From 13313d403ac27761463732ba9cb883b93f56aa53 Mon Sep 17 00:00:00 2001
From: Vikram Auradkar <auradkar@google.com>
Date: Thu, 16 Jun 2022 00:19:18 +0000
Subject: [PATCH] tracing: Add noop tracing

BUG=b:213154559
TEST=presubmit
Change-Id: Idfe23544c8381e664d913c4a80742f4e25a30006

Change-Id: I2bb0b59098ae183c45e92fcf15e1bcfe834df204
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3707622
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Vikram Auradkar <auradkar@google.com>
---
 Cargo.toml          |  1 +
 tracing/Cargo.toml  |  9 +++++++++
 tracing/src/lib.rs  |  8 ++++++++
 tracing/src/noop.rs | 23 +++++++++++++++++++++++
 4 files changed, 41 insertions(+)
 create mode 100644 tracing/Cargo.toml
 create mode 100644 tracing/src/lib.rs
 create mode 100644 tracing/src/noop.rs

diff --git a/Cargo.toml b/Cargo.toml
index f2bf223a76..bae7ef373f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -76,6 +76,7 @@ members = [
     "serde_keyvalue",
     "tpm2",
     "tpm2-sys",
+    "tracing",
     "usb_sys",
     "usb_util",
     "vfio_sys",
diff --git a/tracing/Cargo.toml b/tracing/Cargo.toml
new file mode 100644
index 0000000000..784508d510
--- /dev/null
+++ b/tracing/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "tracing"
+version = "0.1.0"
+authors = ["The Chromium OS Authors"]
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
\ No newline at end of file
diff --git a/tracing/src/lib.rs b/tracing/src/lib.rs
new file mode 100644
index 0000000000..bdcf0b0f14
--- /dev/null
+++ b/tracing/src/lib.rs
@@ -0,0 +1,8 @@
+// Copyright 2022 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// A crate that provides noop tracing.
+mod noop;
+
+pub use noop::*;
diff --git a/tracing/src/noop.rs b/tracing/src/noop.rs
new file mode 100644
index 0000000000..6a04d2f2c6
--- /dev/null
+++ b/tracing/src/noop.rs
@@ -0,0 +1,23 @@
+// Copyright 2022 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Empty macros for when the tracing feature isn't used.
+#[macro_export]
+macro_rules! trace_event {
+    ($category:ident, $name:expr) => {
+        None as Option<bool>
+    };
+}
+
+#[macro_export]
+macro_rules! trace_event_begin {
+    ($category:ident, $name:expr) => {};
+}
+
+#[macro_export]
+macro_rules! trace_event_end {
+    ($category:ident) => {};
+}
+
+pub fn init() {}