PR feedback, no magic number.

daemon/algod/api/algod.oas2.json

@@ -2511,9 +2511,9 @@
           },
           {
             "name": "initialize",
-            "description": "When set to `true`, catchup will only be used to initialize the node. This means it will only run a fast catchup that advances the round by at least 1 million rounds.",
+            "description": "Specify a number of blocks which the ledger must be advanced by in order to start the catchup. This is useful for simplifying tools which support fast catchup, they can run the catchup unconditionally and the node will skip the catchup if it is not needed.",
             "in": "query",
-            "type": "boolean"
+            "type": "integer"
           }
         ],
         "responses": {

daemon/algod/api/algod.oas3.yml

@@ -4304,11 +4304,11 @@
             "x-algorand-format": "Catchpoint String"
           },
           {
-            "description": "When set to `true`, catchup will only be used to initialize the node. This means it will only run a fast catchup that advances the round by at least 1 million rounds.",
+            "description": "Specify a number of blocks which the ledger must be advanced by in order to start the catchup. This is useful for simplifying tools which support fast catchup, they can run the catchup unconditionally and the node will skip the catchup if it is not needed.",
             "in": "query",
             "name": "initialize",
             "schema": {
-              "type": "boolean"
+              "type": "integer"
             }
           }
         ],

daemon/algod/api/server/v2/handlers.go

@@ -66,10 +66,6 @@ const MaxTealSourceBytes = 200_000
 // become quite large, so we allow up to 1MB
 const MaxTealDryrunBytes = 1_000_000
 
-// MinRoundsToInitialize is the minimum number of rounds that a catchup must
-// advance the node in order for it to be considered an initializing event.
-const MinRoundsToInitialize = 1_000_000
-
 // WaitForBlockTimeout is the timeout for the WaitForBlock endpoint.
 var WaitForBlockTimeout = 1 * time.Minute
 
@@ -1397,16 +1393,16 @@ func (v2 *Handlers) getPendingTransactions(ctx echo.Context, max *uint64, format
 }
 
 // startCatchup Given a catchpoint, it starts catching up to this catchpoint
-func (v2 *Handlers) startCatchup(ctx echo.Context, catchpoint string, initializeOnly bool) error {
+func (v2 *Handlers) startCatchup(ctx echo.Context, catchpoint string, initializeRounds uint64) error {
 	catchpointRound, _, err := ledgercore.ParseCatchpointLabel(catchpoint)
 	if err != nil {
 		return badRequest(ctx, err, errFailedToParseCatchpoint, v2.Log)
 	}
 
-	if initializeOnly {
+	if initializeRounds > 0 {
 		ledgerRound := v2.Node.LedgerForAPI().Latest()
-		if catchpointRound < (ledgerRound + MinRoundsToInitialize) {
-			v2.Log.Infof("Skipping catchup. Catchpoint round %d is not %d rounds ahead of the current round %d so it is not considered an initializing event.", catchpointRound, MinRoundsToInitialize, ledgerRound)
+		if catchpointRound < (ledgerRound + basics.Round(initializeRounds)) {
+			v2.Log.Infof("Skipping catchup. Catchpoint round %d is not %d rounds ahead of the current round %d so it is not considered an initializing event.", catchpointRound, initializeRounds, ledgerRound)
 			return ctx.JSON(http.StatusOK, model.CatchpointStartResponse{
 				CatchupMessage: errCatchpointWouldNotInitialize,
 			})

daemon/algod/api/server/v2/test/handlers_test.go

@@ -1308,10 +1308,10 @@ func TestSimulateTransactionMultipleGroups(t *testing.T) {
 }
 
 func startCatchupTest(t *testing.T, catchpoint string, nodeError error, expectedCode int) {
-	startCatchupTestFull(t, catchpoint, nodeError, expectedCode, false, "")
+	startCatchupTestFull(t, catchpoint, nodeError, expectedCode, 0, "")
 }
 
-func startCatchupTestFull(t *testing.T, catchpoint string, nodeError error, expectedCode int, initOnly bool, response string) {
+func startCatchupTestFull(t *testing.T, catchpoint string, nodeError error, expectedCode int, initRounds uint64, response string) {
 	numAccounts := 1
 	numTransactions := 1
 	offlineAccounts := true
@@ -1325,8 +1325,8 @@ func startCatchupTestFull(t *testing.T, catchpoint string, nodeError error, expe
 	rec := httptest.NewRecorder()
 	c := e.NewContext(req, rec)
 	var err error
-	if initOnly {
-		err = handler.StartCatchup(c, catchpoint, model.StartCatchupParams{Initialize: &initOnly})
+	if initRounds != 0 {
+		err = handler.StartCatchup(c, catchpoint, model.StartCatchupParams{Initialize: &initRounds})
 	} else {
 		err = handler.StartCatchup(c, catchpoint, model.StartCatchupParams{})
 	}
@@ -1341,11 +1341,13 @@ func TestStartCatchupInit(t *testing.T) {
 	partitiontest.PartitionTest(t)
 	t.Parallel()
 
-	tooSmallCatchpoint := fmt.Sprintf("%d#DVFRZUYHEFKRLK5N6DNJRR4IABEVN2D6H76F3ZSEPIE6MKXMQWQA", v2.MinRoundsToInitialize-1)
-	startCatchupTestFull(t, tooSmallCatchpoint, nil, 200, true, "the node has already been initialized")
+	minRoundsToInitialize := uint64(1_000_000)
 
-	catchpointOK := fmt.Sprintf("%d#DVFRZUYHEFKRLK5N6DNJRR4IABEVN2D6H76F3ZSEPIE6MKXMQWQA", v2.MinRoundsToInitialize)
-	startCatchupTestFull(t, catchpointOK, nil, 201, true, catchpointOK)
+	tooSmallCatchpoint := fmt.Sprintf("%d#DVFRZUYHEFKRLK5N6DNJRR4IABEVN2D6H76F3ZSEPIE6MKXMQWQA", minRoundsToInitialize-1)
+	startCatchupTestFull(t, tooSmallCatchpoint, nil, 200, minRoundsToInitialize, "the node has already been initialized")
+
+	catchpointOK := fmt.Sprintf("%d#DVFRZUYHEFKRLK5N6DNJRR4IABEVN2D6H76F3ZSEPIE6MKXMQWQA", minRoundsToInitialize)
+	startCatchupTestFull(t, catchpointOK, nil, 201, minRoundsToInitialize, catchpointOK)
 }
 
 func TestStartCatchup(t *testing.T) {