Merge pull request #2519 from cockroachdb/bram/sim2

Sim: Add range splitting

storage/simulation/cluster.go

@@ -19,6 +19,7 @@ package main
 
 import (
 	"bytes"
+	"math/rand"
 	"sort"
 
 	"github.com/cockroachdb/cockroach/base"
@@ -28,6 +29,7 @@ import (
 	"github.com/cockroachdb/cockroach/storage"
 	"github.com/cockroachdb/cockroach/testutils/gossiputil"
 	"github.com/cockroachdb/cockroach/util/hlc"
+	"github.com/cockroachdb/cockroach/util/randutil"
 	"github.com/cockroachdb/cockroach/util/stop"
 )
 
@@ -44,11 +46,14 @@ type Cluster struct {
 	nodes         map[proto.NodeID]*Node
 	stores        map[proto.StoreID]*Store
 	ranges        map[proto.RangeID]*Range
+	rand          *rand.Rand
+	seed          int64
 }
 
 // createCluster generates a new cluster using the provided stopper and the
 // number of nodes supplied. Each node will have one store to start.
 func createCluster(stopper *stop.Stopper, nodeCount int) *Cluster {
+	rand, seed := randutil.NewPseudoRand()
 	clock := hlc.NewClock(hlc.UnixNano)
 	rpcContext := rpc.NewContext(&base.Context{}, clock, stopper)
 	g := gossip.New(rpcContext, gossip.TestInterval, gossip.TestBootstrap)
@@ -64,6 +69,8 @@ func createCluster(stopper *stop.Stopper, nodeCount int) *Cluster {
 		nodes:         make(map[proto.NodeID]*Node),
 		stores:        make(map[proto.StoreID]*Store),
 		ranges:        make(map[proto.RangeID]*Range),
+		rand:          rand,
+		seed:          seed,
 	}
 
 	// Add the nodes.
@@ -102,6 +109,22 @@ func (c *Cluster) addRange() *Range {
 	return newRng
 }
 
+func (c *Cluster) splitRangeRandom() {
+	rangeID := proto.RangeID(c.rand.Int63n(int64(len(c.ranges))))
+	c.splitRange(rangeID)
+}
+
+func (c *Cluster) splitRangeLast() {
+	rangeID := proto.RangeID(len(c.ranges) - 1)
+	c.splitRange(rangeID)
+}
+
+func (c *Cluster) splitRange(rangeID proto.RangeID) {
+	newRange := c.addRange()
+	originalRange := c.ranges[rangeID]
+	newRange.splitRange(originalRange)
+}
+
 // String prints out the current status of the cluster.
 func (c *Cluster) String() string {
 	storesRangeCounts := make(map[proto.StoreID]int)

storage/simulation/main.go

@@ -31,4 +31,11 @@ func main() {
 
 	fmt.Printf("A simulation of the cluster's rebalancing.\n\n")
 	fmt.Printf("Cluster Info:\n%s\n", c)
+
+	// Split a random range 100 times.
+	for i := 0; i < 100; i++ {
+		c.splitRangeRandom()
+	}
+
+	fmt.Printf("Cluster Info:\n%s\n", c)
 }

storage/simulation/range.go

@@ -97,6 +97,29 @@ func (r *Range) getStoreIDs() []proto.StoreID {
 	return storeIDs
 }
 
+// getStores returns a shallow copy of the internal stores map.
+func (r *Range) getStores() map[proto.StoreID]*Store {
+	r.RLock()
+	defer r.RUnlock()
+	stores := make(map[proto.StoreID]*Store)
+	for storeID, store := range r.stores {
+		stores[storeID] = store
+	}
+	return stores
+}
+
+// split range adds a replica to all the stores from the passed in range. This
+// function should only be called on new ranges as it will overwrite all of the
+// replicas in the range.
+func (r *Range) splitRange(originalRange *Range) {
+	desc := originalRange.getDesc()
+	stores := originalRange.getStores()
+	r.Lock()
+	defer r.Unlock()
+	r.desc.Replicas = desc.Replicas
+	r.stores = stores
+}
+
 // String returns a human readable string with details about the range.
 func (r *Range) String() string {
 	r.RLock()