Merge pull request #1436 from cloudflare/dominik/autogates2

Autogate fixes and improvements.

src/workerd/server/BUILD.bazel

@@ -124,7 +124,7 @@ wd_cc_library(
     srcs = ["autogate.c++"],
     hdrs = ["autogate.h"],
     visibility = ["//visibility:public"],
-    deps = ["@capnp-cpp//src/kj:kj", ":workerd_capnp"],
+    deps = ["@capnp-cpp//src/kj:kj", ":workerd_capnp", "//src/workerd/util:sentry"],
 )
 
 [kj_test(

src/workerd/server/autogate.c++

@@ -2,9 +2,12 @@
 // Licensed under the Apache 2.0 license found in the LICENSE file or at:
 //     https://opensource.org/licenses/Apache-2.0
 #include "autogate.h"
+#include <workerd/util/sentry.h>
 
 namespace workerd::server {
 
+kj::Maybe<Autogate> globalAutogate;
+
 kj::StringPtr KJ_STRINGIFY(AutogateKey key) {
   switch (key) {
     case AutogateKey::TEST_WORKERD:
@@ -21,6 +24,7 @@ Autogate::Autogate(capnp::List<config::Config::Autogate, capnp::Kind::STRUCT>::R
     }
     auto name = autogate.getName();
     if (!name.startsWith("workerd-autogate-")) {
+      LOG_ERROR_ONCE("Autogate configuration includes gate with invalid prefix.");
       continue;
     }
     auto sliced = name.slice(17);
@@ -35,21 +39,28 @@ Autogate::Autogate(capnp::List<config::Config::Autogate, capnp::Kind::STRUCT>::R
   }
 }
 
-bool Autogate::isEnabled(AutogateKey key) const {
-  return gates.find(key).orDefault(false);
+bool Autogate::isEnabled(AutogateKey key) {
+  KJ_IF_SOME(a, globalAutogate) {
+    return a.gates.find(key).orDefault(false);
+  }
+  LOG_ERROR_PERIODICALLY(
+      kj::str("Autogates not initialised, check for ", key, " will have no effect"));
+  return false;
 }
 
-kj::Maybe<Autogate> globalAutogate;
-void initAutogate(config::Config::Reader config) {
+void Autogate::initAutogate(config::Config::Reader config) {
   if (!config.hasAutogates()) {
     return;
   }
 
   globalAutogate = Autogate(config.getAutogates());
 }
 
-void initAutogate(capnp::List<config::Config::Autogate, capnp::Kind::STRUCT>::Reader autogates) {
+void Autogate::initAutogate(capnp::List<config::Config::Autogate,
+    capnp::Kind::STRUCT>::Reader autogates) {
   globalAutogate = Autogate(autogates);
 }
 
+void Autogate::deinitAutogate() { globalAutogate = kj::none; }
+
 }  // namespace workerd::server

src/workerd/server/autogate.h

@@ -26,26 +26,30 @@ enum class AutogateKey {
 //     #include <workerd/server/autogate.h>
 //     Autogate::isEnabled(AutogateKey::YOUR_FEATURE_KEY)
 //
-// When making structural changes here, ensure you align them with autogate.h in workerd.
+// When making structural changes here, ensure you align them with autogate.h in the internal repo.
 class Autogate {
 
 public:
-  Autogate(capnp::List<config::Config::Autogate, capnp::Kind::STRUCT>::Reader autogates);
-
-  bool isEnabled(AutogateKey key) const;
-
+  static bool isEnabled(AutogateKey key);
+
+  // Creates a global Autogate and seeds it with gates that are specified in the config.
+  //
+  // This function is not thread safe, it should be called exactly once close to the start of the
+  // process before any threads are created.
+  static void initAutogate(config::Config::Reader config);
+  static void initAutogate(
+      capnp::List<config::Config::Autogate, capnp::Kind::STRUCT>::Reader autogates);
+  // Destroys an initialised global Autogate instance. Used only for testing.
+  static void deinitAutogate();
 private:
   kj::HashMap<AutogateKey, bool> gates;
+
+  Autogate(capnp::List<config::Config::Autogate, capnp::Kind::STRUCT>::Reader autogates);
 };
 
 // Retrieves the name of the gate.
 //
 // When adding a new gate, add it into this method as well.
 kj::StringPtr KJ_STRINGIFY(AutogateKey key);
 
-extern kj::Maybe<Autogate> globalAutogate;
-
-void initAutogate(config::Config::Reader config);
-void initAutogate(capnp::List<config::Config::Autogate, capnp::Kind::STRUCT>::Reader autogates);
-
 }  // namespace workerd::server

src/workerd/server/workerd.c++

@@ -849,7 +849,7 @@ public:
     }
 
     KJ_IF_SOME(c, config) {
-      initAutogate(c);
+      Autogate::initAutogate(c);
     }
   }