VEX-6030: Reduce buffer size based on heap (#13)

This PR changes the behavior on old devices that have poor memory management.

Jira: VEX-6030
https://jira.tenkasu.net/browse/VEX-6030

The solution implied customizing the method shouldContinueLoading from RNVLoadControl to use only the available heap, performing tests on an old Nexus 5 it was determined the ideal bytes allocation to half the reported heap, that provided some buffering during ads but smooth playback during the video with no crashes (23:39 of 23:39 at the moment of writing this, video kept playing as expected after 3 ad breaks)

The fix is only targeting Marshmallow as the reduction of buffer is substantial and other versions that work properly should not get affected.

Depending on the test result of VEX-5758, this same fix can be applied to Nougat

Reviews
Major reviewer (domain expert): @armadilio3
Minor reviewer: @nickfujita

README.md

@@ -385,6 +385,7 @@ minBufferMs | number | The default minimum duration of media that the player wil
 maxBufferMs | number | The default maximum duration of media that the player will attempt to buffer, in milliseconds.
 bufferForPlaybackMs | number | The default duration of media that must be buffered for playback to start or resume following a user action such as a seek, in milliseconds.
 bufferForPlaybackAfterRebufferMs | number | The default duration of media that must be buffered for playback to resume after a rebuffer, in milliseconds. A rebuffer is defined to be caused by buffer depletion rather than a user action.
+maxHeapAllocationPercent | number | The percentage of available heap that the video can use to buffer, between 0 and 1
 
 This prop should only be set when you are setting the source, changing it after the media is loaded will cause it to be reloaded.
 

Video.js

@@ -468,6 +468,7 @@ Video.propTypes = {
     maxBufferMs: PropTypes.number,
     bufferForPlaybackMs: PropTypes.number,
     bufferForPlaybackAfterRebufferMs: PropTypes.number,
+    maxHeapAllocationPercent: PropTypes.number,
   }),
   stereoPan: PropTypes.number,
   rate: PropTypes.number,

android-exoplayer/src/main/java/com/brentvatne/exoplayer/ReactExoplayerView.java

@@ -2,6 +2,7 @@ package com.brentvatne.exoplayer;
 
 import android.annotation.SuppressLint;
 import android.app.Activity;
+import android.app.ActivityManager;
 import android.content.Context;
 import android.media.AudioManager;
 import android.net.Uri;
@@ -111,6 +112,8 @@ class ReactExoplayerView extends FrameLayout implements
         MetadataOutput,
         DrmSessionEventListener {
 
+    public static final double DEFAULT_MAX_HEAP_ALLOCATION_PERCENT = 1;
+
     private static final String TAG = "ReactExoplayerView";
 
     private static final CookieManager DEFAULT_COOKIE_MANAGER;
@@ -157,6 +160,7 @@ class ReactExoplayerView extends FrameLayout implements
     private int maxBufferMs = DefaultLoadControl.DEFAULT_MAX_BUFFER_MS;
     private int bufferForPlaybackMs = DefaultLoadControl.DEFAULT_BUFFER_FOR_PLAYBACK_MS;
     private int bufferForPlaybackAfterRebufferMs = DefaultLoadControl.DEFAULT_BUFFER_FOR_PLAYBACK_AFTER_REBUFFER_MS;
+    private double maxHeapAllocationPercent = ReactExoplayerView.DEFAULT_MAX_HEAP_ALLOCATION_PERCENT;
 
     private Handler mainHandler;
     private Timer bufferCheckTimer;
@@ -418,6 +422,7 @@ class ReactExoplayerView extends FrameLayout implements
     }
 
     private class RNVLoadControl extends DefaultLoadControl {
+        private int availableHeapInBytes = 0;
         public RNVLoadControl(DefaultAllocator allocator, int minBufferMs, int maxBufferMs, int bufferForPlaybackMs, int bufferForPlaybackAfterRebufferMs, int targetBufferBytes, boolean prioritizeTimeOverSizeThresholds, int backBufferDurationMs, boolean retainBackBufferFromKeyframe) {
             super(allocator,
                     minBufferMs,
@@ -428,6 +433,8 @@ class ReactExoplayerView extends FrameLayout implements
                     prioritizeTimeOverSizeThresholds,
                     backBufferDurationMs,
                     retainBackBufferFromKeyframe);
+            ActivityManager activityManager = (ActivityManager) themedReactContext.getSystemService(themedReactContext.ACTIVITY_SERVICE);
+            availableHeapInBytes = (int) Math.floor(activityManager.getMemoryClass() * maxHeapAllocationPercent * 1024 * 1024);
         }
 
         @Override
@@ -435,6 +442,11 @@ class ReactExoplayerView extends FrameLayout implements
             if (ReactExoplayerView.this.disableBuffering) {
                 return false;
             }
+            int loadedBytes = getAllocator().getTotalBytesAllocated();
+            boolean isHeapReached = availableHeapInBytes > 0 && loadedBytes >= availableHeapInBytes;
+            if (isHeapReached) {
+                return false;
+            }
             return super.shouldContinueLoading(playbackPositionUs, bufferedDurationUs, playbackSpeed);
         }
     }
@@ -1660,11 +1672,12 @@ class ReactExoplayerView extends FrameLayout implements
         exoPlayerView.setHideShutterView(hideShutterView);
     }
 
-    public void setBufferConfig(int newMinBufferMs, int newMaxBufferMs, int newBufferForPlaybackMs, int newBufferForPlaybackAfterRebufferMs) {
+    public void setBufferConfig(int newMinBufferMs, int newMaxBufferMs, int newBufferForPlaybackMs, int newBufferForPlaybackAfterRebufferMs, double newMaxHeapAllocationPercent) {
         minBufferMs = newMinBufferMs;
         maxBufferMs = newMaxBufferMs;
         bufferForPlaybackMs = newBufferForPlaybackMs;
         bufferForPlaybackAfterRebufferMs = newBufferForPlaybackAfterRebufferMs;
+        maxHeapAllocationPercent = newMaxHeapAllocationPercent;
         releasePlayer();
         initializePlayer();
     }

android-exoplayer/src/main/java/com/brentvatne/exoplayer/ReactExoplayerViewManager.java

@@ -55,6 +55,7 @@ public class ReactExoplayerViewManager extends ViewGroupManager<ReactExoplayerVi
     private static final String PROP_BUFFER_CONFIG_MAX_BUFFER_MS = "maxBufferMs";
     private static final String PROP_BUFFER_CONFIG_BUFFER_FOR_PLAYBACK_MS = "bufferForPlaybackMs";
     private static final String PROP_BUFFER_CONFIG_BUFFER_FOR_PLAYBACK_AFTER_REBUFFER_MS = "bufferForPlaybackAfterRebufferMs";
+    private static final String PROP_BUFFER_CONFIG_MAX_HEAP_ALLOCATION_PERCENT = "maxHeapAllocationPercent";
     private static final String PROP_PREVENTS_DISPLAY_SLEEP_DURING_VIDEO_PLAYBACK = "preventsDisplaySleepDuringVideoPlayback";
     private static final String PROP_PROGRESS_UPDATE_INTERVAL = "progressUpdateInterval";
     private static final String PROP_REPORT_BANDWIDTH = "reportBandwidth";
@@ -344,6 +345,7 @@ public class ReactExoplayerViewManager extends ViewGroupManager<ReactExoplayerVi
         int maxBufferMs = DefaultLoadControl.DEFAULT_MAX_BUFFER_MS;
         int bufferForPlaybackMs = DefaultLoadControl.DEFAULT_BUFFER_FOR_PLAYBACK_MS;
         int bufferForPlaybackAfterRebufferMs = DefaultLoadControl.DEFAULT_BUFFER_FOR_PLAYBACK_AFTER_REBUFFER_MS;
+        double maxHeapAllocationPercent = ReactExoplayerView.DEFAULT_MAX_HEAP_ALLOCATION_PERCENT;
         if (bufferConfig != null) {
             minBufferMs = bufferConfig.hasKey(PROP_BUFFER_CONFIG_MIN_BUFFER_MS)
                     ? bufferConfig.getInt(PROP_BUFFER_CONFIG_MIN_BUFFER_MS) : minBufferMs;
@@ -353,7 +355,9 @@ public class ReactExoplayerViewManager extends ViewGroupManager<ReactExoplayerVi
                     ? bufferConfig.getInt(PROP_BUFFER_CONFIG_BUFFER_FOR_PLAYBACK_MS) : bufferForPlaybackMs;
             bufferForPlaybackAfterRebufferMs = bufferConfig.hasKey(PROP_BUFFER_CONFIG_BUFFER_FOR_PLAYBACK_AFTER_REBUFFER_MS)
                     ? bufferConfig.getInt(PROP_BUFFER_CONFIG_BUFFER_FOR_PLAYBACK_AFTER_REBUFFER_MS) : bufferForPlaybackAfterRebufferMs;
-            videoView.setBufferConfig(minBufferMs, maxBufferMs, bufferForPlaybackMs, bufferForPlaybackAfterRebufferMs);
+            maxHeapAllocationPercent = bufferConfig.hasKey(PROP_BUFFER_CONFIG_MAX_HEAP_ALLOCATION_PERCENT)
+                    ? bufferConfig.getDouble(PROP_BUFFER_CONFIG_MAX_HEAP_ALLOCATION_PERCENT) : maxHeapAllocationPercent;
+            videoView.setBufferConfig(minBufferMs, maxBufferMs, bufferForPlaybackMs, bufferForPlaybackAfterRebufferMs, maxHeapAllocationPercent);
         }
     }