fix(csharp): use -1 as default for max_retries to denote not set

Change DefaultMaxRetries from 0 to -1 so that -1 clearly means "not set"
and 0 can mean "no retries at all" if needed. Guard checks updated from
> 0 to >= 0 accordingly.

Co-authored-by: Isaac

Author: eric-wang-1990

csharp/src/DatabricksParameters.cs

@@ -53,8 +53,8 @@ public class DatabricksParameters : SparkParameters
 
         /// <summary>
         /// Maximum number of retry attempts for CloudFetch downloads.
-        /// Default value is 0 (no limit, use timeout only) if not specified.
-        /// When set, the retry loop exits if either this count or the timeout is reached.
+        /// Default value is -1 (not set, use timeout only).
+        /// When set to a non-negative value, the retry loop exits if either this count or the timeout is reached.
         /// </summary>
         public const string CloudFetchMaxRetries = "adbc.databricks.cloudfetch.max_retries";
 

csharp/src/Reader/CloudFetch/CloudFetchConfiguration.cs

@@ -33,7 +33,7 @@ internal sealed class CloudFetchConfiguration
         internal const int DefaultPrefetchCount = 2;
         internal const int DefaultMemoryBufferSizeMB = 200;
         internal const int DefaultTimeoutMinutes = 5;
-        internal const int DefaultMaxRetries = 0; // 0 = no limit (use timeout only)
+        internal const int DefaultMaxRetries = -1; // -1 = not set (use timeout only)
         internal const int DefaultRetryTimeoutSeconds = 300; // 5 minutes
         internal const int DefaultRetryDelayMs = 500;
         internal const int DefaultMaxUrlRefreshAttempts = 3;
@@ -61,8 +61,8 @@ internal sealed class CloudFetchConfiguration
 
         /// <summary>
         /// Maximum retry attempts for failed downloads.
-        /// 0 means no limit (use timeout only). When set, the retry loop exits
-        /// if either this count or the timeout is reached.
+        /// -1 means not set (use timeout only). When set to a non-negative value,
+        /// the retry loop exits if either this count or the timeout is reached.
         /// </summary>
         public int MaxRetries { get; set; } = DefaultMaxRetries;
 
@@ -133,7 +133,7 @@ public static CloudFetchConfiguration FromProperties(
                 PrefetchCount = PropertyHelper.GetPositiveIntPropertyWithValidation(properties, DatabricksParameters.CloudFetchPrefetchCount, DefaultPrefetchCount),
                 MemoryBufferSizeMB = PropertyHelper.GetPositiveIntPropertyWithValidation(properties, DatabricksParameters.CloudFetchMemoryBufferSize, DefaultMemoryBufferSizeMB),
                 TimeoutMinutes = PropertyHelper.GetPositiveIntPropertyWithValidation(properties, DatabricksParameters.CloudFetchTimeoutMinutes, DefaultTimeoutMinutes),
-                MaxRetries = properties.TryGetValue(DatabricksParameters.CloudFetchMaxRetries, out string? maxRetriesStr) && int.TryParse(maxRetriesStr, out int maxRetries) && maxRetries > 0 ? maxRetries : DefaultMaxRetries,
+                MaxRetries = properties.TryGetValue(DatabricksParameters.CloudFetchMaxRetries, out string? maxRetriesStr) && int.TryParse(maxRetriesStr, out int maxRetries) && maxRetries >= 0 ? maxRetries : DefaultMaxRetries,
                 RetryTimeoutSeconds = PropertyHelper.GetPositiveIntPropertyWithValidation(properties, DatabricksParameters.CloudFetchRetryTimeoutSeconds, DefaultRetryTimeoutSeconds),
                 RetryDelayMs = PropertyHelper.GetPositiveIntPropertyWithValidation(properties, DatabricksParameters.CloudFetchRetryDelayMs, DefaultRetryDelayMs),
                 MaxUrlRefreshAttempts = PropertyHelper.GetPositiveIntPropertyWithValidation(properties, DatabricksParameters.CloudFetchMaxUrlRefreshAttempts, DefaultMaxUrlRefreshAttempts),

csharp/src/Reader/CloudFetch/CloudFetchDownloader.cs

@@ -503,7 +503,7 @@ await _activityTracer.TraceActivityAsync(async activity =>
                 while (!cancellationToken.IsCancellationRequested)
                 {
                     // Check if we've exceeded the max retry count (if set)
-                    if (_maxRetries > 0 && attemptCount >= _maxRetries)
+                    if (_maxRetries >= 0 && attemptCount >= _maxRetries)
                     {
                         activity?.AddEvent("cloudfetch.download_max_retries_exceeded", [
                             new("offset", downloadResult.StartRowOffset),
@@ -645,7 +645,7 @@ await _activityTracer.TraceActivityAsync(async activity =>
 
                     // Release the memory we acquired
                     _memoryManager.ReleaseMemory(size);
-                    string retryLimits = _maxRetries > 0
+                    string retryLimits = _maxRetries >= 0
                         ? $"max_retries: {_maxRetries}, timeout: {_retryTimeoutSeconds}s"
                         : $"timeout: {_retryTimeoutSeconds}s";
                     throw new InvalidOperationException(

csharp/test/E2E/CloudFetch/CloudFetchDownloaderTest.cs

@@ -178,7 +178,7 @@ public async Task DownloadFileAsync_ProcessesFile_AndAddsToResultQueue()
                 _mockResultFetcher.Object,
                 1, // maxParallelDownloads
                 false, // isLz4Compressed
-                maxRetries: 0,
+                maxRetries: -1,
                 retryTimeoutSeconds: 5,
                 retryDelayMs: 10);
 
@@ -263,7 +263,7 @@ public async Task DownloadFileAsync_HandlesHttpError_AndSetsFailedOnDownloadResu
                 _mockResultFetcher.Object,
                 1, // maxParallelDownloads
                 false, // isLz4Compressed
-                maxRetries: 0,
+                maxRetries: -1,
                 retryTimeoutSeconds: 1,
                 retryDelayMs: 10);
 
@@ -353,7 +353,7 @@ public async Task DownloadFileAsync_WithError_StopsProcessingRemainingFiles()
                 _mockResultFetcher.Object,
                 1, // maxParallelDownloads
                 false, // isLz4Compressed
-                maxRetries: 0,
+                maxRetries: -1,
                 retryTimeoutSeconds: 1,
                 retryDelayMs: 10);
 
@@ -687,7 +687,7 @@ public async Task DownloadFileAsync_RefreshesExpiredUrl_WhenHttpErrorOccurs()
                 _mockResultFetcher.Object,
                 1, // maxParallelDownloads
                 false, // isLz4Compressed
-                maxRetries: 0,
+                maxRetries: -1,
                 retryTimeoutSeconds: 5,
                 retryDelayMs: 10);