What causes "Delta length is invalid." in EllanJiang/GameFramework?

Only fire the update-length event when the delta is > 0

EllanJiang/GameFramework · error · GameFrameworkException

Delta length is invalid.

Error message

Delta length is invalid.

What it means

DownloadAgentHelperUpdateLengthEventArgs.Create requires a strictly positive delta length because it represents newly downloaded byte count used for progress and speed calculation. A zero or negative delta would corrupt the download statistics, so the library rejects it at creation time.

Solutions

Only fire the update-length event when the delta is > 0
Compute delta as currentLength - lastReportedLength and skip the call when it is 0
Check for integer underflow when subtracting length counters

Example fix

// before
helperCallback.UpdateLength(deltaLength); // deltaLength may be 0
// after
if (deltaLength > 0) helperCallback.UpdateLength(deltaLength);

Defensive patterns

Strategy: validation

Validate before calling

if (deltaLength <= 0) return; // skip event when no new bytes arrived

Type guard

bool IsPositiveDelta(int deltaLength) => deltaLength > 0;

Try / catch

try { var args = DownloadAgentHelperUpdateLengthEventArgs.Create(deltaLength); } catch (GameFrameworkException ex) { Log.Warning("Invalid download delta length: {0}", ex.Message); }

Prevention

Only fire progress events on actual byte movement
Watch for signed integer underflow in length math
Log deltas periodically to catch zero-increment spam early

When it happens

Trigger: Calling DownloadAgentHelperUpdateLengthEventArgs.Create with deltaLength <= 0, typically from a custom IDownloadAgentHelper reporting a download-progress event with a non-positive increment.

Common situations: Custom helper implementations calling the update-length callback on every poll tick even when no bytes arrived, or a signed underflow when computing the increment.

Related errors

AI-assisted analysis of EllanJiang/GameFramework@d0c010b051 (2026-09-15). Data as JSON: /api/errors/7501918eb697ca58. Report an issue: GitHub.

Appendix: source

Thrown at GameFramework/Download/DownloadAgentHelperUpdateLengthEventArgs.cs:41

        /// <summary>
        /// 获取下载的增量数据大小。
        /// </summary>
        public int DeltaLength
        {
            get;
            private set;
        }

        /// <summary>
        /// 创建下载代理辅助器更新数据大小事件。
        /// </summary>
        /// <param name="deltaLength">下载的增量数据大小。</param>
        /// <returns>创建的下载代理辅助器更新数据大小事件。</returns>
        public static DownloadAgentHelperUpdateLengthEventArgs Create(int deltaLength)
        {
            if (deltaLength <= 0)
            {
                throw new GameFrameworkException("Delta length is invalid.");
            }

            DownloadAgentHelperUpdateLengthEventArgs downloadAgentHelperUpdateLengthEventArgs = ReferencePool.Acquire<DownloadAgentHelperUpdateLengthEventArgs>();
            downloadAgentHelperUpdateLengthEventArgs.DeltaLength = deltaLength;
            return downloadAgentHelperUpdateLengthEventArgs;
        }

        /// <summary>
        /// 清理下载代理辅助器更新数据大小事件。
        /// </summary>
        public override void Clear()
        {
            DeltaLength = 0;
        }
    }
}

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