From 14c6648c71b4b8a12ac0905ff23fcd4de7f0556f Mon Sep 17 00:00:00 2001
From: Oliver Reiche <oliver.reiche@huawei.com>
Date: Mon, 13 Jun 2022 13:30:13 +0200
Subject: multithreading: Add AtomicValue to atomically set/get value

... and use it to replace the commonly used pattern in
Expression, LinkedMap, and GitTreeEntry. Furthermore, remove
assignment operators for Expression and LinkedMap as those
are considered to be used in an immutable manner anyway.
---
 .../build_engine/expression/expression.hpp         | 25 ++++++----------------
 1 file changed, 6 insertions(+), 19 deletions(-)

(limited to 'src/buildtool/build_engine/expression/expression.hpp')

diff --git a/src/buildtool/build_engine/expression/expression.hpp b/src/buildtool/build_engine/expression/expression.hpp
index 412de057..6acb1e0e 100644
--- a/src/buildtool/build_engine/expression/expression.hpp
+++ b/src/buildtool/build_engine/expression/expression.hpp
@@ -20,7 +20,7 @@
 #include "src/buildtool/build_engine/expression/target_result.hpp"
 #include "src/buildtool/common/artifact_description.hpp"
 #include "src/buildtool/crypto/hash_generator.hpp"
-#include "src/utils/cpp/atomic.hpp"
+#include "src/buildtool/multithreading/atomic_value.hpp"
 #include "src/utils/cpp/hex_string.hpp"
 #include "src/utils/cpp/json.hpp"
 
@@ -63,22 +63,10 @@ class Expression {
 
     Expression() noexcept = default;
     ~Expression() noexcept = default;
-    Expression(Expression const& other) noexcept
-        : data_{other.data_}, hash_{other.hash_.load()} {}
-    Expression(Expression&& other) noexcept
-        : data_{std::move(other.data_)}, hash_{other.hash_.load()} {}
-    auto operator=(Expression const& other) noexcept -> Expression& {
-        if (this != &other) {
-            data_ = other.data_;
-        }
-        hash_ = other.hash_.load();
-        return *this;
-    }
-    auto operator=(Expression&& other) noexcept -> Expression& {
-        data_ = std::move(other.data_);
-        hash_ = other.hash_.load();
-        return *this;
-    }
+    Expression(Expression const& other) noexcept = default;
+    Expression(Expression&& other) noexcept = default;
+    auto operator=(Expression const& other) noexcept = delete;
+    auto operator=(Expression&& other) noexcept = delete;
 
     template <class T>
     requires(IsValidType<std::remove_cvref_t<T>>())
@@ -256,8 +244,7 @@ class Expression {
                  map_t>
         data_{none_t{}};
 
-    mutable atomic_shared_ptr<std::string> hash_{};
-    mutable std::atomic<bool> hash_loading_{};
+    AtomicValue<std::string> hash_{};
 
     template <class T, std::size_t kIndex = 0>
     requires(IsValidType<T>()) [[nodiscard]] static consteval auto GetIndexOf()
-- 
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