fix(runtime): `Deno.memoryUsage().rss` should return correct value (#17088)

This commit changes implementation of "Deno.memoryUsage()" to return
correct value for "rss" field. To do that we implement a specialized function
per os to retrieve this information.

1 files changed, 127 insertions, 1 deletions

diff --git a/runtime/ops/os/mod.rs b/runtime/ops/os/mod.rs
index b93935955..613b4507d 100644
--- a/runtime/ops/os/mod.rs
+++ b/runtime/ops/os/mod.rs
@@ -4,11 +4,14 @@ use super::utils::into_string;
 use crate::permissions::Permissions;
 use crate::worker::ExitCode;
 use deno_core::error::{type_error, AnyError};
+use deno_core::op;
 use deno_core::url::Url;
+use deno_core::v8;
 use deno_core::Extension;
+use deno_core::ExtensionBuilder;
 use deno_core::OpState;
-use deno_core::{op, ExtensionBuilder};
 use deno_node::NODE_ENV_VAR_ALLOWLIST;
+use serde::Serialize;
 use std::collections::HashMap;
 use std::env;
 
@@ -30,6 +33,7 @@ fn init_ops(builder: &mut ExtensionBuilder) -> &mut ExtensionBuilder {
     op_set_exit_code::decl(),
     op_system_memory_info::decl(),
     op_uid::decl(),
+    op_runtime_memory_usage::decl(),
   ])
 }
 
@@ -297,3 +301,125 @@ fn op_uid(state: &mut OpState) -> Result<Option<u32>, AnyError> {
     .check("uid", Some("Deno.uid()"))?;
   Ok(None)
 }
+
+// HeapStats stores values from a isolate.get_heap_statistics() call
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+struct MemoryUsage {
+  rss: usize,
+  heap_total: usize,
+  heap_used: usize,
+  external: usize,
+}
+
+#[op(v8)]
+fn op_runtime_memory_usage(scope: &mut v8::HandleScope) -> MemoryUsage {
+  let mut s = v8::HeapStatistics::default();
+  scope.get_heap_statistics(&mut s);
+  MemoryUsage {
+    rss: rss(),
+    heap_total: s.total_heap_size(),
+    heap_used: s.used_heap_size(),
+    external: s.external_memory(),
+  }
+}
+
+#[cfg(target_os = "linux")]
+fn rss() -> usize {
+  // Inspired by https://github.com/Arc-blroth/memory-stats/blob/5364d0d09143de2a470d33161b2330914228fde9/src/linux.rs
+
+  // Extracts a positive integer from a string that
+  // may contain leading spaces and trailing chars.
+  // Returns the extracted number and the index of
+  // the next character in the string.
+  fn scan_int(string: &str) -> (usize, usize) {
+    let mut out = 0;
+    let mut idx = 0;
+    let mut chars = string.chars().peekable();
+    while let Some(' ') = chars.next_if_eq(&' ') {
+      idx += 1;
+    }
+    for n in chars {
+      idx += 1;
+      if ('0'..='9').contains(&n) {
+        out *= 10;
+        out += n as usize - '0' as usize;
+      } else {
+        break;
+      }
+    }
+    (out, idx)
+  }
+
+  let statm_content = if let Ok(c) = std::fs::read_to_string("/proc/self/statm")
+  {
+    c
+  } else {
+    return 0;
+  };
+
+  // statm returns the virtual size and rss, in
+  // multiples of the page size, as the first
+  // two columns of output.
+  // SAFETY: libc call
+  let page_size = unsafe { libc::sysconf(libc::_SC_PAGESIZE) };
+
+  if page_size < 0 {
+    return 0;
+  }
+
+  let (_total_size_pages, idx) = scan_int(&statm_content);
+  let (total_rss_pages, _) = scan_int(&statm_content[idx..]);
+
+  total_rss_pages * page_size as usize
+}
+
+#[cfg(target_os = "macos")]
+fn rss() -> usize {
+  // Inspired by https://github.com/Arc-blroth/memory-stats/blob/5364d0d09143de2a470d33161b2330914228fde9/src/darwin.rs
+
+  let mut task_info =
+    std::mem::MaybeUninit::<libc::mach_task_basic_info_data_t>::uninit();
+  let mut count = libc::MACH_TASK_BASIC_INFO_COUNT;
+  // SAFETY: libc calls
+  let r = unsafe {
+    libc::task_info(
+      libc::mach_task_self(),
+      libc::MACH_TASK_BASIC_INFO,
+      task_info.as_mut_ptr() as libc::task_info_t,
+      &mut count as *mut libc::mach_msg_type_number_t,
+    )
+  };
+  // According to libuv this should never fail
+  assert_eq!(r, libc::KERN_SUCCESS);
+  // SAFETY: we just asserted that it was success
+  let task_info = unsafe { task_info.assume_init() };
+  task_info.resident_size as usize
+}
+
+#[cfg(windows)]
+fn rss() -> usize {
+  use winapi::shared::minwindef::DWORD;
+  use winapi::shared::minwindef::FALSE;
+  use winapi::um::processthreadsapi::GetCurrentProcess;
+  use winapi::um::psapi::GetProcessMemoryInfo;
+  use winapi::um::psapi::PROCESS_MEMORY_COUNTERS;
+
+  // SAFETY: winapi calls
+  unsafe {
+    // this handle is a constant—no need to close it
+    let current_process = GetCurrentProcess();
+    let mut pmc: PROCESS_MEMORY_COUNTERS = std::mem::zeroed();
+
+    if GetProcessMemoryInfo(
+      current_process,
+      &mut pmc,
+      std::mem::size_of::<PROCESS_MEMORY_COUNTERS>() as DWORD,
+    ) != FALSE
+    {
+      pmc.WorkingSetSize
+    } else {
+      0
+    }
+  }
+}