Harden chunk plan cache storage and reuse

internal/framework/chunkplan/store_test.go

@@ -3,6 +3,8 @@ package chunkplan
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
+	"fmt"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -125,6 +127,7 @@ func TestFilesystemStoreReportsInvalidRecordsAsRecoverable(t *testing.T) {
 		{name: "unknown field", mutate: func(data []byte) []byte {
 			return bytes.Replace(data, []byte(`{"schema_version"`), []byte(`{"unknown":true,"schema_version"`), 1)
 		}, want: "unknown"},
+		{name: "truncated JSON", mutate: func(data []byte) []byte { return data[:len(data)/2] }, want: "decode"},
 		{name: "schema mismatch", mutate: replaceJSON(`notarius.chunk-plan.v1`, `notarius.chunk-plan.v2`), want: "schema_version"},
 		{name: "source mismatch", mutate: replaceJSON(testSourceDigest, "sha256:"+strings.Repeat("b", 64)), want: "source_digest"},
 		{name: "plan digest mismatch", mutate: func(data []byte) []byte {
@@ -138,6 +141,9 @@ func TestFilesystemStoreReportsInvalidRecordsAsRecoverable(t *testing.T) {
 		{name: "noncanonical annotation", mutate: func(data []byte) []byte {
 			return bytes.Replace(data, []byte(`{"value":1}`), []byte(`{ "value": 1 }`), 1)
 		}, want: "canonical JSON"},
+		{name: "bad boundary", mutate: func(data []byte) []byte {
+			return bytes.Replace(data, []byte(`"start_unit_id":1`), []byte(`"start_unit_id":0`), 1)
+		}, want: "boundaries must be positive"},
 		{name: "trailing JSON", mutate: func(data []byte) []byte { return append(data, []byte(` {}`)...) }, want: "trailing"},
 	}
 	for _, tc := range tests {
@@ -226,6 +232,77 @@ func TestFilesystemStoreConcurrentWritersExposeCompleteRecord(t *testing.T) {
 	}
 }
 
+func TestFilesystemStoreReadersObserveOnlyCompleteRecordsDuringWrites(t *testing.T) {
+	store := newStore(t, t.TempDir())
+	if err := store.Save(testRecord(t, 1)); err != nil {
+		t.Fatal(err)
+	}
+	const writers = 12
+	const readers = 12
+	errs := make(chan error, writers+readers)
+	start := make(chan struct{})
+	var writersDone sync.WaitGroup
+	for i := 0; i < writers; i++ {
+		writersDone.Add(1)
+		go func(value int) {
+			defer writersDone.Done()
+			<-start
+			errs <- store.Save(testRecord(t, value+2))
+		}(i)
+	}
+	for i := 0; i < readers; i++ {
+		go func() {
+			<-start
+			for attempt := 0; attempt < 50; attempt++ {
+				record, decision, err := store.Load(testSourceDigest)
+				if err != nil || decision.Status != pipeline.ChunkPlanHit {
+					errs <- fmt.Errorf("Load() decision=%#v error=%v", decision, err)
+					return
+				}
+				if err := validateRecord(record, testSourceDigest); err != nil {
+					errs <- fmt.Errorf("reader observed invalid record: %w", err)
+					return
+				}
+			}
+			errs <- nil
+		}()
+	}
+	close(start)
+	writersDone.Wait()
+	for i := 0; i < readers+writers; i++ {
+		if err := <-errs; err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+func TestFilesystemStoreInterruptedWritesPreservePreviousRecord(t *testing.T) {
+	store := newStore(t, t.TempDir()).(*filesystemStore)
+	first := testRecord(t, 1)
+	if err := store.Save(first); err != nil {
+		t.Fatal(err)
+	}
+	for _, tc := range []struct {
+		name  string
+		hooks atomicWriteHooks
+	}{
+		{name: "before temporary file", hooks: atomicWriteHooks{BeforeCreateTemp: func() error { return errors.New("interrupted before temporary file") }}},
+		{name: "before rename", hooks: atomicWriteHooks{BeforeRename: func() error { return errors.New("interrupted before rename") }}},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			store.write = func(target string, data []byte) error { return writeAtomicWithHooks(target, data, tc.hooks) }
+			if err := store.Save(testRecord(t, 2)); err == nil {
+				t.Fatal("Save() error = nil")
+			}
+			store.write = writeAtomic
+			got, decision, err := store.Load(testSourceDigest)
+			if err != nil || decision.Status != pipeline.ChunkPlanHit || !reflect.DeepEqual(got, first) {
+				t.Fatalf("record after interruption=%#v decision=%#v error=%v", got, decision, err)
+			}
+		})
+	}
+}
+
 func newStore(t *testing.T, root string) pipeline.ChunkPlanStore {
 	t.Helper()
 	store, err := NewFilesystemStore(root)