From ec7a3599bd30b3b1c4fb8890b1385d5957e0281e Mon Sep 17 00:00:00 2001
From: Levi McCallum <levi@pinterest.com>
Date: Wed, 27 Jan 2016 14:52:37 -0800
Subject: [PATCH] Add `setNeedsDataFetch` method to queue off screen
 `fetchData` calls

---
 AsyncDisplayKit/ASDisplayNode.h               |  8 +++++-
 AsyncDisplayKit/ASDisplayNode.mm              | 14 ++++++++--
 AsyncDisplayKit/ASDisplayNodeExtras.h         | 27 +++++++++++++++++++
 .../Private/ASDisplayNodeInternal.h           |  2 ++
 4 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/AsyncDisplayKit/ASDisplayNode.h b/AsyncDisplayKit/ASDisplayNode.h
index ab3b40b524..e462e0a76b 100644
--- a/AsyncDisplayKit/ASDisplayNode.h
+++ b/AsyncDisplayKit/ASDisplayNode.h
@@ -442,7 +442,6 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * @see displaySuspended and setNeedsDisplay
  */
-
 - (void)recursivelyClearContents;
 
 /**
@@ -465,6 +464,13 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (void)recursivelyFetchData;
 
+/**
+ * @abstract Marks the node as needing to call fetchData
+ * @discussion If the node is outside of the preload range, it is queued to call fetchData the next time it enters the range.
+ * Otherwise, fetchData is called immediately if the node is currently within the preload range.
+ */
+- (void)setNeedsDataFetch;
+
 /**
  * @abstract Toggle displaying a placeholder over the node that covers content until the node and all subnodes are
  * displayed.
diff --git a/AsyncDisplayKit/ASDisplayNode.mm b/AsyncDisplayKit/ASDisplayNode.mm
index 9c7cbe6d75..9921de366a 100644
--- a/AsyncDisplayKit/ASDisplayNode.mm
+++ b/AsyncDisplayKit/ASDisplayNode.mm
@@ -1727,6 +1727,15 @@ static BOOL ShouldUseNewRenderingRange = YES;
   // subclass override
 }
 
+- (void)setNeedsDataFetch
+{
+  if (ASInterfaceStateIncludesFetchData(_interfaceState)) {
+    [self fetchData];
+  } else {
+    _needsDataFetch = YES;
+  }
+}
+
 // TODO: Replace this with ASDisplayNodePerformBlockOnEveryNode or enterInterfaceState:
 - (void)recursivelyFetchData
 {
@@ -1793,9 +1802,10 @@ static BOOL ShouldUseNewRenderingRange = YES;
   BOOL nowFetchData = ASInterfaceStateIncludesFetchData(newState);
   BOOL wasFetchData = ASInterfaceStateIncludesFetchData(oldState);
   
-  if (nowFetchData != wasFetchData) {
-    if (nowFetchData) {
+  if (nowFetchData != wasFetchData || _needsDataFetch) {
+    if (nowFetchData || _needsDataFetch) {
       [self fetchData];
+      _needsDataFetch = NO;
     } else {
       if ([self supportsRangeManagedInterfaceState]) {
         [self clearFetchedData];
diff --git a/AsyncDisplayKit/ASDisplayNodeExtras.h b/AsyncDisplayKit/ASDisplayNodeExtras.h
index 0ab9957cc3..e453c84ea7 100644
--- a/AsyncDisplayKit/ASDisplayNodeExtras.h
+++ b/AsyncDisplayKit/ASDisplayNodeExtras.h
@@ -29,6 +29,33 @@ inline BOOL ASInterfaceStateIncludesFetchData(ASInterfaceState interfaceState)
   return ((interfaceState & ASInterfaceStateFetchData) == ASInterfaceStateFetchData);
 }
 
+inline BOOL ASInterfaceStateIncludesMeasureLayout(ASInterfaceState interfaceState)
+{
+  return ((interfaceState & ASInterfaceStateMeasureLayout) == ASInterfaceStateMeasureLayout);
+}
+
+inline NSString * _Nonnull NSStringFromASInterfaceState(ASInterfaceState interfaceState)
+{
+  NSMutableString *result = [NSMutableString stringWithString:@"{ "];
+  if (interfaceState == ASInterfaceStateNone) {
+    [result appendString:@"No state"];
+  }
+  if (ASInterfaceStateIncludesMeasureLayout(interfaceState)) {
+    [result appendString:@"MeasureLayout"];
+  }
+  if (ASInterfaceStateIncludesFetchData(interfaceState)) {
+    [result appendString:@" - FetchData"];
+  }
+  if (ASInterfaceStateIncludesDisplay(interfaceState)) {
+    [result appendString:@" - Display"];
+  }
+  if (ASInterfaceStateIncludesVisible(interfaceState)) {
+    [result appendString:@" - Visible"];
+  }
+  [result appendString:@" }"];
+  return result;
+}
+
 NS_ASSUME_NONNULL_BEGIN
 
 ASDISPLAYNODE_EXTERN_C_BEGIN
diff --git a/AsyncDisplayKit/Private/ASDisplayNodeInternal.h b/AsyncDisplayKit/Private/ASDisplayNodeInternal.h
index f1ffb377e9..ade418dd89 100644
--- a/AsyncDisplayKit/Private/ASDisplayNodeInternal.h
+++ b/AsyncDisplayKit/Private/ASDisplayNodeInternal.h
@@ -100,6 +100,8 @@ typedef NS_OPTIONS(NSUInteger, ASDisplayNodeMethodOverrides)
   } _flags;
 
   ASDisplayNodeExtraIvars _extra;
+  
+  BOOL _needsDataFetch;
 
 #if TIME_DISPLAYNODE_OPS
 @public