remove thread unsafe dictionary (#1617)

metal/paddle-mobile/paddle-mobile/Src/Operators/Kernels/ConvAddKernel.swift

@@ -15,16 +15,6 @@
 import Foundation
 import MetalPerformanceShaders
 
-@available(iOS 10.0, *)
-var convDic: [String : MPSCNNConvolution] = [:]
-
-/// 获取唯一字符串
-///
-/// - Returns: 唯一字符串
-func getUniqueKey() -> String {
-    return UUID.init().uuidString
-}
-
 @available(iOS 11.0, *)
 class ConvDataSource<P: PrecisionProtocol>: NSObject, MPSCNNConvolutionDataSource {
     
@@ -99,8 +89,7 @@ class ConvDataSource<P: PrecisionProtocol>: NSObject, MPSCNNConvolutionDataSourc
 
 class ConvAddKernel<P: PrecisionProtocol>: Kernel, Computable {
     var metalParam: MetalConvParam!
-    
-    let identifyingKey: String = getUniqueKey()
+    var mpsConvOp: Any?
     
     required init(device: MTLDevice, param: ConvAddParam<P>, initContext: InitContext) throws {
         do {
@@ -139,7 +128,7 @@ class ConvAddKernel<P: PrecisionProtocol>: Kernel, Computable {
     
     func compute(commandBuffer: MTLCommandBuffer, param: ConvAddParam<P>) throws {
         if #available(iOS 10.0, *) {
-            if let conv = convDic[identifyingKey] {
+            if let conv = mpsConvOp as? MPSCNNConvolution {
                 let inputImage = MPSImage.init(texture: param.input.metalTexture, featureChannels: param.input.tensorDim[1])
                 let outputImage = MPSImage.init(texture: param.output.metalTexture, featureChannels: param.output.tensorDim[1])
                 conv.encode(commandBuffer: commandBuffer, sourceImage: inputImage, destinationImage: outputImage)
@@ -158,18 +147,10 @@ class ConvAddKernel<P: PrecisionProtocol>: Kernel, Computable {
         encoder.endEncoding()
     }
     
-    deinit {
-        if #available(iOS 10.0, *) {
-            convDic.removeValue(forKey: identifyingKey)
-        }
-    }
-    
     func setupWithMPS(device: MTLDevice, param: ConvAddParam<P>) {
         let offsetX = (Int(param.dilations[0]) * (param.filter.tensorDim[3] - 1) + 1) / 2 - Int(param.paddings[0])
         let offsetY = (Int(param.dilations[1]) * (param.filter.tensorDim[2] - 1) + 1) / 2 - Int(param.paddings[1])
         
-        let key = identifyingKey
-        
         let isDepthWise = param.filter.tensorDim[1] == 1 && param.filter.tensorDim[0] == param.input.tensorDim[1]
         if #available(iOS 11.0, *) {
             param.input.useMPS = true
@@ -192,7 +173,7 @@ class ConvAddKernel<P: PrecisionProtocol>: Kernel, Computable {
             let conv = MPSCNNConvolution.init(device: device, weights: dataSource)
             conv.offset = MPSOffset.init(x: offsetX, y: offsetY, z: 0)
             conv.edgeMode = .zero
-            convDic[key] = conv
+            mpsConvOp = conv
         }
     }