leveldb: concurrent level0 compaction

go.mod

@@ -4,6 +4,12 @@ go 1.14
 
 require (
 	github.com/golang/snappy v0.0.1
+	github.com/gonum/blas v0.0.0-20181208220705-f22b278b28ac // indirect
+	github.com/gonum/floats v0.0.0-20181209220543-c233463c7e82 // indirect
+	github.com/gonum/internal v0.0.0-20181124074243-f884aa714029 // indirect
+	github.com/gonum/lapack v0.0.0-20181123203213-e4cdc5a0bff9 // indirect
+	github.com/gonum/matrix v0.0.0-20181209220409-c518dec07be9 // indirect
+	github.com/gonum/stat v0.0.0-20181125101827-41a0da705a5b
 	github.com/onsi/ginkgo v1.14.0
 	github.com/onsi/gomega v1.10.1
 	golang.org/x/net v0.0.0-20200813134508-3edf25e44fcc // indirect

go.sum

@@ -11,6 +11,18 @@ github.com/golang/protobuf v1.4.2 h1:+Z5KGCizgyZCbGh1KZqA0fcLLkwbsjIzS4aV2v7wJX0
 github.com/golang/protobuf v1.4.2/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw735rRwI=
 github.com/golang/snappy v0.0.1 h1:Qgr9rKW7uDUkrbSmQeiDsGa8SjGyCOGtuasMWwvp2P4=
 github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
+github.com/gonum/blas v0.0.0-20181208220705-f22b278b28ac h1:Q0Jsdxl5jbxouNs1TQYt0gxesYMU4VXRbsTlgDloZ50=
+github.com/gonum/blas v0.0.0-20181208220705-f22b278b28ac/go.mod h1:P32wAyui1PQ58Oce/KYkOqQv8cVw1zAapXOl+dRFGbc=
+github.com/gonum/floats v0.0.0-20181209220543-c233463c7e82 h1:EvokxLQsaaQjcWVWSV38221VAK7qc2zhaO17bKys/18=
+github.com/gonum/floats v0.0.0-20181209220543-c233463c7e82/go.mod h1:PxC8OnwL11+aosOB5+iEPoV3picfs8tUpkVd0pDo+Kg=
+github.com/gonum/internal v0.0.0-20181124074243-f884aa714029 h1:8jtTdc+Nfj9AR+0soOeia9UZSvYBvETVHZrugUowJ7M=
+github.com/gonum/internal v0.0.0-20181124074243-f884aa714029/go.mod h1:Pu4dmpkhSyOzRwuXkOgAvijx4o+4YMUJJo9OvPYMkks=
+github.com/gonum/lapack v0.0.0-20181123203213-e4cdc5a0bff9 h1:7qnwS9+oeSiOIsiUMajT+0R7HR6hw5NegnKPmn/94oI=
+github.com/gonum/lapack v0.0.0-20181123203213-e4cdc5a0bff9/go.mod h1:XA3DeT6rxh2EAE789SSiSJNqxPaC0aE9J8NTOI0Jo/A=
+github.com/gonum/matrix v0.0.0-20181209220409-c518dec07be9 h1:V2IgdyerlBa/MxaEFRbV5juy/C3MGdj4ePi+g6ePIp4=
+github.com/gonum/matrix v0.0.0-20181209220409-c518dec07be9/go.mod h1:0EXg4mc1CNP0HCqCz+K4ts155PXIlUywf0wqN+GfPZw=
+github.com/gonum/stat v0.0.0-20181125101827-41a0da705a5b h1:fbskpz/cPqWH8VqkQ7LJghFkl2KPAiIFUHrTJ2O3RGk=
+github.com/gonum/stat v0.0.0-20181125101827-41a0da705a5b/go.mod h1:Z4GIJBJO3Wa4gD4vbwQxXXZ+WHmW6E9ixmNrwvs0iZs=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.4.0 h1:xsAVV57WRhGj6kEIi8ReJzQlHHqcBYCElAvkovg3B/4=

leveldb/db.go

@@ -40,6 +40,7 @@ type DB struct {
 
 	// Compaction statistic
 	memComp       uint32 // The cumulative number of memory compaction
+	level0SubComp uint32 // The cumulative number of memory compaction
 	level0Comp    uint32 // The cumulative number of level0 compaction
 	nonLevel0Comp uint32 // The cumulative number of non-level0 compaction
 	seekComp      uint32 // The cumulative number of seek compaction
@@ -1047,6 +1048,7 @@ type DBStats struct {
 	LevelDurations    []time.Duration
 
 	MemComp       uint32
+	Level0SubComp uint32
 	Level0Comp    uint32
 	NonLevel0Comp uint32
 	SeekComp      uint32
@@ -1094,6 +1096,7 @@ func (db *DB) Stats(s *DBStats) error {
 		s.LevelTablesCounts = append(s.LevelTablesCounts, len(tables))
 	}
 	s.MemComp = atomic.LoadUint32(&db.memComp)
+	s.Level0SubComp = atomic.LoadUint32(&db.level0SubComp)
 	s.Level0Comp = atomic.LoadUint32(&db.level0Comp)
 	s.NonLevel0Comp = atomic.LoadUint32(&db.nonLevel0Comp)
 	s.SeekComp = atomic.LoadUint32(&db.seekComp)