add and show build wait reason

lib/distributor.js

@@ -37,6 +37,9 @@ Distributor.prototype._runNext = function(callback) {
 
 	Steppy(
 		function() {
+			// update wait reasons for all queue items before run
+			self._updateWaitReasons();
+
 			var node;
 			var queueItemIndex = _(self.queue).findIndex(function(item) {
 				node = _(self.nodes).find(function(node) {
@@ -88,11 +91,28 @@ Distributor.prototype._runNext = function(callback) {
 			executor.once('scmData', function(scmData) {
 				self._updateBuild(build, {scm: scmData});
 			});
+
+			// update wait reasons for all queue items after run
+			self._updateWaitReasons();
 		},
 		callback
 	);
 };
 
+Distributor.prototype._updateWaitReasons = function() {
+	var self = this;
+	_(self.queue).each(function(item) {
+		var waitReasons = _(self.nodes).map(function(node) {
+			return node.getExecutorWaitReason(item.project);
+		});
+
+		var waitReason = _(waitReasons).compact().join(', ');
+		if (waitReason !== item.build.waitReason) {
+			self._updateBuild(item.build, {waitReason: waitReason});
+		}
+	});
+};
+
 Distributor.prototype._onBuildComplete = function(err, build, callback) {
 	var self = this;
 

lib/node.js

@@ -12,13 +12,21 @@ function Node(params) {
 
 exports.Node = Node;
 
+Node.prototype.getExecutorWaitReason = function(project) {
+	var waitReason;
+
+	if (_(this.executors).size() >= this.maxExecutorsCount) {
+		waitReason = 'All executors are busy';
+	} else if (project.name in this.executors) {
+		waitReason = 'Project already running on node';
+	}
+
+	return waitReason;
+};
+
 Node.prototype.hasFreeExecutor = function(project) {
-	return (
+	return !this.getExecutorWaitReason(project);
-		// can't build same project twice at the same time on same node
+};
-		project.name in this.executors === false &&
-		_(this.executors).size() < this.maxExecutorsCount
-	);
-}
 
 Node.prototype._createExecutor = function(project) {
 	return createExecutor({
@@ -29,8 +37,12 @@ Node.prototype._createExecutor = function(project) {
 
 Node.prototype.run = function(project, params, callback) {
 	var self = this;
-	if (!this.hasFreeExecutor(project)) {
+
-		throw new Error('No free executors for project: ' + project.name);
+	var waitReason = this.getExecutorWaitReason(project);
+	if (waitReason) {
+		throw new Error(
+			'Project "' + project.name + '" should wait because: ' + waitReason
+		);
 	}
 
 	this.executors[project.name] = this._createExecutor(project);

static/js/app/components/builds/item.jade

@@ -30,6 +30,11 @@ mixin statusText(build)
 			span #
 			span= build.number
 
+		if build.waitReason
+			span  (
+			span= build.waitReason
+			span , waiting)
+
 		if build.status === 'in-progress' && build.currentStep
 			span  (
 			span= build.currentStep

test/distributor.js

@@ -69,14 +69,20 @@ describe('Distributor', function() {
 			expect(changes.completed).equal(false);
 		});
 
-		it('build should be in-progress', function() {
+		it('build should have empty wait reason', function() {
 			var changes = updateBuildSpy.getCall(1).args[1];
+			expect(changes).only.have.keys('waitReason');
+			expect(changes.waitReason).equal('');
+		});
+
+		it('build should be in-progress', function() {
+			var changes = updateBuildSpy.getCall(2).args[1];
 			expect(changes).only.have.keys('startDate', 'status');
 			expect(changes.status).equal('in-progress');
 		});
 
 		it('build should be done', function() {
-			var changes = updateBuildSpy.getCall(2).args[1];
+			var changes = updateBuildSpy.getCall(3).args[1];
 			expect(changes).only.have.keys(
 				'endDate', 'status', 'completed', 'error'
 			);
@@ -85,8 +91,8 @@ describe('Distributor', function() {
 			expect(changes.error).equal(null);
 		});
 
-		it('update build called 3 times in total', function() {
+		it('update build called 4 times in total', function() {
-			expect(updateBuildSpy.callCount).equal(3);
+			expect(updateBuildSpy.callCount).equal(4);
 		});
 
 		after(function() {
@@ -128,20 +134,26 @@ describe('Distributor', function() {
 			expect(changes.status).equal('queued');
 		});
 
-		it('build should be in-progress', function() {
+		it('build should have empty wait reason', function() {
 			var changes = updateBuildSpy.getCall(1).args[1];
+			expect(changes).only.have.keys('waitReason');
+			expect(changes.waitReason).equal('');
+		});
+
+		it('build should be in-progress', function() {
+			var changes = updateBuildSpy.getCall(2).args[1];
 			expect(changes.status).equal('in-progress');
 		});
 
 		it('build should be fail', function() {
-			var changes = updateBuildSpy.getCall(2).args[1];
+			var changes = updateBuildSpy.getCall(3).args[1];
 			expect(changes.status).equal('error');
 			expect(changes.completed).equal(true);
 			expect(changes.error).equal('Some error');
 		});
 
-		it('update build called 3 times in total', function() {
+		it('update build called 4 times in total', function() {
-			expect(updateBuildSpy.callCount).equal(3);
+			expect(updateBuildSpy.callCount).equal(4);
 		});
 
 		after(function() {