CLDSRV-894: report turn-around time for PutObject and UploadPart

objectPut and objectPutPart return early from the request processing
waterfall in api.js, skipping the request 'end' handler that sets
startTurnAroundTime. Add the listener before the early return so the
timestamp is captured when the last byte of the request body arrives.

Author: dvasilas

lib/api/api.js

@@ -263,6 +263,11 @@ const api = {
                     request.serverAccessLog.analyticsUserName    = authNames.userName;
                 }
                 if (apiMethod === 'objectPut' || apiMethod === 'objectPutPart') {
+                    request.on('end', () => {
+                        if (request.serverAccessLog) {
+                            request.serverAccessLog.startTurnAroundTime = process.hrtime.bigint();
+                        }
+                    });
                     return next(null, userInfo, authorizationResults, streamingV4Params, infos);
                 }
                 // issue 100 Continue to the client

tests/unit/api/api.js

@@ -115,6 +115,25 @@ describe('api.callApiMethod', () => {
         api.callApiMethod('multipartDelete', request, response, log);
     });
 
+    ['objectPut', 'objectPutPart'].forEach(method => {
+        it(`should set startTurnAroundTime on request end for ${method}`, done => {
+            sandbox.stub(api, method).callsFake(
+                (userInfo, _request, streamingV4Params, _log, cb) => {
+                    request.on('end', () => {
+                        assert.strictEqual(typeof request.serverAccessLog.startTurnAroundTime, 'bigint');
+                        cb();
+                    });
+                    request.resume();
+                });
+            request.objectKey = 'testobject';
+            request.serverAccessLog = {};
+            api.callApiMethod(method, request, response, log, err => {
+                assert.ifError(err);
+                done();
+            });
+        });
+    });
+
     describe('MD5 checksum validation', () => {
         const methodsWithChecksumValidation = [
             'bucketPutACL',