DPL TestWorkflows: add example for two synchronized timers

This reproduces the issue reported in https://its.cern.ch/jira/browse/O2-4328.

Framework/TestWorkflows/CMakeLists.txt

@@ -33,6 +33,10 @@ o2_add_dpl_workflow(diamond-workflow
                   SOURCES src/o2DiamondWorkflow.cxx
                   COMPONENT_NAME TestWorkflows)
 
+o2_add_dpl_workflow(two-timers
+                  SOURCES src/o2TwoTimers.cxx
+                  COMPONENT_NAME TestWorkflows)
+
 o2_add_dpl_workflow(dummy-calibration-workflow
                   SOURCES src/o2DummyCalibrationWorkflow.cxx
                   COMPONENT_NAME TestWorkflows)

Framework/TestWorkflows/src/o2TwoTimers.cxx

@@ -0,0 +1,61 @@
+// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+#include "Framework/ConfigParamSpec.h"
+#include "Framework/DataTakingContext.h"
+#include "Framework/CompletionPolicyHelpers.h"
+#include "Framework/DeviceSpec.h"
+#include "Framework/RawDeviceService.h"
+#include "Framework/ControlService.h"
+#include "Framework/Configurable.h"
+#include "Framework/RunningWorkflowInfo.h"
+#include "Framework/CallbackService.h"
+#include "Framework/RateLimiter.h"
+#include "Framework/ConfigContext.h"
+#include <fairmq/Device.h>
+
+#include <iostream>
+#include <chrono>
+#include <thread>
+#include <vector>
+
+using namespace o2::framework;
+#include "Framework/runDataProcessing.h"
+
+// This is how you can define your processing in a declarative way
+WorkflowSpec defineDataProcessing(ConfigContext const& specs)
+{
+  DataProcessorSpec timer1{
+    .name = "timer1",
+    .inputs = {InputSpec{"x", "TIM", "A1", Lifetime::Timer}},
+    .outputs = {OutputSpec{{"output"}, "TST", "A1"}},
+    .algorithm = AlgorithmSpec{adaptStateless(
+      [](DataAllocator& outputs, RawDeviceService& device, DataTakingContext& context, ProcessingContext& pcx) {
+        auto& aData = outputs.make<int>(OutputRef{"output"}, 1);
+        LOG(info) << "timer1: " << aData[0];
+      })},
+    .options = {
+      ConfigParamSpec{"some-device-param", VariantType::Int, 1, {"Some device parameter"}},
+    }};
+  DataProcessorSpec timer2{
+    .name = "timer2",
+    .inputs = {InputSpec{"x", "TIM", "A1", Lifetime::Timer}},
+    .outputs = {OutputSpec{{"output"}, "TST", "A2"}},
+    .algorithm = AlgorithmSpec{adaptStateless(
+      [](DataAllocator& outputs, RawDeviceService& device, DataTakingContext& context, ProcessingContext& pcx) {
+        auto& aData = outputs.make<int>(OutputRef{"output"}, 1);
+        LOG(info) << "timer2: " << aData[0];
+      })},
+    .options = {
+      ConfigParamSpec{"some-device-param", VariantType::Int, 1, {"Some device parameter"}},
+    }};
+
+  return workflow::concat(WorkflowSpec{timer1, timer2});
+}