Add value-based stall detection to catch stuck progress

Also refactors the test-stall-detection test suite.

Author: m7kvqbe1

lib/StallDetector.ts

@@ -9,6 +9,8 @@ export class StallDetector {
 
   private intervalId: ReturnType<typeof setInterval> | null = null
   private lastProgressTime = 0
+  private lastProgressValue = 0
+  private progressValueCount = 0
   private isActive = false
 
   constructor(
@@ -30,6 +32,8 @@ export class StallDetector {
     }
 
     this.lastProgressTime = Date.now()
+    this.lastProgressValue = 0
+    this.progressValueCount = 0
     this.isActive = true
 
     log(
@@ -43,7 +47,9 @@ export class StallDetector {
       }
 
       const now = Date.now()
-      if (this._isProgressStalled(now)) {
+      if (this._isProgressValueStalled()) {
+        this._handleStall('progress value not changing')
+      } else if (this._isProgressStalled(now)) {
         this._handleStall('no progress events received')
       }
     }, this.options.checkInterval)
@@ -62,9 +68,18 @@ export class StallDetector {
 
   /**
    * Update progress information
+   * @param progressValue The current progress value (bytes uploaded)
    */
-  updateProgress(): void {
+  updateProgress(progressValue: number): void {
     this.lastProgressTime = Date.now()
+
+    // Track if the progress value has changed
+    if (progressValue === this.lastProgressValue) {
+      this.progressValueCount++
+    } else {
+      this.lastProgressValue = progressValue
+      this.progressValueCount = 0
+    }
   }
 
   /**
@@ -82,6 +97,25 @@ export class StallDetector {
     return isStalled
   }
 
+  /**
+   * Check if upload has stalled based on progress value not changing
+   */
+  private _isProgressValueStalled(): boolean {
+    // Calculate how many times we expect progress to have changed based on check intervals
+    const expectedProgressChanges = Math.floor(
+      this.options.stallTimeout / this.options.checkInterval,
+    )
+    const isStalled = this.progressValueCount >= expectedProgressChanges
+
+    if (isStalled) {
+      log(
+        `tus: progress value stuck at ${this.lastProgressValue} bytes for ${this.progressValueCount} checks`,
+      )
+    }
+
+    return isStalled
+  }
+
   /**
    * Handle a detected stall
    */

lib/upload.ts

@@ -872,7 +872,7 @@ export class BaseUpload {
     req.setProgressHandler((bytesSent) => {
       // Update per-request stall detector if active
       if (stallDetector) {
-        stallDetector.updateProgress()
+        stallDetector.updateProgress(start + bytesSent)
       }
       this._emitProgress(start + bytesSent, this._size)
     })
@@ -921,20 +921,19 @@ export class BaseUpload {
       )
     }
 
-    let response: HttpResponse
     if (value == null) {
-      response = await this._sendRequest(req, undefined, stallDetector)
-    } else {
-      if (
-        this.options.protocol === PROTOCOL_IETF_DRAFT_03 ||
-        this.options.protocol === PROTOCOL_IETF_DRAFT_05
-      ) {
-        req.setHeader('Upload-Complete', done ? '?1' : '?0')
-      }
-      response = await this._sendRequest(req, value, stallDetector)
+      return await this._sendRequest(req, undefined, stallDetector)
+    }
+
+    if (
+      this.options.protocol === PROTOCOL_IETF_DRAFT_03 ||
+      this.options.protocol === PROTOCOL_IETF_DRAFT_05
+    ) {
+      req.setHeader('Upload-Complete', done ? '?1' : '?0')
     }
 
-    return response
+    this._emitProgress(this._offset, this._size)
+    return await this._sendRequest(req, value, stallDetector)
   }
 
   /**