Re-compile on userfaultfd phenotype flag change.

After this change, odrefresh re-compiles everything when the phenotype
flag `runtime_native_boot.enable_uffd_gc` changes. It writes the value
of the flag to cache-info.xml for change detection.

According to go/platform-experiment-namespaces#namespace-types, the
phenotype flag is back by a persistent system property. Therefore, we
can directly read the flag from the system property instead of depending
on the `server_configurable_flags` library. This behavior is consistent
with the existing ART code (particularly, `art::Flag`), which reads
other phenotype flags.

Bug: 231298279
Test: atest odsign_e2e_tests_full
Ignore-AOSP-First: Merge conflict. Will cherry-pick later.
Change-Id: I02b70569ecd96d4ded6d2d3be22c34b2c6a4c5b4

1 files changed, 121 insertions, 13 deletions

diff --git a/odrefresh/odrefresh.cc b/odrefresh/odrefresh.cc
index 1d12b94fce..70cf48e918 100644
--- a/odrefresh/odrefresh.cc
+++ b/odrefresh/odrefresh.cc
@@ -648,6 +648,11 @@ Result<void> OnDeviceRefresh::WriteCacheInfo() const {
     return Errorf("Could not create directory {}", QuotePath(dir_name));
   }
 
+  std::vector<art_apex::KeyValuePair> system_properties;
+  for (const auto& [key, value] : config_.GetSystemProperties()) {
+    system_properties.emplace_back(key, value);
+  }
+
   std::optional<std::vector<apex::ApexInfo>> apex_info_list = GetApexInfoList();
   if (!apex_info_list.has_value()) {
     return Errorf("Could not update {}: no APEX info", QuotePath(cache_info_filename_));
@@ -685,15 +690,16 @@ Result<void> OnDeviceRefresh::WriteCacheInfo() const {
     return Errorf("Cannot open {} for writing.", QuotePath(cache_info_filename_));
   }
 
-  art_apex::CacheInfo info(
+  std::unique_ptr<art_apex::CacheInfo> info(new art_apex::CacheInfo(
+      {art_apex::KeyValuePairList(system_properties)},
       {art_module_info},
       {art_apex::ModuleInfoList(module_info_list)},
       {art_apex::Classpath(bcp_components.value())},
       {art_apex::Classpath(bcp_compilable_components.value())},
       {art_apex::SystemServerComponents(system_server_components.value())},
-      config_.GetCompilationOsMode() ? std::make_optional(true) : std::nullopt);
+      config_.GetCompilationOsMode() ? std::make_optional(true) : std::nullopt));
 
-  art_apex::write(out, info);
+  art_apex::write(out, *info);
   out.close();
   if (out.fail()) {
     return Errorf("Cannot write to {}", QuotePath(cache_info_filename_));
@@ -836,16 +842,106 @@ WARN_UNUSED bool OnDeviceRefresh::SystemServerArtifactsExist(
   return jars_missing_artifacts->empty();
 }
 
+WARN_UNUSED bool OnDeviceRefresh::CheckSystemPropertiesAreDefault() const {
+  const std::unordered_map<std::string, std::string>& system_properties =
+      config_.GetSystemProperties();
+
+  for (const SystemPropertyConfig& system_property_config : *kSystemProperties.get()) {
+    auto property = system_properties.find(system_property_config.name);
+    DCHECK(property != system_properties.end());
+
+    if (property->second != system_property_config.default_value) {
+      LOG(INFO) << "System property " << system_property_config.name << " has a non-default value ("
+                << property->second << ").";
+      return false;
+    }
+  }
+
+  return true;
+}
+
+WARN_UNUSED bool OnDeviceRefresh::CheckSystemPropertiesHaveNotChanged(
+    const art_apex::CacheInfo& cache_info) const {
+  std::unordered_map<std::string, std::string> cached_system_properties;
+  const art_apex::KeyValuePairList* list = cache_info.getFirstSystemProperties();
+  if (list == nullptr) {
+    // This should never happen. We have already checked the ART module version, and the cache
+    // info is generated by the latest version of the ART module if it exists.
+    LOG(ERROR) << "Missing system properties from cache-info.";
+    return false;
+  }
+
+  for (const art_apex::KeyValuePair& pair : list->getItem()) {
+    cached_system_properties[pair.getK()] = pair.getV();
+  }
+
+  const std::unordered_map<std::string, std::string>& system_properties =
+      config_.GetSystemProperties();
+
+  for (const SystemPropertyConfig& system_property_config : *kSystemProperties.get()) {
+    auto property = system_properties.find(system_property_config.name);
+    DCHECK(property != system_properties.end());
+
+    auto cached_property = cached_system_properties.find(system_property_config.name);
+    if (cached_property == cached_system_properties.end()) {
+      // This should never happen. We have already checked the ART module version, and the cache
+      // info is generated by the latest version of the ART module if it exists.
+      LOG(ERROR) << "Missing system property from cache-info (" << system_property_config.name
+                 << ")";
+      return false;
+    }
+
+    if (property->second != cached_property->second) {
+      LOG(INFO) << "System property " << system_property_config.name
+                << " value changed (before: " << cached_property->second
+                << ", now: " << property->second << ").";
+      return false;
+    }
+  }
+
+  return true;
+}
+
+WARN_UNUSED bool OnDeviceRefresh::BootClasspathArtifactsOnSystemUsable(
+    const apex::ApexInfo& art_apex_info) const {
+  if (!art_apex_info.getIsFactory()) {
+    return false;
+  }
+  LOG(INFO) << "Factory ART APEX mounted.";
+
+  if (!CheckSystemPropertiesAreDefault()) {
+    return false;
+  }
+  LOG(INFO) << "System properties are set to default values.";
+
+  return true;
+}
+
+WARN_UNUSED bool OnDeviceRefresh::SystemServerArtifactsOnSystemUsable(
+    const std::vector<apex::ApexInfo>& apex_info_list) const {
+  if (std::any_of(apex_info_list.begin(),
+                  apex_info_list.end(),
+                  [](const apex::ApexInfo& apex_info) { return !apex_info.getIsFactory(); })) {
+    return false;
+  }
+  LOG(INFO) << "Factory APEXes mounted.";
+
+  if (!CheckSystemPropertiesAreDefault()) {
+    return false;
+  }
+  LOG(INFO) << "System properties are set to default values.";
+
+  return true;
+}
+
 WARN_UNUSED bool OnDeviceRefresh::CheckBootClasspathArtifactsAreUpToDate(
     OdrMetrics& metrics,
     const InstructionSet isa,
     const apex::ApexInfo& art_apex_info,
     const std::optional<art_apex::CacheInfo>& cache_info,
     /*out*/ std::vector<std::string>* checked_artifacts) const {
-  if (art_apex_info.getIsFactory()) {
-    LOG(INFO) << "Factory ART APEX mounted.";
-
-    // ART is not updated, so we can use the artifacts on /system. Check if they exist.
+  if (BootClasspathArtifactsOnSystemUsable(art_apex_info)) {
+    // We can use the artifacts on /system. Check if they exist.
     std::string error_msg;
     if (BootClasspathArtifactsExist(/*on_system=*/true, /*minimal=*/false, isa, &error_msg)) {
       return true;
@@ -900,6 +996,14 @@ WARN_UNUSED bool OnDeviceRefresh::CheckBootClasspathArtifactsAreUpToDate(
     return false;
   }
 
+  if (!CheckSystemPropertiesHaveNotChanged(cache_info.value())) {
+    // We don't have a trigger kind for system property changes. For now, we reuse
+    // `kApexVersionMismatch` as it implies the expected behavior: re-compile regardless of the last
+    // compilation attempt.
+    metrics.SetTrigger(OdrMetrics::Trigger::kApexVersionMismatch);
+    return false;
+  }
+
   // Check boot class components.
   //
   // This checks the size and checksums of odrefresh compilable files on the DEX2OATBOOTCLASSPATH
@@ -961,12 +1065,8 @@ bool OnDeviceRefresh::CheckSystemServerArtifactsAreUpToDate(
   std::set<std::string> jars_missing_artifacts_on_system;
   bool artifacts_on_system_up_to_date = false;
 
-  if (std::all_of(apex_info_list.begin(),
-                  apex_info_list.end(),
-                  [](const apex::ApexInfo& apex_info) { return apex_info.getIsFactory(); })) {
-    LOG(INFO) << "Factory APEXes mounted.";
-
-    // APEXes are not updated, so we can use the artifacts on /system. Check if they exist.
+  if (SystemServerArtifactsOnSystemUsable(apex_info_list)) {
+    // We can use the artifacts on /system. Check if they exist.
     std::string error_msg;
     if (SystemServerArtifactsExist(
             /*on_system=*/true, &error_msg, &jars_missing_artifacts_on_system)) {
@@ -1052,6 +1152,14 @@ bool OnDeviceRefresh::CheckSystemServerArtifactsAreUpToDate(
     }
   }
 
+  if (!CheckSystemPropertiesHaveNotChanged(cache_info.value())) {
+    // We don't have a trigger kind for system property changes. For now, we reuse
+    // `kApexVersionMismatch` as it implies the expected behavior: re-compile regardless of the last
+    // compilation attempt.
+    metrics.SetTrigger(OdrMetrics::Trigger::kApexVersionMismatch);
+    return false;
+  }
+
   // Check system server components.
   //
   // This checks the size and checksums of odrefresh compilable files on the