--- /dev/null
+/*
+ * 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_CORE_LIB_SLICE_SLICE_WEAK_HASH_TABLE_H
+#define GRPC_CORE_LIB_SLICE_SLICE_WEAK_HASH_TABLE_H
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/lib/gprpp/memory.h"
+#include "src/core/lib/gprpp/ref_counted.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/slice/slice_internal.h"
+
+/// Weak hash table implementation.
+///
+/// This entries in this table are weak: an entry may be removed at any time due
+/// to a number of reasons: memory pressure, hash collisions, etc.
+///
+/// The keys are \a grpc_slice objects. The values are of arbitrary type.
+///
+/// This class is thread unsafe. It's the caller's responsibility to ensure
+/// proper locking when accessing its methods.
+
+namespace grpc_core {
+
+template <typename T, size_t Size>
+class SliceWeakHashTable : public RefCounted<SliceWeakHashTable<T, Size>> {
+ public:
+ /// Creates a new table of at most \a size entries.
+ static RefCountedPtr<SliceWeakHashTable> Create() {
+ return MakeRefCounted<SliceWeakHashTable<T, Size>>();
+ }
+
+ /// Add a mapping from \a key to \a value, taking ownership of \a key. This
+ /// operation will always succeed. It may discard older entries.
+ void Add(const grpc_slice& key, T value) {
+ const size_t idx = grpc_slice_hash_internal(key) % Size;
+ entries_[idx].Set(key, std::move(value));
+ return;
+ }
+
+ /// Returns the value from the table associated with / \a key or null if not
+ /// found.
+ const T* Get(const grpc_slice& key) const {
+ const size_t idx = grpc_slice_hash_internal(key) % Size;
+ const auto& entry = entries_[idx];
+ return grpc_slice_eq(entry.key(), key) ? entry.value() : nullptr;
+ }
+
+ private:
+ GRPC_ALLOW_CLASS_TO_USE_NON_PUBLIC_NEW
+ GRPC_ALLOW_CLASS_TO_USE_NON_PUBLIC_DELETE
+
+ SliceWeakHashTable() = default;
+ ~SliceWeakHashTable() = default;
+
+ /// The type of the table "rows".
+ class Entry {
+ public:
+ Entry() = default;
+ ~Entry() {
+ if (is_set_) grpc_slice_unref_internal(key_);
+ }
+ const grpc_slice& key() const { return key_; }
+
+ /// Return the entry's value, or null if unset.
+ const T* value() const {
+ if (!is_set_) return nullptr;
+ return &value_;
+ }
+
+ /// Set the \a key and \a value (which is moved) for the entry.
+ void Set(const grpc_slice& key, T&& value) {
+ if (is_set_) grpc_slice_unref_internal(key_);
+ key_ = key;
+ value_ = std::move(value);
+ is_set_ = true;
+ }
+
+ private:
+ grpc_slice key_;
+ T value_;
+ bool is_set_ = false;
+ };
+
+ Entry entries_[Size];
+};
+
+} // namespace grpc_core
+
+#endif /* GRPC_CORE_LIB_SLICE_SLICE_WEAK_HASH_TABLE_H */