feat: Allow futureOps to queue more Ops (#10469)

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## Description

I modified where we handle queued operations to get all of the future operations from each queued operation that is executed.  We then add any new futureOps to the queued ops list.  This enables simulations to run chains of Operations rather than only being able to go one layer deep.  This is helpful in the case of building simulations around smart contracts that require multiple operations occurring in order.

Closes: #10468

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---

### Author Checklist

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- [x] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [x] added `!` to the type prefix if API or client breaking change
- [x] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [x] provided a link to the relevant issue or specification
- [x] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [x] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [x] added a changelog entry to `CHANGELOG.md`
- [x] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [x] updated the relevant documentation or specification
- [x] reviewed "Files changed" and left comments if necessary
- [x] confirmed all CI checks have passed

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- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

CHANGELOG.md

@@ -130,6 +130,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [\#9699](https://github.com/cosmos/cosmos-sdk/pull/9699) Add `:`, `.`, `-`, and `_` as allowed characters in the default denom regular expression.
 * (genesis) [\#9697](https://github.com/cosmos/cosmos-sdk/pull/9697) Ensure `InitGenesis` returns with non-empty validator set.
 * [\#10341](https://github.com/cosmos/cosmos-sdk/pull/10341) Move from `io/ioutil` to `io` and `os` packages.
+* [\#10468](https://github.com/cosmos/cosmos-sdk/pull/10468) Allow futureOps to queue additional operations in simulations
 
 ### Bug Fixes
 

x/simulation/simulate.go

@@ -168,17 +168,20 @@ func SimulateFromSeed(
 		ctx := app.NewContext(false, header)
 
 		// Run queued operations. Ignores blocksize if blocksize is too small
-		numQueuedOpsRan := runQueuedOperations(
+		numQueuedOpsRan, futureOps := runQueuedOperations(
 			operationQueue, int(header.Height), tb, r, app, ctx, accs, logWriter,
 			eventStats.Tally, config.Lean, config.ChainID,
 		)
 
-		numQueuedTimeOpsRan := runQueuedTimeOperations(
+		numQueuedTimeOpsRan, timeFutureOps := runQueuedTimeOperations(
 			timeOperationQueue, int(header.Height), header.Time,
 			tb, r, app, ctx, accs, logWriter, eventStats.Tally,
 			config.Lean, config.ChainID,
 		)
 
+		futureOps = append(futureOps, timeFutureOps...)
+		queueOperations(operationQueue, timeOperationQueue, futureOps)
+
 		// run standard operations
 		operations := blockSimulator(r, app, ctx, accs, header)
 		opCount += operations + numQueuedOpsRan + numQueuedTimeOpsRan
@@ -321,20 +324,23 @@ Comment: %s`,
 func runQueuedOperations(queueOps map[int][]simulation.Operation,
 	height int, tb testing.TB, r *rand.Rand, app *baseapp.BaseApp,
 	ctx sdk.Context, accounts []simulation.Account, logWriter LogWriter,
-	event func(route, op, evResult string), lean bool, chainID string) (numOpsRan int) {
+	event func(route, op, evResult string), lean bool, chainID string) (numOpsRan int, allFutureOps []simulation.FutureOperation) {
 
 	queuedOp, ok := queueOps[height]
 	if !ok {
-		return 0
+		return 0, nil
 	}
 
+	// Keep all future operations
+	allFutureOps = make([]simulation.FutureOperation, 0)
+
 	numOpsRan = len(queuedOp)
 	for i := 0; i < numOpsRan; i++ {
+		opMsg, futureOps, err := queuedOp[i](r, app, ctx, accounts, chainID)
+		if futureOps != nil && len(futureOps) > 0 {
+			allFutureOps = append(allFutureOps, futureOps...)
+		}
 
-		// For now, queued operations cannot queue more operations.
-		// If a need arises for us to support queued messages to queue more messages, this can
-		// be changed.
-		opMsg, _, err := queuedOp[i](r, app, ctx, accounts, chainID)
 		opMsg.LogEvent(event)
 
 		if !lean || opMsg.OK {
@@ -348,22 +354,22 @@ func runQueuedOperations(queueOps map[int][]simulation.Operation,
 	}
 	delete(queueOps, height)
 
-	return numOpsRan
+	return numOpsRan, allFutureOps
 }
 
 func runQueuedTimeOperations(queueOps []simulation.FutureOperation,
 	height int, currentTime time.Time, tb testing.TB, r *rand.Rand,
 	app *baseapp.BaseApp, ctx sdk.Context, accounts []simulation.Account,
 	logWriter LogWriter, event func(route, op, evResult string),
-	lean bool, chainID string) (numOpsRan int) {
+	lean bool, chainID string) (numOpsRan int, allFutureOps []simulation.FutureOperation) {
+
+	// Keep all future operations
+	allFutureOps = make([]simulation.FutureOperation, 0)
 
 	numOpsRan = 0
 	for len(queueOps) > 0 && currentTime.After(queueOps[0].BlockTime) {
+		opMsg, futureOps, err := queueOps[0].Op(r, app, ctx, accounts, chainID)
 
-		// For now, queued operations cannot queue more operations.
-		// If a need arises for us to support queued messages to queue more messages, this can
-		// be changed.
-		opMsg, _, err := queueOps[0].Op(r, app, ctx, accounts, chainID)
 		opMsg.LogEvent(event)
 
 		if !lean || opMsg.OK {
@@ -375,9 +381,13 @@ func runQueuedTimeOperations(queueOps []simulation.FutureOperation,
 			tb.FailNow()
 		}
 
+		if futureOps != nil && len(futureOps) > 0 {
+			allFutureOps = append(allFutureOps, futureOps...)
+		}
+
 		queueOps = queueOps[1:]
 		numOpsRan++
 	}
 
-	return numOpsRan
+	return numOpsRan, allFutureOps
 }