Max origin concurrent auctions

src/adaptermanager.js

@@ -273,7 +273,7 @@ exports.checkBidRequestSizes = (adUnits) => {
   return adUnits;
 }
 
-exports.callBids = (adUnits, bidRequests, addBidResponse, doneCb) => {
+exports.callBids = (adUnits, bidRequests, addBidResponse, doneCb, requestCallbacks) => {
   if (!bidRequests.length) {
     utils.logWarn('callBids executed with no bidRequests.  Were they filtered by labels or sizing?');
     return;
@@ -285,7 +285,10 @@ exports.callBids = (adUnits, bidRequests, addBidResponse, doneCb) => {
   }, [[], []]);
 
   if (serverBidRequests.length) {
-    const s2sAjax = ajaxBuilder(serverBidRequests[0].timeout);
+    const s2sAjax = ajaxBuilder(serverBidRequests[0].timeout, requestCallbacks ? {
+      request: requestCallbacks.request.bind(null, 's2s'),
+      done: requestCallbacks.done
+    } : undefined);
     let adaptersServerSide = _s2sConfig.bidders;
     const s2sAdapter = _bidderRegistry[_s2sConfig.adapter];
     let tid = serverBidRequests[0].tid;
@@ -336,7 +339,6 @@ exports.callBids = (adUnits, bidRequests, addBidResponse, doneCb) => {
     }
   }
 
-  const ajax = (clientBidRequests.length) ? ajaxBuilder(clientBidRequests[0].timeout) : null;
   // handle client adapter requests
   clientBidRequests.forEach(bidRequest => {
     bidRequest.start = timestamp();
@@ -347,6 +349,10 @@ exports.callBids = (adUnits, bidRequests, addBidResponse, doneCb) => {
       events.emit(CONSTANTS.EVENTS.BID_REQUESTED, bidRequest);
       bidRequest.doneCbCallCount = 0;
       let done = doneCb(bidRequest.bidderRequestId);
+      let ajax = ajaxBuilder(clientBidRequests[0].timeout, requestCallbacks ? {
+        request: requestCallbacks.request.bind(null, bidRequest.bidderCode),
+        done: requestCallbacks.done
+      } : undefined);
       adapter.callBids(bidRequest, addBidResponse, done, ajax);
     } else {
       utils.logError(`Adapter trying to be called which does not exist: ${bidRequest.bidderCode} adaptermanager.callBids`);

src/ajax.js

@@ -15,12 +15,13 @@ const XHR_DONE = 4;
  */
 export const ajax = ajaxBuilder();
 
-export function ajaxBuilder(timeout = 3000) {
+export function ajaxBuilder(timeout = 3000, {request, done} = {}) {
   return function(url, callback, data, options = {}) {
     try {
       let x;
-      let useXDomainRequest = false;
       let method = options.method || (data ? 'POST' : 'GET');
+      let parser = document.createElement('a');
+      parser.href = url;
 
       let callbacks = typeof callback === 'object' && callback !== null ? callback : {
         success: function() {
@@ -35,46 +36,24 @@ export function ajaxBuilder(timeout = 3000) {
         callbacks.success = callback;
       }
 
-      if (!window.XMLHttpRequest) {
-        useXDomainRequest = true;
-      } else {
-        x = new window.XMLHttpRequest();
-        if (x.responseType === undefined) {
-          useXDomainRequest = true;
-        }
-      }
-
-      if (useXDomainRequest) {
-        x = new window.XDomainRequest();
-        x.onload = function () {
-          callbacks.success(x.responseText, x);
-        };
+      x = new window.XMLHttpRequest();
 
-        // http://stackoverflow.com/questions/15786966/xdomainrequest-aborts-post-on-ie-9
-        x.onerror = function () {
-          callbacks.error('error', x);
-        };
-        x.ontimeout = function () {
-          callbacks.error('timeout', x);
-        };
-        x.onprogress = function() {
-          utils.logMessage('xhr onprogress');
-        };
-      } else {
-        x.onreadystatechange = function () {
-          if (x.readyState === XHR_DONE) {
-            let status = x.status;
-            if ((status >= 200 && status < 300) || status === 304) {
-              callbacks.success(x.responseText, x);
-            } else {
-              callbacks.error(x.statusText, x);
-            }
+      x.onreadystatechange = function () {
+        if (x.readyState === XHR_DONE) {
+          if (typeof done === 'function') {
+            done(parser.origin);
           }
-        };
-        x.ontimeout = function () {
-          utils.logError('  xhr timeout after ', x.timeout, 'ms');
-        };
-      }
+          let status = x.status;
+          if ((status >= 200 && status < 300) || status === 304) {
+            callbacks.success(x.responseText, x);
+          } else {
+            callbacks.error(x.statusText, x);
+          }
+        }
+      };
+      x.ontimeout = function () {
+        utils.logError('  xhr timeout after ', x.timeout, 'ms');
+      };
 
       if (method === 'GET' && data) {
         let urlInfo = parseURL(url, options);
@@ -86,18 +65,21 @@ export function ajaxBuilder(timeout = 3000) {
       // IE needs timoeut to be set after open - see #1410
       x.timeout = timeout;
 
-      if (!useXDomainRequest) {
-        if (options.withCredentials) {
-          x.withCredentials = true;
-        }
-        utils._each(options.customHeaders, (value, header) => {
-          x.setRequestHeader(header, value);
-        });
-        if (options.preflight) {
-          x.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
-        }
-        x.setRequestHeader('Content-Type', options.contentType || 'text/plain');
+      if (options.withCredentials) {
+        x.withCredentials = true;
       }
+      utils._each(options.customHeaders, (value, header) => {
+        x.setRequestHeader(header, value);
+      });
+      if (options.preflight) {
+        x.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
+      }
+      x.setRequestHeader('Content-Type', options.contentType || 'text/plain');
+
+      if (typeof request === 'function') {
+        request(parser.origin);
+      }
+
       if (method === 'POST' && data) {
         x.send(data);
       } else {

src/auction.js

@@ -74,6 +74,11 @@ events.on(CONSTANTS.EVENTS.BID_ADJUSTMENT, function (bid) {
   adjustBids(bid);
 });
 
+const MAX_REQUESTS_PER_ORIGIN = 4;
+const outstandingRequests = {};
+const sourceInfo = {};
+const queuedCalls = [];
+
 /**
   * Creates new auction instance
   *
@@ -176,26 +181,103 @@ export function newAuction({adUnits, adUnitCodes, callback, cbTimeout, labels})
   }
 
   function callBids() {
-    startAuctionTimer();
     _auctionStatus = AUCTION_STARTED;
     _auctionStart = Date.now();
 
-    const auctionInit = {
-      timestamp: _auctionStart,
-      auctionId: _auctionId,
-      timeout: _timeout
-    };
-    events.emit(CONSTANTS.EVENTS.AUCTION_INIT, auctionInit);
-
     let bidRequests = adaptermanager.makeBidRequests(_adUnits, _auctionStart, _auctionId, _timeout, _labels);
     utils.logInfo(`Bids Requested for Auction with id: ${_auctionId}`, bidRequests);
     bidRequests.forEach(bidRequest => {
       addBidRequests(bidRequest);
     });
 
-    _auctionStatus = AUCTION_IN_PROGRESS;
-    adaptermanager.callBids(_adUnits, bidRequests, addBidResponse.bind(this), done.bind(this));
-  };
+    let requests = {};
+
+    let call = {
+      bidRequests,
+      run: () => {
+        startAuctionTimer();
+
+        _auctionStatus = AUCTION_IN_PROGRESS;
+
+        const auctionInit = {
+          timestamp: _auctionStart,
+          auctionId: _auctionId,
+          timeout: _timeout
+        };
+        events.emit(CONSTANTS.EVENTS.AUCTION_INIT, auctionInit);
+
+        adaptermanager.callBids(_adUnits, bidRequests, addBidResponse.bind(this), done.bind(this), {
+          request(source, origin) {
+            increment(outstandingRequests, origin);
+            increment(requests, source);
+
+            if (!sourceInfo[source]) {
+              sourceInfo[source] = {
+                SRA: true,
+                origin
+              };
+            }
+            if (requests[source] > 1) {
+              sourceInfo[source].SRA = false;
+            }
+          },
+          done(origin) {
+            outstandingRequests[origin]--;
+            if (queuedCalls[0]) {
+              if (runIfOriginHasCapacity(queuedCalls[0])) {
+                queuedCalls.shift();
+              }
+            }
+          }
+        });
+      }
+    };
+
+    if (!runIfOriginHasCapacity(call)) {
+      utils.logWarn('queueing auction due to limited endpoint capacity');
+      queuedCalls.push(call);
+    }
+
+    function runIfOriginHasCapacity(call) {
+      let hasCapacity = true;
+
+      let maxRequests = config.getConfig('maxRequestsPerOrigin') || MAX_REQUESTS_PER_ORIGIN;
+
+      call.bidRequests.some(bidRequest => {
+        let requests = 1;
+        let source = (typeof bidRequest.src !== 'undefined' && bidRequest.src === CONSTANTS.S2S.SRC) ? 's2s'
+          : bidRequest.bidderCode;
+        // if we have no previous info on this source just let them through
+        if (sourceInfo[source]) {
+          if (sourceInfo[source].SRA === false) {
+            // some bidders might use more than the MAX_REQUESTS_PER_ORIGIN in a single auction.  In those cases
+            // set their request count to MAX_REQUESTS_PER_ORIGIN so the auction isn't permanently queued waiting
+            // for capacity for that bidder
+            requests = Math.min(bidRequest.bids.length, maxRequests);
+          }
+          if (outstandingRequests[sourceInfo[source].origin] + requests > maxRequests) {
+            hasCapacity = false;
+          }
+        }
+        // return only used for terminating this .some() iteration early if it is determined we don't have capacity
+        return !hasCapacity;
+      });
+
+      if (hasCapacity) {
+        call.run();
+      }
+
+      return hasCapacity;
+    }
+
+    function increment(obj, prop) {
+      if (typeof obj[prop] === 'undefined') {
+        obj[prop] = 1
+      } else {
+        obj[prop]++;
+      }
+    }
+  }
 
   return {
     addBidReceived,

test/spec/unit/pbjs_api_spec.js

@@ -1305,6 +1305,7 @@ describe('Unit: Prebid Module', function () {
           ]
         }];
         adUnitCodes = ['adUnit-code'];
+        configObj.setConfig({maxRequestsPerOrigin: Number.MAX_SAFE_INTEGER || 99999999});
         let auction = auctionModule.newAuction({adUnits, adUnitCodes, callback: function() {}, cbTimeout: timeout});
         spyCallBids = sinon.spy(adaptermanager, 'callBids');
         createAuctionStub = sinon.stub(auctionModule, 'newAuction');