Done with chapter 1. Basic http/json log server.

internal/server/log.go

@@ -0,0 +1,46 @@
+package server
+
+import (
+	"errors"
+	"sync"
+)
+
+// Log represents a commit log.
+type Log struct {
+	mu      sync.Mutex
+	records []Record
+}
+
+// NewLog returns a new ready to use Log.
+func NewLog() *Log {
+	return &Log{}
+}
+
+// Append adds a new record to a log.
+func (c *Log) Append(record Record) (uint64, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	record.Offset = uint64(len(c.records))
+	c.records = append(c.records, record)
+	return record.Offset, nil
+}
+
+// Read returns an individual record from the log given its offset.
+// Returns an error if the offset does not exist.
+func (c *Log) Read(offset uint64) (Record, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if offset >= uint64(len(c.records)) {
+		return Record{}, ErrOffsetNotFound
+	}
+
+	return c.records[offset], nil
+}
+
+// Record represents a single record in a commit log.
+type Record struct {
+	Value  []byte `json:"value"`
+	Offset uint64 `json:"offset"`
+}
+
+var ErrOffsetNotFound = errors.New("offset not found")