Throttler: fix nil pointer dereference error

[shlomi-noach]

Description

Fixes #15179 by removing excessive and ineffective line of code.

This needs to be backported to release 19

The nil pointer dereference error could happen when a v19 primary runs with a v18 replica.

Related Issue(s)

#15179

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

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[shlomi-noach]

The current unit test failure is unrelated to this change:

2024-02-08T16:33:42.6950434Z === RUN   TestMtlsAuthUnauthorizedFails
2024-02-08T16:33:42.6950904Z I0208 16:30:59.991164   25468 tlstest.go:167] Creating test root CA in /tmp/TestMtlsAuthUnauthorizedFails1273706000/001
2024-02-08T16:33:42.6951238Z I0208 16:30:59.991604   25468 tlstest.go:236] Creating signed cert and key vtctld.example.com
2024-02-08T16:33:42.6951537Z I0208 16:30:59.992025   25468 tlstest.go:236] Creating signed cert and key AnotherApp
2024-02-08T16:33:42.6951755Z I0208 16:30:59.992812   25468 main.go:297] Starting local cluster...
2024-02-08T16:33:42.6955027Z I0208 16:30:59.992830   25468 main.go:298] config: vttest.Config{Topology:(*vttest.VTTestTopology)(0xc00085e960), Seed:(*vttest.SeedConfig)(nil), SchemaDir:"data/schema", DefaultSchemaDir:"", DataDir:"", Charset:"utf8mb4", PlannerVersion:"", ExtraMyCnf:[]string(nil), OnlyMySQL:false, PersistentMode:false, VtComboBindAddress:"localhost", MySQLBindHost:"localhost", SnapshotFile:"", EnableSystemSettings:true, TransactionMode:"MULTI", TransactionTimeout:0, TabletHostName:"localhost", InitWorkflowManager:false, VSchemaDDLAuthorizedUsers:"%", ForeignKeyMode:"allow", EnableOnlineDDL:true, EnableDirectDDL:true, ExternalTopoImplementation:"", ExternalTopoGlobalServerAddress:"", ExternalTopoGlobalRoot:"", VtgateTabletRefreshInterval:10000000000}
2024-02-08T16:33:42.6955423Z I0208 16:30:59.992865   25468 local_cluster.go:351] No environment in cluster settings. Creating default...
2024-02-08T16:33:42.6956795Z I0208 16:30:59.992963   25468 local_cluster.go:358] LocalCluster environment: &{BasePort:24616 TmpPath:/tmp/vttest1461989537 DefaultMyCnf:[/home/runner/work/vitess/vitess/config/mycnf/test-suite.cnf] Env:[VTDATAROOT=/tmp/vttest1461989537 VTTEST=endtoend] EnableToxiproxy:false}
2024-02-08T16:33:42.6957159Z I0208 16:30:59.992995   25468 local_cluster.go:381] Initializing MySQL Manager (*vttest.Mysqlctl)...
2024-02-08T16:33:42.6957481Z E0208 16:31:59.994745   25468 local_cluster.go:383] Mysqlctl failed to start: signal: killed
2024-02-08T16:33:42.6959559Z E0208 16:31:59.994788   25468 local_cluster.go:385] stderr: W0208 16:31:00.001579   36028 log.go:39] Failed to read in config : Config File "vtconfig" Not Found in "[/home/runner/work/vitess/vitess/go/cmd/vttestserver/cli]". This is optional, and can be ignored if you are not using config files. For a detailed explanation, see https://github.com/vitessio/vitess/blob/main/doc/viper/viper.md#config-files.
2024-02-08T16:33:42.6959802Z I0208 16:31:00.003594   36028 dbconfigs.go:372] DBConfigs: allprivs:
2024-02-08T16:33:42.6959937Z   password: '****'
2024-02-08T16:33:42.6960025Z app:
2024-02-08T16:33:42.6960158Z   password: '****'
2024-02-08T16:33:42.6960248Z appdebug:
2024-02-08T16:33:42.6960379Z   password: '****'
2024-02-08T16:33:42.6960473Z charset: utf8mb4
2024-02-08T16:33:42.6960557Z dba:
2024-02-08T16:33:42.6960678Z   password: '****'
2024-02-08T16:33:42.6960776Z   useSsl: true
2024-02-08T16:33:42.6960880Z   user: vt_dba
2024-02-08T16:33:42.6960968Z filtered:
2024-02-08T16:33:42.6961098Z   password: '****'
2024-02-08T16:33:42.6961180Z repl:
2024-02-08T16:33:42.6961302Z   password: '****'
2024-02-08T16:33:42.6961313Z 
2024-02-08T16:33:42.6961604Z I0208 16:31:00.011934   36028 mysqld.go:195] Using flavor: mysql, version: {5 7 42}
2024-02-08T16:33:42.6962217Z I0208 16:31:00.011996   36028 mysqld.go:690] mysqlctl.Init running with contents previously embedded from /home/runner/work/vitess/vitess/config/init_db.sql
2024-02-08T16:33:42.6962430Z I0208 16:31:00.012007   36028 mysqld.go:672] mysqlctl.InitConfig
2024-02-08T16:33:42.6962778Z I0208 16:31:00.012013   36028 mysqld.go:984] creating directory /tmp/vttest1461989537/vt_0000000001
2024-02-08T16:33:42.6963158Z I0208 16:31:00.012152   36028 mysqld.go:1018] creating directory /tmp/vttest1461989537/vt_0000000001/data
2024-02-08T16:33:42.6963532Z I0208 16:31:00.012219   36028 mysqld.go:1018] creating directory /tmp/vttest1461989537/vt_0000000001/innodb
2024-02-08T16:33:42.6964021Z I0208 16:31:00.012278   36028 mysqld.go:1018] creating directory /tmp/vttest1461989537/vt_0000000001/relay-logs
2024-02-08T16:33:42.6964487Z I0208 16:31:00.012332   36028 mysqld.go:1018] creating directory /tmp/vttest1461989537/vt_0000000001/bin-logs
2024-02-08T16:33:42.6964862Z I0208 16:31:00.012376   36028 mysqld.go:994] creating directory /tmp/vttest1461989537/vt_0000000001/data
2024-02-08T16:33:42.6965256Z I0208 16:31:00.012390   36028 mysqld.go:994] creating directory /tmp/vttest1461989537/vt_0000000001/innodb/data
2024-02-08T16:33:42.6965650Z I0208 16:31:00.012431   36028 mysqld.go:994] creating directory /tmp/vttest1461989537/vt_0000000001/innodb/logs
2024-02-08T16:33:42.6966150Z I0208 16:31:00.012476   36028 mysqld.go:994] creating directory /tmp/vttest1461989537/vt_0000000001/tmp
2024-02-08T16:33:42.6966627Z I0208 16:31:00.012523   36028 mysqld.go:994] creating directory /tmp/vttest1461989537/vt_0000000001/relay-logs
2024-02-08T16:33:42.6967089Z I0208 16:31:00.012536   36028 mysqld.go:994] creating directory /tmp/vttest1461989537/vt_0000000001/bin-logs
2024-02-08T16:33:42.6967513Z I0208 16:31:00.012554   36028 mysqld.go:830] make_mycnf hook doesn't exist, reading template files
2024-02-08T16:33:42.6967929Z I0208 16:31:00.012879   36028 mysqld.go:786] Installing data dir with mysqld --initialize-insecure
2024-02-08T16:33:42.6968370Z I0208 16:31:01.572765   36028 mysqld.go:352] Mysqld.Start(1707409861): No mysqld_start hook, running mysqld_safe directly
2024-02-08T16:33:42.6972072Z I0208 16:31:01.573000   36028 mysqld.go:392] Mysqld.Start(1707409861) &exec.Cmd{Path:"/usr/bin/mysqld_safe", Args:[]string{"/usr/bin/mysqld_safe", "--defaults-file=/tmp/vttest1461989537/vt_0000000001/my.cnf", "--basedir=/usr"}, Env:[]string{"LD_LIBRARY_PATH=/usr/lib/mysql", "LD_PRELOAD=libeatmydata.so"}, Dir:"/usr", Stdin:io.Reader(nil), Stdout:io.Writer(nil), Stderr:io.Writer(nil), ExtraFiles:[]*os.File(nil), SysProcAttr:(*syscall.SysProcAttr)(nil), Process:(*os.Process)(nil), ProcessState:(*os.ProcessState)(nil), ctx:context.Context(nil), Err:error(nil), Cancel:(func() error)(nil), WaitDelay:0, childIOFiles:[]io.Closer(nil), parentIOPipes:[]io.Closer(nil), goroutine:[]func() error(nil), goroutineErr:(<-chan error)(nil), ctxResult:(<-chan exec.ctxResult)(nil), createdByStack:[]uint8(nil), lookPathErr:error(nil)}
2024-02-08T16:33:42.6972705Z I0208 16:31:01.573453   36028 mysqld.go:501] Waiting for mysqld socket file (/tmp/vttest1461989537/vt_0000000001/mysql.sock) to be ready...
2024-02-08T16:33:42.6973500Z I0208 16:31:01.931998   36028 mysqld.go:410] Mysqld.Start(1707409861) stdout: 2024-02-08T16:31:01.931699Z mysqld_safe Logging to '/tmp/vttest1461989537/vt_0000000001/error.log'.
2024-02-08T16:33:42.6974409Z I0208 16:31:01.954839   36028 mysqld.go:410] Mysqld.Start(1707409861) stdout: 2024-02-08T16:31:01.954544Z mysqld_safe Starting mysqld daemon with databases from /tmp/vttest1461989537/vt_0000000001/data
2024-02-08T16:33:42.6975263Z I0208 16:31:03.586006   36028 mysqld.go:410] Mysqld.Start(1707409861) stdout: 2024-02-08T16:31:03.585652Z mysqld_safe mysqld from pid file /tmp/vttest1461989537/vt_0000000001/mysql.pid ended
2024-02-08T16:33:42.6975538Z I0208 16:31:03.586945   36028 mysqld.go:423] Mysqld.Start(1707409861) exit: <nil>
2024-02-08T16:33:42.6975688Z     main_test.go:306: 
2024-02-08T16:33:42.6976218Z         	Error Trace:	/home/runner/work/vitess/vitess/go/cmd/vttestserver/cli/main_test.go:306
2024-02-08T16:33:42.6976822Z         	Error:      	"signal: killed" does not contain "code = Unauthenticated desc = client certificate not authorized"
2024-02-08T16:33:42.6977058Z         	Test:       	TestMtlsAuthUnauthorizedFails
2024-02-08T16:33:42.6977277Z --- FAIL: TestMtlsAuthUnauthorizedFails (60.05s)
2024-02-08T16:33:42.6977361Z FAIL

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3a98b4c) 67.28% compared to head (0d28546) 67.28%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #15180   +/-   ##
=======================================
  Coverage   67.28%   67.28%           
=======================================
  Files        1559     1559           
  Lines      192056   192061    +5     
=======================================
+ Hits       129219   129225    +6     
+ Misses      62837    62836    -1     

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