Reapply "[experiments] Explicit requirement check" (#34911) (#34915)

This reverts commit b0e0659bab.

Closes #34915

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/34915 from ctiller:requires2 8e4f033317
PiperOrigin-RevId: 583110606

bazel/experiments.bzl

@@ -16,6 +16,57 @@
 
 """Dictionary of tags to experiments so we know when to test different experiments."""
 
+EXPERIMENT_ENABLES = {
+    "block_excessive_requests_before_settings_ack": "block_excessive_requests_before_settings_ack",
+    "call_status_override_on_cancellation": "call_status_override_on_cancellation",
+    "canary_client_privacy": "canary_client_privacy",
+    "client_idleness": "client_idleness",
+    "client_privacy": "client_privacy",
+    "combiner_offload_to_event_engine": "combiner_offload_to_event_engine",
+    "chttp2_batch_requests": "chttp2_batch_requests,combiner_offload_to_event_engine",
+    "chttp2_offload_on_rst_stream": "chttp2_offload_on_rst_stream,combiner_offload_to_event_engine",
+    "event_engine_client": "event_engine_client",
+    "event_engine_dns": "event_engine_dns",
+    "event_engine_listener": "event_engine_listener",
+    "free_large_allocator": "free_large_allocator",
+    "http2_stats_fix": "http2_stats_fix",
+    "keepalive_fix": "keepalive_fix",
+    "keepalive_server_fix": "keepalive_server_fix",
+    "lazier_stream_updates": "lazier_stream_updates",
+    "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",
+    "ping_on_rst_stream": "ping_on_rst_stream",
+    "promise_based_client_call": "promise_based_client_call",
+    "promise_based_inproc_transport": "promise_based_inproc_transport",
+    "promise_based_server_call": "lazier_stream_updates,promise_based_server_call",
+    "red_max_concurrent_streams": "red_max_concurrent_streams",
+    "registered_method_lookup_in_transport": "registered_method_lookup_in_transport",
+    "registered_methods_map": "registered_methods_map",
+    "rfc_max_concurrent_streams": "rfc_max_concurrent_streams",
+    "round_robin_delegate_to_pick_first": "round_robin_delegate_to_pick_first",
+    "rstpit": "rstpit",
+    "schedule_cancellation_over_write": "schedule_cancellation_over_write",
+    "separate_ping_from_keepalive": "separate_ping_from_keepalive",
+    "server_privacy": "server_privacy",
+    "settings_timeout": "settings_timeout",
+    "tarpit": "tarpit",
+    "tcp_frame_size_tuning": "tcp_frame_size_tuning",
+    "tcp_rcv_lowat": "tcp_rcv_lowat",
+    "trace_record_callops": "trace_record_callops",
+    "unconstrained_max_quota_buffer_size": "unconstrained_max_quota_buffer_size",
+    "uniquely_unowned": "uniquely_unowned",
+    "work_serializer_clears_time_cache": "work_serializer_clears_time_cache",
+    "work_serializer_dispatch": "work_serializer_dispatch",
+    "write_size_policy": "write_size_policy",
+    "write_size_cap": "write_size_cap,write_size_policy",
+    "wrr_delegate_to_pick_first": "wrr_delegate_to_pick_first",
+}
+
 EXPERIMENTS = {
     "windows": {
         "dbg": {

bazel/grpc_build_system.bzl

@@ -29,8 +29,8 @@ Contains macros used throughout the repo.
 
 load("//bazel:cc_grpc_library.bzl", "cc_grpc_library")
 load("//bazel:copts.bzl", "GRPC_DEFAULT_COPTS")
-load("//bazel:experiments.bzl", "EXPERIMENTS")
-load("//bazel:test_experiments.bzl", "TEST_EXPERIMENTS")
+load("//bazel:experiments.bzl", "EXPERIMENTS", "EXPERIMENT_ENABLES")
+load("//bazel:test_experiments.bzl", "TEST_EXPERIMENTS", "TEST_EXPERIMENT_ENABLES")
 load("@build_bazel_rules_apple//apple:ios.bzl", "ios_unit_test")
 load("@build_bazel_rules_apple//apple/testing/default_runner:ios_test_runner.bzl", "ios_test_runner")
 load("@com_google_protobuf//bazel:upb_proto_library.bzl", "upb_proto_library", "upb_proto_reflection_library")
@@ -418,6 +418,7 @@ def expand_tests(name, srcs, deps, tags, args, exclude_pollers, uses_polling, us
         return tags
 
     experiment_config = list(poller_config)
+    experiment_enables = {k: v for k, v in EXPERIMENT_ENABLES.items() + TEST_EXPERIMENT_ENABLES.items()}
     for mode, config in mode_config.items():
         enabled_tags, disabled_tags = config
         if enabled_tags != None:
@@ -426,7 +427,7 @@ def expand_tests(name, srcs, deps, tags, args, exclude_pollers, uses_polling, us
                     config = dict(config)
                     config["name"] = config["name"] + "@experiment=" + experiment
                     env = dict(config["env"])
-                    env["GRPC_EXPERIMENTS"] = experiment
+                    env["GRPC_EXPERIMENTS"] = experiment_enables[experiment]
                     env["GRPC_CI_EXPERIMENTS"] = "1"
                     config["env"] = env
                     tags = config["tags"] + ["experiment_variation"]

bazel/test_experiments.bzl

@@ -16,6 +16,13 @@
 
 """Dictionary of tags to experiments so we know when to test different experiments."""
 
+TEST_EXPERIMENT_ENABLES = {
+    "test_experiment_1": "test_experiment_1",
+    "test_experiment_2": "test_experiment_2",
+    "test_experiment_3": "test_experiment_3",
+    "test_experiment_4": "test_experiment_4",
+}
+
 TEST_EXPERIMENTS = {
     "windows": {
         "dbg": {

src/core/lib/experiments/config.cc

@@ -135,6 +135,19 @@ GPR_ATTRIBUTE_NOINLINE Experiments LoadExperimentsFromConfigVariable() {
               std::string(experiment).c_str());
     }
   }
+  for (size_t i = 0; i < kNumExperiments; i++) {
+    // If required experiments are not enabled, disable this one too.
+    for (size_t j = 0; j < g_experiment_metadata[i].num_required_experiments;
+         j++) {
+      // Require that we can check dependent requirements with a linear sweep
+      // (implies the experiments generator must DAG sort the experiments)
+      GPR_ASSERT(g_experiment_metadata[i].required_experiments[j] < i);
+      if (!experiments
+               .enabled[g_experiment_metadata[i].required_experiments[j]]) {
+        experiments.enabled[i] = false;
+      }
+    }
+  }
   return experiments;
 }
 

src/core/lib/experiments/config.h

@@ -18,6 +18,7 @@
 #include <grpc/support/port_platform.h>
 
 #include <stddef.h>
+#include <stdint.h>
 
 #include "absl/functional/any_invocable.h"
 #include "absl/strings/string_view.h"
@@ -30,6 +31,8 @@ struct ExperimentMetadata {
   const char* name;
   const char* description;
   const char* additional_constaints;
+  const uint8_t* required_experiments;
+  uint8_t num_required_experiments;
   bool default_value;
   bool allow_in_fuzzing_config;
 };

src/core/lib/experiments/experiments.cc

@@ -18,6 +18,8 @@
 
 #include "src/core/lib/experiments/experiments.h"
 
+#include <stdint.h>
+
 #ifndef GRPC_EXPERIMENTS_ARE_FINAL
 
 #if defined(GRPC_CFSTREAM)
@@ -34,13 +36,6 @@ const char* const additional_constraints_call_status_override_on_cancellation =
 const char* const description_canary_client_privacy =
     "If set, canary client privacy";
 const char* const additional_constraints_canary_client_privacy = "{}";
-const char* const description_chttp2_batch_requests =
-    "Cap the number of requests received by one transport read prior to "
-    "offload.";
-const char* const additional_constraints_chttp2_batch_requests = "{}";
-const char* const description_chttp2_offload_on_rst_stream =
-    "Offload work on RST_STREAM.";
-const char* const additional_constraints_chttp2_offload_on_rst_stream = "{}";
 const char* const description_client_idleness =
     "If enabled, client channel idleness is enabled by default.";
 const char* const additional_constraints_client_idleness = "{}";
@@ -50,6 +45,17 @@ const char* const description_combiner_offload_to_event_engine =
     "Offload Combiner work onto the EventEngine instead of the Executor.";
 const char* const additional_constraints_combiner_offload_to_event_engine =
     "{}";
+const char* const description_chttp2_batch_requests =
+    "Cap the number of requests received by one transport read prior to "
+    "offload.";
+const char* const additional_constraints_chttp2_batch_requests = "{}";
+const uint8_t required_experiments_chttp2_batch_requests[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdCombinerOffloadToEventEngine)};
+const char* const description_chttp2_offload_on_rst_stream =
+    "Offload work on RST_STREAM.";
+const char* const additional_constraints_chttp2_offload_on_rst_stream = "{}";
+const uint8_t required_experiments_chttp2_offload_on_rst_stream[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdCombinerOffloadToEventEngine)};
 const char* const description_event_engine_client =
     "Use EventEngine clients instead of iomgr's grpc_tcp_client";
 const char* const additional_constraints_event_engine_client = "{}";
@@ -121,6 +127,8 @@ 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 uint8_t required_experiments_promise_based_server_call[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdLazierStreamUpdates)};
 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.";
@@ -193,12 +201,14 @@ const char* const description_work_serializer_dispatch =
     "callback, instead of running things inline in the first thread that "
     "successfully enqueues work.";
 const char* const additional_constraints_work_serializer_dispatch = "{}";
-const char* const description_write_size_cap =
-    "Limit outgoing writes proportional to the target write size";
-const char* const additional_constraints_write_size_cap = "{}";
 const char* const description_write_size_policy =
     "Try to size writes such that they don't create too large of a backlog";
 const char* const additional_constraints_write_size_policy = "{}";
+const char* const description_write_size_cap =
+    "Limit outgoing writes proportional to the target write size";
+const char* const additional_constraints_write_size_cap = "{}";
+const uint8_t required_experiments_write_size_cap[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdWriteSizePolicy)};
 const char* const description_wrr_delegate_to_pick_first =
     "Change WRR code to delegate to pick_first as per dualstack backend "
     "design.";
@@ -215,109 +225,126 @@ namespace grpc_core {
 const ExperimentMetadata g_experiment_metadata[] = {
     {"block_excessive_requests_before_settings_ack",
      description_block_excessive_requests_before_settings_ack,
-     additional_constraints_block_excessive_requests_before_settings_ack, true,
-     true},
+     additional_constraints_block_excessive_requests_before_settings_ack,
+     nullptr, 0, true, true},
     {"call_status_override_on_cancellation",
      description_call_status_override_on_cancellation,
-     additional_constraints_call_status_override_on_cancellation,
+     additional_constraints_call_status_override_on_cancellation, nullptr, 0,
      kDefaultForDebugOnly, true},
     {"canary_client_privacy", description_canary_client_privacy,
-     additional_constraints_canary_client_privacy, false, false},
-    {"chttp2_batch_requests", description_chttp2_batch_requests,
-     additional_constraints_chttp2_batch_requests, true, true},
-    {"chttp2_offload_on_rst_stream", description_chttp2_offload_on_rst_stream,
-     additional_constraints_chttp2_offload_on_rst_stream, true, true},
+     additional_constraints_canary_client_privacy, nullptr, 0, false, false},
     {"client_idleness", description_client_idleness,
-     additional_constraints_client_idleness, true, true},
+     additional_constraints_client_idleness, nullptr, 0, true, true},
     {"client_privacy", description_client_privacy,
-     additional_constraints_client_privacy, false, false},
+     additional_constraints_client_privacy, nullptr, 0, false, false},
     {"combiner_offload_to_event_engine",
      description_combiner_offload_to_event_engine,
-     additional_constraints_combiner_offload_to_event_engine, true, true},
+     additional_constraints_combiner_offload_to_event_engine, nullptr, 0, true,
+     true},
+    {"chttp2_batch_requests", description_chttp2_batch_requests,
+     additional_constraints_chttp2_batch_requests,
+     required_experiments_chttp2_batch_requests, 1, true, true},
+    {"chttp2_offload_on_rst_stream", description_chttp2_offload_on_rst_stream,
+     additional_constraints_chttp2_offload_on_rst_stream,
+     required_experiments_chttp2_offload_on_rst_stream, 1, true, true},
     {"event_engine_client", description_event_engine_client,
-     additional_constraints_event_engine_client, false, true},
+     additional_constraints_event_engine_client, nullptr, 0, false, true},
     {"event_engine_dns", description_event_engine_dns,
-     additional_constraints_event_engine_dns, false, false},
+     additional_constraints_event_engine_dns, nullptr, 0, false, false},
     {"event_engine_listener", description_event_engine_listener,
-     additional_constraints_event_engine_listener, false, true},
+     additional_constraints_event_engine_listener, nullptr, 0, false, true},
     {"free_large_allocator", description_free_large_allocator,
-     additional_constraints_free_large_allocator, false, true},
+     additional_constraints_free_large_allocator, nullptr, 0, false, true},
     {"http2_stats_fix", description_http2_stats_fix,
-     additional_constraints_http2_stats_fix, true, true},
+     additional_constraints_http2_stats_fix, nullptr, 0, true, true},
     {"keepalive_fix", description_keepalive_fix,
-     additional_constraints_keepalive_fix, false, false},
+     additional_constraints_keepalive_fix, nullptr, 0, false, false},
     {"keepalive_server_fix", description_keepalive_server_fix,
-     additional_constraints_keepalive_server_fix, false, false},
+     additional_constraints_keepalive_server_fix, nullptr, 0, false, false},
     {"lazier_stream_updates", description_lazier_stream_updates,
-     additional_constraints_lazier_stream_updates, true, true},
+     additional_constraints_lazier_stream_updates, nullptr, 0, true, true},
     {"memory_pressure_controller", description_memory_pressure_controller,
-     additional_constraints_memory_pressure_controller, false, true},
+     additional_constraints_memory_pressure_controller, nullptr, 0, false,
+     true},
     {"monitoring_experiment", description_monitoring_experiment,
-     additional_constraints_monitoring_experiment, true, true},
+     additional_constraints_monitoring_experiment, nullptr, 0, true, true},
     {"multiping", description_multiping, additional_constraints_multiping,
-     false, true},
+     nullptr, 0, false, true},
     {"overload_protection", description_overload_protection,
-     additional_constraints_overload_protection, true, true},
+     additional_constraints_overload_protection, nullptr, 0, true, true},
     {"peer_state_based_framing", description_peer_state_based_framing,
-     additional_constraints_peer_state_based_framing, false, true},
+     additional_constraints_peer_state_based_framing, nullptr, 0, false, true},
     {"pending_queue_cap", description_pending_queue_cap,
-     additional_constraints_pending_queue_cap, true, true},
+     additional_constraints_pending_queue_cap, nullptr, 0, true, true},
     {"pick_first_happy_eyeballs", description_pick_first_happy_eyeballs,
-     additional_constraints_pick_first_happy_eyeballs, true, true},
+     additional_constraints_pick_first_happy_eyeballs, nullptr, 0, true, true},
     {"ping_on_rst_stream", description_ping_on_rst_stream,
-     additional_constraints_ping_on_rst_stream, true, true},
+     additional_constraints_ping_on_rst_stream, nullptr, 0, true, true},
     {"promise_based_client_call", description_promise_based_client_call,
-     additional_constraints_promise_based_client_call, false, true},
+     additional_constraints_promise_based_client_call, nullptr, 0, false, true},
     {"promise_based_inproc_transport",
      description_promise_based_inproc_transport,
-     additional_constraints_promise_based_inproc_transport, false, false},
+     additional_constraints_promise_based_inproc_transport, nullptr, 0, false,
+     false},
     {"promise_based_server_call", description_promise_based_server_call,
-     additional_constraints_promise_based_server_call, false, true},
+     additional_constraints_promise_based_server_call,
+     required_experiments_promise_based_server_call, 1, false, true},
     {"red_max_concurrent_streams", description_red_max_concurrent_streams,
-     additional_constraints_red_max_concurrent_streams, false, true},
+     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, true, true},
+     additional_constraints_registered_method_lookup_in_transport, nullptr, 0,
+     true, true},
     {"registered_methods_map", description_registered_methods_map,
-     additional_constraints_registered_methods_map, false, true},
+     additional_constraints_registered_methods_map, nullptr, 0, false, true},
     {"rfc_max_concurrent_streams", description_rfc_max_concurrent_streams,
-     additional_constraints_rfc_max_concurrent_streams, false, true},
+     additional_constraints_rfc_max_concurrent_streams, nullptr, 0, false,
+     true},
     {"round_robin_delegate_to_pick_first",
      description_round_robin_delegate_to_pick_first,
-     additional_constraints_round_robin_delegate_to_pick_first, true, true},
-    {"rstpit", description_rstpit, additional_constraints_rstpit, false, true},
+     additional_constraints_round_robin_delegate_to_pick_first, nullptr, 0,
+     true, true},
+    {"rstpit", description_rstpit, additional_constraints_rstpit, nullptr, 0,
+     false, true},
     {"schedule_cancellation_over_write",
      description_schedule_cancellation_over_write,
-     additional_constraints_schedule_cancellation_over_write, false, true},
+     additional_constraints_schedule_cancellation_over_write, nullptr, 0, false,
+     true},
     {"separate_ping_from_keepalive", description_separate_ping_from_keepalive,
-     additional_constraints_separate_ping_from_keepalive, true, true},
+     additional_constraints_separate_ping_from_keepalive, nullptr, 0, true,
+     true},
     {"server_privacy", description_server_privacy,
-     additional_constraints_server_privacy, false, false},
+     additional_constraints_server_privacy, nullptr, 0, false, false},
     {"settings_timeout", description_settings_timeout,
-     additional_constraints_settings_timeout, true, true},
-    {"tarpit", description_tarpit, additional_constraints_tarpit, true, true},
+     additional_constraints_settings_timeout, nullptr, 0, true, true},
+    {"tarpit", description_tarpit, additional_constraints_tarpit, nullptr, 0,
+     true, true},
     {"tcp_frame_size_tuning", description_tcp_frame_size_tuning,
-     additional_constraints_tcp_frame_size_tuning, false, true},
+     additional_constraints_tcp_frame_size_tuning, nullptr, 0, false, true},
     {"tcp_rcv_lowat", description_tcp_rcv_lowat,
-     additional_constraints_tcp_rcv_lowat, false, true},
+     additional_constraints_tcp_rcv_lowat, nullptr, 0, false, true},
     {"trace_record_callops", description_trace_record_callops,
-     additional_constraints_trace_record_callops, false, true},
+     additional_constraints_trace_record_callops, nullptr, 0, false, true},
     {"unconstrained_max_quota_buffer_size",
      description_unconstrained_max_quota_buffer_size,
-     additional_constraints_unconstrained_max_quota_buffer_size, false, true},
+     additional_constraints_unconstrained_max_quota_buffer_size, nullptr, 0,
+     false, true},
     {"uniquely_unowned", description_uniquely_unowned,
-     additional_constraints_uniquely_unowned, true, true},
+     additional_constraints_uniquely_unowned, nullptr, 0, true, true},
     {"work_serializer_clears_time_cache",
      description_work_serializer_clears_time_cache,
-     additional_constraints_work_serializer_clears_time_cache, true, true},
+     additional_constraints_work_serializer_clears_time_cache, nullptr, 0, true,
+     true},
     {"work_serializer_dispatch", description_work_serializer_dispatch,
-     additional_constraints_work_serializer_dispatch, false, true},
-    {"write_size_cap", description_write_size_cap,
-     additional_constraints_write_size_cap, true, true},
+     additional_constraints_work_serializer_dispatch, nullptr, 0, false, true},
     {"write_size_policy", description_write_size_policy,
-     additional_constraints_write_size_policy, true, true},
+     additional_constraints_write_size_policy, nullptr, 0, true, true},
+    {"write_size_cap", description_write_size_cap,
+     additional_constraints_write_size_cap, required_experiments_write_size_cap,
+     1, true, true},
     {"wrr_delegate_to_pick_first", description_wrr_delegate_to_pick_first,
-     additional_constraints_wrr_delegate_to_pick_first, true, true},
+     additional_constraints_wrr_delegate_to_pick_first, nullptr, 0, true, true},
 };
 
 }  // namespace grpc_core
@@ -336,13 +363,6 @@ const char* const additional_constraints_call_status_override_on_cancellation =
 const char* const description_canary_client_privacy =
     "If set, canary client privacy";
 const char* const additional_constraints_canary_client_privacy = "{}";
-const char* const description_chttp2_batch_requests =
-    "Cap the number of requests received by one transport read prior to "
-    "offload.";
-const char* const additional_constraints_chttp2_batch_requests = "{}";
-const char* const description_chttp2_offload_on_rst_stream =
-    "Offload work on RST_STREAM.";
-const char* const additional_constraints_chttp2_offload_on_rst_stream = "{}";
 const char* const description_client_idleness =
     "If enabled, client channel idleness is enabled by default.";
 const char* const additional_constraints_client_idleness = "{}";
@@ -352,6 +372,17 @@ const char* const description_combiner_offload_to_event_engine =
     "Offload Combiner work onto the EventEngine instead of the Executor.";
 const char* const additional_constraints_combiner_offload_to_event_engine =
     "{}";
+const char* const description_chttp2_batch_requests =
+    "Cap the number of requests received by one transport read prior to "
+    "offload.";
+const char* const additional_constraints_chttp2_batch_requests = "{}";
+const uint8_t required_experiments_chttp2_batch_requests[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdCombinerOffloadToEventEngine)};
+const char* const description_chttp2_offload_on_rst_stream =
+    "Offload work on RST_STREAM.";
+const char* const additional_constraints_chttp2_offload_on_rst_stream = "{}";
+const uint8_t required_experiments_chttp2_offload_on_rst_stream[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdCombinerOffloadToEventEngine)};
 const char* const description_event_engine_client =
     "Use EventEngine clients instead of iomgr's grpc_tcp_client";
 const char* const additional_constraints_event_engine_client = "{}";
@@ -423,6 +454,8 @@ 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 uint8_t required_experiments_promise_based_server_call[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdLazierStreamUpdates)};
 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.";
@@ -495,12 +528,14 @@ const char* const description_work_serializer_dispatch =
     "callback, instead of running things inline in the first thread that "
     "successfully enqueues work.";
 const char* const additional_constraints_work_serializer_dispatch = "{}";
-const char* const description_write_size_cap =
-    "Limit outgoing writes proportional to the target write size";
-const char* const additional_constraints_write_size_cap = "{}";
 const char* const description_write_size_policy =
     "Try to size writes such that they don't create too large of a backlog";
 const char* const additional_constraints_write_size_policy = "{}";
+const char* const description_write_size_cap =
+    "Limit outgoing writes proportional to the target write size";
+const char* const additional_constraints_write_size_cap = "{}";
+const uint8_t required_experiments_write_size_cap[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdWriteSizePolicy)};
 const char* const description_wrr_delegate_to_pick_first =
     "Change WRR code to delegate to pick_first as per dualstack backend "
     "design.";
@@ -517,109 +552,126 @@ namespace grpc_core {
 const ExperimentMetadata g_experiment_metadata[] = {
     {"block_excessive_requests_before_settings_ack",
      description_block_excessive_requests_before_settings_ack,
-     additional_constraints_block_excessive_requests_before_settings_ack, true,
-     true},
+     additional_constraints_block_excessive_requests_before_settings_ack,
+     nullptr, 0, true, true},
     {"call_status_override_on_cancellation",
      description_call_status_override_on_cancellation,
-     additional_constraints_call_status_override_on_cancellation,
+     additional_constraints_call_status_override_on_cancellation, nullptr, 0,
      kDefaultForDebugOnly, true},
     {"canary_client_privacy", description_canary_client_privacy,
-     additional_constraints_canary_client_privacy, false, false},
-    {"chttp2_batch_requests", description_chttp2_batch_requests,
-     additional_constraints_chttp2_batch_requests, true, true},
-    {"chttp2_offload_on_rst_stream", description_chttp2_offload_on_rst_stream,
-     additional_constraints_chttp2_offload_on_rst_stream, true, true},
+     additional_constraints_canary_client_privacy, nullptr, 0, false, false},
     {"client_idleness", description_client_idleness,
-     additional_constraints_client_idleness, true, true},
+     additional_constraints_client_idleness, nullptr, 0, true, true},
     {"client_privacy", description_client_privacy,
-     additional_constraints_client_privacy, false, false},
+     additional_constraints_client_privacy, nullptr, 0, false, false},
     {"combiner_offload_to_event_engine",
      description_combiner_offload_to_event_engine,
-     additional_constraints_combiner_offload_to_event_engine, true, true},
+     additional_constraints_combiner_offload_to_event_engine, nullptr, 0, true,
+     true},
+    {"chttp2_batch_requests", description_chttp2_batch_requests,
+     additional_constraints_chttp2_batch_requests,
+     required_experiments_chttp2_batch_requests, 1, true, true},
+    {"chttp2_offload_on_rst_stream", description_chttp2_offload_on_rst_stream,
+     additional_constraints_chttp2_offload_on_rst_stream,
+     required_experiments_chttp2_offload_on_rst_stream, 1, true, true},
     {"event_engine_client", description_event_engine_client,
-     additional_constraints_event_engine_client, false, true},
+     additional_constraints_event_engine_client, nullptr, 0, false, true},
     {"event_engine_dns", description_event_engine_dns,
-     additional_constraints_event_engine_dns, false, false},
+     additional_constraints_event_engine_dns, nullptr, 0, false, false},
     {"event_engine_listener", description_event_engine_listener,
-     additional_constraints_event_engine_listener, true, true},
+     additional_constraints_event_engine_listener, nullptr, 0, true, true},
     {"free_large_allocator", description_free_large_allocator,
-     additional_constraints_free_large_allocator, false, true},
+     additional_constraints_free_large_allocator, nullptr, 0, false, true},
     {"http2_stats_fix", description_http2_stats_fix,
-     additional_constraints_http2_stats_fix, true, true},
+     additional_constraints_http2_stats_fix, nullptr, 0, true, true},
     {"keepalive_fix", description_keepalive_fix,
-     additional_constraints_keepalive_fix, false, false},
+     additional_constraints_keepalive_fix, nullptr, 0, false, false},
     {"keepalive_server_fix", description_keepalive_server_fix,
-     additional_constraints_keepalive_server_fix, false, false},
+     additional_constraints_keepalive_server_fix, nullptr, 0, false, false},
     {"lazier_stream_updates", description_lazier_stream_updates,
-     additional_constraints_lazier_stream_updates, true, true},
+     additional_constraints_lazier_stream_updates, nullptr, 0, true, true},
     {"memory_pressure_controller", description_memory_pressure_controller,
-     additional_constraints_memory_pressure_controller, false, true},
+     additional_constraints_memory_pressure_controller, nullptr, 0, false,
+     true},
     {"monitoring_experiment", description_monitoring_experiment,
-     additional_constraints_monitoring_experiment, true, true},
+     additional_constraints_monitoring_experiment, nullptr, 0, true, true},
     {"multiping", description_multiping, additional_constraints_multiping,
-     false, true},
+     nullptr, 0, false, true},
     {"overload_protection", description_overload_protection,
-     additional_constraints_overload_protection, true, true},
+     additional_constraints_overload_protection, nullptr, 0, true, true},
     {"peer_state_based_framing", description_peer_state_based_framing,
-     additional_constraints_peer_state_based_framing, false, true},
+     additional_constraints_peer_state_based_framing, nullptr, 0, false, true},
     {"pending_queue_cap", description_pending_queue_cap,
-     additional_constraints_pending_queue_cap, true, true},
+     additional_constraints_pending_queue_cap, nullptr, 0, true, true},
     {"pick_first_happy_eyeballs", description_pick_first_happy_eyeballs,
-     additional_constraints_pick_first_happy_eyeballs, true, true},
+     additional_constraints_pick_first_happy_eyeballs, nullptr, 0, true, true},
     {"ping_on_rst_stream", description_ping_on_rst_stream,
-     additional_constraints_ping_on_rst_stream, true, true},
+     additional_constraints_ping_on_rst_stream, nullptr, 0, true, true},
     {"promise_based_client_call", description_promise_based_client_call,
-     additional_constraints_promise_based_client_call, false, true},
+     additional_constraints_promise_based_client_call, nullptr, 0, false, true},
     {"promise_based_inproc_transport",
      description_promise_based_inproc_transport,
-     additional_constraints_promise_based_inproc_transport, false, false},
+     additional_constraints_promise_based_inproc_transport, nullptr, 0, false,
+     false},
     {"promise_based_server_call", description_promise_based_server_call,
-     additional_constraints_promise_based_server_call, false, true},
+     additional_constraints_promise_based_server_call,
+     required_experiments_promise_based_server_call, 1, false, true},
     {"red_max_concurrent_streams", description_red_max_concurrent_streams,
-     additional_constraints_red_max_concurrent_streams, false, true},
+     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, true, true},
+     additional_constraints_registered_method_lookup_in_transport, nullptr, 0,
+     true, true},
     {"registered_methods_map", description_registered_methods_map,
-     additional_constraints_registered_methods_map, false, true},
+     additional_constraints_registered_methods_map, nullptr, 0, false, true},
     {"rfc_max_concurrent_streams", description_rfc_max_concurrent_streams,
-     additional_constraints_rfc_max_concurrent_streams, false, true},
+     additional_constraints_rfc_max_concurrent_streams, nullptr, 0, false,
+     true},
     {"round_robin_delegate_to_pick_first",
      description_round_robin_delegate_to_pick_first,
-     additional_constraints_round_robin_delegate_to_pick_first, true, true},
-    {"rstpit", description_rstpit, additional_constraints_rstpit, false, true},
+     additional_constraints_round_robin_delegate_to_pick_first, nullptr, 0,
+     true, true},
+    {"rstpit", description_rstpit, additional_constraints_rstpit, nullptr, 0,
+     false, true},
     {"schedule_cancellation_over_write",
      description_schedule_cancellation_over_write,
-     additional_constraints_schedule_cancellation_over_write, false, true},
+     additional_constraints_schedule_cancellation_over_write, nullptr, 0, false,
+     true},
     {"separate_ping_from_keepalive", description_separate_ping_from_keepalive,
-     additional_constraints_separate_ping_from_keepalive, true, true},
+     additional_constraints_separate_ping_from_keepalive, nullptr, 0, true,
+     true},
     {"server_privacy", description_server_privacy,
-     additional_constraints_server_privacy, false, false},
+     additional_constraints_server_privacy, nullptr, 0, false, false},
     {"settings_timeout", description_settings_timeout,
-     additional_constraints_settings_timeout, true, true},
-    {"tarpit", description_tarpit, additional_constraints_tarpit, true, true},
+     additional_constraints_settings_timeout, nullptr, 0, true, true},
+    {"tarpit", description_tarpit, additional_constraints_tarpit, nullptr, 0,
+     true, true},
     {"tcp_frame_size_tuning", description_tcp_frame_size_tuning,
-     additional_constraints_tcp_frame_size_tuning, false, true},
+     additional_constraints_tcp_frame_size_tuning, nullptr, 0, false, true},
     {"tcp_rcv_lowat", description_tcp_rcv_lowat,
-     additional_constraints_tcp_rcv_lowat, false, true},
+     additional_constraints_tcp_rcv_lowat, nullptr, 0, false, true},
     {"trace_record_callops", description_trace_record_callops,
-     additional_constraints_trace_record_callops, false, true},
+     additional_constraints_trace_record_callops, nullptr, 0, false, true},
     {"unconstrained_max_quota_buffer_size",
      description_unconstrained_max_quota_buffer_size,
-     additional_constraints_unconstrained_max_quota_buffer_size, false, true},
+     additional_constraints_unconstrained_max_quota_buffer_size, nullptr, 0,
+     false, true},
     {"uniquely_unowned", description_uniquely_unowned,
-     additional_constraints_uniquely_unowned, true, true},
+     additional_constraints_uniquely_unowned, nullptr, 0, true, true},
     {"work_serializer_clears_time_cache",
      description_work_serializer_clears_time_cache,
-     additional_constraints_work_serializer_clears_time_cache, true, true},
+     additional_constraints_work_serializer_clears_time_cache, nullptr, 0, true,
+     true},
     {"work_serializer_dispatch", description_work_serializer_dispatch,
-     additional_constraints_work_serializer_dispatch, false, true},
-    {"write_size_cap", description_write_size_cap,
-     additional_constraints_write_size_cap, true, true},
+     additional_constraints_work_serializer_dispatch, nullptr, 0, false, true},
     {"write_size_policy", description_write_size_policy,
-     additional_constraints_write_size_policy, true, true},
+     additional_constraints_write_size_policy, nullptr, 0, true, true},
+    {"write_size_cap", description_write_size_cap,
+     additional_constraints_write_size_cap, required_experiments_write_size_cap,
+     1, true, true},
     {"wrr_delegate_to_pick_first", description_wrr_delegate_to_pick_first,
-     additional_constraints_wrr_delegate_to_pick_first, true, true},
+     additional_constraints_wrr_delegate_to_pick_first, nullptr, 0, true, true},
 };
 
 }  // namespace grpc_core
@@ -638,13 +690,6 @@ const char* const additional_constraints_call_status_override_on_cancellation =
 const char* const description_canary_client_privacy =
     "If set, canary client privacy";
 const char* const additional_constraints_canary_client_privacy = "{}";
-const char* const description_chttp2_batch_requests =
-    "Cap the number of requests received by one transport read prior to "
-    "offload.";
-const char* const additional_constraints_chttp2_batch_requests = "{}";
-const char* const description_chttp2_offload_on_rst_stream =
-    "Offload work on RST_STREAM.";
-const char* const additional_constraints_chttp2_offload_on_rst_stream = "{}";
 const char* const description_client_idleness =
     "If enabled, client channel idleness is enabled by default.";
 const char* const additional_constraints_client_idleness = "{}";
@@ -654,6 +699,17 @@ const char* const description_combiner_offload_to_event_engine =
     "Offload Combiner work onto the EventEngine instead of the Executor.";
 const char* const additional_constraints_combiner_offload_to_event_engine =
     "{}";
+const char* const description_chttp2_batch_requests =
+    "Cap the number of requests received by one transport read prior to "
+    "offload.";
+const char* const additional_constraints_chttp2_batch_requests = "{}";
+const uint8_t required_experiments_chttp2_batch_requests[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdCombinerOffloadToEventEngine)};
+const char* const description_chttp2_offload_on_rst_stream =
+    "Offload work on RST_STREAM.";
+const char* const additional_constraints_chttp2_offload_on_rst_stream = "{}";
+const uint8_t required_experiments_chttp2_offload_on_rst_stream[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdCombinerOffloadToEventEngine)};
 const char* const description_event_engine_client =
     "Use EventEngine clients instead of iomgr's grpc_tcp_client";
 const char* const additional_constraints_event_engine_client = "{}";
@@ -725,6 +781,8 @@ 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 uint8_t required_experiments_promise_based_server_call[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdLazierStreamUpdates)};
 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.";
@@ -797,12 +855,14 @@ const char* const description_work_serializer_dispatch =
     "callback, instead of running things inline in the first thread that "
     "successfully enqueues work.";
 const char* const additional_constraints_work_serializer_dispatch = "{}";
-const char* const description_write_size_cap =
-    "Limit outgoing writes proportional to the target write size";
-const char* const additional_constraints_write_size_cap = "{}";
 const char* const description_write_size_policy =
     "Try to size writes such that they don't create too large of a backlog";
 const char* const additional_constraints_write_size_policy = "{}";
+const char* const description_write_size_cap =
+    "Limit outgoing writes proportional to the target write size";
+const char* const additional_constraints_write_size_cap = "{}";
+const uint8_t required_experiments_write_size_cap[] = {
+    static_cast<uint8_t>(grpc_core::kExperimentIdWriteSizePolicy)};
 const char* const description_wrr_delegate_to_pick_first =
     "Change WRR code to delegate to pick_first as per dualstack backend "
     "design.";
@@ -819,109 +879,126 @@ namespace grpc_core {
 const ExperimentMetadata g_experiment_metadata[] = {
     {"block_excessive_requests_before_settings_ack",
      description_block_excessive_requests_before_settings_ack,
-     additional_constraints_block_excessive_requests_before_settings_ack, true,
-     true},
+     additional_constraints_block_excessive_requests_before_settings_ack,
+     nullptr, 0, true, true},
     {"call_status_override_on_cancellation",
      description_call_status_override_on_cancellation,
-     additional_constraints_call_status_override_on_cancellation,
+     additional_constraints_call_status_override_on_cancellation, nullptr, 0,
      kDefaultForDebugOnly, true},
     {"canary_client_privacy", description_canary_client_privacy,
-     additional_constraints_canary_client_privacy, false, false},
-    {"chttp2_batch_requests", description_chttp2_batch_requests,
-     additional_constraints_chttp2_batch_requests, true, true},
-    {"chttp2_offload_on_rst_stream", description_chttp2_offload_on_rst_stream,
-     additional_constraints_chttp2_offload_on_rst_stream, true, true},
+     additional_constraints_canary_client_privacy, nullptr, 0, false, false},
     {"client_idleness", description_client_idleness,
-     additional_constraints_client_idleness, true, true},
+     additional_constraints_client_idleness, nullptr, 0, true, true},
     {"client_privacy", description_client_privacy,
-     additional_constraints_client_privacy, false, false},
+     additional_constraints_client_privacy, nullptr, 0, false, false},
     {"combiner_offload_to_event_engine",
      description_combiner_offload_to_event_engine,
-     additional_constraints_combiner_offload_to_event_engine, true, true},
+     additional_constraints_combiner_offload_to_event_engine, nullptr, 0, true,
+     true},
+    {"chttp2_batch_requests", description_chttp2_batch_requests,
+     additional_constraints_chttp2_batch_requests,
+     required_experiments_chttp2_batch_requests, 1, true, true},
+    {"chttp2_offload_on_rst_stream", description_chttp2_offload_on_rst_stream,
+     additional_constraints_chttp2_offload_on_rst_stream,
+     required_experiments_chttp2_offload_on_rst_stream, 1, true, true},
     {"event_engine_client", description_event_engine_client,
-     additional_constraints_event_engine_client, false, true},
+     additional_constraints_event_engine_client, nullptr, 0, false, true},
     {"event_engine_dns", description_event_engine_dns,
-     additional_constraints_event_engine_dns, false, false},
+     additional_constraints_event_engine_dns, nullptr, 0, false, false},
     {"event_engine_listener", description_event_engine_listener,
-     additional_constraints_event_engine_listener, true, true},
+     additional_constraints_event_engine_listener, nullptr, 0, true, true},
     {"free_large_allocator", description_free_large_allocator,
-     additional_constraints_free_large_allocator, false, true},
+     additional_constraints_free_large_allocator, nullptr, 0, false, true},
     {"http2_stats_fix", description_http2_stats_fix,
-     additional_constraints_http2_stats_fix, true, true},
+     additional_constraints_http2_stats_fix, nullptr, 0, true, true},
     {"keepalive_fix", description_keepalive_fix,
-     additional_constraints_keepalive_fix, false, false},
+     additional_constraints_keepalive_fix, nullptr, 0, false, false},
     {"keepalive_server_fix", description_keepalive_server_fix,
-     additional_constraints_keepalive_server_fix, false, false},
+     additional_constraints_keepalive_server_fix, nullptr, 0, false, false},
     {"lazier_stream_updates", description_lazier_stream_updates,
-     additional_constraints_lazier_stream_updates, true, true},
+     additional_constraints_lazier_stream_updates, nullptr, 0, true, true},
     {"memory_pressure_controller", description_memory_pressure_controller,
-     additional_constraints_memory_pressure_controller, false, true},
+     additional_constraints_memory_pressure_controller, nullptr, 0, false,
+     true},
     {"monitoring_experiment", description_monitoring_experiment,
-     additional_constraints_monitoring_experiment, true, true},
+     additional_constraints_monitoring_experiment, nullptr, 0, true, true},
     {"multiping", description_multiping, additional_constraints_multiping,
-     false, true},
+     nullptr, 0, false, true},
     {"overload_protection", description_overload_protection,
-     additional_constraints_overload_protection, true, true},
+     additional_constraints_overload_protection, nullptr, 0, true, true},
     {"peer_state_based_framing", description_peer_state_based_framing,
-     additional_constraints_peer_state_based_framing, false, true},
+     additional_constraints_peer_state_based_framing, nullptr, 0, false, true},
     {"pending_queue_cap", description_pending_queue_cap,
-     additional_constraints_pending_queue_cap, true, true},
+     additional_constraints_pending_queue_cap, nullptr, 0, true, true},
     {"pick_first_happy_eyeballs", description_pick_first_happy_eyeballs,
-     additional_constraints_pick_first_happy_eyeballs, true, true},
+     additional_constraints_pick_first_happy_eyeballs, nullptr, 0, true, true},
     {"ping_on_rst_stream", description_ping_on_rst_stream,
-     additional_constraints_ping_on_rst_stream, true, true},
+     additional_constraints_ping_on_rst_stream, nullptr, 0, true, true},
     {"promise_based_client_call", description_promise_based_client_call,
-     additional_constraints_promise_based_client_call, false, true},
+     additional_constraints_promise_based_client_call, nullptr, 0, false, true},
     {"promise_based_inproc_transport",
      description_promise_based_inproc_transport,
-     additional_constraints_promise_based_inproc_transport, false, false},
+     additional_constraints_promise_based_inproc_transport, nullptr, 0, false,
+     false},
     {"promise_based_server_call", description_promise_based_server_call,
-     additional_constraints_promise_based_server_call, false, true},
+     additional_constraints_promise_based_server_call,
+     required_experiments_promise_based_server_call, 1, false, true},
     {"red_max_concurrent_streams", description_red_max_concurrent_streams,
-     additional_constraints_red_max_concurrent_streams, false, true},
+     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, true, true},
+     additional_constraints_registered_method_lookup_in_transport, nullptr, 0,
+     true, true},
     {"registered_methods_map", description_registered_methods_map,
-     additional_constraints_registered_methods_map, false, true},
+     additional_constraints_registered_methods_map, nullptr, 0, false, true},
     {"rfc_max_concurrent_streams", description_rfc_max_concurrent_streams,
-     additional_constraints_rfc_max_concurrent_streams, false, true},
+     additional_constraints_rfc_max_concurrent_streams, nullptr, 0, false,
+     true},
     {"round_robin_delegate_to_pick_first",
      description_round_robin_delegate_to_pick_first,
-     additional_constraints_round_robin_delegate_to_pick_first, true, true},
-    {"rstpit", description_rstpit, additional_constraints_rstpit, false, true},
+     additional_constraints_round_robin_delegate_to_pick_first, nullptr, 0,
+     true, true},
+    {"rstpit", description_rstpit, additional_constraints_rstpit, nullptr, 0,
+     false, true},
     {"schedule_cancellation_over_write",
      description_schedule_cancellation_over_write,
-     additional_constraints_schedule_cancellation_over_write, false, true},
+     additional_constraints_schedule_cancellation_over_write, nullptr, 0, false,
+     true},
     {"separate_ping_from_keepalive", description_separate_ping_from_keepalive,
-     additional_constraints_separate_ping_from_keepalive, true, true},
+     additional_constraints_separate_ping_from_keepalive, nullptr, 0, true,
+     true},
     {"server_privacy", description_server_privacy,
-     additional_constraints_server_privacy, false, false},
+     additional_constraints_server_privacy, nullptr, 0, false, false},
     {"settings_timeout", description_settings_timeout,
-     additional_constraints_settings_timeout, true, true},
-    {"tarpit", description_tarpit, additional_constraints_tarpit, true, true},
+     additional_constraints_settings_timeout, nullptr, 0, true, true},
+    {"tarpit", description_tarpit, additional_constraints_tarpit, nullptr, 0,
+     true, true},
     {"tcp_frame_size_tuning", description_tcp_frame_size_tuning,
-     additional_constraints_tcp_frame_size_tuning, false, true},
+     additional_constraints_tcp_frame_size_tuning, nullptr, 0, false, true},
     {"tcp_rcv_lowat", description_tcp_rcv_lowat,
-     additional_constraints_tcp_rcv_lowat, false, true},
+     additional_constraints_tcp_rcv_lowat, nullptr, 0, false, true},
     {"trace_record_callops", description_trace_record_callops,
-     additional_constraints_trace_record_callops, false, true},
+     additional_constraints_trace_record_callops, nullptr, 0, false, true},
     {"unconstrained_max_quota_buffer_size",
      description_unconstrained_max_quota_buffer_size,
-     additional_constraints_unconstrained_max_quota_buffer_size, false, true},
+     additional_constraints_unconstrained_max_quota_buffer_size, nullptr, 0,
+     false, true},
     {"uniquely_unowned", description_uniquely_unowned,
-     additional_constraints_uniquely_unowned, true, true},
+     additional_constraints_uniquely_unowned, nullptr, 0, true, true},
     {"work_serializer_clears_time_cache",
      description_work_serializer_clears_time_cache,
-     additional_constraints_work_serializer_clears_time_cache, true, true},
+     additional_constraints_work_serializer_clears_time_cache, nullptr, 0, true,
+     true},
     {"work_serializer_dispatch", description_work_serializer_dispatch,
-     additional_constraints_work_serializer_dispatch, false, true},
-    {"write_size_cap", description_write_size_cap,
-     additional_constraints_write_size_cap, true, true},
+     additional_constraints_work_serializer_dispatch, nullptr, 0, false, true},
     {"write_size_policy", description_write_size_policy,
-     additional_constraints_write_size_policy, true, true},
+     additional_constraints_write_size_policy, nullptr, 0, true, true},
+    {"write_size_cap", description_write_size_cap,
+     additional_constraints_write_size_cap, required_experiments_write_size_cap,
+     1, true, true},
     {"wrr_delegate_to_pick_first", description_wrr_delegate_to_pick_first,
-     additional_constraints_wrr_delegate_to_pick_first, true, true},
+     additional_constraints_wrr_delegate_to_pick_first, nullptr, 0, true, true},
 };
 
 }  // namespace grpc_core

src/core/lib/experiments/experiments.h

@@ -70,15 +70,15 @@ inline bool IsCallStatusOverrideOnCancellationEnabled() {
 #endif
 }
 inline bool IsCanaryClientPrivacyEnabled() { return false; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_BATCH_REQUESTS
-inline bool IsChttp2BatchRequestsEnabled() { return true; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_OFFLOAD_ON_RST_STREAM
-inline bool IsChttp2OffloadOnRstStreamEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_CLIENT_IDLENESS
 inline bool IsClientIdlenessEnabled() { return true; }
 inline bool IsClientPrivacyEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_COMBINER_OFFLOAD_TO_EVENT_ENGINE
 inline bool IsCombinerOffloadToEventEngineEnabled() { return true; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_BATCH_REQUESTS
+inline bool IsChttp2BatchRequestsEnabled() { return true; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_OFFLOAD_ON_RST_STREAM
+inline bool IsChttp2OffloadOnRstStreamEnabled() { return true; }
 inline bool IsEventEngineClientEnabled() { return false; }
 inline bool IsEventEngineDnsEnabled() { return false; }
 inline bool IsEventEngineListenerEnabled() { return false; }
@@ -130,10 +130,10 @@ inline bool IsUniquelyUnownedEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WORK_SERIALIZER_CLEARS_TIME_CACHE
 inline bool IsWorkSerializerClearsTimeCacheEnabled() { return true; }
 inline bool IsWorkSerializerDispatchEnabled() { return false; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_CAP
-inline bool IsWriteSizeCapEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_POLICY
 inline bool IsWriteSizePolicyEnabled() { return true; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_CAP
+inline bool IsWriteSizeCapEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WRR_DELEGATE_TO_PICK_FIRST
 inline bool IsWrrDelegateToPickFirstEnabled() { return true; }
 
@@ -151,15 +151,15 @@ inline bool IsCallStatusOverrideOnCancellationEnabled() {
 #endif
 }
 inline bool IsCanaryClientPrivacyEnabled() { return false; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_BATCH_REQUESTS
-inline bool IsChttp2BatchRequestsEnabled() { return true; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_OFFLOAD_ON_RST_STREAM
-inline bool IsChttp2OffloadOnRstStreamEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_CLIENT_IDLENESS
 inline bool IsClientIdlenessEnabled() { return true; }
 inline bool IsClientPrivacyEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_COMBINER_OFFLOAD_TO_EVENT_ENGINE
 inline bool IsCombinerOffloadToEventEngineEnabled() { return true; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_BATCH_REQUESTS
+inline bool IsChttp2BatchRequestsEnabled() { return true; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_OFFLOAD_ON_RST_STREAM
+inline bool IsChttp2OffloadOnRstStreamEnabled() { return true; }
 inline bool IsEventEngineClientEnabled() { return false; }
 inline bool IsEventEngineDnsEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_EVENT_ENGINE_LISTENER
@@ -212,10 +212,10 @@ inline bool IsUniquelyUnownedEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WORK_SERIALIZER_CLEARS_TIME_CACHE
 inline bool IsWorkSerializerClearsTimeCacheEnabled() { return true; }
 inline bool IsWorkSerializerDispatchEnabled() { return false; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_CAP
-inline bool IsWriteSizeCapEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_POLICY
 inline bool IsWriteSizePolicyEnabled() { return true; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_CAP
+inline bool IsWriteSizeCapEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WRR_DELEGATE_TO_PICK_FIRST
 inline bool IsWrrDelegateToPickFirstEnabled() { return true; }
 
@@ -233,15 +233,15 @@ inline bool IsCallStatusOverrideOnCancellationEnabled() {
 #endif
 }
 inline bool IsCanaryClientPrivacyEnabled() { return false; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_BATCH_REQUESTS
-inline bool IsChttp2BatchRequestsEnabled() { return true; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_OFFLOAD_ON_RST_STREAM
-inline bool IsChttp2OffloadOnRstStreamEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_CLIENT_IDLENESS
 inline bool IsClientIdlenessEnabled() { return true; }
 inline bool IsClientPrivacyEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_COMBINER_OFFLOAD_TO_EVENT_ENGINE
 inline bool IsCombinerOffloadToEventEngineEnabled() { return true; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_BATCH_REQUESTS
+inline bool IsChttp2BatchRequestsEnabled() { return true; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_OFFLOAD_ON_RST_STREAM
+inline bool IsChttp2OffloadOnRstStreamEnabled() { return true; }
 inline bool IsEventEngineClientEnabled() { return false; }
 inline bool IsEventEngineDnsEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_EVENT_ENGINE_LISTENER
@@ -294,10 +294,10 @@ inline bool IsUniquelyUnownedEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WORK_SERIALIZER_CLEARS_TIME_CACHE
 inline bool IsWorkSerializerClearsTimeCacheEnabled() { return true; }
 inline bool IsWorkSerializerDispatchEnabled() { return false; }
-#define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_CAP
-inline bool IsWriteSizeCapEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_POLICY
 inline bool IsWriteSizePolicyEnabled() { return true; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_CAP
+inline bool IsWriteSizeCapEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WRR_DELEGATE_TO_PICK_FIRST
 inline bool IsWrrDelegateToPickFirstEnabled() { return true; }
 #endif
@@ -307,11 +307,11 @@ enum ExperimentIds {
   kExperimentIdBlockExcessiveRequestsBeforeSettingsAck,
   kExperimentIdCallStatusOverrideOnCancellation,
   kExperimentIdCanaryClientPrivacy,
-  kExperimentIdChttp2BatchRequests,
-  kExperimentIdChttp2OffloadOnRstStream,
   kExperimentIdClientIdleness,
   kExperimentIdClientPrivacy,
   kExperimentIdCombinerOffloadToEventEngine,
+  kExperimentIdChttp2BatchRequests,
+  kExperimentIdChttp2OffloadOnRstStream,
   kExperimentIdEventEngineClient,
   kExperimentIdEventEngineDns,
   kExperimentIdEventEngineListener,
@@ -349,8 +349,8 @@ enum ExperimentIds {
   kExperimentIdUniquelyUnowned,
   kExperimentIdWorkSerializerClearsTimeCache,
   kExperimentIdWorkSerializerDispatch,
-  kExperimentIdWriteSizeCap,
   kExperimentIdWriteSizePolicy,
+  kExperimentIdWriteSizeCap,
   kExperimentIdWrrDelegateToPickFirst,
   kNumExperiments
 };
@@ -367,14 +367,6 @@ inline bool IsCallStatusOverrideOnCancellationEnabled() {
 inline bool IsCanaryClientPrivacyEnabled() {
   return IsExperimentEnabled(kExperimentIdCanaryClientPrivacy);
 }
-#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_BATCH_REQUESTS
-inline bool IsChttp2BatchRequestsEnabled() {
-  return IsExperimentEnabled(kExperimentIdChttp2BatchRequests);
-}
-#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_OFFLOAD_ON_RST_STREAM
-inline bool IsChttp2OffloadOnRstStreamEnabled() {
-  return IsExperimentEnabled(kExperimentIdChttp2OffloadOnRstStream);
-}
 #define GRPC_EXPERIMENT_IS_INCLUDED_CLIENT_IDLENESS
 inline bool IsClientIdlenessEnabled() {
   return IsExperimentEnabled(kExperimentIdClientIdleness);
@@ -387,6 +379,14 @@ inline bool IsClientPrivacyEnabled() {
 inline bool IsCombinerOffloadToEventEngineEnabled() {
   return IsExperimentEnabled(kExperimentIdCombinerOffloadToEventEngine);
 }
+#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_BATCH_REQUESTS
+inline bool IsChttp2BatchRequestsEnabled() {
+  return IsExperimentEnabled(kExperimentIdChttp2BatchRequests);
+}
+#define GRPC_EXPERIMENT_IS_INCLUDED_CHTTP2_OFFLOAD_ON_RST_STREAM
+inline bool IsChttp2OffloadOnRstStreamEnabled() {
+  return IsExperimentEnabled(kExperimentIdChttp2OffloadOnRstStream);
+}
 #define GRPC_EXPERIMENT_IS_INCLUDED_EVENT_ENGINE_CLIENT
 inline bool IsEventEngineClientEnabled() {
   return IsExperimentEnabled(kExperimentIdEventEngineClient);
@@ -535,14 +535,14 @@ inline bool IsWorkSerializerClearsTimeCacheEnabled() {
 inline bool IsWorkSerializerDispatchEnabled() {
   return IsExperimentEnabled(kExperimentIdWorkSerializerDispatch);
 }
-#define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_CAP
-inline bool IsWriteSizeCapEnabled() {
-  return IsExperimentEnabled(kExperimentIdWriteSizeCap);
-}
 #define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_POLICY
 inline bool IsWriteSizePolicyEnabled() {
   return IsExperimentEnabled(kExperimentIdWriteSizePolicy);
 }
+#define GRPC_EXPERIMENT_IS_INCLUDED_WRITE_SIZE_CAP
+inline bool IsWriteSizeCapEnabled() {
+  return IsExperimentEnabled(kExperimentIdWriteSizeCap);
+}
 #define GRPC_EXPERIMENT_IS_INCLUDED_WRR_DELEGATE_TO_PICK_FIRST
 inline bool IsWrrDelegateToPickFirstEnabled() {
   return IsExperimentEnabled(kExperimentIdWrrDelegateToPickFirst);

src/core/lib/experiments/experiments.yaml

@@ -22,6 +22,10 @@
 # allow_in_fuzzing_config: optional boolean (true if not specified)
 #              if false, this experiment will not be included in fuzzers that
 #              explore the config space
+# requires:    A list of names of experiments that this experiment depends on.
+#              Defaults to the empty list.
+#              If any of the experiments in the required list is determined to
+#              be disabled at runtime, this experiment is disabled at runtime.
 #
 # Well known test tags:
 #   core_end2end_test:   all tests, fixtures in the core end2end suite
@@ -59,12 +63,14 @@
   expiry: 2024/03/03
   owner: ctiller@google.com
   test_tags: ["cpp_end2end_test", "flow_control_test"]
+  requires: [combiner_offload_to_event_engine]
 - name: chttp2_offload_on_rst_stream
   description:
     Offload work on RST_STREAM.
   expiry: 2024/03/03
   owner: ctiller@google.com
   test_tags: ["cpp_end2end_test", "flow_control_test"]
+  requires: [combiner_offload_to_event_engine]
 - name: client_idleness
   description: If enabled, client channel idleness is enabled by default.
   expiry: 2023/12/15
@@ -210,6 +216,7 @@
   expiry: 2024/06/14
   owner: ctiller@google.com
   test_tags: ["core_end2end_test", "cpp_end2end_test", "xds_end2end_test", "logging_test"]
+  requires: [lazier_stream_updates]
 - name: red_max_concurrent_streams
   description:
     Perform random early rejection of requests that would exceed a newly reduced
@@ -331,6 +338,7 @@
   expiry: 2024/03/03
   owner: ctiller@google.com
   test_tags: [flow_control_test]
+  requires: [write_size_policy]
 - name: write_size_policy
   description:
     Try to size writes such that they don't create too large of a backlog

src/core/lib/experiments/rollouts.yaml

@@ -22,6 +22,10 @@
 #              - debug   - the experiment defaults to on in debug builds,
 #                          off in release builds in all platforms.
 #              - true    - the experiment defaults to on in all platforms.
+# requires:    A list of names of experiments that this experiment depends on.
+#              Defaults to the empty list.
+#              If any of the experiments in the required list is determined to
+#              be disabled at runtime, this experiment is disabled at runtime.
 #
 # [OR] the default can be platform specific:
 #  -----------------------------------------

test/core/experiments/fixtures/experiments.cc

@@ -41,13 +41,14 @@ namespace grpc_core {
 
 const ExperimentMetadata g_test_experiment_metadata[] = {
     {"test_experiment_1", description_test_experiment_1,
-     additional_constraints_test_experiment_1, false, true},
+     additional_constraints_test_experiment_1, nullptr, 0, false, true},
     {"test_experiment_2", description_test_experiment_2,
-     additional_constraints_test_experiment_2, true, true},
+     additional_constraints_test_experiment_2, nullptr, 0, true, true},
     {"test_experiment_3", description_test_experiment_3,
-     additional_constraints_test_experiment_3, kDefaultForDebugOnly, true},
+     additional_constraints_test_experiment_3, nullptr, 0, kDefaultForDebugOnly,
+     true},
     {"test_experiment_4", description_test_experiment_4,
-     additional_constraints_test_experiment_4, true, true},
+     additional_constraints_test_experiment_4, nullptr, 0, true, true},
 };
 
 }  // namespace grpc_core
@@ -73,13 +74,14 @@ namespace grpc_core {
 
 const ExperimentMetadata g_test_experiment_metadata[] = {
     {"test_experiment_1", description_test_experiment_1,
-     additional_constraints_test_experiment_1, false, true},
+     additional_constraints_test_experiment_1, nullptr, 0, false, true},
     {"test_experiment_2", description_test_experiment_2,
-     additional_constraints_test_experiment_2, false, true},
+     additional_constraints_test_experiment_2, nullptr, 0, false, true},
     {"test_experiment_3", description_test_experiment_3,
-     additional_constraints_test_experiment_3, kDefaultForDebugOnly, true},
+     additional_constraints_test_experiment_3, nullptr, 0, kDefaultForDebugOnly,
+     true},
     {"test_experiment_4", description_test_experiment_4,
-     additional_constraints_test_experiment_4, true, true},
+     additional_constraints_test_experiment_4, nullptr, 0, true, true},
 };
 
 }  // namespace grpc_core
@@ -105,13 +107,16 @@ namespace grpc_core {
 
 const ExperimentMetadata g_test_experiment_metadata[] = {
     {"test_experiment_1", description_test_experiment_1,
-     additional_constraints_test_experiment_1, kDefaultForDebugOnly, true},
+     additional_constraints_test_experiment_1, nullptr, 0, kDefaultForDebugOnly,
+     true},
     {"test_experiment_2", description_test_experiment_2,
-     additional_constraints_test_experiment_2, kDefaultForDebugOnly, true},
+     additional_constraints_test_experiment_2, nullptr, 0, kDefaultForDebugOnly,
+     true},
     {"test_experiment_3", description_test_experiment_3,
-     additional_constraints_test_experiment_3, kDefaultForDebugOnly, true},
+     additional_constraints_test_experiment_3, nullptr, 0, kDefaultForDebugOnly,
+     true},
     {"test_experiment_4", description_test_experiment_4,
-     additional_constraints_test_experiment_4, false, true},
+     additional_constraints_test_experiment_4, nullptr, 0, false, true},
 };
 
 }  // namespace grpc_core

tools/codegen/core/experiments_compiler.py

@@ -198,6 +198,7 @@ class ExperimentDefinition(object):
         self._default = {}
         self._additional_constraints = {}
         self._test_tags = []
+        self._requires = set()
 
         if "allow_in_fuzzing_config" in attributes:
             self._allow_in_fuzzing_config = attributes[
@@ -207,6 +208,9 @@ class ExperimentDefinition(object):
         if "test_tags" in attributes:
             self._test_tags = attributes["test_tags"]
 
+        for requirement in attributes.get("requires", []):
+            self._requires.add(requirement)
+
     def IsValid(self, check_expiry=False):
         if self._error:
             return False
@@ -244,6 +248,8 @@ class ExperimentDefinition(object):
                 " experiment: %s" % self._name
             )
             return False
+        for requirement in rollout_attributes.get("requires", []):
+            self._requires.add(requirement)
         if "default" not in rollout_attributes:
             print(
                 "ERROR: no default for experiment %s"
@@ -310,7 +316,7 @@ class ExperimentsCompiler(object):
         self._final_define = final_define
         self._platforms_define = platforms_define
         self._bzl_list_for_defaults = bzl_list_for_defaults
-        self._experiment_definitions = {}
+        self._experiment_definitions = collections.OrderedDict()
         self._experiment_rollouts = {}
 
     def AddExperimentDefinition(self, experiment_definition):
@@ -344,6 +350,27 @@ class ExperimentsCompiler(object):
             self._defaults, self._platforms_define, rollout_attributes
         )
 
+    def _FinalizeExperiments(self):
+        queue = collections.OrderedDict()
+        for name, exp in self._experiment_definitions.items():
+            queue[name] = exp._requires
+        done = set()
+        final = collections.OrderedDict()
+        while queue:
+            take = None
+            for name, requires in queue.items():
+                if requires.issubset(done):
+                    take = name
+                    break
+            if take is None:
+                print("ERROR: circular dependency in experiments")
+                return False
+            done.add(take)
+            final[take] = self._experiment_definitions[take]
+            del queue[take]
+        self._experiment_definitions = final
+        return True
+
     def _GenerateExperimentsHdrForPlatform(self, platform, file_desc):
         for _, exp in self._experiment_definitions.items():
             define_fmt = self._final_define[exp.default(platform)]
@@ -363,6 +390,7 @@ class ExperimentsCompiler(object):
             )
 
     def GenerateExperimentsHdr(self, output_file, mode):
+        assert self._FinalizeExperiments()
         with open(output_file, "w") as H:
             PutCopyright(H, "//")
             PutBanner(
@@ -463,6 +491,18 @@ class ExperimentsCompiler(object):
                 file=file_desc,
             )
             have_defaults.add(self._defaults[exp.default(platform)])
+            if exp._requires:
+                print(
+                    "const uint8_t required_experiments_%s[] = {%s};"
+                    % (
+                        exp.name,
+                        ",".join(
+                            f"static_cast<uint8_t>(grpc_core::kExperimentId{SnakeToPascal(name)})"
+                            for name in sorted(exp._requires)
+                        ),
+                    ),
+                    file=file_desc,
+                )
         if "kDefaultForDebugOnly" in have_defaults:
             print("#ifdef NDEBUG", file=file_desc)
             if "kDefaultForDebugOnly" in have_defaults:
@@ -487,11 +527,15 @@ class ExperimentsCompiler(object):
         )
         for _, exp in self._experiment_definitions.items():
             print(
-                "  {%s, description_%s, additional_constraints_%s, %s, %s},"
+                "  {%s, description_%s, additional_constraints_%s, %s, %d, %s, %s},"
                 % (
                     ToCStr(exp.name),
                     exp.name,
                     exp.name,
+                    f"required_experiments_{exp.name}"
+                    if exp._requires
+                    else "nullptr",
+                    len(exp._requires),
                     self._defaults[exp.default(platform)],
                     "true" if exp.allow_in_fuzzing_config else "false",
                 ),
@@ -502,6 +546,7 @@ class ExperimentsCompiler(object):
         print("}  // namespace grpc_core", file=file_desc)
 
     def GenerateExperimentsSrc(self, output_file, header_file_path, mode):
+        assert self._FinalizeExperiments()
         with open(output_file, "w") as C:
             PutCopyright(C, "//")
             PutBanner(
@@ -510,7 +555,15 @@ class ExperimentsCompiler(object):
                 "//",
             )
 
+            any_requires = False
+            for _, exp in self._experiment_definitions.items():
+                if exp._requires:
+                    any_requires = True
+                    break
+
             print("#include <grpc/support/port_platform.h>", file=C)
+            if any_requires:
+                print("#include <stdint.h>", file=C)
             print(f'#include "{header_file_path}"', file=C)
             print(file=C)
             print("#ifndef GRPC_EXPERIMENTS_ARE_FINAL", file=C)
@@ -540,6 +593,7 @@ class ExperimentsCompiler(object):
         return defs
 
     def GenTest(self, output_file):
+        assert self._FinalizeExperiments()
         with open(output_file, "w") as C:
             PutCopyright(C, "//")
             PutBanner(
@@ -567,6 +621,7 @@ class ExperimentsCompiler(object):
             print(_EXPERIMENTS_TEST_SKELETON(defs, test_body), file=C)
 
     def GenExperimentsBzl(self, mode, output_file):
+        assert self._FinalizeExperiments()
         if self._bzl_list_for_defaults is None:
             return
 
@@ -610,6 +665,19 @@ class ExperimentsCompiler(object):
                 file=B,
             )
 
+            print(file=B)
+            if mode == "test":
+                print("TEST_EXPERIMENT_ENABLES = {", file=B)
+            else:
+                print("EXPERIMENT_ENABLES = {", file=B)
+            for name, exp in self._experiment_definitions.items():
+                enables = exp._requires.copy()
+                enables.add(name)
+                print(
+                    f"    \"{name}\": \"{','.join(sorted(enables))}\",", file=B
+                )
+            print("}", file=B)
+
             print(file=B)
             if mode == "test":
                 print("TEST_EXPERIMENTS = {", file=B)