Adds segment

Author: ashishkujoy

go.mod

@@ -4,7 +4,12 @@ go 1.24
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/fatih/color v1.18.0 // indirect
+	github.com/mattn/go-colorable v0.1.14 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/rakyll/gotest v0.0.6 // indirect
 	github.com/stretchr/testify v1.10.0 // indirect
+	golang.org/x/sys v0.32.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,9 +1,26 @@
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fatih/color v1.9.0/go.mod h1:eQcE1qtQxscV5RaZvpXrrb8Drkc3/DdQ+uUYCNjL+zU=
+github.com/fatih/color v1.18.0 h1:S8gINlzdQ840/4pfAwic/ZE0djQEH3wM94VfqLTZcOM=
+github.com/fatih/color v1.18.0/go.mod h1:4FelSpRwEGDpQ12mAdzqdOukCy4u8WUtOY6lkT/6HfU=
+github.com/mattn/go-colorable v0.1.4/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
+github.com/mattn/go-colorable v0.1.14 h1:9A9LHSqF/7dyVVX6g0U9cwm9pG3kP9gSzcuIPHPsaIE=
+github.com/mattn/go-colorable v0.1.14/go.mod h1:6LmQG8QLFO4G5z1gPvYEzlUgJ2wF+stgPZH1UqBm1s8=
+github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
+github.com/mattn/go-isatty v0.0.11/go.mod h1:PhnuNfih5lzO57/f3n+odYbM4JtupLOxQOAqxQCu2WE=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rakyll/gotest v0.0.6 h1:hBTqkO3jiuwYW/M9gL4bu0oTYcm8J6knQAAPUsJsz1I=
+github.com/rakyll/gotest v0.0.6/go.mod h1:SkoesdNCWmiD4R2dljIUcfSnNdVZ12y8qK4ojDkc2Sc=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.32.0 h1:s77OFDvIQeibCmezSnk/q6iAfkdiQaJi4VzroCFrN20=
+golang.org/x/sys v0.32.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/storage/config.go

@@ -0,0 +1,5 @@
+package storage
+
+type Config struct {
+	segmentsRoot string
+}

internal/storage/index.go

@@ -0,0 +1,25 @@
+package storage
+
+type Index struct {
+	entries   map[int]int
+	elementId int
+}
+
+func NewIndex() *Index {
+	return &Index{
+		entries:   make(map[int]int),
+		elementId: 0,
+	}
+}
+
+func (i *Index) Append(offset int) int {
+	currentElementId := i.elementId
+	i.entries[currentElementId] = offset
+	i.elementId++
+	return currentElementId
+}
+
+func (i *Index) GetOffset(elementId int) (int, bool) {
+	v, ok := i.entries[elementId]
+	return v, ok
+}

internal/storage/segment.go

@@ -0,0 +1,41 @@
+package storage
+
+import (
+	"fmt"
+)
+
+type Segment struct {
+	store *Store
+	index *Index
+}
+
+func NewSegment(startingIndex int, config *Config, index *Index) (*Segment, error) {
+	filePath := fmt.Sprintf("%s/segment-%d", config.segmentsRoot, startingIndex)
+	store, err := NewStore(filePath)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Segment{store: store, index: index}, nil
+}
+
+func (s *Segment) Append(data []byte) (int, error) {
+	offset, err := s.store.Append(data)
+	if err != nil {
+		return 0, err
+	}
+	elementIndex := s.index.Append(offset)
+	return elementIndex, nil
+}
+
+func (s *Segment) Read(id int) ([]byte, error) {
+	offset, ok := s.index.GetOffset(id)
+	if !ok {
+		return nil, fmt.Errorf("unknown message id: %d", id)
+	}
+	return s.store.Read(offset)
+}
+
+func (s *Segment) Close() error {
+	return s.store.Close()
+}

internal/storage/segment_test.go

@@ -0,0 +1,65 @@
+package storage
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAppendToTheSegment(t *testing.T) {
+	config := &Config{segmentsRoot: os.TempDir()}
+	defer os.Remove(fmt.Sprintf("%s/segment_10", os.TempDir()))
+
+	index := NewIndex()
+
+	segment, err := NewSegment(10, config, index)
+	assert.NoError(t, err)
+	defer segment.Close()
+
+	id, err := segment.Append([]byte("Hello World"))
+	assert.NoError(t, err)
+	assert.Equal(t, id, 0)
+	_, ok := index.entries[0]
+	assert.True(t, ok)
+}
+
+func TestReadFromTheSegment(t *testing.T) {
+	config := &Config{segmentsRoot: os.TempDir()}
+	defer os.Remove(fmt.Sprintf("%s/segment_10", os.TempDir()))
+
+	index := NewIndex()
+
+	segment, err := NewSegment(10, config, index)
+	assert.NoError(t, err)
+	defer segment.Close()
+
+	id1, err := segment.Append([]byte("Hello World"))
+	assert.NoError(t, err)
+
+	id2, err := segment.Append([]byte("Bye World"))
+	assert.NoError(t, err)
+
+	data2, err := segment.Read(id2)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("Bye World"), data2)
+
+	data1, err := segment.Read(id1)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("Hello World"), data1)
+}
+
+func TestReadNonExistingMessage(t *testing.T) {
+	config := &Config{segmentsRoot: os.TempDir()}
+	defer os.Remove(fmt.Sprintf("%s/segment_12", os.TempDir()))
+
+	index := NewIndex()
+
+	segment, err := NewSegment(12, config, index)
+	assert.NoError(t, err)
+	defer segment.Close()
+
+	_, err = segment.Read(13)
+	assert.Error(t, err)
+}