From 8e104b4b157035ebe2673bf4ec029c5ef3a68e75 Mon Sep 17 00:00:00 2001
From: Thomas Jungblut <tjungblu@redhat.com>
Date: Tue, 9 Jul 2024 19:04:43 +0200
Subject: [PATCH] ensure hashmap init clears maps

This reorders some statements in the hashmap initialization to ensure we
always start fresh, even when no pageids were passed to it.

fixes #791

Signed-off-by: Thomas Jungblut <tjungblu@redhat.com>
---
 internal/freelist/freelist_test.go | 24 ++++++++++++++++++++++++
 internal/freelist/hashmap.go       | 16 ++++++++--------
 2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/internal/freelist/freelist_test.go b/internal/freelist/freelist_test.go
index df7c7697e..2fb2e0b32 100644
--- a/internal/freelist/freelist_test.go
+++ b/internal/freelist/freelist_test.go
@@ -179,6 +179,30 @@ func TestFreelist_releaseRange(t *testing.T) {
 	}
 }
 
+func TestFreeList_reload_page_dedupe(t *testing.T) {
+	buf := make([]byte, 4096)
+	f := newTestFreelist()
+	f.Init([]common.Pgid{5, 6, 8})
+
+	p := common.LoadPage(buf)
+	f.Write(p)
+
+	f2 := newTestFreelist()
+	f.Init([]common.Pgid{})
+
+	f2.Free(common.Txid(5), common.NewPage(5, common.LeafPageFlag, 0, 4))
+
+	// reload should deduplicate as a pending page when reading from p's freelist
+	f2.Reload(p)
+
+	if len(f2.freePageIds()) != 0 {
+		t.Fatalf("expected empty; got=%v", f2.freePageIds())
+	}
+	if exp := []common.Pgid{5, 6, 7, 8, 9}; !reflect.DeepEqual(exp, f2.pendingPageIds()[5].ids) {
+		t.Fatalf("exp=%v; got=%v", exp, f2.pendingPageIds()[5].ids)
+	}
+}
+
 // Ensure that a freelist can deserialize from a freelist page.
 func TestFreelist_read(t *testing.T) {
 	// Create a page.
diff --git a/internal/freelist/hashmap.go b/internal/freelist/hashmap.go
index a6bad8976..1dca8e971 100644
--- a/internal/freelist/hashmap.go
+++ b/internal/freelist/hashmap.go
@@ -21,22 +21,22 @@ type hashMap struct {
 }
 
 func (f *hashMap) Init(pgids common.Pgids) {
+	// reset the counter when freelist init
+	f.freePagesCount = 0
+	f.freemaps = make(map[uint64]pidSet)
+	f.forwardMap = make(map[common.Pgid]uint64)
+	f.backwardMap = make(map[common.Pgid]uint64)
+
 	if len(pgids) == 0 {
 		return
 	}
 
-	size := uint64(1)
-	start := pgids[0]
-	// reset the counter when freelist init
-	f.freePagesCount = 0
-
 	if !sort.SliceIsSorted([]common.Pgid(pgids), func(i, j int) bool { return pgids[i] < pgids[j] }) {
 		panic("pgids not sorted")
 	}
 
-	f.freemaps = make(map[uint64]pidSet)
-	f.forwardMap = make(map[common.Pgid]uint64)
-	f.backwardMap = make(map[common.Pgid]uint64)
+	size := uint64(1)
+	start := pgids[0]
 
 	for i := 1; i < len(pgids); i++ {
 		// continuous page