feat: expose systemMemoryInfo API for main worker (#338)

Adding it to EdgeRuntime namespace instead of Deno namespace, to prevent
accidentally exposing it in user workers. Also, we are implementing customized version of it for performance reasons (ie. only support Linux
via sysinfo)

crates/sb_core/js/main_worker.js

@@ -1,6 +1,6 @@
-import { SUPABASE_USER_WORKERS } from "ext:sb_user_workers/user_workers.js";
-import { applySupabaseTag } from "ext:sb_core_main_js/js/http.js";
-import { core } from "ext:core/mod.js";
+import { SUPABASE_USER_WORKERS } from 'ext:sb_user_workers/user_workers.js';
+import { applySupabaseTag } from 'ext:sb_core_main_js/js/http.js';
+import { core } from 'ext:core/mod.js';
 
 const ops = core.ops;
 
@@ -10,6 +10,7 @@ Object.defineProperty(globalThis, 'EdgeRuntime', {
 			userWorkers: SUPABASE_USER_WORKERS,
 			getRuntimeMetrics: () => /* async */ ops.op_runtime_metrics(),
 			applySupabaseTag: (src, dest) => applySupabaseTag(src, dest),
+			systemMemoryInfo: () => ops.op_system_memory_info(),
 		};
 	},
 	configurable: true,

crates/sb_os/lib.rs

@@ -1,5 +1,57 @@
+use deno_core::op2;
 use std::collections::HashMap;
 
 pub type EnvVars = HashMap<String, String>;
 
-deno_core::extension!(sb_os, esm_entry_point = "ext:sb_os/os.js", esm = ["os.js"]);
+#[derive(serde::Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct MemInfo {
+    pub total: u64,
+    pub free: u64,
+    pub available: u64,
+    pub buffers: u64,
+    pub cached: u64,
+    pub swap_total: u64,
+    pub swap_free: u64,
+}
+
+#[op2]
+#[serde]
+fn op_system_memory_info() -> Option<MemInfo> {
+    let mut mem_info = MemInfo {
+        total: 0,
+        free: 0,
+        available: 0,
+        buffers: 0,
+        cached: 0,
+        swap_total: 0,
+        swap_free: 0,
+    };
+
+    #[cfg(any(target_os = "android", target_os = "linux"))]
+    {
+        let mut info = std::mem::MaybeUninit::uninit();
+        // SAFETY: `info` is a valid pointer to a `libc::sysinfo` struct.
+        let res = unsafe { libc::sysinfo(info.as_mut_ptr()) };
+        if res == 0 {
+            // SAFETY: `sysinfo` initializes the struct.
+            let info = unsafe { info.assume_init() };
+            let mem_unit = info.mem_unit as u64;
+            mem_info.swap_total = info.totalswap * mem_unit;
+            mem_info.swap_free = info.freeswap * mem_unit;
+            mem_info.total = info.totalram * mem_unit;
+            mem_info.free = info.freeram * mem_unit;
+            mem_info.available = mem_info.free;
+            mem_info.buffers = info.bufferram * mem_unit;
+        }
+    }
+
+    Some(mem_info)
+}
+
+deno_core::extension!(
+    sb_os,
+    ops = [op_system_memory_info],
+    esm_entry_point = "ext:sb_os/os.js",
+    esm = ["os.js"]
+);

examples/main/index.ts

@@ -1,11 +1,14 @@
 // @ts-ignore
-import { STATUS_CODE } from "https://deno.land/std/http/status.ts";
+import { STATUS_CODE } from 'https://deno.land/std/http/status.ts';
 
 console.log('main function started');
 
+// log system memory usage every 30s
+// setInterval(() => console.log(EdgeRuntime.systemMemoryInfo()), 30 * 1000);
+
 Deno.serve(async (req: Request) => {
 	const headers = new Headers({
-		"Content-Type": "application/json"
+		'Content-Type': 'application/json',
 	});
 
 	const url = new URL(req.url);
@@ -17,7 +20,7 @@ Deno.serve(async (req: Request) => {
 			JSON.stringify({ 'message': 'ok' }),
 			{
 				status: STATUS_CODE.OK,
-				headers
+				headers,
 			},
 		);
 	}
@@ -128,7 +131,7 @@ Deno.serve(async (req: Request) => {
 			console.error(e);
 
 			if (e instanceof Deno.errors.WorkerRequestCancelled) {
-				headers.append("Connection", "close");
+				headers.append('Connection', 'close');
 
 				// XXX(Nyannyacha): I can't think right now how to re-poll
 				// inside the worker pool without exposing the error to the
@@ -150,7 +153,7 @@ Deno.serve(async (req: Request) => {
 				JSON.stringify(error),
 				{
 					status: STATUS_CODE.InternalServerError,
-					headers
+					headers,
 				},
 			);
 		}