From c053fdd9ca7204ba9c287500362ad4cb28143261 Mon Sep 17 00:00:00 2001
From: Bhavik Shah <bhavik@memreel.io>
Date: Sat, 29 Aug 2026 18:39:20 -0700
Subject: [PATCH] fix: make WaveformExtractor.stop() idempotent
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stop() is reachable from two threads: the MediaCodec callback thread,
when decoding completes on its own (handleBufferDivision once progress
exceeds 1.0, and onOutputBufferAvailable at EOF), and the platform
thread, when Flutter calls stopExtraction — which PlayerController.dispose
does unconditionally, and which createOrUpdateExtractor does before
starting a new extraction on the same key.

Because the decoder reference was never cleared and stop() had no guard,
the later caller invoked MediaCodec.stop() on an already-released codec:

  java.lang.IllegalStateException: codec is released already
    at android.media.MediaCodec.native_stop(Native Method)
    at android.media.MediaCodec.stop(MediaCodec.java:2579)

On the Flutter side this surfaces as a PlatformException thrown out of
PlayerController.dispose(), which is `void ... async`, so it escapes as
an unhandled async error rather than something callers can catch.

Guard stop() with an AtomicBoolean compare-and-set, tolerate
IllegalStateException on each release, and null out decoder/extractor
afterwards — which also makes the existing null checks in
onInputBufferAvailable and onOutputBufferAvailable effective, where
previously they could never fire.

iOS is unaffected: WaveformExtractor.cancel() is already flag-guarded.
---
 .../audio_waveforms/WaveformExtractor.kt      | 32 +++++++++++++++++--
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/android/src/main/kotlin/com/simform/audio_waveforms/WaveformExtractor.kt b/android/src/main/kotlin/com/simform/audio_waveforms/WaveformExtractor.kt
index 46201a91..b182ac30 100644
--- a/android/src/main/kotlin/com/simform/audio_waveforms/WaveformExtractor.kt
+++ b/android/src/main/kotlin/com/simform/audio_waveforms/WaveformExtractor.kt
@@ -10,6 +10,7 @@ import android.util.Log
 import io.flutter.plugin.common.MethodChannel
 import java.nio.ByteBuffer
 import java.util.concurrent.CountDownLatch
+import java.util.concurrent.atomic.AtomicBoolean
 import kotlin.math.pow
 import kotlin.math.sqrt
 import androidx.core.net.toUri
@@ -68,6 +69,8 @@ class WaveformExtractor(
     private var perSamplePoints = 0L
     /** Flag to prevent submitting multiple results */
     private var isReplySubmitted = false
+    /** Guards [stop] so the codec is only stopped and released once */
+    private val isStopped = AtomicBoolean(false)
 
     /**
      * Retrieves the audio format from the given media file
@@ -402,9 +405,32 @@ class WaveformExtractor(
      * 3. Signals completion via the countdown latch
      */
     fun stop() {
-        decoder?.stop()
-        decoder?.release()
-        extractor?.release()
+        // stop() reaches us from two threads: the MediaCodec callback thread
+        // when decoding finishes on its own, and the platform thread when
+        // Flutter calls stopExtraction (PlayerController.dispose does this).
+        // Whichever loses the race would otherwise call stop() on a codec that
+        // is already released, which throws IllegalStateException.
+        if (!isStopped.compareAndSet(false, true)) return
+
+        try {
+            decoder?.stop()
+        } catch (e: IllegalStateException) {
+            Log.w(Constants.LOG_TAG, "Decoder already stopped: ${e.message}")
+        }
+        try {
+            decoder?.release()
+        } catch (e: IllegalStateException) {
+            Log.w(Constants.LOG_TAG, "Decoder already released: ${e.message}")
+        }
+        decoder = null
+
+        try {
+            extractor?.release()
+        } catch (e: IllegalStateException) {
+            Log.w(Constants.LOG_TAG, "Extractor already released: ${e.message}")
+        }
+        extractor = null
+
         finishCount.countDown()
     }
 }