5 files changed, 76 insertions, 0 deletions

diff --git a/cli/dts/lib.deno.unstable.d.ts b/cli/dts/lib.deno.unstable.d.ts
index 9c5590f97..fad31a3f2 100644
--- a/cli/dts/lib.deno.unstable.d.ts
+++ b/cli/dts/lib.deno.unstable.d.ts
@@ -130,6 +130,43 @@ declare namespace Deno {
    */
   export function osRelease(): string;
 
+  /** **Unstable** new API. yet to be vetted. 
+   *
+   * Displays the total amount of free and used physical and swap memory in the
+   * system, as well as the buffers and caches used by the kernel.
+   * 
+   * This is similar to the `free` command in Linux
+   *
+   * ```ts
+   * console.log(Deno.systemMemoryInfo());
+   * ```
+   *
+   * Requires `allow-env` permission.
+   *
+   */
+  export function systemMemoryInfo(): SystemMemoryInfo;
+
+  export interface SystemMemoryInfo {
+    /** Total installed memory */
+    total: number;
+    /** Unused memory */
+    free: number;
+    /** Estimation of how much memory is available  for  starting  new
+     * applications, without  swapping. Unlike the data provided by the cache or
+     * free fields, this field takes into account page cache and also that not
+     * all reclaimable memory slabs will be reclaimed due to items being in use
+     */
+    available: number;
+    /** Memory used by kernel buffers */
+    buffers: number;
+    /** Memory  used  by  the  page  cache  and  slabs */
+    cached: number;
+    /** Total swap memory */
+    swapTotal: number;
+    /** Unused swap memory */
+    swapFree: number;
+  }
+
   /** **UNSTABLE**: new API, yet to be vetted.
    *
    * Open and initialize a plugin.
diff --git a/cli/ops/os.rs b/cli/ops/os.rs
index 4778d49a4..a38b5b08a 100644
--- a/cli/ops/os.rs
+++ b/cli/ops/os.rs
@@ -21,6 +21,7 @@ pub fn init(s: &Rc<State>) {
   s.register_op_json_sync("op_hostname", op_hostname);
   s.register_op_json_sync("op_loadavg", op_loadavg);
   s.register_op_json_sync("op_os_release", op_os_release);
+  s.register_op_json_sync("op_system_memory_info", op_system_memory_info);
 }
 
 fn op_exec_path(
@@ -147,3 +148,24 @@ fn op_os_release(
   let release = sys_info::os_release().unwrap_or_else(|_| "".to_string());
   Ok(json!(release))
 }
+
+fn op_system_memory_info(
+  state: &State,
+  _args: Value,
+  _zero_copy: &mut [ZeroCopyBuf],
+) -> Result<Value, ErrBox> {
+  state.check_unstable("Deno.systemMemoryInfo");
+  state.check_env()?;
+  match sys_info::mem_info() {
+    Ok(info) => Ok(json!({
+      "total": info.total,
+      "free": info.free,
+      "available": info.avail,
+      "buffers": info.buffers,
+      "cached": info.cached,
+      "swapTotal": info.swap_total,
+      "swapFree": info.swap_free
+    })),
+    Err(_) => Ok(json!({})),
+  }
+}
diff --git a/cli/rt/30_os.js b/cli/rt/30_os.js
index 743ecd585..adf256fc6 100644
--- a/cli/rt/30_os.js
+++ b/cli/rt/30_os.js
@@ -15,6 +15,10 @@
     return sendSync("op_os_release");
   }
 
+  function systemMemoryInfo() {
+    return sendSync("op_system_memory_info");
+  }
+
   function exit(code = 0) {
     sendSync("op_exit", { code });
     throw new Error("Code not reachable");
@@ -50,6 +54,7 @@
     execPath,
     exit,
     osRelease,
+    systemMemoryInfo,
     hostname,
     loadavg,
   };
diff --git a/cli/rt/90_deno_ns.js b/cli/rt/90_deno_ns.js
index 82acdef3c..23ab12924 100644
--- a/cli/rt/90_deno_ns.js
+++ b/cli/rt/90_deno_ns.js
@@ -103,6 +103,7 @@ __bootstrap.denoNsUnstable = {
   loadavg: __bootstrap.os.loadavg,
   hostname: __bootstrap.os.hostname,
   osRelease: __bootstrap.os.osRelease,
+  systemMemoryInfo: __bootstrap.os.systemMemoryInfo,
   applySourceMap: __bootstrap.errorStack.opApplySourceMap,
   formatDiagnostics: __bootstrap.errorStack.opFormatDiagnostics,
   shutdown: __bootstrap.net.shutdown,
diff --git a/cli/tests/unit/os_test.ts b/cli/tests/unit/os_test.ts
index 79f70afac..12caed156 100644
--- a/cli/tests/unit/os_test.ts
+++ b/cli/tests/unit/os_test.ts
@@ -177,3 +177,14 @@ unitTest({ perms: { env: false } }, function releasePerm(): void {
     Deno.osRelease();
   }, Deno.errors.PermissionDenied);
 });
+
+unitTest({ perms: { env: true } }, function systemMemoryInfo(): void {
+  const info = Deno.systemMemoryInfo();
+  assert(info.total >= 0);
+  assert(info.free >= 0);
+  assert(info.available >= 0);
+  assert(info.buffers >= 0);
+  assert(info.cached >= 0);
+  assert(info.swapTotal >= 0);
+  assert(info.swapFree >= 0);
+});