[chttp2] Remove a bunch of mostly-rolled-out experiments (#35426)

- `memory_pressure_controller` finally - allows deletion of pid_controller throughout the codebase
- `overload_protection` - one of the http2 rapid reset mitigations
- `red_max_concurrent_streams` - another http2 rapid reset mitigation

Closes #35426

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/35426 from ctiller:new-years-cleanse 4651672e7e
PiperOrigin-RevId: 595205029

CMakeLists.txt

@@ -1194,7 +1194,6 @@ if(gRPC_BUILD_TESTS)
   add_dependencies(buildtests_cxx percent_encoding_test)
   add_dependencies(buildtests_cxx periodic_update_test)
   add_dependencies(buildtests_cxx pick_first_test)
-  add_dependencies(buildtests_cxx pid_controller_test)
   add_dependencies(buildtests_cxx ping_abuse_policy_test)
   add_dependencies(buildtests_cxx ping_callbacks_test)
   add_dependencies(buildtests_cxx ping_configuration_test)
@@ -2505,7 +2504,6 @@ add_library(grpc
   src/core/lib/transport/http_connect_handshaker.cc
   src/core/lib/transport/metadata_batch.cc
   src/core/lib/transport/parsed_metadata.cc
-  src/core/lib/transport/pid_controller.cc
   src/core/lib/transport/status_conversion.cc
   src/core/lib/transport/tcp_connect_handshaker.cc
   src/core/lib/transport/timeout_encoding.cc
@@ -3198,7 +3196,6 @@ add_library(grpc_unsecure
   src/core/lib/transport/http_connect_handshaker.cc
   src/core/lib/transport/metadata_batch.cc
   src/core/lib/transport/parsed_metadata.cc
-  src/core/lib/transport/pid_controller.cc
   src/core/lib/transport/status_conversion.cc
   src/core/lib/transport/tcp_connect_handshaker.cc
   src/core/lib/transport/timeout_encoding.cc
@@ -12230,7 +12227,6 @@ add_executable(flow_control_test
   src/core/lib/slice/slice_refcount.cc
   src/core/lib/slice/slice_string_helpers.cc
   src/core/lib/transport/bdp_estimator.cc
-  src/core/lib/transport/pid_controller.cc
   test/core/transport/chttp2/flow_control_test.cc
   third_party/upb/upb/hash/common.c
   third_party/upb/upb/message/accessors.c
@@ -17805,49 +17801,6 @@ target_link_libraries(pick_first_test
 )
 
 
-endif()
-if(gRPC_BUILD_TESTS)
-
-add_executable(pid_controller_test
-  test/core/transport/pid_controller_test.cc
-  test/core/util/cmdline.cc
-  test/core/util/fuzzer_util.cc
-  test/core/util/grpc_profiler.cc
-  test/core/util/histogram.cc
-  test/core/util/mock_endpoint.cc
-  test/core/util/parse_hexstring.cc
-  test/core/util/passthru_endpoint.cc
-  test/core/util/resolve_localhost_ip46.cc
-  test/core/util/slice_splitter.cc
-  test/core/util/tracer_util.cc
-)
-target_compile_features(pid_controller_test PUBLIC cxx_std_14)
-target_include_directories(pid_controller_test
-  PRIVATE
-    ${CMAKE_CURRENT_SOURCE_DIR}
-    ${CMAKE_CURRENT_SOURCE_DIR}/include
-    ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
-    ${_gRPC_RE2_INCLUDE_DIR}
-    ${_gRPC_SSL_INCLUDE_DIR}
-    ${_gRPC_UPB_GENERATED_DIR}
-    ${_gRPC_UPB_GRPC_GENERATED_DIR}
-    ${_gRPC_UPB_INCLUDE_DIR}
-    ${_gRPC_XXHASH_INCLUDE_DIR}
-    ${_gRPC_ZLIB_INCLUDE_DIR}
-    third_party/googletest/googletest/include
-    third_party/googletest/googletest
-    third_party/googletest/googlemock/include
-    third_party/googletest/googlemock
-    ${_gRPC_PROTO_GENS_DIR}
-)
-
-target_link_libraries(pid_controller_test
-  ${_gRPC_ALLTARGETS_LIBRARIES}
-  gtest
-  grpc_test_util
-)
-
-
 endif()
 if(gRPC_BUILD_TESTS)
 

Makefile

@@ -1705,7 +1705,6 @@ LIBGRPC_SRC = \
     src/core/lib/transport/http_connect_handshaker.cc \
     src/core/lib/transport/metadata_batch.cc \
     src/core/lib/transport/parsed_metadata.cc \
-    src/core/lib/transport/pid_controller.cc \
     src/core/lib/transport/status_conversion.cc \
     src/core/lib/transport/tcp_connect_handshaker.cc \
     src/core/lib/transport/timeout_encoding.cc \
@@ -2248,7 +2247,6 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/lib/transport/http_connect_handshaker.cc \
     src/core/lib/transport/metadata_batch.cc \
     src/core/lib/transport/parsed_metadata.cc \
-    src/core/lib/transport/pid_controller.cc \
     src/core/lib/transport/status_conversion.cc \
     src/core/lib/transport/tcp_connect_handshaker.cc \
     src/core/lib/transport/timeout_encoding.cc \

Package.swift

@@ -1898,8 +1898,6 @@ let package = Package(
         "src/core/lib/transport/metadata_compression_traits.h",
         "src/core/lib/transport/parsed_metadata.cc",
         "src/core/lib/transport/parsed_metadata.h",
-        "src/core/lib/transport/pid_controller.cc",
-        "src/core/lib/transport/pid_controller.h",
         "src/core/lib/transport/simple_slice_based_metadata.h",
         "src/core/lib/transport/status_conversion.cc",
         "src/core/lib/transport/status_conversion.h",

bazel/experiments.bzl

@@ -28,16 +28,13 @@ EXPERIMENT_ENABLES = {
     "http2_stats_fix": "http2_stats_fix",
     "keepalive_fix": "keepalive_fix",
     "keepalive_server_fix": "keepalive_server_fix",
-    "memory_pressure_controller": "memory_pressure_controller",
     "monitoring_experiment": "monitoring_experiment",
     "multiping": "multiping",
-    "overload_protection": "overload_protection",
     "peer_state_based_framing": "peer_state_based_framing",
     "pending_queue_cap": "pending_queue_cap",
     "pick_first_happy_eyeballs": "pick_first_happy_eyeballs",
     "promise_based_client_call": "promise_based_client_call",
     "promise_based_server_call": "promise_based_server_call",
-    "red_max_concurrent_streams": "red_max_concurrent_streams",
     "registered_method_lookup_in_transport": "registered_method_lookup_in_transport",
     "promise_based_inproc_transport": "promise_based_client_call,promise_based_inproc_transport,promise_based_server_call,registered_method_lookup_in_transport",
     "registered_methods_map": "registered_methods_map",
@@ -88,7 +85,6 @@ EXPERIMENTS = {
             "flow_control_test": [
                 "multiping",
                 "peer_state_based_framing",
-                "red_max_concurrent_streams",
                 "rstpit",
                 "tcp_frame_size_tuning",
                 "tcp_rcv_lowat",
@@ -104,7 +100,6 @@ EXPERIMENTS = {
             ],
             "resource_quota_test": [
                 "free_large_allocator",
-                "memory_pressure_controller",
                 "unconstrained_max_quota_buffer_size",
             ],
             "xds_end2end_test": [
@@ -125,7 +120,6 @@ EXPERIMENTS = {
                 "event_engine_listener",
             ],
             "flow_control_test": [
-                "overload_protection",
                 "write_size_cap",
                 "write_size_policy",
             ],
@@ -170,7 +164,6 @@ EXPERIMENTS = {
             "flow_control_test": [
                 "multiping",
                 "peer_state_based_framing",
-                "red_max_concurrent_streams",
                 "rstpit",
                 "tcp_frame_size_tuning",
                 "tcp_rcv_lowat",
@@ -186,7 +179,6 @@ EXPERIMENTS = {
             ],
             "resource_quota_test": [
                 "free_large_allocator",
-                "memory_pressure_controller",
                 "unconstrained_max_quota_buffer_size",
             ],
             "xds_end2end_test": [
@@ -201,7 +193,6 @@ EXPERIMENTS = {
                 "wrr_delegate_to_pick_first",
             ],
             "flow_control_test": [
-                "overload_protection",
                 "write_size_cap",
                 "write_size_policy",
             ],
@@ -253,7 +244,6 @@ EXPERIMENTS = {
             "flow_control_test": [
                 "multiping",
                 "peer_state_based_framing",
-                "red_max_concurrent_streams",
                 "rstpit",
                 "tcp_frame_size_tuning",
                 "tcp_rcv_lowat",
@@ -272,7 +262,6 @@ EXPERIMENTS = {
             ],
             "resource_quota_test": [
                 "free_large_allocator",
-                "memory_pressure_controller",
                 "unconstrained_max_quota_buffer_size",
             ],
             "xds_end2end_test": [
@@ -293,7 +282,6 @@ EXPERIMENTS = {
                 "event_engine_listener",
             ],
             "flow_control_test": [
-                "overload_protection",
                 "write_size_cap",
                 "write_size_policy",
             ],

build_autogenerated.yaml

@@ -1175,7 +1175,6 @@ libs:
   - src/core/lib/transport/metadata_batch.h
   - src/core/lib/transport/metadata_compression_traits.h
   - src/core/lib/transport/parsed_metadata.h
-  - src/core/lib/transport/pid_controller.h
   - src/core/lib/transport/simple_slice_based_metadata.h
   - src/core/lib/transport/status_conversion.h
   - src/core/lib/transport/tcp_connect_handshaker.h
@@ -1965,7 +1964,6 @@ libs:
   - src/core/lib/transport/http_connect_handshaker.cc
   - src/core/lib/transport/metadata_batch.cc
   - src/core/lib/transport/parsed_metadata.cc
-  - src/core/lib/transport/pid_controller.cc
   - src/core/lib/transport/status_conversion.cc
   - src/core/lib/transport/tcp_connect_handshaker.cc
   - src/core/lib/transport/timeout_encoding.cc
@@ -2606,7 +2604,6 @@ libs:
   - src/core/lib/transport/metadata_batch.h
   - src/core/lib/transport/metadata_compression_traits.h
   - src/core/lib/transport/parsed_metadata.h
-  - src/core/lib/transport/pid_controller.h
   - src/core/lib/transport/simple_slice_based_metadata.h
   - src/core/lib/transport/status_conversion.h
   - src/core/lib/transport/tcp_connect_handshaker.h
@@ -3016,7 +3013,6 @@ libs:
   - src/core/lib/transport/http_connect_handshaker.cc
   - src/core/lib/transport/metadata_batch.cc
   - src/core/lib/transport/parsed_metadata.cc
-  - src/core/lib/transport/pid_controller.cc
   - src/core/lib/transport/status_conversion.cc
   - src/core/lib/transport/tcp_connect_handshaker.cc
   - src/core/lib/transport/timeout_encoding.cc
@@ -9283,7 +9279,6 @@ targets:
   - src/core/lib/slice/slice_string_helpers.h
   - src/core/lib/transport/bdp_estimator.h
   - src/core/lib/transport/http2_errors.h
-  - src/core/lib/transport/pid_controller.h
   - third_party/upb/upb/base/internal/log2.h
   - third_party/upb/upb/generated_code_support.h
   - third_party/upb/upb/hash/common.h
@@ -9365,7 +9360,6 @@ targets:
   - src/core/lib/slice/slice_refcount.cc
   - src/core/lib/slice/slice_string_helpers.cc
   - src/core/lib/transport/bdp_estimator.cc
-  - src/core/lib/transport/pid_controller.cc
   - test/core/transport/chttp2/flow_control_test.cc
   - third_party/upb/upb/hash/common.c
   - third_party/upb/upb/message/accessors.c
@@ -12712,38 +12706,6 @@ targets:
   - protobuf
   - grpc_test_util
   uses_polling: false
-- name: pid_controller_test
-  gtest: true
-  build: test
-  language: c++
-  headers:
-  - test/core/util/cmdline.h
-  - test/core/util/evaluate_args_test_util.h
-  - test/core/util/fuzzer_util.h
-  - test/core/util/grpc_profiler.h
-  - test/core/util/histogram.h
-  - test/core/util/mock_authorization_endpoint.h
-  - test/core/util/mock_endpoint.h
-  - test/core/util/parse_hexstring.h
-  - test/core/util/passthru_endpoint.h
-  - test/core/util/resolve_localhost_ip46.h
-  - test/core/util/slice_splitter.h
-  - test/core/util/tracer_util.h
-  src:
-  - test/core/transport/pid_controller_test.cc
-  - test/core/util/cmdline.cc
-  - test/core/util/fuzzer_util.cc
-  - test/core/util/grpc_profiler.cc
-  - test/core/util/histogram.cc
-  - test/core/util/mock_endpoint.cc
-  - test/core/util/parse_hexstring.cc
-  - test/core/util/passthru_endpoint.cc
-  - test/core/util/resolve_localhost_ip46.cc
-  - test/core/util/slice_splitter.cc
-  - test/core/util/tracer_util.cc
-  deps:
-  - gtest
-  - grpc_test_util
 - name: ping_abuse_policy_test
   gtest: true
   build: test

config.m4

@@ -837,7 +837,6 @@ if test "$PHP_GRPC" != "no"; then
     src/core/lib/transport/http_connect_handshaker.cc \
     src/core/lib/transport/metadata_batch.cc \
     src/core/lib/transport/parsed_metadata.cc \
-    src/core/lib/transport/pid_controller.cc \
     src/core/lib/transport/status_conversion.cc \
     src/core/lib/transport/tcp_connect_handshaker.cc \
     src/core/lib/transport/timeout_encoding.cc \

config.w32

@@ -802,7 +802,6 @@ if (PHP_GRPC != "no") {
     "src\\core\\lib\\transport\\http_connect_handshaker.cc " +
     "src\\core\\lib\\transport\\metadata_batch.cc " +
     "src\\core\\lib\\transport\\parsed_metadata.cc " +
-    "src\\core\\lib\\transport\\pid_controller.cc " +
     "src\\core\\lib\\transport\\status_conversion.cc " +
     "src\\core\\lib\\transport\\tcp_connect_handshaker.cc " +
     "src\\core\\lib\\transport\\timeout_encoding.cc " +

gRPC-C++.podspec

@@ -1270,7 +1270,6 @@ Pod::Spec.new do |s|
                       'src/core/lib/transport/metadata_batch.h',
                       'src/core/lib/transport/metadata_compression_traits.h',
                       'src/core/lib/transport/parsed_metadata.h',
-                      'src/core/lib/transport/pid_controller.h',
                       'src/core/lib/transport/simple_slice_based_metadata.h',
                       'src/core/lib/transport/status_conversion.h',
                       'src/core/lib/transport/tcp_connect_handshaker.h',
@@ -2512,7 +2511,6 @@ Pod::Spec.new do |s|
                               'src/core/lib/transport/metadata_batch.h',
                               'src/core/lib/transport/metadata_compression_traits.h',
                               'src/core/lib/transport/parsed_metadata.h',
-                              'src/core/lib/transport/pid_controller.h',
                               'src/core/lib/transport/simple_slice_based_metadata.h',
                               'src/core/lib/transport/status_conversion.h',
                               'src/core/lib/transport/tcp_connect_handshaker.h',

gRPC-Core.podspec

@@ -1997,8 +1997,6 @@ Pod::Spec.new do |s|
                       'src/core/lib/transport/metadata_compression_traits.h',
                       'src/core/lib/transport/parsed_metadata.cc',
                       'src/core/lib/transport/parsed_metadata.h',
-                      'src/core/lib/transport/pid_controller.cc',
-                      'src/core/lib/transport/pid_controller.h',
                       'src/core/lib/transport/simple_slice_based_metadata.h',
                       'src/core/lib/transport/status_conversion.cc',
                       'src/core/lib/transport/status_conversion.h',
@@ -3279,7 +3277,6 @@ Pod::Spec.new do |s|
                               'src/core/lib/transport/metadata_batch.h',
                               'src/core/lib/transport/metadata_compression_traits.h',
                               'src/core/lib/transport/parsed_metadata.h',
-                              'src/core/lib/transport/pid_controller.h',
                               'src/core/lib/transport/simple_slice_based_metadata.h',
                               'src/core/lib/transport/status_conversion.h',
                               'src/core/lib/transport/tcp_connect_handshaker.h',

grpc.gemspec

@@ -1900,8 +1900,6 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/transport/metadata_compression_traits.h )
   s.files += %w( src/core/lib/transport/parsed_metadata.cc )
   s.files += %w( src/core/lib/transport/parsed_metadata.h )
-  s.files += %w( src/core/lib/transport/pid_controller.cc )
-  s.files += %w( src/core/lib/transport/pid_controller.h )
   s.files += %w( src/core/lib/transport/simple_slice_based_metadata.h )
   s.files += %w( src/core/lib/transport/status_conversion.cc )
   s.files += %w( src/core/lib/transport/status_conversion.h )

grpc.gyp

@@ -1024,7 +1024,6 @@
         'src/core/lib/transport/http_connect_handshaker.cc',
         'src/core/lib/transport/metadata_batch.cc',
         'src/core/lib/transport/parsed_metadata.cc',
-        'src/core/lib/transport/pid_controller.cc',
         'src/core/lib/transport/status_conversion.cc',
         'src/core/lib/transport/tcp_connect_handshaker.cc',
         'src/core/lib/transport/timeout_encoding.cc',
@@ -1508,7 +1507,6 @@
         'src/core/lib/transport/http_connect_handshaker.cc',
         'src/core/lib/transport/metadata_batch.cc',
         'src/core/lib/transport/parsed_metadata.cc',
-        'src/core/lib/transport/pid_controller.cc',
         'src/core/lib/transport/status_conversion.cc',
         'src/core/lib/transport/tcp_connect_handshaker.cc',
         'src/core/lib/transport/timeout_encoding.cc',

package.xml

@@ -1882,8 +1882,6 @@
     <file baseinstalldir="/" name="src/core/lib/transport/metadata_compression_traits.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/transport/parsed_metadata.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/transport/parsed_metadata.h" role="src" />
-    <file baseinstalldir="/" name="src/core/lib/transport/pid_controller.cc" role="src" />
-    <file baseinstalldir="/" name="src/core/lib/transport/pid_controller.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/transport/simple_slice_based_metadata.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/transport/status_conversion.cc" role="src" />
     <file baseinstalldir="/" name="src/core/lib/transport/status_conversion.h" role="src" />

src/core/BUILD

@@ -2609,20 +2609,6 @@ grpc_cc_library(
     ],
 )
 
-grpc_cc_library(
-    name = "pid_controller",
-    srcs = [
-        "lib/transport/pid_controller.cc",
-    ],
-    hdrs = [
-        "lib/transport/pid_controller.h",
-    ],
-    deps = [
-        "useful",
-        "//:gpr_platform",
-    ],
-)
-
 grpc_cc_library(
     name = "bdp_estimator",
     srcs = [
@@ -5907,7 +5893,6 @@ grpc_cc_library(
         "experiments",
         "http2_settings",
         "memory_quota",
-        "pid_controller",
         "time",
         "useful",
         "//:gpr",

src/core/ext/transport/chttp2/transport/chttp2_transport.cc

@@ -646,7 +646,7 @@ static void read_channel_args(grpc_chttp2_transport* t,
 
   t->max_concurrent_streams_overload_protection =
       channel_args.GetBool(GRPC_ARG_MAX_CONCURRENT_STREAMS_OVERLOAD_PROTECTION)
-          .value_or(grpc_core::IsOverloadProtectionEnabled());
+          .value_or(true);
 }
 
 static void init_keepalive_pings_if_enabled_locked(

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

@@ -104,16 +104,7 @@ TransportFlowControl::TransportFlowControl(absl::string_view name,
                                            MemoryOwner* memory_owner)
     : memory_owner_(memory_owner),
       enable_bdp_probe_(enable_bdp_probe),
-      bdp_estimator_(name),
+      bdp_estimator_(name) {}
-      pid_controller_(PidController::Args()
-                          .set_gain_p(4)
-                          .set_gain_i(8)
-                          .set_gain_d(0)
-                          .set_initial_control_value(TargetLogBdp())
-                          .set_min_control_value(-1)
-                          .set_max_control_value(25)
-                          .set_integral_range(10)),
-      last_pid_update_(Timestamp::Now()) {}
 
 uint32_t TransportFlowControl::DesiredAnnounceSize(bool writing_anyway) const {
   const uint32_t target_announced_window =
@@ -184,41 +175,6 @@ FlowControlAction TransportFlowControl::UpdateAction(FlowControlAction action) {
   return action;
 }
 
-// Take in a target and modifies it based on the memory pressure of the system
-static double AdjustForMemoryPressure(double memory_pressure, double target) {
-  // do not increase window under heavy memory pressure.
-  static const double kLowMemPressure = 0.1;
-  static const double kZeroTarget = 22;
-  static const double kHighMemPressure = 0.8;
-  static const double kMaxMemPressure = 0.9;
-  if (memory_pressure < kLowMemPressure && target < kZeroTarget) {
-    target = (target - kZeroTarget) * memory_pressure / kLowMemPressure +
-             kZeroTarget;
-  } else if (memory_pressure > kHighMemPressure) {
-    target *= 1 - std::min(1.0, (memory_pressure - kHighMemPressure) /
-                                    (kMaxMemPressure - kHighMemPressure));
-  }
-  return target;
-}
-
-double TransportFlowControl::TargetLogBdp() {
-  return AdjustForMemoryPressure(
-      memory_owner_->is_valid()
-          ? memory_owner_->GetPressureInfo().pressure_control_value
-          : 0.0,
-      1 + log2(bdp_estimator_.EstimateBdp()));
-}
-
-double TransportFlowControl::SmoothLogBdp(double value) {
-  Timestamp now = Timestamp::Now();
-  double bdp_error = value - pid_controller_.last_control_value();
-  const double dt = (now - last_pid_update_).seconds();
-  last_pid_update_ = now;
-  // Limit dt to 100ms
-  const double kMaxDt = 0.1;
-  return pid_controller_.Update(bdp_error, dt > kMaxDt ? kMaxDt : dt);
-}
-
 double
 TransportFlowControl::TargetInitialWindowSizeBasedOnMemoryPressureAndBdp()
     const {
@@ -323,10 +279,8 @@ FlowControlAction TransportFlowControl::PeriodicUpdate() {
     // TODO(ncteisen): experiment with setting target to be huge under low
     // memory pressure.
     uint32_t target = static_cast<uint32_t>(RoundUpToPowerOf2(
-        Clamp(IsMemoryPressureControllerEnabled()
+        Clamp(TargetInitialWindowSizeBasedOnMemoryPressureAndBdp(), 0.0,
-                  ? TargetInitialWindowSizeBasedOnMemoryPressureAndBdp()
+              static_cast<double>(kMaxInitialWindowSize))));
-                  : pow(2, SmoothLogBdp(TargetLogBdp())),
-              0.0, static_cast<double>(kMaxInitialWindowSize))));
     if (target < kMinPositiveInitialWindowSize) target = 0;
     if (g_test_only_transport_target_window_estimates_mocker != nullptr) {
       // Hook for simulating unusual flow control situations in tests.

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

@@ -40,7 +40,6 @@
 #include "src/core/lib/gprpp/time.h"
 #include "src/core/lib/resource_quota/memory_quota.h"
 #include "src/core/lib/transport/bdp_estimator.h"
-#include "src/core/lib/transport/pid_controller.h"
 
 extern grpc_core::TraceFlag grpc_flowctl_trace;
 
@@ -330,8 +329,6 @@ class TransportFlowControl final {
   }
 
  private:
-  double TargetLogBdp();
-  double SmoothLogBdp(double value);
   double TargetInitialWindowSizeBasedOnMemoryPressureAndBdp() const;
   static void UpdateSetting(grpc_chttp2_setting_id id, int64_t* desired_value,
                             uint32_t new_desired_value,
@@ -359,10 +356,6 @@ class TransportFlowControl final {
   // bdp estimation
   BdpEstimator bdp_estimator_;
 
-  // pid controller
-  PidController pid_controller_;
-  Timestamp last_pid_update_;
-
   int64_t remote_window_ = kDefaultWindow;
   int64_t target_initial_window_size_ = kDefaultWindow;
   int64_t target_frame_size_ = kDefaultFrameSize;

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

@@ -674,7 +674,6 @@ static grpc_error_handle init_header_frame_parser(grpc_chttp2_transport* t,
       grpc_chttp2_initiate_write(t, GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM);
       return init_header_skip_frame_parser(t, priority_type, is_eoh);
     } else if (GPR_UNLIKELY(
-                   grpc_core::IsRedMaxConcurrentStreamsEnabled() &&
                    t->stream_map.size() >=
                        t->max_concurrent_streams_policy.AdvertiseValue() &&
                    grpc_core::RandomEarlyDetection(

src/core/lib/experiments/experiments.cc

@@ -60,19 +60,12 @@ const char* const description_keepalive_server_fix =
     "Allows overriding keepalive_permit_without_calls for servers. Refer "
     "https://github.com/grpc/grpc/pull/33917 for more information.";
 const char* const additional_constraints_keepalive_server_fix = "{}";
-const char* const description_memory_pressure_controller =
-    "New memory pressure controller";
-const char* const additional_constraints_memory_pressure_controller = "{}";
 const char* const description_monitoring_experiment =
     "Placeholder experiment to prove/disprove our monitoring is working";
 const char* const additional_constraints_monitoring_experiment = "{}";
 const char* const description_multiping =
     "Allow more than one ping to be in flight at a time by default.";
 const char* const additional_constraints_multiping = "{}";
-const char* const description_overload_protection =
-    "If chttp2 has more streams than it can handle open, send RST_STREAM "
-    "immediately on new streams appearing.";
-const char* const additional_constraints_overload_protection = "{}";
 const char* const description_peer_state_based_framing =
     "If set, the max sizes of frames sent to lower layers is controlled based "
     "on the peer's memory pressure which is reflected in its max http2 frame "
@@ -97,10 +90,6 @@ const char* const description_promise_based_server_call =
     "If set, use the new gRPC promise based call code when it's appropriate "
     "(ie when all filters in a stack are promise based)";
 const char* const additional_constraints_promise_based_server_call = "{}";
-const char* const description_red_max_concurrent_streams =
-    "Perform random early rejection of requests that would exceed a newly "
-    "reduced MAX_CONCURRENT_STREAMS but are allowed by the current.";
-const char* const additional_constraints_red_max_concurrent_streams = "{}";
 const char* const description_registered_method_lookup_in_transport =
     "Change registered method's lookup point to transport";
 const char* const additional_constraints_registered_method_lookup_in_transport =
@@ -219,15 +208,10 @@ const ExperimentMetadata g_experiment_metadata[] = {
      additional_constraints_keepalive_fix, nullptr, 0, false, false},
     {"keepalive_server_fix", description_keepalive_server_fix,
      additional_constraints_keepalive_server_fix, nullptr, 0, false, false},
-    {"memory_pressure_controller", description_memory_pressure_controller,
-     additional_constraints_memory_pressure_controller, nullptr, 0, false,
-     true},
     {"monitoring_experiment", description_monitoring_experiment,
      additional_constraints_monitoring_experiment, nullptr, 0, true, true},
     {"multiping", description_multiping, additional_constraints_multiping,
      nullptr, 0, false, true},
-    {"overload_protection", description_overload_protection,
-     additional_constraints_overload_protection, nullptr, 0, true, true},
     {"peer_state_based_framing", description_peer_state_based_framing,
      additional_constraints_peer_state_based_framing, nullptr, 0, false, true},
     {"pending_queue_cap", description_pending_queue_cap,
@@ -238,9 +222,6 @@ const ExperimentMetadata g_experiment_metadata[] = {
      additional_constraints_promise_based_client_call, nullptr, 0, false, true},
     {"promise_based_server_call", description_promise_based_server_call,
      additional_constraints_promise_based_server_call, nullptr, 0, false, true},
-    {"red_max_concurrent_streams", description_red_max_concurrent_streams,
-     additional_constraints_red_max_concurrent_streams, nullptr, 0, false,
-     true},
     {"registered_method_lookup_in_transport",
      description_registered_method_lookup_in_transport,
      additional_constraints_registered_method_lookup_in_transport, nullptr, 0,
@@ -339,19 +320,12 @@ const char* const description_keepalive_server_fix =
     "Allows overriding keepalive_permit_without_calls for servers. Refer "
     "https://github.com/grpc/grpc/pull/33917 for more information.";
 const char* const additional_constraints_keepalive_server_fix = "{}";
-const char* const description_memory_pressure_controller =
-    "New memory pressure controller";
-const char* const additional_constraints_memory_pressure_controller = "{}";
 const char* const description_monitoring_experiment =
     "Placeholder experiment to prove/disprove our monitoring is working";
 const char* const additional_constraints_monitoring_experiment = "{}";
 const char* const description_multiping =
     "Allow more than one ping to be in flight at a time by default.";
 const char* const additional_constraints_multiping = "{}";
-const char* const description_overload_protection =
-    "If chttp2 has more streams than it can handle open, send RST_STREAM "
-    "immediately on new streams appearing.";
-const char* const additional_constraints_overload_protection = "{}";
 const char* const description_peer_state_based_framing =
     "If set, the max sizes of frames sent to lower layers is controlled based "
     "on the peer's memory pressure which is reflected in its max http2 frame "
@@ -376,10 +350,6 @@ const char* const description_promise_based_server_call =
     "If set, use the new gRPC promise based call code when it's appropriate "
     "(ie when all filters in a stack are promise based)";
 const char* const additional_constraints_promise_based_server_call = "{}";
-const char* const description_red_max_concurrent_streams =
-    "Perform random early rejection of requests that would exceed a newly "
-    "reduced MAX_CONCURRENT_STREAMS but are allowed by the current.";
-const char* const additional_constraints_red_max_concurrent_streams = "{}";
 const char* const description_registered_method_lookup_in_transport =
     "Change registered method's lookup point to transport";
 const char* const additional_constraints_registered_method_lookup_in_transport =
@@ -498,15 +468,10 @@ const ExperimentMetadata g_experiment_metadata[] = {
      additional_constraints_keepalive_fix, nullptr, 0, false, false},
     {"keepalive_server_fix", description_keepalive_server_fix,
      additional_constraints_keepalive_server_fix, nullptr, 0, false, false},
-    {"memory_pressure_controller", description_memory_pressure_controller,
-     additional_constraints_memory_pressure_controller, nullptr, 0, false,
-     true},
     {"monitoring_experiment", description_monitoring_experiment,
      additional_constraints_monitoring_experiment, nullptr, 0, true, true},
     {"multiping", description_multiping, additional_constraints_multiping,
      nullptr, 0, false, true},
-    {"overload_protection", description_overload_protection,
-     additional_constraints_overload_protection, nullptr, 0, true, true},
     {"peer_state_based_framing", description_peer_state_based_framing,
      additional_constraints_peer_state_based_framing, nullptr, 0, false, true},
     {"pending_queue_cap", description_pending_queue_cap,
@@ -517,9 +482,6 @@ const ExperimentMetadata g_experiment_metadata[] = {
      additional_constraints_promise_based_client_call, nullptr, 0, false, true},
     {"promise_based_server_call", description_promise_based_server_call,
      additional_constraints_promise_based_server_call, nullptr, 0, false, true},
-    {"red_max_concurrent_streams", description_red_max_concurrent_streams,
-     additional_constraints_red_max_concurrent_streams, nullptr, 0, false,
-     true},
     {"registered_method_lookup_in_transport",
      description_registered_method_lookup_in_transport,
      additional_constraints_registered_method_lookup_in_transport, nullptr, 0,
@@ -618,19 +580,12 @@ const char* const description_keepalive_server_fix =
     "Allows overriding keepalive_permit_without_calls for servers. Refer "
     "https://github.com/grpc/grpc/pull/33917 for more information.";
 const char* const additional_constraints_keepalive_server_fix = "{}";
-const char* const description_memory_pressure_controller =
-    "New memory pressure controller";
-const char* const additional_constraints_memory_pressure_controller = "{}";
 const char* const description_monitoring_experiment =
     "Placeholder experiment to prove/disprove our monitoring is working";
 const char* const additional_constraints_monitoring_experiment = "{}";
 const char* const description_multiping =
     "Allow more than one ping to be in flight at a time by default.";
 const char* const additional_constraints_multiping = "{}";
-const char* const description_overload_protection =
-    "If chttp2 has more streams than it can handle open, send RST_STREAM "
-    "immediately on new streams appearing.";
-const char* const additional_constraints_overload_protection = "{}";
 const char* const description_peer_state_based_framing =
     "If set, the max sizes of frames sent to lower layers is controlled based "
     "on the peer's memory pressure which is reflected in its max http2 frame "
@@ -655,10 +610,6 @@ const char* const description_promise_based_server_call =
     "If set, use the new gRPC promise based call code when it's appropriate "
     "(ie when all filters in a stack are promise based)";
 const char* const additional_constraints_promise_based_server_call = "{}";
-const char* const description_red_max_concurrent_streams =
-    "Perform random early rejection of requests that would exceed a newly "
-    "reduced MAX_CONCURRENT_STREAMS but are allowed by the current.";
-const char* const additional_constraints_red_max_concurrent_streams = "{}";
 const char* const description_registered_method_lookup_in_transport =
     "Change registered method's lookup point to transport";
 const char* const additional_constraints_registered_method_lookup_in_transport =
@@ -777,15 +728,10 @@ const ExperimentMetadata g_experiment_metadata[] = {
      additional_constraints_keepalive_fix, nullptr, 0, false, false},
     {"keepalive_server_fix", description_keepalive_server_fix,
      additional_constraints_keepalive_server_fix, nullptr, 0, false, false},
-    {"memory_pressure_controller", description_memory_pressure_controller,
-     additional_constraints_memory_pressure_controller, nullptr, 0, false,
-     true},
     {"monitoring_experiment", description_monitoring_experiment,
      additional_constraints_monitoring_experiment, nullptr, 0, true, true},
     {"multiping", description_multiping, additional_constraints_multiping,
      nullptr, 0, false, true},
-    {"overload_protection", description_overload_protection,
-     additional_constraints_overload_protection, nullptr, 0, true, true},
     {"peer_state_based_framing", description_peer_state_based_framing,
      additional_constraints_peer_state_based_framing, nullptr, 0, false, true},
     {"pending_queue_cap", description_pending_queue_cap,
@@ -796,9 +742,6 @@ const ExperimentMetadata g_experiment_metadata[] = {
      additional_constraints_promise_based_client_call, nullptr, 0, false, true},
     {"promise_based_server_call", description_promise_based_server_call,
      additional_constraints_promise_based_server_call, nullptr, 0, false, true},
-    {"red_max_concurrent_streams", description_red_max_concurrent_streams,
-     additional_constraints_red_max_concurrent_streams, nullptr, 0, false,
-     true},
     {"registered_method_lookup_in_transport",
      description_registered_method_lookup_in_transport,
      additional_constraints_registered_method_lookup_in_transport, nullptr, 0,

src/core/lib/experiments/experiments.h

@@ -79,12 +79,9 @@ inline bool IsFreeLargeAllocatorEnabled() { return false; }
 inline bool IsHttp2StatsFixEnabled() { return true; }
 inline bool IsKeepaliveFixEnabled() { return false; }
 inline bool IsKeepaliveServerFixEnabled() { return false; }
-inline bool IsMemoryPressureControllerEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_MONITORING_EXPERIMENT
 inline bool IsMonitoringExperimentEnabled() { return true; }
 inline bool IsMultipingEnabled() { return false; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_OVERLOAD_PROTECTION
-inline bool IsOverloadProtectionEnabled() { return true; }
 inline bool IsPeerStateBasedFramingEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_PENDING_QUEUE_CAP
 inline bool IsPendingQueueCapEnabled() { return true; }
@@ -92,7 +89,6 @@ inline bool IsPendingQueueCapEnabled() { return true; }
 inline bool IsPickFirstHappyEyeballsEnabled() { return true; }
 inline bool IsPromiseBasedClientCallEnabled() { return false; }
 inline bool IsPromiseBasedServerCallEnabled() { return false; }
-inline bool IsRedMaxConcurrentStreamsEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_REGISTERED_METHOD_LOOKUP_IN_TRANSPORT
 inline bool IsRegisteredMethodLookupInTransportEnabled() { return true; }
 inline bool IsPromiseBasedInprocTransportEnabled() { return false; }
@@ -145,12 +141,9 @@ inline bool IsFreeLargeAllocatorEnabled() { return false; }
 inline bool IsHttp2StatsFixEnabled() { return true; }
 inline bool IsKeepaliveFixEnabled() { return false; }
 inline bool IsKeepaliveServerFixEnabled() { return false; }
-inline bool IsMemoryPressureControllerEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_MONITORING_EXPERIMENT
 inline bool IsMonitoringExperimentEnabled() { return true; }
 inline bool IsMultipingEnabled() { return false; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_OVERLOAD_PROTECTION
-inline bool IsOverloadProtectionEnabled() { return true; }
 inline bool IsPeerStateBasedFramingEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_PENDING_QUEUE_CAP
 inline bool IsPendingQueueCapEnabled() { return true; }
@@ -158,7 +151,6 @@ inline bool IsPendingQueueCapEnabled() { return true; }
 inline bool IsPickFirstHappyEyeballsEnabled() { return true; }
 inline bool IsPromiseBasedClientCallEnabled() { return false; }
 inline bool IsPromiseBasedServerCallEnabled() { return false; }
-inline bool IsRedMaxConcurrentStreamsEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_REGISTERED_METHOD_LOOKUP_IN_TRANSPORT
 inline bool IsRegisteredMethodLookupInTransportEnabled() { return true; }
 inline bool IsPromiseBasedInprocTransportEnabled() { return false; }
@@ -211,12 +203,9 @@ inline bool IsFreeLargeAllocatorEnabled() { return false; }
 inline bool IsHttp2StatsFixEnabled() { return true; }
 inline bool IsKeepaliveFixEnabled() { return false; }
 inline bool IsKeepaliveServerFixEnabled() { return false; }
-inline bool IsMemoryPressureControllerEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_MONITORING_EXPERIMENT
 inline bool IsMonitoringExperimentEnabled() { return true; }
 inline bool IsMultipingEnabled() { return false; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_OVERLOAD_PROTECTION
-inline bool IsOverloadProtectionEnabled() { return true; }
 inline bool IsPeerStateBasedFramingEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_PENDING_QUEUE_CAP
 inline bool IsPendingQueueCapEnabled() { return true; }
@@ -224,7 +213,6 @@ inline bool IsPendingQueueCapEnabled() { return true; }
 inline bool IsPickFirstHappyEyeballsEnabled() { return true; }
 inline bool IsPromiseBasedClientCallEnabled() { return false; }
 inline bool IsPromiseBasedServerCallEnabled() { return false; }
-inline bool IsRedMaxConcurrentStreamsEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_REGISTERED_METHOD_LOOKUP_IN_TRANSPORT
 inline bool IsRegisteredMethodLookupInTransportEnabled() { return true; }
 inline bool IsPromiseBasedInprocTransportEnabled() { return false; }
@@ -267,16 +255,13 @@ enum ExperimentIds {
   kExperimentIdHttp2StatsFix,
   kExperimentIdKeepaliveFix,
   kExperimentIdKeepaliveServerFix,
-  kExperimentIdMemoryPressureController,
   kExperimentIdMonitoringExperiment,
   kExperimentIdMultiping,
-  kExperimentIdOverloadProtection,
   kExperimentIdPeerStateBasedFraming,
   kExperimentIdPendingQueueCap,
   kExperimentIdPickFirstHappyEyeballs,
   kExperimentIdPromiseBasedClientCall,
   kExperimentIdPromiseBasedServerCall,
-  kExperimentIdRedMaxConcurrentStreams,
   kExperimentIdRegisteredMethodLookupInTransport,
   kExperimentIdPromiseBasedInprocTransport,
   kExperimentIdRegisteredMethodsMap,
@@ -344,10 +329,6 @@ inline bool IsKeepaliveFixEnabled() {
 inline bool IsKeepaliveServerFixEnabled() {
   return IsExperimentEnabled(kExperimentIdKeepaliveServerFix);
 }
-#define GRPC_EXPERIMENT_IS_INCLUDED_MEMORY_PRESSURE_CONTROLLER
-inline bool IsMemoryPressureControllerEnabled() {
-  return IsExperimentEnabled(kExperimentIdMemoryPressureController);
-}
 #define GRPC_EXPERIMENT_IS_INCLUDED_MONITORING_EXPERIMENT
 inline bool IsMonitoringExperimentEnabled() {
   return IsExperimentEnabled(kExperimentIdMonitoringExperiment);
@@ -356,10 +337,6 @@ inline bool IsMonitoringExperimentEnabled() {
 inline bool IsMultipingEnabled() {
   return IsExperimentEnabled(kExperimentIdMultiping);
 }
-#define GRPC_EXPERIMENT_IS_INCLUDED_OVERLOAD_PROTECTION
-inline bool IsOverloadProtectionEnabled() {
-  return IsExperimentEnabled(kExperimentIdOverloadProtection);
-}
 #define GRPC_EXPERIMENT_IS_INCLUDED_PEER_STATE_BASED_FRAMING
 inline bool IsPeerStateBasedFramingEnabled() {
   return IsExperimentEnabled(kExperimentIdPeerStateBasedFraming);
@@ -380,10 +357,6 @@ inline bool IsPromiseBasedClientCallEnabled() {
 inline bool IsPromiseBasedServerCallEnabled() {
   return IsExperimentEnabled(kExperimentIdPromiseBasedServerCall);
 }
-#define GRPC_EXPERIMENT_IS_INCLUDED_RED_MAX_CONCURRENT_STREAMS
-inline bool IsRedMaxConcurrentStreamsEnabled() {
-  return IsExperimentEnabled(kExperimentIdRedMaxConcurrentStreams);
-}
 #define GRPC_EXPERIMENT_IS_INCLUDED_REGISTERED_METHOD_LOOKUP_IN_TRANSPORT
 inline bool IsRegisteredMethodLookupInTransportEnabled() {
   return IsExperimentEnabled(kExperimentIdRegisteredMethodLookupInTransport);

src/core/lib/experiments/experiments.yaml

@@ -107,11 +107,6 @@
   owner: yashkt@google.com
   test_tags: []
   allow_in_fuzzing_config: false
-- name: memory_pressure_controller
-  description: New memory pressure controller
-  expiry: 2024/05/05
-  owner: ctiller@google.com
-  test_tags: [resource_quota_test]
 - name: monitoring_experiment
   description: Placeholder experiment to prove/disprove our monitoring is working
   expiry: never-ever
@@ -123,13 +118,6 @@
   expiry: 2024/01/15
   owner: ctiller@google.com
   test_tags: [flow_control_test]
-- name: overload_protection
-  description:
-    If chttp2 has more streams than it can handle open, send RST_STREAM immediately
-    on new streams appearing.
-  expiry: 2024/03/03
-  owner: ctiller@google.com
-  test_tags: [flow_control_test]
 - name: peer_state_based_framing
   description:
     If set, the max sizes of frames sent to lower layers is controlled based
@@ -177,13 +165,6 @@
   expiry: 2024/06/14
   owner: ctiller@google.com
   test_tags: ["core_end2end_test", "cpp_end2end_test", "xds_end2end_test", "logging_test"]
-- name: red_max_concurrent_streams
-  description:
-    Perform random early rejection of requests that would exceed a newly reduced
-    MAX_CONCURRENT_STREAMS but are allowed by the current.
-  expiry: 2024/03/03
-  owner: ctiller@google.com
-  test_tags: [flow_control_test]
 - name: registered_method_lookup_in_transport
   description:
     Change registered method's lookup point to transport

src/core/lib/experiments/rollouts.yaml

@@ -78,12 +78,8 @@
   default: false
 - name: keepalive_server_fix
   default: false
-- name: memory_pressure_controller
-  default: false
 - name: monitoring_experiment
   default: true
-- name: overload_protection
-  default: true
 - name: peer_state_based_framing
   default: false
 - name: pending_queue_cap
@@ -94,8 +90,6 @@
   default: false
 - name: promise_based_server_call
   default: false
-- name: red_max_concurrent_streams
-  default: false
 - name: registered_method_lookup_in_transport
   default: true
 - name: registered_methods_map

src/core/lib/resource_quota/memory_quota.cc

@@ -658,14 +658,9 @@ BasicMemoryQuota::PressureInfo BasicMemoryQuota::GetPressureInfo() {
   if (size < 1) return PressureInfo{1, 1, 1};
   PressureInfo pressure_info;
   pressure_info.instantaneous_pressure = std::max(0.0, (size - free) / size);
-  if (IsMemoryPressureControllerEnabled()) {
+  pressure_info.pressure_control_value =
-    pressure_info.pressure_control_value =
+      pressure_tracker_.AddSampleAndGetControlValue(
-        pressure_tracker_.AddSampleAndGetControlValue(
+          pressure_info.instantaneous_pressure);
-            pressure_info.instantaneous_pressure);
-  } else {
-    pressure_info.pressure_control_value =
-        std::min(pressure_info.instantaneous_pressure, 1.0);
-  }
   pressure_info.max_recommended_allocation_size = quota_size / 16;
   return pressure_info;
 }

src/core/lib/transport/pid_controller.cc

@@ -1,51 +0,0 @@
-//
-//
-// Copyright 2016 gRPC authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-//
-
-#include <grpc/support/port_platform.h>
-
-#include "src/core/lib/transport/pid_controller.h"
-
-#include "src/core/lib/gpr/useful.h"
-
-namespace grpc_core {
-
-PidController::PidController(const Args& args)
-    : last_control_value_(args.initial_control_value()), args_(args) {}
-
-double PidController::Update(double error, double dt) {
-  if (dt <= 0) return last_control_value_;
-  // integrate error using the trapezoid rule
-  error_integral_ += dt * (last_error_ + error) * 0.5;
-  error_integral_ =
-      Clamp(error_integral_, -args_.integral_range(), args_.integral_range());
-  double diff_error = (error - last_error_) / dt;
-  // calculate derivative of control value vs time
-  double dc_dt = args_.gain_p() * error + args_.gain_i() * error_integral_ +
-                 args_.gain_d() * diff_error;
-  // and perform trapezoidal integration
-  double new_control_value =
-      last_control_value_ + dt * (last_dc_dt_ + dc_dt) * 0.5;
-  new_control_value = Clamp(new_control_value, args_.min_control_value(),
-                            args_.max_control_value());
-  last_error_ = error;
-  last_dc_dt_ = dc_dt;
-  last_control_value_ = new_control_value;
-  return new_control_value;
-}
-
-}  // namespace grpc_core

src/core/lib/transport/pid_controller.h

@@ -1,116 +0,0 @@
-//
-//
-// Copyright 2016 gRPC authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-//
-
-#ifndef GRPC_SRC_CORE_LIB_TRANSPORT_PID_CONTROLLER_H
-#define GRPC_SRC_CORE_LIB_TRANSPORT_PID_CONTROLLER_H
-
-#include <grpc/support/port_platform.h>
-
-#include <limits>
-
-// \file Simple PID controller.
-// Implements a proportional-integral-derivative controller.
-// Used when we want to iteratively control a variable to converge some other
-// observed value to a 'set-point'.
-// Gains can be set to adjust sensitivity to current error (p), the integral
-// of error (i), and the derivative of error (d).
-
-namespace grpc_core {
-
-class PidController {
- public:
-  class Args {
-   public:
-    double gain_p() const { return gain_p_; }
-    double gain_i() const { return gain_i_; }
-    double gain_d() const { return gain_d_; }
-    double initial_control_value() const { return initial_control_value_; }
-    double min_control_value() const { return min_control_value_; }
-    double max_control_value() const { return max_control_value_; }
-    double integral_range() const { return integral_range_; }
-
-    Args& set_gain_p(double gain_p) {
-      gain_p_ = gain_p;
-      return *this;
-    }
-    Args& set_gain_i(double gain_i) {
-      gain_i_ = gain_i;
-      return *this;
-    }
-    Args& set_gain_d(double gain_d) {
-      gain_d_ = gain_d;
-      return *this;
-    }
-    Args& set_initial_control_value(double initial_control_value) {
-      initial_control_value_ = initial_control_value;
-      return *this;
-    }
-    Args& set_min_control_value(double min_control_value) {
-      min_control_value_ = min_control_value;
-      return *this;
-    }
-    Args& set_max_control_value(double max_control_value) {
-      max_control_value_ = max_control_value;
-      return *this;
-    }
-    Args& set_integral_range(double integral_range) {
-      integral_range_ = integral_range;
-      return *this;
-    }
-
-   private:
-    double gain_p_ = 0.0;
-    double gain_i_ = 0.0;
-    double gain_d_ = 0.0;
-    double initial_control_value_ = 0.0;
-    double min_control_value_ = std::numeric_limits<double>::min();
-    double max_control_value_ = std::numeric_limits<double>::max();
-    double integral_range_ = std::numeric_limits<double>::max();
-  };
-
-  explicit PidController(const Args& args);
-
-  /// Reset the controller internal state: useful when the environment has
-  /// changed significantly
-  void Reset() {
-    last_error_ = 0.0;
-    last_dc_dt_ = 0.0;
-    error_integral_ = 0.0;
-  }
-
-  /// Update the controller: given a current error estimate, and the time since
-  /// the last update, returns a new control value
-  double Update(double error, double dt);
-
-  /// Returns the last control value calculated
-  double last_control_value() const { return last_control_value_; }
-
-  /// Returns the current error integral (mostly for testing)
-  double error_integral() const { return error_integral_; }
-
- private:
-  double last_error_ = 0.0;
-  double error_integral_ = 0.0;
-  double last_control_value_;
-  double last_dc_dt_ = 0.0;
-  const Args args_;
-};
-
-}  // namespace grpc_core
-
-#endif  // GRPC_SRC_CORE_LIB_TRANSPORT_PID_CONTROLLER_H

src/python/grpcio/grpc_core_dependencies.py

@@ -811,7 +811,6 @@ CORE_SOURCE_FILES = [
     'src/core/lib/transport/http_connect_handshaker.cc',
     'src/core/lib/transport/metadata_batch.cc',
     'src/core/lib/transport/parsed_metadata.cc',
-    'src/core/lib/transport/pid_controller.cc',
     'src/core/lib/transport/status_conversion.cc',
     'src/core/lib/transport/tcp_connect_handshaker.cc',
     'src/core/lib/transport/timeout_encoding.cc',

test/core/transport/BUILD

@@ -94,21 +94,6 @@ grpc_cc_test(
     ],
 )
 
-grpc_cc_test(
-    name = "pid_controller_test",
-    srcs = ["pid_controller_test.cc"],
-    external_deps = [
-        "gtest",
-    ],
-    language = "C++",
-    deps = [
-        "//:gpr",
-        "//:grpc",
-        "//test/core/util:grpc_test_util",
-        "//test/core/util:grpc_test_util_base",
-    ],
-)
-
 grpc_cc_test(
     name = "promise_endpoint_test",
     srcs = ["promise_endpoint_test.cc"],

test/core/transport/pid_controller_test.cc

@@ -1,89 +0,0 @@
-//
-//
-// Copyright 2016 gRPC authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-//
-
-#include "src/core/lib/transport/pid_controller.h"
-
-#include <math.h>
-
-#include <memory>
-#include <ostream>
-
-#include "gtest/gtest.h"
-
-#include "test/core/util/test_config.h"
-
-namespace grpc_core {
-namespace testing {
-
-TEST(PidController, NoOp) {
-  PidController pid(PidController::Args()
-                        .set_gain_p(1)
-                        .set_gain_i(1)
-                        .set_gain_d(1)
-                        .set_initial_control_value(1));
-}
-
-struct SimpleConvergenceTestArgs {
-  double gain_p;
-  double gain_i;
-  double gain_d;
-  double dt;
-  double set_point;
-  double start;
-};
-
-std::ostream& operator<<(std::ostream& out, SimpleConvergenceTestArgs args) {
-  return out << "gain_p:" << args.gain_p << " gain_i:" << args.gain_i
-             << " gain_d:" << args.gain_d << " dt:" << args.dt
-             << " set_point:" << args.set_point << " start:" << args.start;
-}
-
-class SimpleConvergenceTest
-    : public ::testing::TestWithParam<SimpleConvergenceTestArgs> {};
-
-TEST_P(SimpleConvergenceTest, Converges) {
-  PidController pid(PidController::Args()
-                        .set_gain_p(GetParam().gain_p)
-                        .set_gain_i(GetParam().gain_i)
-                        .set_gain_d(GetParam().gain_d)
-                        .set_initial_control_value(GetParam().start));
-
-  for (int i = 0; i < 100000; i++) {
-    pid.Update(GetParam().set_point - pid.last_control_value(), GetParam().dt);
-  }
-
-  EXPECT_LT(fabs(GetParam().set_point - pid.last_control_value()), 0.1);
-  if (GetParam().gain_i > 0) {
-    EXPECT_LT(fabs(pid.error_integral()), 0.1);
-  }
-}
-
-INSTANTIATE_TEST_SUITE_P(
-    X, SimpleConvergenceTest,
-    ::testing::Values(SimpleConvergenceTestArgs{0.2, 0, 0, 1, 100, 0},
-                      SimpleConvergenceTestArgs{0.2, 0.1, 0, 1, 100, 0},
-                      SimpleConvergenceTestArgs{0.2, 0.1, 0.1, 1, 100, 0}));
-
-}  // namespace testing
-}  // namespace grpc_core
-
-int main(int argc, char** argv) {
-  grpc::testing::TestEnvironment env(&argc, argv);
-  ::testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
-}

tools/doxygen/Doxyfile.c++.internal

@@ -2899,8 +2899,6 @@ src/core/lib/transport/metadata_batch.h \
 src/core/lib/transport/metadata_compression_traits.h \
 src/core/lib/transport/parsed_metadata.cc \
 src/core/lib/transport/parsed_metadata.h \
-src/core/lib/transport/pid_controller.cc \
-src/core/lib/transport/pid_controller.h \
 src/core/lib/transport/simple_slice_based_metadata.h \
 src/core/lib/transport/status_conversion.cc \
 src/core/lib/transport/status_conversion.h \

tools/doxygen/Doxyfile.core.internal

@@ -2680,8 +2680,6 @@ src/core/lib/transport/metadata_batch.h \
 src/core/lib/transport/metadata_compression_traits.h \
 src/core/lib/transport/parsed_metadata.cc \
 src/core/lib/transport/parsed_metadata.h \
-src/core/lib/transport/pid_controller.cc \
-src/core/lib/transport/pid_controller.h \
 src/core/lib/transport/simple_slice_based_metadata.h \
 src/core/lib/transport/status_conversion.cc \
 src/core/lib/transport/status_conversion.h \

tools/run_tests/generated/tests.json

@@ -6601,30 +6601,6 @@
     ],
     "uses_polling": false
   },
-  {
-    "args": [],
-    "benchmark": false,
-    "ci_platforms": [
-      "linux",
-      "mac",
-      "posix",
-      "windows"
-    ],
-    "cpu_cost": 1.0,
-    "exclude_configs": [],
-    "exclude_iomgrs": [],
-    "flaky": false,
-    "gtest": true,
-    "language": "c++",
-    "name": "pid_controller_test",
-    "platforms": [
-      "linux",
-      "mac",
-      "posix",
-      "windows"
-    ],
-    "uses_polling": true
-  },
   {
     "args": [],
     "benchmark": false,