add TeeInputStream

2 files changed, 178 insertions, 0 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/io/TeeInputStream.java b/vespajlib/src/main/java/com/yahoo/io/TeeInputStream.java
new file mode 100644
index 00000000000..7ecd6f0ccea
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/io/TeeInputStream.java
@@ -0,0 +1,96 @@
+package com.yahoo.io;
+
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.IOException;
+
+/**
+ * Forwards input from a source InputStream while making a copy of it into an outputstream.
+ * Note that it also does read-ahead and copies up to 64K of data more than was used.
+ */
+class TeeInputStream extends InputStream {
+    final InputStream src;
+    final OutputStream dst;
+
+    static final int CAPACITY = 65536;
+
+    byte[] buf = new byte[CAPACITY];
+    int readPos = 0;
+    int writePos = 0;
+
+    private int inBuf() { return writePos - readPos; }
+
+    private void fillBuf(boolean block) throws IOException {
+        if (readPos == writePos) {
+            readPos = 0;
+            writePos = 0;
+        }
+        if (readPos * 3 > CAPACITY) {
+            int had = inBuf();
+            System.arraycopy(buf, readPos, buf, 0, had);
+            readPos = 0;
+            writePos = had;
+        }
+        int wantToRead = CAPACITY - writePos;
+        if (inBuf() > 0 || !block) {
+            wantToRead = Math.min(wantToRead, src.available());
+        }
+        if (wantToRead > 0) {
+            int got = src.read(buf, writePos, wantToRead);
+            if (got > 0) {
+                dst.write(buf, writePos, got);
+                writePos += got;
+            }
+        }
+    }
+
+    /** Construct a Tee */
+    public TeeInputStream(InputStream from, OutputStream to) {
+        super();
+        this.src = from;
+        this.dst = to;
+    }
+
+    public @Override int available() throws IOException {
+        return inBuf() + src.available();
+    }
+
+    public @Override void close() throws IOException {
+        fillBuf(false);
+        src.close();
+        dst.close();
+    }
+
+    public @Override void mark(int readlimit) {}
+    public @Override boolean markSupported() { return false; }
+    public @Override void reset() {}
+
+    public @Override int read() throws IOException {
+        fillBuf(true);
+        if (inBuf() > 0) {
+            int r = buf[readPos++];
+            return r & 0xff;
+        }
+        return -1;
+    }
+
+    public @Override int read(byte[] b) throws IOException {
+        return read(b, 0, b.length);
+    }
+
+    public @Override int read(byte[] b, int off, int len) throws IOException {
+        if (len <= 0) {
+            return 0;
+        }
+        fillBuf(true);
+        int had = inBuf();
+        if (had > 0) {
+            len = Math.min(len, had);
+            System.arraycopy(buf, readPos, b, off, len);
+            readPos += len;
+            return len;
+        }
+        return -1;
+    }
+
+}
diff --git a/vespajlib/src/test/java/com/yahoo/io/TeeInputStreamTest.java b/vespajlib/src/test/java/com/yahoo/io/TeeInputStreamTest.java
new file mode 100644
index 00000000000..315e8d5f8d4
--- /dev/null
+++ b/vespajlib/src/test/java/com/yahoo/io/TeeInputStreamTest.java
@@ -0,0 +1,82 @@
+package com.yahoo.io;
+
+import java.io.*;
+import java.nio.charset.StandardCharsets;
+
+import org.junit.Test;
+import static org.hamcrest.Matchers.greaterThan;
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.*;
+
+/**
+ * @author arnej
+ */
+public class TeeInputStreamTest {
+
+    @Test
+    public void testSimpleInput() throws IOException {
+        byte[] input = "very simple input".getBytes(StandardCharsets.UTF_8);
+        ByteArrayInputStream in = new ByteArrayInputStream(input);
+        ByteArrayOutputStream gotten = new ByteArrayOutputStream();
+
+        TeeInputStream tee = new TeeInputStream(in, gotten);
+        int b = tee.read();
+        assertThat(b, is((int)'v'));
+        assertThat(gotten.toString(), is("very simple input"));
+        for (int i = 0; i < 16; i++) {
+            b = tee.read();
+            // System.out.println("got["+i+"]: "+(char)b);
+            assertThat(b, is(greaterThan(0)));
+        }
+        assertThat(tee.read(), is(-1));
+    }
+
+    private class Generator implements Runnable {
+        private OutputStream dst;
+        public Generator(OutputStream dst) { this.dst = dst; }
+        public @Override void run() {
+            for (int i = 0; i < 123456789; i++) {
+                int b = i & 0x7f;
+                if (b < 32) continue;
+                if (b > 126) b = '\n';
+                try {
+                    dst.write(b);
+                } catch (IOException e) {
+                    return;
+                }
+            }
+        }
+    }
+
+    @Test
+    public void testPipedInput() throws IOException {
+        PipedOutputStream input = new PipedOutputStream();
+        PipedInputStream in = new PipedInputStream(input);
+        ByteArrayOutputStream gotten = new ByteArrayOutputStream();
+        TeeInputStream tee = new TeeInputStream(in, gotten);
+        input.write("first input".getBytes(StandardCharsets.UTF_8));
+        int b = tee.read();
+        assertThat(b, is((int)'f'));
+        assertThat(gotten.toString(), is("first input"));
+        input.write(" second input".getBytes(StandardCharsets.UTF_8));
+        b = tee.read();
+        assertThat(b, is((int)'i'));
+        assertThat(gotten.toString(), is("first input second input"));
+        new Thread(new Generator(input)).start();
+        b = tee.read();
+        assertThat(b, is((int)'r'));
+        byte[] ba = new byte[9];
+        for (int i = 0; i < 12345; i++) {
+            b = tee.read();
+            // System.out.println("got["+i+"]: "+(char)b);
+            assertThat(b, is(greaterThan(0)));
+            assertThat(tee.read(ba), is(greaterThan(0)));
+        }
+        tee.close();
+        String got = gotten.toString();
+        // System.out.println("got length: "+got.length());
+        // System.out.println("got: "+got);
+        assertThat(got.length(), is(greaterThan(34567)));
+    }
+
+}