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diff --git a/src/core/lib/promise/inter_activity_latch.h b/src/core/lib/promise/inter_activity_latch.h
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+++ b/src/core/lib/promise/inter_activity_latch.h
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+// Copyright 2021 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_PROMISE_INTER_ACTIVITY_LATCH_H
+#define GRPC_SRC_CORE_LIB_PROMISE_INTER_ACTIVITY_LATCH_H
+
+#include <grpc/support/port_platform.h>
+
+#include <stdint.h>
+
+#include <string>
+
+#include "absl/base/thread_annotations.h"
+#include "absl/strings/str_cat.h"
+
+#include <grpc/support/log.h>
+
+#include "src/core/lib/gprpp/sync.h"
+#include "src/core/lib/promise/activity.h"
+#include "src/core/lib/promise/poll.h"
+#include "src/core/lib/promise/trace.h"
+#include "src/core/lib/promise/wait_set.h"
+
+namespace grpc_core {
+
+// A latch providing true cross activity wakeups
+template <typename T>
+class InterActivityLatch;
+
+template <>
+class InterActivityLatch<void> {
+ public:
+  InterActivityLatch() = default;
+  InterActivityLatch(const InterActivityLatch&) = delete;
+  InterActivityLatch& operator=(const InterActivityLatch&) = delete;
+
+  // Produce a promise to wait for this latch.
+  auto Wait() {
+    return [this]() -> Poll<Empty> {
+      MutexLock lock(&mu_);
+      if (grpc_trace_promise_primitives.enabled()) {
+        gpr_log(GPR_INFO, "%sPollWait %s", DebugTag().c_str(),
+                StateString().c_str());
+      }
+      if (is_set_) {
+        return Empty{};
+      } else {
+        return waiters_.AddPending(Activity::current()->MakeNonOwningWaker());
+      }
+    };
+  }
+
+  // Set the latch.
+  void Set() {
+    MutexLock lock(&mu_);
+    if (grpc_trace_promise_primitives.enabled()) {
+      gpr_log(GPR_INFO, "%sSet %s", DebugTag().c_str(), StateString().c_str());
+    }
+    is_set_ = true;
+    waiters_.WakeupAsync();
+  }
+
+  bool IsSet() const ABSL_LOCKS_EXCLUDED(mu_) {
+    MutexLock lock(&mu_);
+    return is_set_;
+  }
+
+ private:
+  std::string DebugTag() {
+    return absl::StrCat(Activity::current()->DebugTag(),
+                        " INTER_ACTIVITY_LATCH[0x",
+                        reinterpret_cast<uintptr_t>(this), "]: ");
+  }
+
+  std::string StateString() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mu_) {
+    return absl::StrCat("is_set:", is_set_);
+  }
+
+  mutable Mutex mu_;
+  // True if we have a value set, false otherwise.
+  bool is_set_ = false;
+  WaitSet waiters_ ABSL_GUARDED_BY(mu_);
+};
+
+}  // namespace grpc_core
+
+#endif  // GRPC_SRC_CORE_LIB_PROMISE_INTER_ACTIVITY_LATCH_H