// readEnvironmentVariables populates all context values that are environment
// variable based. Note that this only happens when initializing a node and not
// when NewContext is called.
func (cfg *Config) readEnvironmentVariables() {
	// cockroach-linearizable
	cfg.Linearizable = envutil.EnvOrDefaultBool("COCKROACH_LINEARIZABLE", cfg.Linearizable)
	cfg.ConsistencyCheckPanicOnFailure = envutil.EnvOrDefaultBool("COCKROACH_CONSISTENCY_CHECK_PANIC_ON_FAILURE", cfg.ConsistencyCheckPanicOnFailure)
	cfg.MaxOffset = envutil.EnvOrDefaultDuration("COCKROACH_MAX_OFFSET", cfg.MaxOffset)
	cfg.MetricsSampleInterval = envutil.EnvOrDefaultDuration("COCKROACH_METRICS_SAMPLE_INTERVAL", cfg.MetricsSampleInterval)
	cfg.ScanInterval = envutil.EnvOrDefaultDuration("COCKROACH_SCAN_INTERVAL", cfg.ScanInterval)
	cfg.ScanMaxIdleTime = envutil.EnvOrDefaultDuration("COCKROACH_SCAN_MAX_IDLE_TIME", cfg.ScanMaxIdleTime)
	cfg.TimeUntilStoreDead = envutil.EnvOrDefaultDuration("COCKROACH_TIME_UNTIL_STORE_DEAD", cfg.TimeUntilStoreDead)
	cfg.ConsistencyCheckInterval = envutil.EnvOrDefaultDuration("COCKROACH_CONSISTENCY_CHECK_INTERVAL", cfg.ConsistencyCheckInterval)
}

	"golang.org/x/net/context"

	"github.com/cockroachdb/cockroach/pkg/internal/client"
	"github.com/cockroachdb/cockroach/pkg/roachpb"
	"github.com/cockroachdb/cockroach/pkg/rpc"
	"github.com/cockroachdb/cockroach/pkg/util/envutil"
	"github.com/cockroachdb/cockroach/pkg/util/log"
	"github.com/cockroachdb/cockroach/pkg/util/syncutil"
	"github.com/opentracing/opentracing-go"
	"google.golang.org/grpc"
)

// Allow local calls to be dispatched directly to the local server without
// sending an RPC.
var enableLocalCalls = envutil.EnvOrDefaultBool("COCKROACH_ENABLE_LOCAL_CALLS", true)

// A SendOptions structure describes the algorithm for sending RPCs to one or
// more replicas, depending on error conditions and how many successful
// responses are required.
type SendOptions struct {
	ctx context.Context

	// SendNextTimeout is the duration after which RPCs are sent to
	// other replicas in a set.
	SendNextTimeout time.Duration

	transportFactory TransportFactory
}

type batchClient struct {

//
//  - for each an internal planNode we start with the plan of the child node(s)
//    and add processing stages (connected to the result routers of the children
//    node).
type distSQLPlanner struct {
	nodeDesc     roachpb.NodeDescriptor
	rpcContext   *rpc.Context
	distSQLSrv   *distsql.ServerImpl
	spanResolver *distsql.SpanResolver
}

const resolverPolicy = distsql.BinPackingLeaseHolderChoice

// If true, the plan diagram (in JSON) is logged for each plan (used for
// debugging).
var logPlanDiagram = envutil.EnvOrDefaultBool("COCKROACH_DISTSQL_LOG_PLAN", false)

func newDistSQLPlanner(
	nodeDesc roachpb.NodeDescriptor,
	rpcCtx *rpc.Context,
	distSQLSrv *distsql.ServerImpl,
	distSender *kv.DistSender,
	gossip *gossip.Gossip,
) *distSQLPlanner {
	return &distSQLPlanner{
		nodeDesc:     nodeDesc,
		rpcContext:   rpcCtx,
		distSQLSrv:   distSQLSrv,
		spanResolver: distsql.NewSpanResolver(distSender, gossip, nodeDesc, resolverPolicy),
	}
}

// Stress returns true iff the process is running as part of CockroachDB's
// nightly stress tests.
func Stress() bool {
	return envutil.EnvOrDefaultBool(StressEnv, false)
}

	source, ok := a.storePool.getStoreDescriptor(leaseStoreID)
	if !ok {
		return false
	}
	sl, _, _ := a.storePool.getStoreList(rangeID)
	sl = sl.filter(constraints)
	if log.V(3) {
		log.Infof(context.TODO(), "transfer-lease-source (lease-holder=%d):\n%s", leaseStoreID, sl)
	}
	return a.shouldTransferLease(sl, source, existing)
}

// EnableLeaseRebalancing controls whether lease rebalancing is enabled or
// not. Exported for testing.
var EnableLeaseRebalancing = envutil.EnvOrDefaultBool("COCKROACH_ENABLE_LEASE_REBALANCING", true)

func (a Allocator) shouldTransferLease(
	sl StoreList, source roachpb.StoreDescriptor, existing []roachpb.ReplicaDescriptor,
) bool {
	if !EnableLeaseRebalancing {
		return false
	}
	// Allow lease transfer if we're above the overfull threshold, which is
	// mean*(1+rebalanceThreshold).
	overfullLeaseThreshold := int32(math.Ceil(sl.candidateLeases.mean * (1 + rebalanceThreshold)))
	minOverfullThreshold := int32(math.Ceil(sl.candidateLeases.mean + 5))
	if overfullLeaseThreshold < minOverfullThreshold {
		overfullLeaseThreshold = minOverfullThreshold
	}
	if source.Capacity.LeaseCount > overfullLeaseThreshold {

//.........这里部分代码省略.........
	// Begin recording time series data collected by the status monitor.
	s.tsDB.PollSource(
		s.cfg.AmbientCtx, s.recorder, s.cfg.MetricsSampleInterval, ts.Resolution10s, s.stopper,
	)

	// Begin recording status summaries.
	s.node.startWriteSummaries(s.cfg.MetricsSampleInterval)

	// Create and start the schema change manager only after a NodeID
	// has been assigned.
	testingKnobs := &sql.SchemaChangerTestingKnobs{}
	if s.cfg.TestingKnobs.SQLSchemaChanger != nil {
		testingKnobs = s.cfg.TestingKnobs.SQLSchemaChanger.(*sql.SchemaChangerTestingKnobs)
	}
	sql.NewSchemaChangeManager(testingKnobs, *s.db, s.gossip, s.leaseMgr).Start(s.stopper)

	s.distSQLServer.Start()

	log.Infof(ctx, "starting %s server at %s", s.cfg.HTTPRequestScheme(), unresolvedHTTPAddr)
	log.Infof(ctx, "starting grpc/postgres server at %s", unresolvedListenAddr)
	log.Infof(ctx, "advertising CockroachDB node at %s", unresolvedAdvertAddr)
	if len(s.cfg.SocketFile) != 0 {
		log.Infof(ctx, "starting postgres server at unix:%s", s.cfg.SocketFile)
	}

	s.stopper.RunWorker(func() {
		netutil.FatalIfUnexpected(m.Serve())
	})

	log.Event(ctx, "accepting connections")

	// Initialize grpc-gateway mux and context.
	jsonpb := &protoutil.JSONPb{
		EnumsAsInts:  true,
		EmitDefaults: true,
		Indent:       "  ",
	}
	protopb := new(protoutil.ProtoPb)
	gwMux := gwruntime.NewServeMux(
		gwruntime.WithMarshalerOption(gwruntime.MIMEWildcard, jsonpb),
		gwruntime.WithMarshalerOption(httputil.JSONContentType, jsonpb),
		gwruntime.WithMarshalerOption(httputil.AltJSONContentType, jsonpb),
		gwruntime.WithMarshalerOption(httputil.ProtoContentType, protopb),
		gwruntime.WithMarshalerOption(httputil.AltProtoContentType, protopb),
	)
	gwCtx, gwCancel := context.WithCancel(s.AnnotateCtx(context.Background()))
	s.stopper.AddCloser(stop.CloserFn(gwCancel))

	// Setup HTTP<->gRPC handlers.
	conn, err := s.rpcContext.GRPCDial(s.cfg.Addr)
	if err != nil {
		return errors.Errorf("error constructing grpc-gateway: %s; are your certificates valid?", err)
	}

	for _, gw := range []grpcGatewayServer{s.admin, s.status, &s.tsServer} {
		if err := gw.RegisterGateway(gwCtx, gwMux, conn); err != nil {
			return err
		}
	}

	var uiFileSystem http.FileSystem
	uiDebug := envutil.EnvOrDefaultBool("COCKROACH_DEBUG_UI", false)
	if uiDebug {
		uiFileSystem = http.Dir("pkg/ui")
	} else {
		uiFileSystem = &assetfs.AssetFS{
			Asset:     ui.Asset,
			AssetDir:  ui.AssetDir,
			AssetInfo: ui.AssetInfo,
		}
	}
	uiFileServer := http.FileServer(uiFileSystem)

	s.mux.HandleFunc("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path == "/" {
			if uiDebug {
				r.URL.Path = "debug.html"
			} else {
				r.URL.Path = "release.html"
			}
		}
		uiFileServer.ServeHTTP(w, r)
	}))

	// TODO(marc): when cookie-based authentication exists,
	// apply it for all web endpoints.
	s.mux.Handle(adminPrefix, gwMux)
	s.mux.Handle(ts.URLPrefix, gwMux)
	s.mux.Handle(statusPrefix, gwMux)
	s.mux.Handle("/health", gwMux)
	s.mux.Handle(statusVars, http.HandlerFunc(s.status.handleVars))
	log.Event(ctx, "added http endpoints")

	if err := sdnotify.Ready(); err != nil {
		log.Errorf(ctx, "failed to signal readiness using systemd protocol: %s", err)
	}
	log.Event(ctx, "server ready")

	return nil
}

//.........这里部分代码省略.........
		RPCContext:     s.rpcContext,
		Stopper:        s.stopper,
	}
	s.distSQLServer = distsql.NewServer(distSQLCfg)
	distsql.RegisterDistSQLServer(s.grpc, s.distSQLServer)

	// Set up admin memory metrics for use by admin SQL executors.
	s.adminMemMetrics = sql.MakeMemMetrics("admin")
	s.registry.AddMetricStruct(s.adminMemMetrics)

	// Set up Executor
	execCfg := sql.ExecutorConfig{
		AmbientCtx:            s.cfg.AmbientCtx,
		NodeID:                &s.nodeIDContainer,
		DB:                    s.db,
		Gossip:                s.gossip,
		DistSender:            s.distSender,
		RPCContext:            s.rpcContext,
		LeaseManager:          s.leaseMgr,
		Clock:                 s.clock,
		DistSQLSrv:            s.distSQLServer,
		MetricsSampleInterval: s.cfg.MetricsSampleInterval,
	}
	if s.cfg.TestingKnobs.SQLExecutor != nil {
		execCfg.TestingKnobs = s.cfg.TestingKnobs.SQLExecutor.(*sql.ExecutorTestingKnobs)
	} else {
		execCfg.TestingKnobs = &sql.ExecutorTestingKnobs{}
	}
	if s.cfg.TestingKnobs.SQLSchemaChanger != nil {
		execCfg.SchemaChangerTestingKnobs =
			s.cfg.TestingKnobs.SQLSchemaChanger.(*sql.SchemaChangerTestingKnobs)
	} else {
		execCfg.SchemaChangerTestingKnobs = &sql.SchemaChangerTestingKnobs{}
	}
	s.sqlExecutor = sql.NewExecutor(execCfg, s.stopper)
	s.registry.AddMetricStruct(s.sqlExecutor)

	s.pgServer = pgwire.MakeServer(
		s.cfg.AmbientCtx, s.cfg.Config, s.sqlExecutor, &s.internalMemMetrics, s.cfg.SQLMemoryPoolSize,
	)
	s.registry.AddMetricStruct(s.pgServer.Metrics())

	s.tsDB = ts.NewDB(s.db)
	s.tsServer = ts.MakeServer(s.cfg.AmbientCtx, s.tsDB, s.cfg.TimeSeriesServerConfig, s.stopper)

	// TODO(bdarnell): make StoreConfig configurable.
	storeCfg := storage.StoreConfig{
		AmbientCtx:                     s.cfg.AmbientCtx,
		Clock:                          s.clock,
		DB:                             s.db,
		Gossip:                         s.gossip,
		NodeLiveness:                   s.nodeLiveness,
		Transport:                      s.raftTransport,
		RangeRetryOptions:              s.cfg.RetryOptions,
		RaftTickInterval:               s.cfg.RaftTickInterval,
		ScanInterval:                   s.cfg.ScanInterval,
		ScanMaxIdleTime:                s.cfg.ScanMaxIdleTime,
		ConsistencyCheckInterval:       s.cfg.ConsistencyCheckInterval,
		ConsistencyCheckPanicOnFailure: s.cfg.ConsistencyCheckPanicOnFailure,
		MetricsSampleInterval:          s.cfg.MetricsSampleInterval,
		StorePool:                      s.storePool,
		SQLExecutor: sql.InternalExecutor{
			LeaseManager: s.leaseMgr,
		},
		LogRangeEvents: s.cfg.EventLogEnabled,
		AllocatorOptions: storage.AllocatorOptions{
			AllowRebalance: true,
		},
		RangeLeaseActiveDuration:  active,
		RangeLeaseRenewalDuration: renewal,
		TimeSeriesDataStore:       s.tsDB,

		EnableEpochRangeLeases: envutil.EnvOrDefaultBool(
			"COCKROACH_ENABLE_EPOCH_RANGE_LEASES", false),
	}
	if s.cfg.TestingKnobs.Store != nil {
		storeCfg.TestingKnobs = *s.cfg.TestingKnobs.Store.(*storage.StoreTestingKnobs)
	}

	s.recorder = status.NewMetricsRecorder(s.clock)
	s.registry.AddMetricStruct(s.rpcContext.RemoteClocks.Metrics())

	s.runtime = status.MakeRuntimeStatSampler(s.clock)
	s.registry.AddMetricStruct(s.runtime)

	s.node = NewNode(storeCfg, s.recorder, s.registry, s.stopper, txnMetrics, sql.MakeEventLogger(s.leaseMgr))
	roachpb.RegisterInternalServer(s.grpc, s.node)
	storage.RegisterConsistencyServer(s.grpc, s.node.storesServer)
	storage.RegisterFreezeServer(s.grpc, s.node.storesServer)

	s.admin = newAdminServer(s)
	s.status = newStatusServer(
		s.cfg.AmbientCtx, s.db, s.gossip, s.recorder, s.rpcContext, s.node.stores,
	)
	for _, gw := range []grpcGatewayServer{s.admin, s.status, &s.tsServer} {
		gw.RegisterService(s.grpc)
	}

	return s, nil
}

		// If we are not recording the spans, there is no need to keep them in
		// memory. Events still get passed to netTraceIntegrator.
		opts.DropAllLogs = true
	} else {
		opts.Recorder = CallbackRecorder(recorder)
		// Set a comfortable limit of log events per span.
		opts.MaxLogsPerSpan = maxLogsPerSpan
	}
	return opts
}

var lightstepToken = envutil.EnvOrDefaultString("COCKROACH_LIGHTSTEP_TOKEN", "")

// By default, if a lightstep token is specified we trace to both Lightstep and
// net/trace. If this flag is enabled, we will only trace to Lightstep.
var lightstepOnly = envutil.EnvOrDefaultBool("COCKROACH_LIGHTSTEP_ONLY", false)

// newTracer implements NewTracer and allows that function to be mocked out via Disable().
var newTracer = func() opentracing.Tracer {
	if lightstepToken != "" {
		lsTr := lightstep.NewTracer(lightstep.Options{
			AccessToken:    lightstepToken,
			MaxLogsPerSpan: maxLogsPerSpan,
			UseGRPC:        true,
		})
		if lightstepOnly {
			return lsTr
		}
		basicTr := basictracer.NewWithOptions(basictracerOptions(nil))
		// The TeeTracer uses the first tracer for serialization of span contexts;
		// lightspan needs to be first because it correlates spans between nodes.

	opentracing "github.com/opentracing/opentracing-go"
	"github.com/pkg/errors"
)

// COCKROACH_TRACE_SQL=duration can be used to log SQL transactions that take
// longer than duration to complete. For example, COCKROACH_TRACE_SQL=1s will
// log the trace for any transaction that takes 1s or longer. To log traces for
// all transactions use COCKROACH_TRACE_SQL=1ns. Note that any positive
// duration will enable tracing and will slow down all execution because traces
// are gathered for all transactions even if they are not output.
var traceSQLDuration = envutil.EnvOrDefaultDuration("COCKROACH_TRACE_SQL", 0)
var traceSQL = traceSQLDuration > 0

// COCKROACH_TRACE_7881 can be used to trace all SQL transactions, in the hope
// that we'll catch #7881 and dump the current trace for debugging.
var traceSQLFor7881 = envutil.EnvOrDefaultBool("COCKROACH_TRACE_7881", false)

// span baggage key used for marking a span
const keyFor7881Sample = "found#7881"

// Session contains the state of a SQL client connection.
// Create instances using NewSession().
type Session struct {
	Database string
	// SearchPath is a list of databases that will be searched for a table name
	// before the database. Currently, this is used only for SELECTs.
	// Names in the search path must have been normalized already.
	//
	// NOTE: If we allow the user to set this, we'll need to handle the case where
	// the session database or pg_catalog are in this path.
	SearchPath  []string

// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
//
// Author: Peter Mattis ([email protected])

package tracing

// static void annotateTrace() {
// }
import "C"

import "github.com/cockroachdb/cockroach/pkg/util/envutil"

var annotationEnabled = envutil.EnvOrDefaultBool("COCKROACH_ANNOTATE_TRACES", false)

// AnnotateTrace adds an annotation to the golang executation tracer by calling
// a no-op cgo function.
func AnnotateTrace() {
	if annotationEnabled {
		C.annotateTrace()
	}
}