Merge pull request #12 from Preetam/stats

Add collection stats

lm2.go

@@ -26,6 +26,7 @@ type Collection struct {
 	f     *os.File
 	wal   *wal
 	cache *recordCache
+	stats Stats
 
 	metaLock sync.RWMutex
 }
@@ -240,6 +241,8 @@ func (c *Collection) readRecord(offset int64) (*record, error) {
 	c.cache.lock.RLock()
 	if rec := c.cache.cache[offset]; rec != nil {
 		c.cache.lock.RUnlock()
+		c.stats.incRecordsRead(1)
+		c.stats.incCacheHits(1)
 		return rec, nil
 	}
 	c.cache.lock.RUnlock()
@@ -277,6 +280,8 @@ func (c *Collection) readRecord(offset int64) (*record, error) {
 		Key:          key,
 		Value:        value,
 	}
+	c.stats.incRecordsRead(1)
+	c.stats.incCacheMisses(1)
 
 	c.cache.push(rec)
 
@@ -654,6 +659,7 @@ func (c *Collection) Update(wb *WriteBatch) (int64, error) {
 		}
 	}
 
+	c.stats.incRecordsWritten(uint64(len(newlyInserted)))
 	return c.LastCommit, c.f.Sync()
 }
 
@@ -816,3 +822,8 @@ func (c *Collection) Version() int64 {
 	defer c.metaLock.RUnlock()
 	return c.LastCommit
 }
+
+// Stats returns collection statistics.
+func (c *Collection) Stats() Stats {
+	return c.stats.clone()
+}

lm2_test.go

@@ -105,6 +105,8 @@ func TestCopy(t *testing.T) {
 	if count1 != count2 || count1 != N {
 		t.Errorf("incorrect count. N = %d, count1 = %d, count2 = %d", N, count1, count2)
 	}
+	t.Logf("%+v", c.Stats())
+	t.Logf("%+v", c2.Stats())
 }
 
 func TestWriteBatch(t *testing.T) {
@@ -332,6 +334,7 @@ func TestWriteBatch2(t *testing.T) {
 		}
 		i++
 	}
+	t.Logf("%+v", c.Stats())
 }
 
 func TestWriteCloseOpen(t *testing.T) {
@@ -401,6 +404,7 @@ func TestWriteCloseOpen(t *testing.T) {
 		}
 		i++
 	}
+	t.Logf("%+v", c.Stats())
 }
 
 func TestReadLastEntry(t *testing.T) {
@@ -431,4 +435,5 @@ func TestReadLastEntry(t *testing.T) {
 	if entry.NumRecords != 2 {
 		t.Errorf("expected %d records, got %d", 2, entry.NumRecords)
 	}
+	t.Logf("%+v", c.Stats())
 }

stats.go

@@ -0,0 +1,36 @@
+package lm2
+
+import "sync/atomic"
+
+// Stats holds collection statistics.
+type Stats struct {
+	RecordsWritten uint64
+	RecordsRead    uint64
+	CacheHits      uint64
+	CacheMisses    uint64
+}
+
+func (s *Stats) incRecordsWritten(count uint64) {
+	atomic.AddUint64(&s.RecordsWritten, count)
+}
+
+func (s *Stats) incRecordsRead(count uint64) {
+	atomic.AddUint64(&s.RecordsRead, count)
+}
+
+func (s *Stats) incCacheHits(count uint64) {
+	atomic.AddUint64(&s.CacheHits, count)
+}
+
+func (s *Stats) incCacheMisses(count uint64) {
+	atomic.AddUint64(&s.CacheMisses, count)
+}
+
+func (s *Stats) clone() Stats {
+	return Stats{
+		RecordsWritten: atomic.LoadUint64(&s.RecordsWritten),
+		RecordsRead:    atomic.LoadUint64(&s.RecordsRead),
+		CacheHits:      atomic.LoadUint64(&s.CacheHits),
+		CacheMisses:    atomic.LoadUint64(&s.CacheMisses),
+	}
+}