[hpack] Use NoDestruct type to simplify HPackTable (#30496)

* [hpack] Use NoDestruct type to simplify HPackTable

* experiment

BUILD

@@ -6567,6 +6567,7 @@ grpc_cc_library(
         "iomgr_fwd",
         "iomgr_timer",
         "memory_quota",
+        "no_destruct",
         "poll",
         "ref_counted",
         "ref_counted_ptr",

src/core/ext/transport/chttp2/transport/hpack_parser_table.cc

@@ -78,10 +78,6 @@ void HPackTable::MementoRingBuffer::Rebuild(uint32_t max_entries) {
   entries_.swap(entries);
 }
 
-HPackTable::HPackTable() : static_metadata_(GetStaticMementos()) {}
-
-HPackTable::~HPackTable() = default;
-
 /* Evict one element from the table */
 void HPackTable::EvictOne() {
   auto first_entry = entries_.PopOne();
@@ -229,7 +225,7 @@ const StaticTableEntry kStaticTable[hpack_constants::kLastStaticEntry] = {
     {"www-authenticate", ""},
 };
 
-GPR_ATTRIBUTE_NOINLINE HPackTable::Memento MakeMemento(size_t i) {
+HPackTable::Memento MakeMemento(size_t i) {
   auto sm = kStaticTable[i];
   return grpc_metadata_batch::Parse(
       sm.key, Slice::FromStaticString(sm.value),
@@ -241,11 +237,6 @@ GPR_ATTRIBUTE_NOINLINE HPackTable::Memento MakeMemento(size_t i) {
 
 }  // namespace
 
-auto HPackTable::GetStaticMementos() -> const StaticMementos& {
-  static const StaticMementos* const static_mementos = new StaticMementos();
-  return *static_mementos;
-}
-
 HPackTable::StaticMementos::StaticMementos() {
   for (uint32_t i = 0; i < hpack_constants::kLastStaticEntry; i++) {
     memento[i] = MakeMemento(i);

src/core/ext/transport/chttp2/transport/hpack_parser_table.h

@@ -26,6 +26,7 @@
 #include <vector>
 
 #include "src/core/ext/transport/chttp2/transport/hpack_constants.h"
+#include "src/core/lib/gprpp/no_destruct.h"
 #include "src/core/lib/iomgr/error.h"
 #include "src/core/lib/transport/metadata_batch.h"
 #include "src/core/lib/transport/parsed_metadata.h"
@@ -35,8 +36,8 @@ namespace grpc_core {
 // HPACK header table
 class HPackTable {
  public:
-  HPackTable();
-  ~HPackTable();
+  HPackTable() = default;
+  ~HPackTable() = default;
 
   HPackTable(const HPackTable&) = delete;
   HPackTable& operator=(const HPackTable&) = delete;
@@ -55,7 +56,7 @@ class HPackTable {
     // reading the core static metadata table here; at that point we'd need our
     // own singleton static metadata in the correct order.
     if (index <= hpack_constants::kLastStaticEntry) {
-      return &static_metadata_.memento[index - 1];
+      return &NoDestructSingleton<StaticMementos>::Get()->memento[index - 1];
     } else {
       return LookupDynamic(index);
     }
@@ -72,7 +73,6 @@ class HPackTable {
     StaticMementos();
     Memento memento[hpack_constants::kLastStaticEntry];
   };
-  static const StaticMementos& GetStaticMementos() GPR_ATTRIBUTE_NOINLINE;
 
   class MementoRingBuffer {
    public:
@@ -123,8 +123,6 @@ class HPackTable {
   uint32_t current_table_bytes_ = hpack_constants::kInitialTableSize;
   // HPack table entries
   MementoRingBuffer entries_;
-  // Mementos for static data
-  const StaticMementos& static_metadata_;
 };
 
 }  // namespace grpc_core