From 2509b0ba62d42b68d99a08f1de8ef01de0356ca4 Mon Sep 17 00:00:00 2001
From: Nathan Whitaker <17734409+nathanwhit@users.noreply.github.com>
Date: Tue, 29 Oct 2024 10:56:35 -0700
Subject: [PATCH] feat: add binding for
 `ResourceConstraints::ConfigureDefaults` (#1651)

* add binding for `ResourceConstraints::ConfigureDefaults`

* fmt

* fix types
---
 src/binding.cc               |  6 +++++
 src/isolate_create_params.rs | 50 ++++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/src/binding.cc b/src/binding.cc
index 8eac7309..0f8c791f 100644
--- a/src/binding.cc
+++ b/src/binding.cc
@@ -385,6 +385,12 @@ void v8__ResourceConstraints__ConfigureDefaultsFromHeapSize(
                                              maximum_heap_size_in_bytes);
 }
 
+void v8__ResourceConstraints__ConfigureDefaults(
+    v8::ResourceConstraints* constraints, uint64_t physical_memory,
+    uint64_t virtual_memory_limit) {
+  constraints->ConfigureDefaults(physical_memory, virtual_memory_limit);
+}
+
 void v8__HandleScope__CONSTRUCT(uninit_t<v8::HandleScope>* buf,
                                 v8::Isolate* isolate) {
   construct_in_place<v8::HandleScope>(buf, isolate);
diff --git a/src/isolate_create_params.rs b/src/isolate_create_params.rs
index d0fad119..3165218c 100644
--- a/src/isolate_create_params.rs
+++ b/src/isolate_create_params.rs
@@ -160,6 +160,37 @@ impl CreateParams {
     self
   }
 
+  /// Configures the constraints with reasonable default values based on the capabilities
+  /// of the current device the VM is running on.
+  ///
+  /// By default V8 starts with a small heap and dynamically grows it to match
+  /// the set of live objects. This may lead to ineffective garbage collections
+  /// at startup if the live set is large. Setting the initial heap size avoids
+  /// such garbage collections. Note that this does not affect young generation
+  /// garbage collections.
+  ///
+  /// When the heap size approaches its maximum, V8 will perform series of
+  /// garbage collections and invoke the
+  /// [NearHeapLimitCallback](struct.Isolate.html#method.add_near_heap_limit_callback).
+  /// If the garbage collections do not help and the callback does not
+  /// increase the limit, then V8 will crash with V8::FatalProcessOutOfMemory.
+  ///
+  /// # Arguments
+  ///
+  /// * `physical_memory` - The total amount of physical memory on the current device, in bytes.
+  /// * `virtual_memory_limit` - The amount of virtual memory on the current device, in bytes, or zero, if there is no limit.
+  pub fn heap_limits_from_system_memory(
+    mut self,
+    physical_memory: u64,
+    virtual_memory_limit: u64,
+  ) -> Self {
+    self
+      .raw
+      .constraints
+      .configure_defaults(physical_memory, virtual_memory_limit);
+    self
+  }
+
   /// A CppHeap used to construct the Isolate. V8 takes ownership of the
   /// CppHeap passed this way.
   pub fn cpp_heap(mut self, heap: UniqueRef<Heap>) -> Self {
@@ -269,6 +300,11 @@ pub(crate) mod raw {
       initial_heap_size_in_bytes: usize,
       maximum_heap_size_in_bytes: usize,
     );
+    fn v8__ResourceConstraints__ConfigureDefaults(
+      constraints: *mut ResourceConstraints,
+      physical_memory: u64,
+      virtual_memory_limit: u64,
+    );
   }
 
   impl ResourceConstraints {
@@ -285,5 +321,19 @@ pub(crate) mod raw {
         )
       };
     }
+
+    pub fn configure_defaults(
+      &mut self,
+      physical_memory: u64,
+      virtual_memory_limit: u64,
+    ) {
+      unsafe {
+        v8__ResourceConstraints__ConfigureDefaults(
+          self,
+          physical_memory,
+          virtual_memory_limit,
+        )
+      }
+    }
   }
 }