From dd0d4ae217cd853e1a9e703201ac34e8746a7189 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafael=20=C3=81vila=20de=20Esp=C3=ADndola?=
 <espindola@scylladb.com>
Date: Fri, 20 Mar 2020 16:08:40 -0700
Subject: [PATCH] Add absl wrapper headers
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Using these instead of using the absl headers directly adds support
for heterogeneous lookup with sstring as key.

The is no gain from having the hash function inline, so this
implements it in a .cc file.

Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
---
 absl-flat_hash_map.cc | 26 ++++++++++++++++++++++++
 absl-flat_hash_map.hh | 47 +++++++++++++++++++++++++++++++++++++++++++
 configure.py          |  1 +
 3 files changed, 74 insertions(+)
 create mode 100644 absl-flat_hash_map.cc
 create mode 100644 absl-flat_hash_map.hh

diff --git a/absl-flat_hash_map.cc b/absl-flat_hash_map.cc
new file mode 100644
index 0000000000..fd7944b6e4
--- /dev/null
+++ b/absl-flat_hash_map.cc
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2020 ScyllaDB
+ */
+
+/*
+ * This file is part of Scylla.
+ *
+ * Scylla is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Scylla is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Scylla.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "absl-flat_hash_map.hh"
+
+size_t sstring_hash::operator()(std::string_view v) const noexcept {
+    return absl::Hash<std::string_view>{}(v);
+}
diff --git a/absl-flat_hash_map.hh b/absl-flat_hash_map.hh
new file mode 100644
index 0000000000..82a0aeb6bc
--- /dev/null
+++ b/absl-flat_hash_map.hh
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2020 ScyllaDB
+ */
+
+/*
+ * This file is part of Scylla.
+ *
+ * Scylla is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Scylla is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Scylla.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <absl/container/flat_hash_map.h>
+#include <seastar/core/sstring.hh>
+
+using namespace seastar;
+
+struct sstring_hash {
+    using is_transparent = void;
+    size_t operator()(std::string_view v) const noexcept;
+};
+
+struct sstring_eq {
+    using is_transparent = void;
+    bool operator()(std::string_view a, std::string_view b) const noexcept {
+        return a == b;
+    }
+};
+
+template <typename K, typename V, typename... Ts>
+struct flat_hash_map : public absl::flat_hash_map<K, V, Ts...> {
+};
+
+template <typename V>
+struct flat_hash_map<sstring, V>
+    : public absl::flat_hash_map<sstring, V, sstring_hash, sstring_eq> {};
diff --git a/configure.py b/configure.py
index afb585e2ff..5eebfb53bc 100755
--- a/configure.py
+++ b/configure.py
@@ -492,6 +492,7 @@ extra_cxxflags = {}
 cassandra_interface = Thrift(source='interface/cassandra.thrift', service='Cassandra')
 
 scylla_core = (['database.cc',
+                'absl-flat_hash_map.cc',
                 'table.cc',
                 'atomic_cell.cc',
                 'collection_mutation.cc',