Merge branch 'outputstream-write-refactor' of https://github.com/aciidb0mb3r/swift-package-manager

Author: ddunbar

Sources/Basic/OutputByteStream.swift

@@ -73,20 +73,25 @@ public class OutputByteStream: OutputStream {
     public func write(_ byte: UInt8) {
         buffer.append(byte)
     }
-    
-    /// Write a sequence of bytes to the buffer.
-    public func write(_ bytes: [UInt8]) {
-        buffer += bytes
+
+    /// Write the contents of a UnsafeBufferPointer<UInt8>.
+    func write(_ ptr: UnsafeBufferPointer<UInt8>) {
+        buffer += ptr
     }
 
     /// Write a sequence of bytes to the buffer.
     public func write(_ bytes: ArraySlice<UInt8>) {
         buffer += bytes
     }
+
+    /// Write a sequence of bytes to the buffer.
+    public func write(_ bytes: [UInt8]) {
+        write(ArraySlice(bytes))
+    }
 
     /// Write a sequence of bytes to the buffer.
     public func write<S: Sequence where S.Iterator.Element == UInt8>(_ sequence: S) {
-        buffer += sequence
+        write(ArraySlice(sequence))
     }
 
     /// Write a string to the buffer (as UTF8).
@@ -95,15 +100,15 @@ public class OutputByteStream: OutputStream {
         // doesn't implement this optimization: <rdar://problem/24100375> Missing fast path for [UInt8] += String.UTF8View
         let stringPtrStart = string._contiguousUTF8
         if stringPtrStart != nil {
-            buffer += UnsafeBufferPointer(start: stringPtrStart, count: string.utf8.count)
+            write(UnsafeBufferPointer(start: stringPtrStart, count: string.utf8.count))
         } else {
-            buffer += string.utf8
+            write(string.utf8)
         }
     }
 
     /// Write a character to the buffer (as UTF8).
     public func write(_ character: Character) {
-        buffer += String(character).utf8
+        write(String(character))
     }
 
     /// Write an arbitrary byte streamable to the buffer.
@@ -132,39 +137,39 @@ public class OutputByteStream: OutputStream {
                 //
                 // FIXME: Workaround: <rdar://problem/22546289> Unexpected crash with range to max value for type
             case 0x20...0x21, 0x23...0x5B, 0x5D...0xFE, 0xFF:
-                buffer.append(character)
+                write(character)
 
                 // Single-character escaped characters.
             case 0x22: // '"'
-                buffer.append(0x5C) // '\'
-                buffer.append(0x22) // '"'
+                write(0x5C) // '\'
+                write(0x22) // '"'
             case 0x5C: // '\\'
-                buffer.append(0x5C) // '\'
-                buffer.append(0x5C) // '\'
+                write(0x5C) // '\'
+                write(0x5C) // '\'
             case 0x08: // '\b'
-                buffer.append(0x5C) // '\'
-                buffer.append(0x62) // 'b'
+                write(0x5C) // '\'
+                write(0x62) // 'b'
             case 0x0C: // '\f'
-                buffer.append(0x5C) // '\'
-                buffer.append(0x66) // 'b'
+                write(0x5C) // '\'
+                write(0x66) // 'b'
             case 0x0A: // '\n'
-                buffer.append(0x5C) // '\'
-                buffer.append(0x6E) // 'n'
+                write(0x5C) // '\'
+                write(0x6E) // 'n'
             case 0x0D: // '\r'
-                buffer.append(0x5C) // '\'
-                buffer.append(0x72) // 'r'
+                write(0x5C) // '\'
+                write(0x72) // 'r'
             case 0x09: // '\t'
-                buffer.append(0x5C) // '\'
-                buffer.append(0x74) // 't'
+                write(0x5C) // '\'
+                write(0x74) // 't'
 
                 // Multi-character escaped characters.
             default:
-                buffer.append(0x5C) // '\'
-                buffer.append(0x75) // 'u'
-                buffer.append(hexdigit(0))
-                buffer.append(hexdigit(0))
-                buffer.append(hexdigit(character >> 4))
-                buffer.append(hexdigit(character & 0xF))
+                write(0x5C) // '\'
+                write(0x75) // 'u'
+                write(hexdigit(0))
+                write(hexdigit(0))
+                write(hexdigit(character >> 4))
+                write(hexdigit(character & 0xF))
             }
         }
     }

Tests/Basic/OutputByteStreamPerfTests.swift

@@ -19,6 +19,32 @@ import Basic
 #if false
 
 class OutputByteStreamPerfTests: XCTestCase {
+
+    func test1MBOfByte_X10() {
+        let byte = UInt8(0)
+        measure {
+            for _ in 0..<10 {
+                let stream = OutputByteStream()
+                for _ in 0..<(1 << 20) {
+                    stream <<< byte
+                }
+                XCTAssertEqual(stream.bytes.count, 1 << 20)
+            }
+        }
+    }
+
+    func test1MBOfCharacters_X1() {
+        measure {
+            for _ in 0..<1 {
+                let stream = OutputByteStream()
+                for _ in 0..<(1 << 20) {
+                    stream <<< Character("X")
+                }
+                XCTAssertEqual(stream.bytes.count, 1 << 20)
+            }
+        }
+    }
+
     func test1MBOf16ByteArrays_X100() {
         // Test writing 1MB worth of 16 byte strings.
         let bytes16 = [UInt8](repeating: 0, count: 1 << 4)
@@ -34,6 +60,23 @@ class OutputByteStreamPerfTests: XCTestCase {
         }
     }
 
+    // This should give same performance as 16ByteArrays_X100.
+    func test1MBOf16ByteArraySlice_X100() {
+        let bytes32 = [UInt8](repeating: 0, count: 1 << 5)
+        // Test writing 1MB worth of 16 byte strings.
+        let bytes16 = bytes32.suffix(from: bytes32.count/2)
+
+        measure {
+            for _ in 0..<100 {
+                let stream = OutputByteStream()
+                for _ in 0..<(1 << 16) {
+                    stream <<< bytes16
+                }
+                XCTAssertEqual(stream.bytes.count, 1 << 20)
+            }
+        }
+    }
+
     func test1MBOf1KByteArrays_X1000() {
         // Test writing 1MB worth of 1K byte strings.
         let bytes1k = [UInt8](repeating: 0, count: 1 << 10)