feat(csharp): expose http_request_timeout as configurable parameter

Add `adbc.databricks.http_request_timeout` parameter to allow users to
configure the per-request timeout for dead connection detection. Default
remains 900s (15 min) matching JDBC socketTimeout. Set to 0 to disable.

Co-authored-by: Isaac

Author: eric-wang-1990

csharp/src/DatabricksConnection.cs

@@ -397,6 +397,11 @@ protected internal override bool TrySetGetDirectResults(IRequest request)
         /// </summary>
         protected int RateLimitRetryTimeout { get; private set; } = DatabricksConstants.DefaultRateLimitRetryTimeout;
 
+        /// <summary>
+        /// Gets the per-request timeout in seconds to detect dead connections.
+        /// </summary>
+        protected int HttpRequestTimeout { get; private set; } = DatabricksConstants.DefaultHttpRequestTimeout;
+
         protected override HttpMessageHandler CreateHttpHandler()
         {
             HttpMessageHandler baseHandler = base.CreateHttpHandler();
@@ -417,6 +422,7 @@ protected override HttpMessageHandler CreateHttpHandler()
                 TemporarilyUnavailableRetryTimeout = TemporarilyUnavailableRetryTimeout,
                 RateLimitRetry = RateLimitRetry,
                 RateLimitRetryTimeout = RateLimitRetryTimeout,
+                HttpRequestTimeout = HttpRequestTimeout,
                 TimeoutMinutes = 1,
                 AddThriftErrorHandler = true
             };
@@ -939,6 +945,17 @@ protected override void ValidateOptions()
                 RateLimitRetryTimeout = rateLimitRetryTimeoutValue;
             }
 
+            if (Properties.TryGetValue(DatabricksParameters.HttpRequestTimeout, out string? httpRequestTimeoutStr))
+            {
+                if (!int.TryParse(httpRequestTimeoutStr, out int httpRequestTimeoutValue) ||
+                    httpRequestTimeoutValue < 0)
+                {
+                    throw new ArgumentOutOfRangeException(DatabricksParameters.HttpRequestTimeout, httpRequestTimeoutStr,
+                        $"must be a value of 0 (disabled) or a positive integer representing seconds. Default is 900 seconds (15 minutes).");
+                }
+                HttpRequestTimeout = httpRequestTimeoutValue;
+            }
+
             // When TemporarilyUnavailableRetry is enabled, we need to make sure connection timeout (which is used to cancel the HttpConnection) is equal
             // or greater than TemporarilyUnavailableRetryTimeout so that it won't timeout before server startup timeout (TemporarilyUnavailableRetryTimeout)
             if (TemporarilyUnavailableRetry && TemporarilyUnavailableRetryTimeout * 1000 > ConnectTimeoutMilliseconds)

csharp/src/DatabricksParameters.cs

@@ -135,6 +135,14 @@ public class DatabricksParameters : SparkParameters
         /// </summary>
         public const string RateLimitRetryTimeout = "adbc.databricks.rate_limit_retry_timeout";
 
+        /// <summary>
+        /// Per-request timeout in seconds to detect dead connections (e.g., half-open TCP).
+        /// When a connection hangs without sending data, this timeout fires to cancel the request
+        /// and allow retry. Default value is 900 seconds (15 minutes), matching JDBC socketTimeout.
+        /// Set to 0 to disable the per-request timeout.
+        /// </summary>
+        public const string HttpRequestTimeout = "adbc.databricks.http_request_timeout";
+
         /// <summary>
         /// Maximum number of parallel downloads for CloudFetch operations.
         /// Default value is 3 if not specified.
@@ -421,6 +429,12 @@ public class DatabricksConstants
         /// </summary>
         public const int DefaultRateLimitRetryTimeout = 120; // 2 minutes
 
+        /// <summary>
+        /// Default per-request timeout in seconds to detect dead connections.
+        /// Matches JDBC driver's socketTimeout=900.
+        /// </summary>
+        public const int DefaultHttpRequestTimeout = 900; // 15 minutes
+
         /// <summary>
         /// Default timeout in minutes for CloudFetch HTTP operations.
         /// </summary>

csharp/src/Http/HttpHandlerFactory.cs

@@ -99,6 +99,11 @@ internal class HandlerConfig
             /// </summary>
             public int RateLimitRetryTimeout { get; set; }
 
+            /// <summary>
+            /// Per-request timeout in seconds to detect dead connections.
+            /// </summary>
+            public int HttpRequestTimeout { get; set; } = DatabricksConstants.DefaultHttpRequestTimeout;
+
             /// <summary>
             /// Timeout in minutes for HTTP operations.
             /// </summary>
@@ -314,14 +319,16 @@ public static HandlerCreationResult CreateHandlersWithTokenProvider(HandlerConfi
                     config.TemporarilyUnavailableRetryTimeout,
                     config.RateLimitRetryTimeout,
                     config.TemporarilyUnavailableRetry,
-                    config.RateLimitRetry);
+                    config.RateLimitRetry,
+                    httpRequestTimeoutSeconds: config.HttpRequestTimeout);
                 authHandler = new RetryHttpHandler(
                     authHandler,
                     config.ActivityTracer,
                     config.TemporarilyUnavailableRetryTimeout,
                     config.RateLimitRetryTimeout,
                     config.TemporarilyUnavailableRetry,
-                    config.RateLimitRetry);
+                    config.RateLimitRetry,
+                    httpRequestTimeoutSeconds: config.HttpRequestTimeout);
             }
 
             // Add Thrift error handler if requested (for Thrift connections only)