'docs', true);
     await api.newOrg({name: 'testy', domain: 'testy'});
     owner = await server.createHomeApi('chimpy', 'testy', true);
@@ -63,7 +64,7 @@ describe('DocApi2', function() {
       assert.equal(await fse.pathExists(forkPath2), true);
 
       // Delete the trunk via API.
-      const deleteDocResponse = await axios.delete(`${serverUrl}/api/docs/${docId}`, chimpy);
+      const deleteDocResponse = await axios.delete(`${homeUrl}/api/docs/${docId}`, chimpy);
       assert.equal(deleteDocResponse.status, 200);
 
       // Check that files for the trunk and forks were deleted.
@@ -72,4 +73,166 @@ describe('DocApi2', function() {
       assert.equal(await fse.pathExists(forkPath2), false);
     });
   });
+
+  describe('/docs/{did}/timing', async () => {
+    let docId: string;
+    before(async function() {
+      docId = await owner.newDoc({name: 'doc2'}, wsId);
+    });
+
+    after(async function() {
+      await owner.deleteDoc(docId);
+    });
+
+    // There are two endpoints here /timing/start and /timing/stop.
+    // Here we just test that it is operational, available only for owners
+    // and that it returns sane results. Exact tests are done in python.
+
+    // Smoke test.
+    it('POST /docs/{did}/timing smoke tests', async function() {
+      // We are disabled.
+      let resp = await axios.get(`${homeUrl}/api/docs/${docId}/timing`, chimpy);
+      assert.equal(resp.status, 200);
+      assert.deepEqual(resp.data, {status: 'disabled'});
+
+      // Start it.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/start`, {}, chimpy);
+      assert.equal(resp.status, 200);
+
+      // Stop it.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/stop`, {}, chimpy);
+      assert.equal(resp.status, 200);
+      assert.deepEqual(resp.data, []);
+    });
+
+    it('POST /docs/{did}/timing/start', async function() {
+      // Start timing as non owner, should fail.
+      let resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/start`, {}, kiwi);
+      assert.equal(resp.status, 403);
+
+      // Query status as non owner, should fail.
+      resp = await axios.get(`${homeUrl}/api/docs/${docId}/timing`, kiwi);
+      assert.equal(resp.status, 403);
+
+      // Check as owner.
+      resp = await axios.get(`${homeUrl}/api/docs/${docId}/timing`, chimpy);
+      assert.equal(resp.status, 200);
+      assert.deepEqual(resp.data, {status: 'disabled'});
+
+      // Start timing as owner.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/start`, {}, chimpy);
+      assert.equal(resp.status, 200);
+
+      // Check we are started.
+      resp = await axios.get(`${homeUrl}/api/docs/${docId}/timing`, chimpy);
+      assert.equal(resp.status, 200);
+      assert.deepEqual(resp.data, {status: 'active', timing: []});
+
+      // Starting timing again works as expected, returns 400 as this is already.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/start`, {}, chimpy);
+      assert.equal(resp.status, 400);
+
+      // As non owner
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/stop`, {}, kiwi);
+      assert.equal(resp.status, 403);
+    });
+
+    it('POST /docs/{did}/timing/stop', async function() {
+      // Timings are turned on, so we can stop them.
+      // First as non owner, we should fail.
+      let resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/stop`, {}, kiwi);
+      assert.equal(resp.status, 403);
+
+      // Next as owner.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/stop`, {}, chimpy);
+      assert.equal(resp.status, 200);
+
+      // Now do it once again, we should got 400, as we are not timing.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/stop`, {}, chimpy);
+      assert.equal(resp.status, 400);
+    });
+
+    it('GET /docs/{did}/timing', async function() {
+      // Now we can check the results. Start timing and check that we got [] in response.
+      let resp =  await axios.post(`${homeUrl}/api/docs/${docId}/timing/start`, {}, chimpy);
+      assert.equal(resp.status, 200);
+
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/stop`, {}, chimpy);
+      assert.equal(resp.status, 200);
+      assert.deepEqual(resp.data, []);
+
+      // Now create a table with a formula column and make sure we see it in the results.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/apply`, [
+        ['AddTable', 'Timings', [
+          {id: 'A', formula: '$id' }
+        ]],
+      ], chimpy);
+      assert.equal(resp.status, 200);
+
+      // Now start it again,
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/start`, {}, chimpy);
+      assert.equal(resp.status, 200);
+
+      // Make sure we see that it is active and we have some intermediate results
+      resp = await axios.get(`${homeUrl}/api/docs/${docId}/timing`, chimpy);
+      assert.equal(resp.status, 200);
+      assert.deepEqual(resp.data, {status: 'active', timing: []});
+
+      // And trigger some formula calculations.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/apply`, [
+        ['BulkAddRecord', 'Timings', [null, null], {}],
+      ], chimpy);
+      assert.equal(resp.status, 200, JSON.stringify(resp.data));
+
+      // Make sure we can't stop it as non owner.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/stop`, {}, kiwi);
+      assert.equal(resp.status, 403);
+
+      // Now stop it as owner and make sure the result is sane.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/stop`, {}, chimpy);
+      assert.equal(resp.status, 200, JSON.stringify(resp.data));
+      const data = resp.data as Array<{
+        tableId: string;
+        colId: string;
+        sum: number;
+        count: number;
+        average: number;
+        max: number;
+        markers?: Array<{
+          name: string;
+          sum: number;
+          count: number;
+          average: number;
+          max: number;
+        }>
+      }>;
+
+      assert.isAbove(data.length, 0);
+      assert.equal(data[0].tableId, 'Timings');
+      assert.isTrue(typeof data[0].sum === 'number');
+      assert.isTrue(typeof data[0].count === 'number');
+      assert.isTrue(typeof data[0].average === 'number');
+      assert.isTrue(typeof data[0].max === 'number');
+    });
+
+    it('POST /docs/{did}/timing/start remembers state after reload', async function() {
+      // Make sure we are off.
+      let resp = await axios.get(`${homeUrl}/api/docs/${docId}/timing`, chimpy);
+      assert.equal(resp.status, 200);
+      assert.deepEqual(resp.data, {status: 'disabled'});
+
+      // Now start it.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/timing/start`, {}, chimpy);
+      assert.equal(resp.status, 200);
+
+      // Now reload document.
+      resp = await axios.post(`${homeUrl}/api/docs/${docId}/force-reload`, {}, chimpy);
+      assert.equal(resp.status, 200);
+
+      // And check that we are still on.
+      resp = await axios.get(`${homeUrl}/api/docs/${docId}/timing`, chimpy);
+      assert.equal(resp.status, 200, JSON.stringify(resp.data));
+      assert.deepEqual(resp.data, {status: 'active', timing: []});
+    });
+  });
 });