From d5cdf3736971a94722592ce497f752d16f313d4f Mon Sep 17 00:00:00 2001
From: ashmrtn <3891298+ashmrtn@users.noreply.github.com>
Date: Thu, 28 Sep 2023 18:50:15 -0700
Subject: [PATCH] Lock updating info in lazyItem (#4401)

Don't allow concurrent reads/writes to info in
lazyItem so we can make stronger assumptions
about state

---

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

- [ ] :white_check_mark: Yes, it's included
- [ ] :clock1: Yes, but in a later PR
- [x] :no_entry: No

#### Type of change

- [ ] :sunflower: Feature
- [ ] :bug: Bugfix
- [ ] :world_map: Documentation
- [ ] :robot: Supportability/Tests
- [ ] :computer: CI/Deployment
- [x] :broom: Tech Debt/Cleanup

#### Test Plan

- [ ] :muscle: Manual
- [x] :zap: Unit test
- [x] :green_heart: E2E
---
 src/internal/data/item.go | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/internal/data/item.go b/src/internal/data/item.go
index 2403e63aa..862699a5d 100644
--- a/src/internal/data/item.go
+++ b/src/internal/data/item.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"io"
+	"sync"
 	"time"
 
 	"github.com/alcionai/clues"
@@ -110,6 +111,7 @@ func NewLazyItem(
 // made.
 type lazyItem struct {
 	ctx        context.Context
+	mu         sync.Mutex
 	id         string
 	errs       *fault.Bus
 	itemGetter ItemDataGetter
@@ -127,12 +129,18 @@ type lazyItem struct {
 	delInFlight bool
 }
 
-func (i lazyItem) ID() string {
+func (i *lazyItem) ID() string {
 	return i.id
 }
 
 func (i *lazyItem) ToReader() io.ReadCloser {
 	return lazy.NewLazyReadCloser(func() (io.ReadCloser, error) {
+		// Don't allow getting Item info while trying to initialize said info.
+		// GetData could be a long running call, but in theory nothing should happen
+		// with the item until a reader is returned anyway.
+		i.mu.Lock()
+		defer i.mu.Unlock()
+
 		reader, info, delInFlight, err := i.itemGetter.GetData(i.ctx, i.errs)
 		if err != nil {
 			return nil, clues.Stack(err)
@@ -159,11 +167,14 @@ func (i *lazyItem) ToReader() io.ReadCloser {
 	})
 }
 
-func (i lazyItem) Deleted() bool {
+func (i *lazyItem) Deleted() bool {
 	return false
 }
 
-func (i lazyItem) Info() (details.ItemInfo, error) {
+func (i *lazyItem) Info() (details.ItemInfo, error) {
+	i.mu.Lock()
+	defer i.mu.Unlock()
+
 	if i.delInFlight {
 		return details.ItemInfo{}, clues.Stack(ErrNotFound).WithClues(i.ctx)
 	} else if i.info == nil {
@@ -174,6 +185,6 @@ func (i lazyItem) Info() (details.ItemInfo, error) {
 	return *i.info, nil
 }
 
-func (i lazyItem) ModTime() time.Time {
+func (i *lazyItem) ModTime() time.Time {
 	return i.modTime
 }