Remove unused control option for disabling concurrency limiter (#4677)

<!-- PR description-->

Concurrency limiter is stable and has been in use since several months. We had added a killswitch to disable it for safety reasons. It's not being used by SDK consumers, and hidden in corso cli. 

This PR removes the `--disable-concurrency-limiter` flag & associated control option.

---

#### Does this PR need a docs update or release note?

- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No

#### Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [x] 🧹 Tech Debt/Cleanup

#### Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* #<issue>

#### Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

src/cli/backup/exchange.go

@@ -82,7 +82,6 @@ func addExchangeCommands(cmd *cobra.Command) *cobra.Command {
 		flags.AddFetchParallelismFlag(c)
 		flags.AddDisableDeltaFlag(c)
 		flags.AddEnableImmutableIDFlag(c)
-		flags.AddDisableConcurrencyLimiterFlag(c)
 		flags.AddDeltaPageSizeFlag(c)
 		flags.AddGenericBackupFlags(c)
 

src/cli/backup/exchange_test.go

@@ -108,7 +108,6 @@ func (suite *ExchangeUnitSuite) TestBackupCreateFlags() {
 				// bool flags
 				"--" + flags.DisableDeltaFN,
 				"--" + flags.EnableImmutableIDFN,
-				"--" + flags.DisableConcurrencyLimiterFN,
 			},
 			flagsTD.PreparedGenericBackupFlags(),
 			flagsTD.PreparedProviderFlags(),
@@ -125,7 +124,6 @@ func (suite *ExchangeUnitSuite) TestBackupCreateFlags() {
 	assert.True(t, co.ToggleFeatures.ForceItemDataDownload)
 	assert.True(t, co.ToggleFeatures.DisableDelta)
 	assert.True(t, co.ToggleFeatures.ExchangeImmutableIDs)
-	assert.True(t, co.ToggleFeatures.DisableConcurrencyLimiter)
 	flagsTD.AssertGenericBackupFlags(t, cmd)
 	flagsTD.AssertProviderFlags(t, cmd)
 	flagsTD.AssertStorageFlags(t, cmd)

src/cli/flags/options.go

@@ -5,38 +5,36 @@ import (
 )
 
 const (
-	AlertsFN                    = "alerts"
-	DeltaPageSizeFN             = "delta-page-size"
-	DisableConcurrencyLimiterFN = "disable-concurrency-limiter"
-	DisableDeltaFN              = "disable-delta"
-	DisableIncrementalsFN       = "disable-incrementals"
-	ForceItemDataDownloadFN     = "force-item-data-download"
-	EnableImmutableIDFN         = "enable-immutable-id"
-	FailFastFN                  = "fail-fast"
-	FailedItemsFN               = "failed-items"
-	FetchParallelismFN          = "fetch-parallelism"
-	NoStatsFN                   = "no-stats"
-	RecoveredErrorsFN           = "recovered-errors"
-	NoPermissionsFN             = "no-permissions"
-	RunModeFN                   = "run-mode"
-	SkippedItemsFN              = "skipped-items"
-	SkipReduceFN                = "skip-reduce"
+	AlertsFN                = "alerts"
+	DeltaPageSizeFN         = "delta-page-size"
+	DisableDeltaFN          = "disable-delta"
+	DisableIncrementalsFN   = "disable-incrementals"
+	ForceItemDataDownloadFN = "force-item-data-download"
+	EnableImmutableIDFN     = "enable-immutable-id"
+	FailFastFN              = "fail-fast"
+	FailedItemsFN           = "failed-items"
+	FetchParallelismFN      = "fetch-parallelism"
+	NoStatsFN               = "no-stats"
+	RecoveredErrorsFN       = "recovered-errors"
+	NoPermissionsFN         = "no-permissions"
+	RunModeFN               = "run-mode"
+	SkippedItemsFN          = "skipped-items"
+	SkipReduceFN            = "skip-reduce"
 )
 
 var (
-	DeltaPageSizeFV             int
-	DisableConcurrencyLimiterFV bool
-	DisableDeltaFV              bool
-	DisableIncrementalsFV       bool
-	ForceItemDataDownloadFV     bool
-	EnableImmutableIDFV         bool
-	FailFastFV                  bool
-	FetchParallelismFV          int
-	ListAlertsFV                string
-	ListFailedItemsFV           string
-	ListSkippedItemsFV          string
-	ListRecoveredErrorsFV       string
-	NoStatsFV                   bool
+	DeltaPageSizeFV         int
+	DisableDeltaFV          bool
+	DisableIncrementalsFV   bool
+	ForceItemDataDownloadFV bool
+	EnableImmutableIDFV     bool
+	FailFastFV              bool
+	FetchParallelismFV      int
+	ListAlertsFV            string
+	ListFailedItemsFV       string
+	ListSkippedItemsFV      string
+	ListRecoveredErrorsFV   string
+	NoStatsFV               bool
 	// RunMode describes the type of run, such as:
 	// flagtest, dry, run.  Should default to 'run'.
 	RunModeFV       string
@@ -151,19 +149,6 @@ func AddEnableImmutableIDFlag(cmd *cobra.Command) {
 	cobra.CheckErr(fs.MarkHidden(EnableImmutableIDFN))
 }
 
-// AddDisableConcurrencyLimiterFlag adds a hidden cli flag which, when set,
-// removes concurrency limits when communicating with graph API. This
-// flag is only relevant for exchange backups for now
-func AddDisableConcurrencyLimiterFlag(cmd *cobra.Command) {
-	fs := cmd.Flags()
-	fs.BoolVar(
-		&DisableConcurrencyLimiterFV,
-		DisableConcurrencyLimiterFN,
-		false,
-		"Disable concurrency limiter middleware. Default: false")
-	cobra.CheckErr(fs.MarkHidden(DisableConcurrencyLimiterFN))
-}
-
 // AddRunModeFlag adds the hidden --run-mode flag.
 func AddRunModeFlag(cmd *cobra.Command, persistent bool) {
 	fs := cmd.Flags()

src/cli/flags/testdata/flags.go

@@ -79,12 +79,11 @@ var (
 
 	FetchParallelism = "3"
 
-	FailFast                  = true
-	DisableIncrementals       = true
-	ForceItemDataDownload     = true
-	DisableDelta              = true
-	EnableImmutableID         = true
-	DisableConcurrencyLimiter = true
+	FailFast              = true
+	DisableIncrementals   = true
+	ForceItemDataDownload = true
+	DisableDelta          = true
+	EnableImmutableID     = true
 )
 
 func WithFlags2(

src/cli/utils/options.go

@@ -26,7 +26,6 @@ func Control() control.Options {
 	opt.ToggleFeatures.ForceItemDataDownload = flags.ForceItemDataDownloadFV
 	opt.ToggleFeatures.DisableDelta = flags.DisableDeltaFV
 	opt.ToggleFeatures.ExchangeImmutableIDs = flags.EnableImmutableIDFV
-	opt.ToggleFeatures.DisableConcurrencyLimiter = flags.DisableConcurrencyLimiterFV
 	opt.Parallelism.ItemFetch = flags.FetchParallelismFV
 
 	return opt

src/cli/utils/options_test.go

@@ -35,7 +35,6 @@ func (suite *OptionsUnitSuite) TestAddExchangeCommands() {
 			assert.True(t, flags.NoPermissionsFV, flags.NoPermissionsFN)
 			assert.True(t, flags.SkipReduceFV, flags.SkipReduceFN)
 			assert.Equal(t, 2, flags.FetchParallelismFV, flags.FetchParallelismFN)
-			assert.True(t, flags.DisableConcurrencyLimiterFV, flags.DisableConcurrencyLimiterFN)
 			assert.Equal(t, 499, flags.DeltaPageSizeFV, flags.DeltaPageSizeFN)
 		},
 	}
@@ -50,7 +49,6 @@ func (suite *OptionsUnitSuite) TestAddExchangeCommands() {
 	flags.AddNoPermissionsFlag(cmd)
 	flags.AddSkipReduceFlag(cmd)
 	flags.AddFetchParallelismFlag(cmd)
-	flags.AddDisableConcurrencyLimiterFlag(cmd)
 	flags.AddDeltaPageSizeFlag(cmd)
 
 	// Test arg parsing for few args
@@ -64,7 +62,6 @@ func (suite *OptionsUnitSuite) TestAddExchangeCommands() {
 		"--" + flags.NoPermissionsFN,
 		"--" + flags.SkipReduceFN,
 		"--" + flags.FetchParallelismFN, "2",
-		"--" + flags.DisableConcurrencyLimiterFN,
 		"--" + flags.DeltaPageSizeFN, "499",
 	})
 

src/internal/m365/service/exchange/backup.go

@@ -50,11 +50,9 @@ func ProduceBackupCollections(
 		bpc.Options.ToggleFeatures.DisableDelta = true
 	}
 
-	// Turn on concurrency limiter middleware for exchange backups
-	// unless explicitly disabled through DisableConcurrencyLimiterFN cli flag
 	graph.InitializeConcurrencyLimiter(
 		ctx,
-		bpc.Options.ToggleFeatures.DisableConcurrencyLimiter,
+		true,
 		bpc.Options.Parallelism.ItemFetch)
 
 	cdps, canUsePreviousBackup, err := exchange.ParseMetadataCollections(ctx, bpc.MetadataCollections)

src/pkg/control/options.go

@@ -83,10 +83,6 @@ type Toggles struct {
 
 	RunMigrations bool `json:"runMigrations"`
 
-	// DisableConcurrencyLimiter removes concurrency limits when communicating with
-	// graph API. This flag is only relevant for exchange backups for now
-	DisableConcurrencyLimiter bool `json:"disableConcurrencyLimiter,omitempty"`
-
 	// PreviewBackup denotes that this backup contains a subset of information for
 	// the protected resource. PreviewBackups are used to demonstrate value by
 	// being quick to create.