[Swift] Adds new API to reduce memory copying within swift

benchmarks/swift/Benchmarks/FlatbuffersBenchmarks/FlatbuffersBenchmarks.swift

@@ -15,8 +15,8 @@
  */
 
 import Benchmark
-import CoreFoundation
 import FlatBuffers
+import Foundation
 
 @usableFromInline
 struct AA: NativeStruct {
@@ -29,6 +29,15 @@ struct AA: NativeStruct {
 }
 
 let benchmarks = {
+  let oneGB: Int32 = 1_024_000_000
+  let data = {
+    var array = [8888.88, 8888.88]
+    var data = Data()
+    array.withUnsafeBytes { ptr in
+      data.append(contentsOf: ptr)
+    }
+    return data
+  }()
   let ints: [Int] = Array(repeating: 42, count: 100)
   let bytes: [UInt8] = Array(repeating: 42, count: 100)
   let str10 = (0...9).map { _ -> String in "x" }.joined()
@@ -73,12 +82,25 @@ let benchmarks = {
 
   Benchmark("Allocating 1GB", configuration: singleConfiguration) { benchmark in
     for _ in benchmark.scaledIterations {
-      blackHole(FlatBufferBuilder(initialSize: 1_024_000_000))
+      blackHole(FlatBufferBuilder(initialSize: oneGB))
+    }
+  }
+
+  Benchmark(
+    "Allocating ByteBuffer 1GB",
+    configuration: singleConfiguration)
+  { benchmark in
+    let memory = UnsafeMutableRawPointer.allocate(
+      byteCount: 1_024_000_000,
+      alignment: 1)
+    benchmark.startMeasurement()
+    for _ in benchmark.scaledIterations {
+      blackHole(ByteBuffer(assumingMemoryBound: memory, capacity: Int(oneGB)))
     }
   }
 
   Benchmark("Clearing 1GB", configuration: singleConfiguration) { benchmark in
-    var fb = FlatBufferBuilder(initialSize: 1_024_000_000)
+    var fb = FlatBufferBuilder(initialSize: oneGB)
     benchmark.startMeasurement()
     for _ in benchmark.scaledIterations {
       blackHole(fb.clear())
@@ -158,6 +180,26 @@ let benchmarks = {
     }
   }
 
+  Benchmark(
+    "FlatBufferBuilder Start table",
+    configuration: kiloConfiguration)
+  { benchmark in
+    var fb = FlatBufferBuilder(initialSize: 1024 * 1024 * 32)
+    benchmark.startMeasurement()
+    for _ in benchmark.scaledIterations {
+      let s = fb.startTable(with: 4)
+      blackHole(fb.endTable(at: s))
+    }
+  }
+
+  Benchmark("Struct") { benchmark in
+    var fb = FlatBufferBuilder(initialSize: 1024 * 1024 * 32)
+    benchmark.startMeasurement()
+    for _ in benchmark.scaledIterations {
+      blackHole(fb.create(struct: array.first!))
+    }
+  }
+
   Benchmark("Structs") { benchmark in
     let rawSize = ((16 * 5) * benchmark.scaledIterations.count) / 1024
     var fb = FlatBufferBuilder(initialSize: Int32(rawSize * 1600))
@@ -176,7 +218,7 @@ let benchmarks = {
     let start = fb.startTable(with: 1)
     fb.add(offset: vector, at: 4)
     let root = Offset(offset: fb.endTable(at: start))
-    fb.finish(offset: root)
+    blackHole(fb.finish(offset: root))
   }
 
   Benchmark("Vector of Offsets") { benchmark in
@@ -198,4 +240,11 @@ let benchmarks = {
       blackHole(fb.endTable(at: s))
     }
   }
+
+  Benchmark("Reading Doubles") { benchmark in
+    let byteBuffer = ByteBuffer(data: data)
+    for _ in benchmark.scaledIterations {
+      blackHole(byteBuffer.read(def: Double.self, position: 0))
+    }
+  }
 }

docs-old/source/Tutorial.md

@@ -3261,7 +3261,7 @@ mutators like so:
 </div>
 <div class="language-swift">
 ~~~{.swift}
-  let monster = Monster.getRootAsMonster(bb: ByteBuffer(bytes: buf))
+  let monster: Monster = try! getCheckedRoot(byteBuffer: &byteBuffer)
   monster.mutate(hp: 10) // mutates a value in a table
   /// to mutate structs in swift you have to use the mutable accessors
   monster.mutablePos.mutate(z: 4) // mutates a value in a struct

docs/source/languages/swift.md

@@ -57,7 +57,7 @@ a data object from the server, which you can pass into the `GetRootAsMonster` fu
     let url = URL(fileURLWithPath: path, isDirectory: true).appendingPathComponent("monsterdata_test").appendingPathExtension("mon")
     guard let data = try? Data(contentsOf: url) else { return }
 
-    let monster = Monster.getRootAsMonster(bb: ByteBuffer(data: data))
+    let monster: Monster = try! getCheckedRoot(byteBuffer: &byteBuffer)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Now you can access values like this:

docs/source/tutorial.md

@@ -2011,6 +2011,8 @@ like so:
     let buf = builder.sizedByteArray
     // or you can use to get an object of type Data
     let bufData = ByteBuffer(data: builder.data)
+    // or
+    let buf = builder.sizedBuffer
     ```
 
 === "TypeScript"

grpc/examples/swift/Greeter/Sources/Model/greeter.grpc.swift

@@ -17,8 +17,7 @@ public extension GRPCFlatBufPayload {
     self.init(byteBuffer: FlatBuffers.ByteBuffer(contiguousBytes: serializedByteBuffer.readableBytesView, count: serializedByteBuffer.readableBytes))
   }
   func serialize(into buffer: inout NIO.ByteBuffer) throws {
-    let buf = UnsafeRawBufferPointer(start: self.rawPointer, count: Int(self.size))
-    buffer.writeBytes(buf)
+    withUnsafeReadableBytes { buffer.writeBytes($0) }
   }
 }
 extension Message: GRPCFlatBufPayload {}

grpc/src/compiler/swift_generator.cc

@@ -428,10 +428,7 @@ grpc::string GenerateHeader() {
   code += "  }\n";
 
   code += "  func serialize(into buffer: inout NIO.ByteBuffer) throws {\n";
-  code +=
-      "    let buf = UnsafeRawBufferPointer(start: self.rawPointer, count: "
-      "Int(self.size))\n";
-  code += "    buffer.writeBytes(buf)\n";
+  code += "    withUnsafeReadableBytes { buffer.writeBytes($0) }\n";
   code += "  }\n";
   code += "}\n";
   code += "extension Message: GRPCFlatBufPayload {}\n";