path: root/Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/util/buffer_test.go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package util

import (
    "bytes"
    "io"
    "math/rand"
    "runtime"
    "testing"
)

const N = 10000      // make this bigger for a larger (and slower) test
var data string      // test data for write tests
var testBytes []byte // test data; same as data but as a slice.

func init() {
    testBytes = make([]byte, N)
    for i := 0; i < N; i++ {
        testBytes[i] = 'a' + byte(i%26)
    }
    data = string(testBytes)
}

// Verify that contents of buf match the string s.
func check(t *testing.T, testname string, buf *Buffer, s string) {
    bytes := buf.Bytes()
    str := buf.String()
    if buf.Len() != len(bytes) {
        t.Errorf("%s: buf.Len() == %d, len(buf.Bytes()) == %d", testname, buf.Len(), len(bytes))
    }

    if buf.Len() != len(str) {
        t.Errorf("%s: buf.Len() == %d, len(buf.String()) == %d", testname, buf.Len(), len(str))
    }

    if buf.Len() != len(s) {
        t.Errorf("%s: buf.Len() == %d, len(s) == %d", testname, buf.Len(), len(s))
    }

    if string(bytes) != s {
        t.Errorf("%s: string(buf.Bytes()) == %q, s == %q", testname, string(bytes), s)
    }
}

// Fill buf through n writes of byte slice fub.
// The initial contents of buf corresponds to the string s;
// the result is the final contents of buf returned as a string.
func fillBytes(t *testing.T, testname string, buf *Buffer, s string, n int, fub []byte) string {
    check(t, testname+" (fill 1)", buf, s)
    for ; n > 0; n-- {
        m, err := buf.Write(fub)
        if m != len(fub) {
            t.Errorf(testname+" (fill 2): m == %d, expected %d", m, len(fub))
        }
        if err != nil {
            t.Errorf(testname+" (fill 3): err should always be nil, found err == %s", err)
        }
        s += string(fub)
        check(t, testname+" (fill 4)", buf, s)
    }
    return s
}

func TestNewBuffer(t *testing.T) {
    buf := NewBuffer(testBytes)
    check(t, "NewBuffer", buf, data)
}

// Empty buf through repeated reads into fub.
// The initial contents of buf corresponds to the string s.
func empty(t *testing.T, testname string, buf *Buffer, s string, fub []byte) {
    check(t, testname+" (empty 1)", buf, s)

    for {
        n, err := buf.Read(fub)
        if n == 0 {
            break
        }
        if err != nil {
            t.Errorf(testname+" (empty 2): err should always be nil, found err == %s", err)
        }
        s = s[n:]
        check(t, testname+" (empty 3)", buf, s)
    }

    check(t, testname+" (empty 4)", buf, "")
}

func TestBasicOperations(t *testing.T) {
    var buf Buffer

    for i := 0; i < 5; i++ {
        check(t, "TestBasicOperations (1)", &buf, "")

        buf.Reset()
        check(t, "TestBasicOperations (2)", &buf, "")

        buf.Truncate(0)
        check(t, "TestBasicOperations (3)", &buf, "")

        n, err := buf.Write([]byte(data[0:1]))
        if n != 1 {
            t.Errorf("wrote 1 byte, but n == %d", n)
        }
        if err != nil {
            t.Errorf("err should always be nil, but err == %s", err)
        }
        check(t, "TestBasicOperations (4)", &buf, "a")

        buf.WriteByte(data[1])
        check(t, "TestBasicOperations (5)", &buf, "ab")

        n, err = buf.Write([]byte(data[2:26]))
        if n != 24 {
            t.Errorf("wrote 25 bytes, but n == %d", n)
        }
        check(t, "TestBasicOperations (6)", &buf, string(data[0:26]))

        buf.Truncate(26)
        check(t, "TestBasicOperations (7)", &buf, string(data[0:26]))

        buf.Truncate(20)
        check(t, "TestBasicOperations (8)", &buf, string(data[0:20]))

        empty(t, "TestBasicOperations (9)", &buf, string(data[0:20]), make([]byte, 5))
        empty(t, "TestBasicOperations (10)", &buf, "", make([]byte, 100))

        buf.WriteByte(data[1])
        c, err := buf.ReadByte()
        if err != nil {
            t.Error("ReadByte unexpected eof")
        }
        if c != data[1] {
            t.Errorf("ReadByte wrong value c=%v", c)
        }
        c, err = buf.ReadByte()
        if err == nil {
            t.Error("ReadByte unexpected not eof")
        }
    }
}

func TestLargeByteWrites(t *testing.T) {
    var buf Buffer
    limit := 30
    if testing.Short() {
        limit = 9
    }
    for i := 3; i < limit; i += 3 {
        s := fillBytes(t, "TestLargeWrites (1)", &buf, "", 5, testBytes)
        empty(t, "TestLargeByteWrites (2)", &buf, s, make([]byte, len(data)/i))
    }
    check(t, "TestLargeByteWrites (3)", &buf, "")
}

func TestLargeByteReads(t *testing.T) {
    var buf Buffer
    for i := 3; i < 30; i += 3 {
        s := fillBytes(t, "TestLargeReads (1)", &buf, "", 5, testBytes[0:len(testBytes)/i])
        empty(t, "TestLargeReads (2)", &buf, s, make([]byte, len(data)))
    }
    check(t, "TestLargeByteReads (3)", &buf, "")
}

func TestMixedReadsAndWrites(t *testing.T) {
    var buf Buffer
    s := ""
    for i := 0; i < 50; i++ {
        wlen := rand.Intn(len(data))
        s = fillBytes(t, "TestMixedReadsAndWrites (1)", &buf, s, 1, testBytes[0:wlen])
        rlen := rand.Intn(len(data))
        fub := make([]byte, rlen)
        n, _ := buf.Read(fub)
        s = s[n:]
    }
    empty(t, "TestMixedReadsAndWrites (2)", &buf, s, make([]byte, buf.Len()))
}

func TestNil(t *testing.T) {
    var b *Buffer
    if b.String() != "<nil>" {
        t.Errorf("expected <nil>; got %q", b.String())
    }
}

func TestReadFrom(t *testing.T) {
    var buf Buffer
    for i := 3; i < 30; i += 3 {
        s := fillBytes(t, "TestReadFrom (1)", &buf, "", 5, testBytes[0:len(testBytes)/i])
        var b Buffer
        b.ReadFrom(&buf)
        empty(t, "TestReadFrom (2)", &b, s, make([]byte, len(data)))
    }
}

func TestWriteTo(t *testing.T) {
    var buf Buffer
    for i := 3; i < 30; i += 3 {
        s := fillBytes(t, "TestWriteTo (1)", &buf, "", 5, testBytes[0:len(testBytes)/i])
        var b Buffer
        buf.WriteTo(&b)
        empty(t, "TestWriteTo (2)", &b, s, make([]byte, len(data)))
    }
}

func TestNext(t *testing.T) {
    b := []byte{0, 1, 2, 3, 4}
    tmp := make([]byte, 5)
    for i := 0; i <= 5; i++ {
        for j := i; j <= 5; j++ {
            for k := 0; k <= 6; k++ {
                // 0 <= i <= j <= 5; 0 <= k <= 6
                // Check that if we start with a buffer
                // of length j at offset i and ask for
                // Next(k), we get the right bytes.
                buf := NewBuffer(b[0:j])
                n, _ := buf.Read(tmp[0:i])
                if n != i {
                    t.Fatalf("Read %d returned %d", i, n)
                }
                bb := buf.Next(k)
                want := k
                if want > j-i {
                    want = j - i
                }
                if len(bb) != want {
                    t.Fatalf("in %d,%d: len(Next(%d)) == %d", i, j, k, len(bb))
                }
                for l, v := range bb {
                    if v != byte(l+i) {
                        t.Fatalf("in %d,%d: Next(%d)[%d] = %d, want %d", i, j, k, l, v, l+i)
                    }
                }
            }
        }
    }
}

var readBytesTests = []struct {
    buffer   string
    delim    byte
    expected []string
    err      error
}{
    {"", 0, []string{""}, io.EOF},
    {"a\x00", 0, []string{"a\x00"}, nil},
    {"abbbaaaba", 'b', []string{"ab", "b", "b", "aaab"}, nil},
    {"hello\x01world", 1, []string{"hello\x01"}, nil},
    {"foo\nbar", 0, []string{"foo\nbar"}, io.EOF},
    {"alpha\nbeta\ngamma\n", '\n', []string{"alpha\n", "beta\n", "gamma\n"}, nil},
    {"alpha\nbeta\ngamma", '\n', []string{"alpha\n", "beta\n", "gamma"}, io.EOF},
}

func TestReadBytes(t *testing.T) {
    for _, test := range readBytesTests {
        buf := NewBuffer([]byte(test.buffer))
        var err error
        for _, expected := range test.expected {
            var bytes []byte
            bytes, err = buf.ReadBytes(test.delim)
            if string(bytes) != expected {
                t.Errorf("expected %q, got %q", expected, bytes)
            }
            if err != nil {
                break
            }
        }
        if err != test.err {
            t.Errorf("expected error %v, got %v", test.err, err)
        }
    }
}

func TestGrow(t *testing.T) {
    x := []byte{'x'}
    y := []byte{'y'}
    tmp := make([]byte, 72)
    for _, startLen := range []int{0, 100, 1000, 10000, 100000} {
        xBytes := bytes.Repeat(x, startLen)
        for _, growLen := range []int{0, 100, 1000, 10000, 100000} {
            buf := NewBuffer(xBytes)
            // If we read, this affects buf.off, which is good to test.
            readBytes, _ := buf.Read(tmp)
            buf.Grow(growLen)
            yBytes := bytes.Repeat(y, growLen)
            // Check no allocation occurs in write, as long as we're single-threaded.
            var m1, m2 runtime.MemStats
            runtime.ReadMemStats(&m1)
            buf.Write(yBytes)
            runtime.ReadMemStats(&m2)
            if runtime.GOMAXPROCS(-1) == 1 && m1.Mallocs != m2.Mallocs {
                t.Errorf("allocation occurred during write")
            }
            // Check that buffer has correct data.
            if !bytes.Equal(buf.Bytes()[0:startLen-readBytes], xBytes[readBytes:]) {
                t.Errorf("bad initial data at %d %d", startLen, growLen)
            }
            if !bytes.Equal(buf.Bytes()[startLen-readBytes:startLen-readBytes+growLen], yBytes) {
                t.Errorf("bad written data at %d %d", startLen, growLen)
            }
        }
    }
}

// Was a bug: used to give EOF reading empty slice at EOF.
func TestReadEmptyAtEOF(t *testing.T) {
    b := new(Buffer)
    slice := make([]byte, 0)
    n, err := b.Read(slice)
    if err != nil {
        t.Errorf("read error: %v", err)
    }
    if n != 0 {
        t.Errorf("wrong count; got %d want 0", n)
    }
}

// Tests that we occasionally compact. Issue 5154.
func TestBufferGrowth(t *testing.T) {
    var b Buffer
    buf := make([]byte, 1024)
    b.Write(buf[0:1])
    var cap0 int
    for i := 0; i < 5<<10; i++ {
        b.Write(buf)
        b.Read(buf)
        if i == 0 {
            cap0 = cap(b.buf)
        }
    }
    cap1 := cap(b.buf)
    // (*Buffer).grow allows for 2x capacity slop before sliding,
    // so set our error threshold at 3x.
    if cap1 > cap0*3 {
        t.Errorf("buffer cap = %d; too big (grew from %d)", cap1, cap0)
    }
}

// From Issue 5154.
func BenchmarkBufferNotEmptyWriteRead(b *testing.B) {
    buf := make([]byte, 1024)
    for i := 0; i < b.N; i++ {
        var b Buffer
        b.Write(buf[0:1])
        for i := 0; i < 5<<10; i++ {
            b.Write(buf)
            b.Read(buf)
        }
    }
}

// Check that we don't compact too often. From Issue 5154.
func BenchmarkBufferFullSmallReads(b *testing.B) {
    buf := make([]byte, 1024)
    for i := 0; i < b.N; i++ {
        var b Buffer
        b.Write(buf)
        for b.Len()+20 < cap(b.buf) {
            b.Write(buf[:10])
        }
        for i := 0; i < 5<<10; i++ {
            b.Read(buf[:1])
            b.Write(buf[:1])
        }
    }
}