Create a single connection pool per host (uber#359)

When history service comes up it creates a gocql client for execution manager and then uses the same client for all shards for making persistence calls. Also created config knobs to configure number of connections for both events and execution manager clients.

Also include shard tag for shard manager calls.

fixes uber#307

common/metrics/defs.go

@@ -339,9 +339,9 @@ const (
 var ScopeDefs = map[ServiceIdx]map[int]scopeDefinition{
 	// common scope Names
 	Common: {
-		PersistenceCreateShardScope:                    {operation: "CreateShard"},
-		PersistenceGetShardScope:                       {operation: "GetShard"},
-		PersistenceUpdateShardScope:                    {operation: "UpdateShard"},
+		PersistenceCreateShardScope:                    {operation: "CreateShard", tags: map[string]string{ShardTagName: NoneShardsTagValue}},
+		PersistenceGetShardScope:                       {operation: "GetShard", tags: map[string]string{ShardTagName: NoneShardsTagValue}},
+		PersistenceUpdateShardScope:                    {operation: "UpdateShard", tags: map[string]string{ShardTagName: NoneShardsTagValue}},
 		PersistenceCreateWorkflowExecutionScope:        {operation: "CreateWorkflowExecution"},
 		PersistenceGetWorkflowExecutionScope:           {operation: "GetWorkflowExecution"},
 		PersistenceUpdateWorkflowExecutionScope:        {operation: "UpdateWorkflowExecution"},

common/mocks/ExecutionManagerFactory.go

@@ -50,3 +50,8 @@ func (_m *ExecutionManagerFactory) CreateExecutionManager(shardID int) (persiste
 
 	return r0, r1
 }
+
+// Close is mock implementation for Close of ExecutionManagerFactory
+func (_m *ExecutionManagerFactory) Close() {
+	_m.Called()
+}

common/persistence/cassandraHistoryPersistence.go

@@ -60,14 +60,16 @@ type (
 )
 
 // NewCassandraHistoryPersistence is used to create an instance of HistoryManager implementation
-func NewCassandraHistoryPersistence(hosts string, port int, user, password, dc string, keyspace string, logger bark.Logger) (HistoryManager,
+func NewCassandraHistoryPersistence(hosts string, port int, user, password, dc string, keyspace string,
+	numConns int, logger bark.Logger) (HistoryManager,
 	error) {
 	cluster := common.NewCassandraCluster(hosts, port, user, password, dc)
 	cluster.Keyspace = keyspace
 	cluster.ProtoVersion = cassandraProtoVersion
 	cluster.Consistency = gocql.LocalQuorum
 	cluster.SerialConsistency = gocql.LocalSerial
 	cluster.Timeout = defaultSessionTimeout
+	cluster.NumConns = numConns
 
 	session, err := cluster.CreateSession()
 	if err != nil {

common/persistence/cassandraPersistence.go

@@ -531,20 +531,8 @@ func NewCassandraShardPersistence(hosts string, port int, user, password, dc str
 }
 
 // NewCassandraWorkflowExecutionPersistence is used to create an instance of workflowExecutionManager implementation
-func NewCassandraWorkflowExecutionPersistence(hosts string, port int, user, password, dc string, keyspace string,
-	shardID int, logger bark.Logger) (ExecutionManager, error) {
-	cluster := common.NewCassandraCluster(hosts, port, user, password, dc)
-	cluster.Keyspace = keyspace
-	cluster.ProtoVersion = cassandraProtoVersion
-	cluster.Consistency = gocql.LocalQuorum
-	cluster.SerialConsistency = gocql.LocalSerial
-	cluster.Timeout = defaultSessionTimeout
-
-	session, err := cluster.CreateSession()
-	if err != nil {
-		return nil, err
-	}
-
+func NewCassandraWorkflowExecutionPersistence(shardID int, session *gocql.Session,
+	logger bark.Logger) (ExecutionManager, error) {
 	return &cassandraPersistence{shardID: shardID, session: session, lowConslevel: gocql.One, logger: logger}, nil
 }
 

common/persistence/cassandraPersistenceClientFactory.go

@@ -0,0 +1,81 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package persistence
+
+import (
+	"github.com/gocql/gocql"
+	"github.com/uber-common/bark"
+	"github.com/uber/cadence/common"
+	"github.com/uber/cadence/common/metrics"
+)
+
+type (
+	cassandraPersistenceClientFactory struct {
+		session       *gocql.Session
+		metricsClient metrics.Client
+		logger        bark.Logger
+	}
+)
+
+// NewCassandraPersistenceClientFactory is used to create an instance of ExecutionManagerFactory implementation
+func NewCassandraPersistenceClientFactory(hosts string, port int, user, password, dc string, keyspace string,
+	numConns int, logger bark.Logger, mClient metrics.Client) (ExecutionManagerFactory, error) {
+	cluster := common.NewCassandraCluster(hosts, port, user, password, dc)
+	cluster.Keyspace = keyspace
+	cluster.ProtoVersion = cassandraProtoVersion
+	cluster.Consistency = gocql.LocalQuorum
+	cluster.SerialConsistency = gocql.LocalSerial
+	cluster.Timeout = defaultSessionTimeout
+	cluster.NumConns = numConns
+
+	session, err := cluster.CreateSession()
+	if err != nil {
+		return nil, err
+	}
+
+	return &cassandraPersistenceClientFactory{session: session, metricsClient: mClient, logger: logger}, nil
+}
+
+// CreateExecutionManager implements ExecutionManagerFactory interface
+func (f *cassandraPersistenceClientFactory) CreateExecutionManager(shardID int) (ExecutionManager, error) {
+	mgr, err := NewCassandraWorkflowExecutionPersistence(shardID, f.session, f.logger)
+
+	if err != nil {
+		return nil, err
+	}
+
+	if f.metricsClient == nil {
+		return mgr, nil
+	}
+
+	tags := map[string]string{
+		metrics.ShardTagName: metrics.AllShardsTagValue,
+	}
+	return NewWorkflowExecutionPersistenceClient(
+		mgr, f.metricsClient.Tagged(tags)), nil
+}
+
+// Close releases the underlying resources held by this object
+func (f *cassandraPersistenceClientFactory) Close() {
+	if f.session != nil {
+		f.session.Close()
+	}
+}

common/persistence/dataInterfaces.go

@@ -650,6 +650,7 @@ type (
 
 	// ExecutionManagerFactory creates an instance of ExecutionManager for a given shard
 	ExecutionManagerFactory interface {
+		Closeable
 		CreateExecutionManager(shardID int) (ExecutionManager, error)
 	}
 

common/persistence/persistenceTestBase.go

@@ -97,21 +97,6 @@ type (
 	}
 )
 
-func newTestExecutionMgrFactory(options TestBaseOptions, cassandra CassandraTestCluster,
-	logger bark.Logger) ExecutionManagerFactory {
-	return &testExecutionMgrFactory{
-		options:   options,
-		cassandra: cassandra,
-		logger:    logger,
-	}
-}
-
-func (f *testExecutionMgrFactory) CreateExecutionManager(shardID int) (ExecutionManager, error) {
-	return NewCassandraWorkflowExecutionPersistence(f.options.ClusterHost, f.options.ClusterPort, f.options.ClusterUser,
-		f.options.ClusterPassword, f.options.Datacenter, f.cassandra.keyspace,
-		shardID, f.logger)
-}
-
 func (g *testTransferTaskIDGenerator) GetNextTransferTaskID() (int64, error) {
 	return atomic.AddInt64(&g.seqNum, 1), nil
 }
@@ -128,7 +113,11 @@ func (s *TestBase) SetupWorkflowStoreWithOptions(options TestBaseOptions) {
 	if err != nil {
 		log.Fatal(err)
 	}
-	s.ExecutionMgrFactory = newTestExecutionMgrFactory(options, s.CassandraTestCluster, log)
+	s.ExecutionMgrFactory, err = NewCassandraPersistenceClientFactory(options.ClusterHost, options.ClusterPort,
+		options.ClusterUser, options.ClusterPassword, options.Datacenter, s.CassandraTestCluster.keyspace, 2, log, nil)
+	if err != nil {
+		log.Fatal(err)
+	}
 	// Create an ExecutionManager for the shard for use in unit tests
 	s.WorkflowMgr, err = s.ExecutionMgrFactory.CreateExecutionManager(shardID)
 	if err != nil {
@@ -142,7 +131,7 @@ func (s *TestBase) SetupWorkflowStoreWithOptions(options TestBaseOptions) {
 	}
 
 	s.HistoryMgr, err = NewCassandraHistoryPersistence(options.ClusterHost, options.ClusterPort, options.ClusterUser,
-		options.ClusterPassword, options.Datacenter, s.CassandraTestCluster.keyspace, log)
+		options.ClusterPassword, options.Datacenter, s.CassandraTestCluster.keyspace, 2, log)
 	if err != nil {
 		log.Fatal(err)
 	}

host/onebox.go

@@ -188,7 +188,10 @@ func (c *cadenceImpl) startHistory(logger bark.Logger, shardMgr persistence.Shar
 		params.RingpopFactory = newRingpopFactory(common.FrontendServiceName, rpHosts)
 		params.CassandraConfig.NumHistoryShards = c.numberOfHistoryShards
 		service := service.New(params)
-		handler := history.NewHandler(service, history.NewConfig(c.numberOfHistoryShards), shardMgr, metadataMgr,
+		historyConfig := history.NewConfig(c.numberOfHistoryShards)
+		historyConfig.HistoryMgrNumConns = c.numberOfHistoryShards
+		historyConfig.ExecutionMgrNumConns = c.numberOfHistoryShards
+		handler := history.NewHandler(service, historyConfig, shardMgr, metadataMgr,
 			visibilityMgr, historyMgr, executionMgrFactory)
 		handler.Start()
 		c.historyHandlers = append(c.historyHandlers, handler)

service/frontend/service.go

@@ -31,14 +31,18 @@ type Config struct {
 	DefaultVisibilityMaxPageSize int32
 	DefaultHistoryMaxPageSize    int32
 	RPS                          int
+
+	// Persistence settings
+	HistoryMgrNumConns int
 }
 
 // NewConfig returns new service config with default values
 func NewConfig() *Config {
 	return &Config{
 		DefaultVisibilityMaxPageSize: 1000,
 		DefaultHistoryMaxPageSize:    1000,
-		RPS: 1200, // This limit is based on experimental runs.
+		RPS:                1200, // This limit is based on experimental runs.
+		HistoryMgrNumConns: 10,
 	}
 }
 
@@ -99,6 +103,7 @@ func (s *Service) Start() {
 		p.CassandraConfig.Password,
 		p.CassandraConfig.Datacenter,
 		p.CassandraConfig.Keyspace,
+		s.config.HistoryMgrNumConns,
 		p.Logger)
 
 	if err != nil {

service/history/handler.go

@@ -120,6 +120,7 @@ func (h *Handler) Stop() {
 	h.controller.Stop()
 	h.shardManager.Close()
 	h.historyMgr.Close()
+	h.executionMgrFactory.Close()
 	h.metadataMgr.Close()
 	h.visibilityMgr.Close()
 	h.Service.Stop()

service/history/service.go

@@ -62,6 +62,10 @@ type Config struct {
 	TransferProcessorUpdateAckInterval   time.Duration
 	TransferProcessorForceUpdateInterval time.Duration
 	TransferTaskWorkerCount              int
+
+	// Persistence settings
+	ExecutionMgrNumConns int
+	HistoryMgrNumConns   int
 }
 
 // NewConfig returns new service config with default values
@@ -88,6 +92,8 @@ func NewConfig(numberOfShards int) *Config {
 		TransferProcessorUpdateAckInterval:          10 * time.Second,
 		TransferProcessorForceUpdateInterval:        10 * time.Minute,
 		TransferTaskWorkerCount:                     10,
+		ExecutionMgrNumConns:                        100,
+		HistoryMgrNumConns:                          100,
 	}
 }
 
@@ -181,14 +187,26 @@ func (s *Service) Start() {
 		p.CassandraConfig.Password,
 		p.CassandraConfig.Datacenter,
 		p.CassandraConfig.Keyspace,
+		s.config.HistoryMgrNumConns,
 		p.Logger)
 
 	if err != nil {
 		log.Fatalf("Creating Cassandra history manager persistence failed: %v", err)
 	}
-
 	history = persistence.NewHistoryPersistenceClient(history, base.GetMetricsClient())
-	execMgrFactory := NewExecutionManagerFactory(&p.CassandraConfig, p.Logger, base.GetMetricsClient())
+
+	execMgrFactory, err := persistence.NewCassandraPersistenceClientFactory(p.CassandraConfig.Hosts,
+		p.CassandraConfig.Port,
+		p.CassandraConfig.User,
+		p.CassandraConfig.Password,
+		p.CassandraConfig.Datacenter,
+		p.CassandraConfig.Keyspace,
+		s.config.ExecutionMgrNumConns,
+		p.Logger,
+		base.GetMetricsClient())
+	if err != nil {
+		log.Fatalf("Creating Cassandra execution manager persistence factory failed: %v", err)
+	}
 
 	handler := NewHandler(base,
 		s.config,

service/history/shardController.go

@@ -391,13 +391,6 @@ func (i *historyShardsItem) stopEngine() {
 		i.engine = nil
 		logging.LogShardEngineStoppedEvent(i.logger, i.host.Identity(), i.shardID)
 	}
-
-	// Shutting down executionMgr will close all connections
-	// to cassandra for this engine. So, make sure to
-	// close executionMgr only after stopping the engine
-	if i.executionMgr != nil {
-		i.executionMgr.Close()
-	}
 }
 
 func isShardOwnershiptLostError(err error) bool {