refactor(pusher): push ordered batches, return per-batch outcomes (#222)

## Summary
Change Pusher.Push to take ordered []entity.Batch instead of
controller-pre-resolved []entity.Change, per the extension contract. The
git pusher and the fake gain an injected changeset.Resolver and resolve
each batch's changes themselves; the merge controller drops its private
collectChanges walk and passes the single batch (the list designs for a
future merge-train).

This is the one extension whose output shape also changes: Result now
groups outcomes per batch — Result{Batches []BatchOutcome}, where
BatchOutcome{BatchID, Outcomes []ChangeOutcome} — so each landed batch
stays correlatable, the way conflict.Conflict carries its BatchID.
ChangeOutcome (per-change commit detail) is unchanged. No per-batch
status: push atomicity stays all-or-nothing across the whole call.

## Test Plan


## Issues


## Stack
1. #221
1. @ #222
1. #223
1. #227

Author: behinddwalls

example/submitqueue/orchestrator/server/main.go

@@ -775,16 +775,17 @@ func newChangeProvider(logger *zap.Logger, scope tally.Scope) (changeprovider.Ch
 // "origin", PUSHER_TARGET default "main"). When PUSHER_CHECKOUT_PATH is unset it
 // returns the fake pusher (commits succeed unless a change URI carries a failure
 // marker, see pusher/fake), keeping the example runnable without a git checkout.
-func newPusher(logger *zap.Logger, scope tally.Scope) (pusher.Pusher, error) {
+func newPusher(logger *zap.Logger, scope tally.Scope, resolver changeset.Resolver) (pusher.Pusher, error) {
 	checkout := os.Getenv("PUSHER_CHECKOUT_PATH")
 	if checkout == "" {
 		logger.Warn("PUSHER_CHECKOUT_PATH not set; using fake pusher (commits succeed unless URI-marked)")
-		return pushfake.New(), nil
+		return pushfake.New(resolver), nil
 	}
 	return gitpusher.NewPusher(gitpusher.Params{
 		CheckoutPath: checkout,
 		Remote:       getEnv("PUSHER_REMOTE", "origin"),
 		Target:       getEnv("PUSHER_TARGET", "main"),
+		Resolver:     resolver,
 		Logger:       logger.Sugar(),
 		MetricsScope: scope.SubScope("pusher"),
 	}), nil
@@ -806,7 +807,7 @@ func newQueueRegistry(logger *zap.Logger, scope tally.Scope, resolver changeset.
 	if err != nil {
 		return queueRegistry{}, fmt.Errorf("failed to create change provider: %w", err)
 	}
-	psh, err := newPusher(logger, scope)
+	psh, err := newPusher(logger, scope, resolver)
 	if err != nil {
 		return queueRegistry{}, fmt.Errorf("failed to create pusher: %w", err)
 	}

submitqueue/extension/pusher/fake/BUILD.bazel

@@ -6,6 +6,7 @@ go_library(
     importpath = "github.com/uber/submitqueue/submitqueue/extension/pusher/fake",
     visibility = ["//visibility:public"],
     deps = [
+        "//submitqueue/core/changeset",
         "//submitqueue/core/fakemarker",
         "//submitqueue/entity",
         "//submitqueue/extension/pusher",
@@ -17,6 +18,7 @@ go_test(
     srcs = ["fake_test.go"],
     embed = [":fake"],
     deps = [
+        "//submitqueue/core/changeset/fake",
         "//submitqueue/entity",
         "//submitqueue/extension/pusher",
         "@com_github_stretchr_testify//assert",

submitqueue/extension/pusher/fake/fake.go

@@ -32,6 +32,7 @@ import (
 	"fmt"
 	"sync/atomic"
 
+	"github.com/uber/submitqueue/submitqueue/core/changeset"
 	"github.com/uber/submitqueue/submitqueue/core/fakemarker"
 	"github.com/uber/submitqueue/submitqueue/entity"
 	"github.com/uber/submitqueue/submitqueue/extension/pusher"
@@ -45,35 +46,54 @@ const (
 
 // fakePusher is a pusher.Pusher that reports every change as committed unless a
 // marker token in a change URI requests a failure. The atomic counter hands out
-// unique synthetic commit SHAs and makes the type safe for concurrent use.
+// unique synthetic commit SHAs and makes the type safe for concurrent use. It
+// resolves each batch's changes through the injected resolver.
 type fakePusher struct {
-	counter atomic.Uint64
+	resolver changeset.Resolver
+	counter  atomic.Uint64
 }
 
 // New returns a pusher.Pusher that defaults to committing every change and
-// honors marker tokens embedded in change URIs.
-func New() pusher.Pusher {
-	return &fakePusher{}
+// honors marker tokens embedded in change URIs. The resolver resolves each
+// batch's changes.
+func New(resolver changeset.Resolver) pusher.Pusher {
+	return &fakePusher{resolver: resolver}
 }
 
-// Push reports every change as committed with a synthetic commit SHA, unless a
-// recognized marker token in one of the changes requests a failure.
-func (p *fakePusher) Push(_ context.Context, changes []entity.Change) (pusher.Result, error) {
-	switch fakemarker.TokenInChanges(changes) {
+// Push resolves each batch's changes and reports every change as committed with
+// a synthetic commit SHA, grouped per batch, unless a recognized marker token in
+// one of the changes requests a failure.
+func (p *fakePusher) Push(ctx context.Context, batches []entity.Batch) (pusher.Result, error) {
+	perBatch := make([][]entity.Change, len(batches))
+	var all []entity.Change
+	for i, b := range batches {
+		cs, err := p.resolver.ChangesForBatch(ctx, b)
+		if err != nil {
+			return pusher.Result{}, fmt.Errorf("fake: resolve batch %s: %w", b.ID, err)
+		}
+		perBatch[i] = cs
+		all = append(all, cs...)
+	}
+
+	switch fakemarker.TokenInChanges(all) {
 	case tokenConflict:
 		return pusher.Result{}, pusher.ErrConflict
 	case tokenError:
 		return pusher.Result{}, fmt.Errorf("fake: marked push error")
 	}
 
-	outcomes := make([]pusher.ChangeOutcome, 0, len(changes))
-	for _, change := range changes {
-		sha := fmt.Sprintf("fake-%d", p.counter.Add(1))
-		outcomes = append(outcomes, pusher.ChangeOutcome{
-			Change:     change,
-			Status:     pusher.OutcomeStatusCommitted,
-			CommitSHAs: []string{sha},
-		})
+	result := make([]pusher.BatchOutcome, len(batches))
+	for i, b := range batches {
+		outcomes := make([]pusher.ChangeOutcome, 0, len(perBatch[i]))
+		for _, change := range perBatch[i] {
+			sha := fmt.Sprintf("fake-%d", p.counter.Add(1))
+			outcomes = append(outcomes, pusher.ChangeOutcome{
+				Change:     change,
+				Status:     pusher.OutcomeStatusCommitted,
+				CommitSHAs: []string{sha},
+			})
+		}
+		result[i] = pusher.BatchOutcome{BatchID: b.ID, Outcomes: outcomes}
 	}
-	return pusher.Result{Outcomes: outcomes}, nil
+	return pusher.Result{Batches: result}, nil
 }

submitqueue/extension/pusher/fake/fake_test.go

@@ -21,27 +21,29 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	changesetfake "github.com/uber/submitqueue/submitqueue/core/changeset/fake"
 	"github.com/uber/submitqueue/submitqueue/entity"
 	"github.com/uber/submitqueue/submitqueue/extension/pusher"
 )
 
 func TestNew_ImplementsInterface(t *testing.T) {
-	var _ pusher.Pusher = New()
+	var _ pusher.Pusher = New(changesetfake.New())
 }
 
 func TestPusher_Push_Committed(t *testing.T) {
-	p := New()
 	changes := []entity.Change{
 		{URIs: []string{"github://owner/repo/pull/1/abc"}},
 		{URIs: []string{"github://owner/repo/pull/2/def"}},
 	}
+	p := New(changesetfake.New().Set("b", changes...))
 
-	res, err := p.Push(context.Background(), changes)
+	res, err := p.Push(context.Background(), []entity.Batch{{ID: "b"}})
 	require.NoError(t, err)
-	require.Len(t, res.Outcomes, len(changes))
+	require.Len(t, res.Batches, 1)
+	require.Len(t, res.Batches[0].Outcomes, len(changes))
 
 	seen := map[string]bool{}
-	for i, out := range res.Outcomes {
+	for i, out := range res.Batches[0].Outcomes {
 		assert.Equal(t, changes[i], out.Change)
 		assert.Equal(t, pusher.OutcomeStatusCommitted, out.Status)
 		require.Len(t, out.CommitSHAs, 1)
@@ -51,19 +53,15 @@ func TestPusher_Push_Committed(t *testing.T) {
 }
 
 func TestPusher_Push_ConflictMarker(t *testing.T) {
-	p := New()
-	_, err := p.Push(context.Background(), []entity.Change{
-		{URIs: []string{"github://owner/repo/pull/1/abc?sq-fake=conflict"}},
-	})
+	p := New(changesetfake.New().Set("b", entity.Change{URIs: []string{"github://owner/repo/pull/1/abc?sq-fake=conflict"}}))
+	_, err := p.Push(context.Background(), []entity.Batch{{ID: "b"}})
 	assert.True(t, errors.Is(err, pusher.ErrConflict))
 }
 
 func TestPusher_Push_ErrorMarker(t *testing.T) {
-	p := New()
-	res, err := p.Push(context.Background(), []entity.Change{
-		{URIs: []string{"github://owner/repo/pull/1/abc?sq-fake=push-error"}},
-	})
+	p := New(changesetfake.New().Set("b", entity.Change{URIs: []string{"github://owner/repo/pull/1/abc?sq-fake=push-error"}}))
+	res, err := p.Push(context.Background(), []entity.Batch{{ID: "b"}})
 	require.Error(t, err)
 	// Atomicity: on error no outcomes are reported.
-	assert.Empty(t, res.Outcomes)
+	assert.Empty(t, res.Batches)
 }

submitqueue/extension/pusher/git/BUILD.bazel

@@ -7,6 +7,7 @@ go_library(
     visibility = ["//visibility:public"],
     deps = [
         "//core/metrics",
+        "//submitqueue/core/changeset",
         "//submitqueue/entity",
         "//submitqueue/entity/github",
         "//submitqueue/extension/pusher",
@@ -20,6 +21,7 @@ go_test(
     srcs = ["git_pusher_test.go"],
     embed = [":git"],
     deps = [
+        "//submitqueue/core/changeset/fake",
         "//submitqueue/entity",
         "//submitqueue/extension/pusher",
         "@com_github_stretchr_testify//assert",

submitqueue/extension/pusher/git/git_pusher.go

@@ -62,6 +62,7 @@ import (
 	"go.uber.org/zap"
 
 	coremetrics "github.com/uber/submitqueue/core/metrics"
+	"github.com/uber/submitqueue/submitqueue/core/changeset"
 	"github.com/uber/submitqueue/submitqueue/entity"
 	entitygithub "github.com/uber/submitqueue/submitqueue/entity/github"
 	"github.com/uber/submitqueue/submitqueue/extension/pusher"
@@ -82,6 +83,8 @@ type Params struct {
 	Remote string
 	// Target is the destination branch ref on the remote (e.g. "main").
 	Target string
+	// Resolver resolves each batch's changes.
+	Resolver changeset.Resolver
 	// Logger is the structured logger.
 	Logger *zap.SugaredLogger
 	// MetricsScope is the metrics scope for instrumentation.
@@ -98,6 +101,7 @@ type gitPusher struct {
 	checkoutPath    string
 	remote          string
 	target          string
+	resolver        changeset.Resolver
 	logger          *zap.SugaredLogger
 	metricsScope    tally.Scope
 	maxPushAttempts int
@@ -121,17 +125,31 @@ func NewPusher(params Params) pusher.Pusher {
 		checkoutPath:    params.CheckoutPath,
 		remote:          params.Remote,
 		target:          params.Target,
+		resolver:        params.Resolver,
 		logger:          params.Logger.Named("git_pusher"),
 		metricsScope:    params.MetricsScope.SubScope("git_pusher"),
 		maxPushAttempts: maxAttempts,
 	}
 }
 
 // Push fulfils the pusher.Pusher contract.
-func (p *gitPusher) Push(ctx context.Context, changes []entity.Change) (ret pusher.Result, retErr error) {
+func (p *gitPusher) Push(ctx context.Context, batches []entity.Batch) (ret pusher.Result, retErr error) {
 	op := coremetrics.Begin(p.metricsScope, "push")
 	defer func() { op.Complete(retErr) }()
 
+	// Resolve each batch's changes, keeping per-batch counts so the flat
+	// outcomes can be regrouped per batch on success.
+	perBatch := make([][]entity.Change, len(batches))
+	var changes []entity.Change
+	for i, b := range batches {
+		cs, err := p.resolver.ChangesForBatch(ctx, b)
+		if err != nil {
+			return pusher.Result{}, fmt.Errorf("resolve batch %s: %w", b.ID, err)
+		}
+		perBatch[i] = cs
+		changes = append(changes, cs...)
+	}
+
 	p.mu.Lock()
 	defer p.mu.Unlock()
 
@@ -154,7 +172,7 @@ func (p *gitPusher) Push(ctx context.Context, changes []entity.Change) (ret push
 				"target", p.target,
 				"outcomes", outcomes,
 			)
-			return pusher.Result{Outcomes: outcomes}, nil
+			return pusher.Result{Batches: groupByBatch(batches, perBatch, outcomes)}, nil
 		}
 
 		// Was the failure caused by the remote tip moving under us between
@@ -190,6 +208,19 @@ func (p *gitPusher) Push(ctx context.Context, changes []entity.Change) (ret push
 	return pusher.Result{}, fmt.Errorf("exceeded %d push attempts due to remote contention: %w", p.maxPushAttempts, lastErr)
 }
 
+// groupByBatch splits the flat, apply-ordered outcomes back into one
+// BatchOutcome per input batch, using each batch's resolved change count.
+func groupByBatch(batches []entity.Batch, perBatch [][]entity.Change, outcomes []pusher.ChangeOutcome) []pusher.BatchOutcome {
+	result := make([]pusher.BatchOutcome, len(batches))
+	pos := 0
+	for i, b := range batches {
+		n := len(perBatch[i])
+		result[i] = pusher.BatchOutcome{BatchID: b.ID, Outcomes: outcomes[pos : pos+n]}
+		pos += n
+	}
+	return result
+}
+
 // tryPush runs one full reset+cherry-pick+push cycle. The returned baseSHA
 // is the SHA the cycle was based on (set as soon as resetToRemote completes)
 // so the caller can distinguish concurrent-push contention from other push