MeasureLatency now bails out quickly if it experiences a connection error (#789)

previously it would stall some 40s in this case

3 files changed, 25 insertions, 0 deletions

diff --git a/src/zenhttp/clients/httpclientcpr.cpp b/src/zenhttp/clients/httpclientcpr.cpp
index 6bc63db09..90dcfacbb 100644
--- a/src/zenhttp/clients/httpclientcpr.cpp
+++ b/src/zenhttp/clients/httpclientcpr.cpp
@@ -23,6 +23,21 @@ CreateCprHttpClient(std::string_view BaseUri, const HttpClientSettings& Connecti
 
 static std::atomic<uint32_t> HttpClientRequestIdCounter{0};
 
+bool
+HttpClient::ErrorContext::IsConnectionError() const
+{
+	switch (static_cast<cpr::ErrorCode>(ErrorCode))
+	{
+		case cpr::ErrorCode::CONNECTION_FAILURE:
+		case cpr::ErrorCode::OPERATION_TIMEDOUT:
+		case cpr::ErrorCode::HOST_RESOLUTION_FAILURE:
+		case cpr::ErrorCode::PROXY_RESOLUTION_FAILURE:
+			return true;
+		default:
+			return false;
+	}
+}
+
 // If we want to support different HTTP client implementations then we'll need to make this more abstract
 
 HttpClientError::ResponseClass
diff --git a/src/zenhttp/httpclient.cpp b/src/zenhttp/httpclient.cpp
index 998eb27ea..1cfddb366 100644
--- a/src/zenhttp/httpclient.cpp
+++ b/src/zenhttp/httpclient.cpp
@@ -400,6 +400,13 @@ MeasureLatency(HttpClient& Client, std::string_view Url)
 		else
 		{
 			ErrorMessage = MeasureResponse.ErrorMessage(fmt::format("Unable to measure latency using {}", Url));
+
+			// Connection-level failures (timeout, refused, DNS) mean the endpoint is unreachable.
+			// Bail out immediately — retrying will just burn the connect timeout each time.
+			if (MeasureResponse.Error && MeasureResponse.Error->IsConnectionError())
+			{
+				break;
+			}
 		}
 	}
 
diff --git a/src/zenhttp/include/zenhttp/httpclient.h b/src/zenhttp/include/zenhttp/httpclient.h
index 41a7ce621..f00bbec63 100644
--- a/src/zenhttp/include/zenhttp/httpclient.h
+++ b/src/zenhttp/include/zenhttp/httpclient.h
@@ -125,6 +125,9 @@ public:
 	{
 		int			ErrorCode;
 		std::string ErrorMessage;
+
+		/** True when the error is a transport-level connection failure (connect timeout, refused, DNS) */
+		bool IsConnectionError() const;
 	};
 
 	struct KeyValueMap