Make Yoga thread safe #786

2018-06-19T01:51:18-07:00

nokia6686 commented

2018-06-19 01:51:18 -07:00

(Migrated from github.com)

Issue ref: https://github.com/facebook/yoga/issues/769

Problem

gNodeInstanceCount, gConfigInstanceCount, gCurrentGenerationCount, gDepth are global variables in Yoga.cpp. They are not safe when using multithreading.

My idea

Uses atomic for gNodeInstanceCount and gConfigInstanceCount because of counting instances only.
Store gCurrentGenerationCount and gDepth in root node for multithreading.

My solution

Uses for gNodeInstanceCount and gConfigInstanceCount

std::atomic<int32_t> gNodeInstanceCount(0);
std::atomic<int32_t> gConfigInstanceCount(0);

Every Yoga Node has its root reference (root-ref). New node's root point to itself. Root-ref will be updated when inserting children.
gCurrentGenerationCount and gDepth are stored in YGNode.
When updating children, we must update root-ref for each new child.

struct YGNode {
...
  // We must setChildRoot() for new child
  void replaceChild(YGNodeRef oldChild, YGNodeRef newChild);
  void replaceChild(YGNodeRef child, uint32_t index);
  void insertChild(YGNodeRef child, uint32_t index);
...
  private:
    YGNodeRef pRoot = nullptr;

  public:
    uint32_t  gCurrentGenerationCount = 0;
    uint32_t  gDepth = 0;
    YGNodeRef getRoot();
    void setChildRoot(YGNodeRef node);
}
...
void YGNode::setChildRoot(YGNodeRef node) {
  node->pRoot = getRoot();
  for (auto child: node->children_) {
    setChildRoot(child);
  }
}

Global variables are accessed via root-ref

//gCurrentGenerationCount++;
node->getRoot()->gCurrentGenerationCount++;

//gDepth++;
node->getRoot()->gDepth++;

Issue ref: https://github.com/facebook/yoga/issues/769 ### Problem - `gNodeInstanceCount`, `gConfigInstanceCount`, `gCurrentGenerationCount`, `gDepth` are global variables in `Yoga.cpp`. They are not safe when using multithreading. ### My idea - Uses `atomic` for `gNodeInstanceCount` and `gConfigInstanceCount` because of counting instances only. - Store `gCurrentGenerationCount` and `gDepth` in root node for multithreading. ### My solution - Uses <atomic> for `gNodeInstanceCount` and `gConfigInstanceCount` ```C++ std::atomic<int32_t> gNodeInstanceCount(0); std::atomic<int32_t> gConfigInstanceCount(0); ``` - Every Yoga Node has its root reference (root-ref). New node's root point to itself. Root-ref will be updated when inserting children. - `gCurrentGenerationCount` and `gDepth` are stored in `YGNode`. - When updating children, we must update root-ref for each new child. ```c++ struct YGNode { ... // We must setChildRoot() for new child void replaceChild(YGNodeRef oldChild, YGNodeRef newChild); void replaceChild(YGNodeRef child, uint32_t index); void insertChild(YGNodeRef child, uint32_t index); ... private: YGNodeRef pRoot = nullptr; public: uint32_t gCurrentGenerationCount = 0; uint32_t gDepth = 0; YGNodeRef getRoot(); void setChildRoot(YGNodeRef node); } ... void YGNode::setChildRoot(YGNodeRef node) { node->pRoot = getRoot(); for (auto child: node->children_) { setChildRoot(child); } } ``` - Global variables are accessed via root-ref ```C++ //gCurrentGenerationCount++; node->getRoot()->gCurrentGenerationCount++; //gDepth++; node->getRoot()->gDepth++; ```

👍 1

facebook-github-bot commented

2018-06-19 03:42:44 -07:00

(Migrated from github.com)

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2018-06-21 03:53:34 -07:00

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Reference: DaddyFrosty/yoga#786