Tee sample (#1559)

Co-authored-by: Jesse Wilson <[email protected]>

samples/src/jvmMain/kotlin/okio/samples/TeeSink.kt

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2024 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package okio.samples
+
+import okio.Buffer
+import okio.FileSystem
+import okio.Path.Companion.toPath
+import okio.Sink
+import okio.Timeout
+import okio.buffer
+import okio.sink
+
+/**
+ * A sink that writes all input to both [sinkA] and [sinkB].
+ */
+class TeeSink(
+  private val sinkA: Sink,
+  private val sinkB: Sink,
+) : Sink {
+  private val timeout = Timeout()
+
+  override fun write(source: Buffer, byteCount: Long) {
+    // Writing to sink mutates source. Work around that.
+    sinkA.timeout().intersectWith(timeout) {
+      val buffer = Buffer()
+      source.copyTo(buffer, byteCount = byteCount)
+      sinkA.write(buffer, byteCount)
+    }
+
+    sinkB.timeout().intersectWith(timeout) {
+      sinkB.write(source, byteCount)
+    }
+  }
+
+  override fun flush() {
+    sinkA.flush()
+    sinkB.flush()
+  }
+
+  override fun close() {
+    try {
+      sinkA.close()
+    } catch (tA: Throwable) {
+      try {
+        sinkB.close()
+      } catch (tB: Throwable) {
+        tA.addSuppressed(tB)
+      }
+      throw tA
+    }
+
+    sinkB.close()
+  }
+
+  override fun timeout() = sinkA.timeout()
+}
+
+fun main() {
+  val a = System.out.sink()
+  val b = FileSystem.SYSTEM.sink("tee.txt".toPath())
+
+  TeeSink(a, b).buffer().use { teeSink ->
+    teeSink.writeUtf8("hello\n")
+    teeSink.flush()
+    teeSink.writeUtf8("world!")
+  }
+}