refactor!: Use consteval on hashString (#3833)

This allows us to enforce in more places that the hash is calculated at compile time. To make the distinction explicit, I'm adding another function whose name indicates that the hash will be computed at runtime.

BREAKING CHANGES:

The `hashString` function becomes `consteval`, so requires compile-time execution. Use this if at all possible! If not, switch to `hashStringDynamic`, which remains `constexpr` and can thus be executed at runtime.

Core/include/Acts/EventData/ProxyAccessor.hpp

@@ -75,7 +75,7 @@ struct ProxyAccessorBase {
   /// Create the accessor from a string key
   /// @param _key the key
   constexpr ProxyAccessorBase(const std::string& _key)
-      : key{hashString(_key)} {}
+      : key{hashStringDynamic(_key)} {}
 
   /// Access the stored key on the proxy given as an argument. Mutable version
   /// @tparam proxy_t the type of the proxy

Core/include/Acts/EventData/TrackContainer.hpp

@@ -252,7 +252,7 @@ class TrackContainer {
   /// Check if this track container has a specific dynamic column
   /// @param key the key to check for
   constexpr bool hasColumn(const std::string& key) const {
-    return m_container->hasColumn_impl(hashString(key));
+    return m_container->hasColumn_impl(hashStringDynamic(key));
   }
 
   /// Check if a this track container has a specific dynamic column

Core/include/Acts/EventData/TrackProxy.hpp

@@ -710,7 +710,7 @@ class TrackProxy {
   constexpr T& component(std::string_view key)
     requires(!ReadOnly)
   {
-    return m_container->template component<T>(hashString(key), m_index);
+    return m_container->template component<T>(hashStringDynamic(key), m_index);
   }
 
   /// Retrieve a const reference to a component
@@ -738,7 +738,7 @@ class TrackProxy {
   /// @return Const reference to the component given by @p key
   template <typename T>
   constexpr const T& component(std::string_view key) const {
-    return m_container->template component<T>(hashString(key), m_index);
+    return m_container->template component<T>(hashStringDynamic(key), m_index);
   }
 
   /// @}

Core/include/Acts/EventData/TrackStateProxy.hpp

@@ -1101,7 +1101,7 @@ class TrackStateProxy {
   /// @note This might hash the @p key at runtime instead of compile-time
   /// @return true if the component exists, false if not
   constexpr bool has(std::string_view key) const {
-    return has(hashString(key));
+    return has(hashStringDynamic(key));
   }
 
   /// Retrieve a mutable reference to a component
@@ -1135,7 +1135,7 @@ class TrackStateProxy {
   constexpr T& component(std::string_view key)
     requires(!ReadOnly)
   {
-    return m_traj->template component<T>(hashString(key), m_istate);
+    return m_traj->template component<T>(hashStringDynamic(key), m_istate);
   }
 
   /// Retrieve a const reference to a component
@@ -1163,7 +1163,7 @@ class TrackStateProxy {
   /// @return Const reference to the component given by @p key
   template <typename T>
   constexpr const T& component(std::string_view key) const {
-    return m_traj->template component<T>(hashString(key), m_istate);
+    return m_traj->template component<T>(hashStringDynamic(key), m_istate);
   }
 
   /// @}

Core/include/Acts/EventData/VectorMultiTrajectory.hpp

@@ -456,7 +456,7 @@ class VectorMultiTrajectory final
 
   template <typename T>
   void addColumn_impl(std::string_view key) {
-    HashedString hashedKey = hashString(key);
+    HashedString hashedKey = hashStringDynamic(key);
     m_dynamic.insert({hashedKey, std::make_unique<detail::DynamicColumn<T>>()});
   }
 

Core/include/Acts/EventData/VectorTrackContainer.hpp

@@ -225,7 +225,7 @@ class VectorTrackContainer final : public detail_vtc::VectorTrackContainerBase {
 
   template <typename T>
   constexpr void addColumn_impl(const std::string_view& key) {
-    HashedString hashedKey = hashString(key);
+    HashedString hashedKey = hashStringDynamic(key);
     m_dynamic.insert({hashedKey, std::make_unique<detail::DynamicColumn<T>>()});
   }
 

Core/include/Acts/EventData/detail/MultiTrajectoryTestsCommon.hpp

@@ -1103,8 +1103,8 @@ class MultiTrajectoryTestsCommon {
     auto test = [&](const std::string& col, auto value) {
       using T = decltype(value);
       std::string col2 = col + "_2";
-      HashedString h{hashString(col)};
-      HashedString h2{hashString(col2)};
+      HashedString h{hashStringDynamic(col)};
+      HashedString h2{hashStringDynamic(col2)};
 
       trajectory_t traj = m_factory.create();
       BOOST_CHECK(!traj.hasColumn(h));
@@ -1188,7 +1188,7 @@ class MultiTrajectoryTestsCommon {
       }
     };
 
-    runTest([](const std::string& c) { return hashString(c.c_str()); });
+    runTest([](const std::string& c) { return hashStringDynamic(c.c_str()); });
     // runTest([](const std::string& c) { return c.c_str(); });
     // runTest([](const std::string& c) { return c; });
     // runTest([](std::string_view c) { return c; });

Core/include/Acts/Utilities/HashedString.hpp

@@ -8,9 +8,11 @@
 
 #pragma once
 
+#include <csignal>
 #include <cstddef>
 #include <cstdint>
 #include <string_view>
+#include <type_traits>
 #include <utility>
 
 namespace Acts {
@@ -35,7 +37,11 @@ constexpr int length(const char* str) {
 }
 }  // namespace detail
 
-constexpr HashedString hashString(std::string_view s) {
+consteval HashedString hashString(std::string_view s) {
+  return detail::fnv1a_32(s);
+}
+
+constexpr HashedString hashStringDynamic(std::string_view s) {
   return detail::fnv1a_32(s);
 }
 

Plugins/Podio/include/Acts/Plugins/Podio/PodioTrackContainer.hpp

@@ -238,7 +238,7 @@ class MutablePodioTrackContainer : public PodioTrackContainerBase {
 
   template <typename T>
   constexpr void addColumn_impl(std::string_view key) {
-    Acts::HashedString hashedKey = hashString(key);
+    Acts::HashedString hashedKey = hashStringDynamic(key);
     m_dynamic.insert(
         {hashedKey, std::make_unique<podio_detail::DynamicColumn<T>>(key)});
   }

Plugins/Podio/include/Acts/Plugins/Podio/PodioTrackStateContainer.hpp

@@ -610,7 +610,7 @@ class MutablePodioTrackStateContainer final
 
   template <typename T>
   constexpr void addColumn_impl(std::string_view key) {
-    HashedString hashedKey = hashString(key);
+    HashedString hashedKey = hashStringDynamic(key);
     m_dynamic.insert(
         {hashedKey, std::make_unique<podio_detail::DynamicColumn<T>>(key)});
   }

Plugins/Podio/src/PodioUtil.cpp

@@ -261,7 +261,7 @@ void recoverDynamicColumns(
                                "' is not of allowed type"};
     }
 
-    HashedString hashedKey = hashString(dynName);
+    HashedString hashedKey = hashStringDynamic(dynName);
     dynamic.insert({hashedKey, std::move(up)});
   }
 }

Tests/UnitTests/Core/Utilities/HashedStringTests.cpp

@@ -28,7 +28,7 @@ BOOST_AUTO_TEST_CASE(string_hashes) {
   BOOST_CHECK_EQUAL("abc"_hash, 440920331);
 
   std::string s = "abc";
-  BOOST_CHECK_EQUAL(hashString(s), 440920331);
+  BOOST_CHECK_EQUAL(hashStringDynamic(s), 440920331);
   constexpr std::string_view sv{"abc"};
   BOOST_CHECK_EQUAL(hashString(sv), 440920331);
   static_assert(hashString(sv) == 440920331, "Invalid");