deprecating envoy.reloadable_features.deprecate_global_int

changelogs/current.yaml

@@ -21,6 +21,9 @@ removed_config_or_runtime:
   - area: listener
     change: |
       removed ``envoy.reloadable_features.strict_check_on_ipv4_compat`` and legacy code paths.
+  - area: http
+    change: |
+      removed ``envoy.reloadable_features.deprecate_global_ints`` and legacy code paths.
   - area: http
     change: |
       removed ``envoy.reloadable_features.allow_adding_content_type_in_local_replies`` and legacy code paths.

source/common/http/header_map_impl.cc

@@ -22,6 +22,7 @@ namespace {
 
 constexpr absl::string_view DelimiterForInlineHeaders{","};
 constexpr absl::string_view DelimiterForInlineCookies{"; "};
+const static int kMinHeadersForLazyMap = 3; // Optimal hard-coded value based on benchmarks.
 
 bool validatedLowerCaseString(absl::string_view str) {
   auto lower_case_str = LowerCaseString(str);
@@ -58,7 +59,7 @@ template <> bool HeaderMapImpl::HeaderList::isPseudoHeader(const LowerCaseString
 
 bool HeaderMapImpl::HeaderList::maybeMakeMap() {
   if (lazy_map_.empty()) {
-    if (headers_.size() < lazy_map_min_size_) {
+    if (headers_.size() < kMinHeadersForLazyMap) {
       return false;
     }
     // Add all entries from the list into the map.

source/common/http/header_map_impl.h

@@ -181,10 +181,9 @@ class HeaderMapImpl : NonCopyable {
   /**
    * List of HeaderEntryImpl that keeps the pseudo headers (key starting with ':') in the front
    * of the list (as required by nghttp2) and otherwise maintains insertion order.
-   * When the list size is greater or equal to the envoy.http.headermap.lazy_map_min_size runtime
-   * feature value (defaults to 3, if not set), all headers are added to a map, to allow
-   * fast access given a header key. Once the map is initialized, it will be used even if the number
-   * of headers decreases below the threshold.
+   * When the list size is greater or equal to 3, all headers are added to a map, to allow fast
+   * access given a header key. Once the map is initialized, it will be used even
+   * if the number of headers decreases below the threshold.
    *
    * Note: the internal iterators held in fields make this unsafe to copy and move, since the
    * reference to end() is not preserved across a move (see Notes in
@@ -198,10 +197,7 @@ class HeaderMapImpl : NonCopyable {
     using HeaderNodeVector = absl::InlinedVector<HeaderNode, 1>;
     using HeaderLazyMap = absl::flat_hash_map<absl::string_view, HeaderNodeVector>;
 
-    HeaderList()
-        : pseudo_headers_end_(headers_.end()),
-          lazy_map_min_size_(static_cast<uint32_t>(
-              Runtime::getInteger("envoy.http.headermap.lazy_map_min_size", 3))) {}
+    HeaderList() : pseudo_headers_end_(headers_.end()) {}
 
     template <class Key> bool isPseudoHeader(const Key& key) {
       return !key.getStringView().empty() && key.getStringView()[0] == ':';
@@ -278,8 +274,7 @@ class HeaderMapImpl : NonCopyable {
     }
 
     /*
-     * Creates and populates a map if the number of headers is at least the
-     * envoy.http.headermap.lazy_map_min_size runtime feature value.
+     * Creates and populates a map if the number of headers is at least 3.
      *
      * @return if a map was created.
      */
@@ -311,8 +306,6 @@ class HeaderMapImpl : NonCopyable {
   private:
     std::list<HeaderEntryImpl> headers_;
     HeaderNode pseudo_headers_end_;
-    // The number of headers threshold for lazy map usage.
-    const uint32_t lazy_map_min_size_;
     HeaderLazyMap lazy_map_;
   };
 

source/common/runtime/runtime_features.cc

@@ -41,7 +41,6 @@ RUNTIME_GUARD(envoy_reloadable_features_conn_pool_delete_when_idle);
 RUNTIME_GUARD(envoy_reloadable_features_conn_pool_new_stream_with_early_data_and_http3);
 RUNTIME_GUARD(envoy_reloadable_features_correct_remote_address);
 RUNTIME_GUARD(envoy_reloadable_features_delta_xds_subscription_state_tracking_fix);
-RUNTIME_GUARD(envoy_reloadable_features_deprecate_global_ints);
 RUNTIME_GUARD(envoy_reloadable_features_do_not_await_headers_on_upstream_timeout_to_emit_stats);
 RUNTIME_GUARD(envoy_reloadable_features_do_not_count_mapped_pages_as_free);
 RUNTIME_GUARD(envoy_reloadable_features_enable_compression_bomb_protection);
@@ -213,16 +212,8 @@ void maybeSetDeprecatedInts(absl::string_view name, uint32_t value) {
     return;
   }
 
-  // DO NOT ADD MORE FLAGS HERE. This function deprecated and being removed.
-  if (name == "envoy.http.headermap.lazy_map_min_size") {
-    if (Runtime::runtimeFeatureEnabled("envoy.reloadable_features.deprecate_global_ints")) {
-      IS_ENVOY_BUG(absl::StrCat(
-          "The Envoy community is attempting to remove global integers. Given you use ", name,
-          " please immediately file an upstream issue to retain the functionality as it will "
-          "otherwise be removed following the usual deprecation cycle."));
-    }
-    absl::SetFlag(&FLAGS_envoy_headermap_lazy_map_min_size, value);
-  } else if (name == "re2.max_program_size.error_level") {
+  // DO NOT ADD MORE FLAGS HERE. This function deprecated.
+  else if (name == "re2.max_program_size.error_level") {
     absl::SetFlag(&FLAGS_re2_max_program_size_error_level, value);
   } else if (name == "re2.max_program_size.warn_level") {
     absl::SetFlag(&FLAGS_re2_max_program_size_warn_level, value);

source/docs/header_map.md

@@ -3,8 +3,7 @@
 The Envoy header map implementation (`HeaderMapImpl`) has the following properties:
 * Headers are stored in a linked list (`HeaderList`) in the order they are added, with pseudo
   headers kept at the front of the list.
-* Once the number of headers is at least the runtime configured feature `envoy.http.headermap.lazy_map_min_size`,
-  the header map will also use a map (`HeaderLazyMap`), in addition to the linked list, for faster access to the headers.
+* Once there at at least 3 years, the header map will also use a map (`HeaderLazyMap`), in addition to the linked list, for faster access to the headers.
 * O(1) direct access is possible for common headers needed during data plane processing. This is
   provided by a table of pointers that reach directly into a linked list that is populated when
   headers are added or removed from the map. When O(1) headers are accessed by direct method

test/common/common/regex_test.cc

@@ -82,8 +82,7 @@ TEST(Utility, ParseRegex) {
   // The deprecated field codepath precedes any runtime settings.
   {
     TestScopedRuntime scoped_runtime;
-    scoped_runtime.mergeValues({{"envoy.reloadable_features.deprecate_global_ints", "false"},
-                                {"re2.max_program_size.error_level", "3"}});
+    scoped_runtime.mergeValues({{"re2.max_program_size.error_level", "3"}});
     envoy::type::matcher::v3::RegexMatcher matcher;
     matcher.set_regex("/asdf/.*");
     matcher.mutable_google_re2()->mutable_max_program_size()->set_value(1);
@@ -99,8 +98,7 @@ TEST(Utility, ParseRegex) {
   // Verify that an exception is thrown for the error level max program size.
   {
     TestScopedRuntime scoped_runtime;
-    scoped_runtime.mergeValues({{"envoy.reloadable_features.deprecate_global_ints", "false"},
-                                {"re2.max_program_size.error_level", "1"}});
+    scoped_runtime.mergeValues({{"re2.max_program_size.error_level", "1"}});
     envoy::type::matcher::v3::RegexMatcher matcher;
     matcher.set_regex("/asdf/.*");
     matcher.mutable_google_re2();
@@ -118,7 +116,6 @@ TEST(Utility, ParseRegex) {
   // Verify that the error level max program size defaults to 100 if not set by runtime.
   {
     TestScopedRuntime scoped_runtime;
-    scoped_runtime.mergeValues({{"envoy.reloadable_features.deprecate_global_ints", "false"}});
     envoy::type::matcher::v3::RegexMatcher matcher;
     matcher.set_regex(
         "/asdf/.*/asdf/.*/asdf/.*/asdf/.*/asdf/.*/asdf/.*/asdf/.*/asdf/.*/asdf/.*/asdf/.*");
@@ -137,8 +134,7 @@ TEST(Utility, ParseRegex) {
   // Verify that a warning is logged for the warn level max program size.
   {
     TestScopedRuntime scoped_runtime;
-    scoped_runtime.mergeValues({{"envoy.reloadable_features.deprecate_global_ints", "false"},
-                                {"re2.max_program_size.warn_level", "1"}});
+    scoped_runtime.mergeValues({{"re2.max_program_size.warn_level", "1"}});
     envoy::type::matcher::v3::RegexMatcher matcher;
     matcher.set_regex("/asdf/.*");
     matcher.mutable_google_re2();

test/common/http/header_map_impl_fuzz_test.cc

@@ -18,12 +18,6 @@ namespace Envoy {
 // Fuzz the header map implementation.
 DEFINE_PROTO_FUZZER(const test::common::http::HeaderMapImplFuzzTestCase& input) {
   TestScopedRuntime scoped_runtime;
-  // Set the lazy header-map threshold if found.
-  if (input.has_config()) {
-    scoped_runtime.mergeValues({{"envoy.reloadable_features.deprecate_global_ints", "false"},
-                                {"envoy.http.headermap.lazy_map_min_size",
-                                 absl::StrCat(input.config().lazy_map_min_size())}});
-  }
 
   auto header_map = Http::RequestHeaderMapImpl::create();
   std::vector<std::unique_ptr<Http::LowerCaseString>> lower_case_strings;