DPL: add status endpoint to the driver

Author: ktf

Framework/Core/CMakeLists.txt

@@ -158,6 +158,7 @@ o2_add_library(Framework
                        src/StepTHn.cxx
                        src/Base64.cxx
                        src/DPLWebSocket.cxx
+                       src/StatusWebSocketHandler.cxx
                        src/TimerParamSpec.cxx
                        test/TestClasses.cxx
                TARGETVARNAME targetName

Framework/Core/include/Framework/DeviceInfo.h

@@ -61,6 +61,9 @@ struct DeviceInfo {
   std::string lastError;
   /// An unterminated string which is not ready to be printed yet
   std::string unprinted;
+  /// Total number of log lines ever stored in history (monotonically increasing).
+  /// Used by status clients to track which lines they have already sent.
+  size_t logSeq = 0;
   /// Whether the device is active (running) or not.
   bool active;
   /// Whether the device is ready to quit.

Framework/Core/src/ControlWebSocketHandler.cxx

@@ -11,6 +11,7 @@
 
 #include "ControlWebSocketHandler.h"
 #include "DriverServerContext.h"
+#include "StatusWebSocketHandler.h"
 #include "Framework/DeviceMetricsHelper.h"
 #include "Framework/ServiceMetricsInfo.h"
 #include <regex>
@@ -83,6 +84,10 @@ void ControlWebSocketHandler::endChunk()
   for (auto& callback : *mContext.metricProcessingCallbacks) {
     callback(mContext.registry, ServiceMetricsInfo{*mContext.metrics, *mContext.specs, *mContext.infos, mContext.driver->metrics, *mContext.driver}, timestamp);
   }
+  // Notify status clients before changed flags are reset so they can see what changed.
+  for (auto* statusHandler : mContext.statusHandlers) {
+    statusHandler->sendUpdate(mIndex);
+  }
   for (auto& metricsInfo : *mContext.metrics) {
     std::fill(metricsInfo.changed.begin(), metricsInfo.changed.end(), false);
   }

Framework/Core/src/DPLWebSocket.cxx

@@ -18,6 +18,7 @@
 #include "DriverServerContext.h"
 #include "DriverClientContext.h"
 #include "ControlWebSocketHandler.h"
+#include "StatusWebSocketHandler.h"
 #include "HTTPParser.h"
 #include <algorithm>
 #include <atomic>
@@ -193,9 +194,10 @@ void WSDPLHandler::method(std::string_view const& s)
 
 void WSDPLHandler::target(std::string_view const& s)
 {
-  if (s != "/") {
+  if (s != "/" && s != "/status") {
     throw WSError{404, "Unknown"};
   }
+  mTarget = s;
 }
 
 void populateHeader(std::map<std::string, std::string>& headers, std::string_view const& k, std::string_view const& v)
@@ -294,6 +296,12 @@ void WSDPLHandler::endHeaders()
         break;
       }
     }
+  } else if (mTarget == "/status" && mServerContext->isDriver) {
+    LOGP(info, "Status client connected ({} total)", mServerContext->statusHandlers.size() + 1);
+    auto* statusHandler = new StatusWebSocketHandler(*mServerContext, this);
+    mServerContext->statusHandlers.push_back(statusHandler);
+    mHandler = std::unique_ptr<WebSocketHandler>(statusHandler);
+    mHandler->headers(mHeaders);
   } else {
     if ((mServerContext->isDriver && getenv("DPL_DRIVER_REMOTE_GUI")) || ((mServerContext->isDriver == false) && getenv("DPL_DEVICE_REMOTE_GUI"))) {
       LOG(info) << "Connection not bound to a PID";

Framework/Core/src/DPLWebSocket.h

@@ -62,6 +62,7 @@ struct WSDPLHandler : public HTTPParser {
   bool mHandshaken = false;
   uv_stream_t* mStream = nullptr;
   std::map<std::string, std::string> mHeaders;
+  std::string mTarget;
   DriverServerContext* mServerContext;
 };
 

Framework/Core/src/DriverServerContext.h

@@ -29,6 +29,7 @@ namespace o2::framework
 struct DriverInfo;
 struct ServiceRegistry;
 struct GuiCallbackContext;
+struct StatusWebSocketHandler;
 
 struct DriverServerContext {
   ServiceRegistryRef registry;
@@ -49,6 +50,10 @@ struct DriverServerContext {
   ///        or something like that.
   bool isDriver = false;
 
+  /// Connected MCP/status clients. Updated by StatusWebSocketHandler
+  /// on connect/disconnect; notified by ControlWebSocketHandler::endChunk().
+  std::vector<StatusWebSocketHandler*> statusHandlers;
+
   /// The handle to the server component of the
   /// driver.
   uv_tcp_t serverHandle;