src: Node Tracing Controller

This commit adds support for trace-event tracing to Node.js. It provides
a mechanism to centralize tracing information generated by V8, Node
core, and userspace code. It includes:

 - A trace writer responsible for serializing traces and cycling the
   output files so that no individual file becomes to large.
 - A buffer for aggregating traces to allow for batched flushes.
 - An agent which initializes the tracing controller and ensures that
   trace serialization is done on a separate thread.
 - A set of macros for generating trace events.
 - Tests and documentation.

Author: Raymond Kang <raymondksi@gmail.com>
Author: Kelvin Jin <kelvinjin@google.com>
Author: Matthew Loring <mattloring@google.com>
Author: Jason Ginchereau <jasongin@microsoft.com>

PR-URL: https://github.com/nodejs/node/pull/9304

Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Josh Gavant <josh.gavant@outlook.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/doc/api/tracing.md b/doc/api/tracing.md
new file mode 100644
index 0000000000..28e488201e
--- /dev/null
+++ b/doc/api/tracing.md
@@ -0,0 +1,19 @@
+# Tracing
+
+Trace Event provides a mechanism to centralize tracing information generated by
+V8, Node core, and userspace code.
+
+Tracing can be enabled by passing the `--trace-events-enabled` flag when starting a
+Node.js application.
+
+The set of categories for which traces are recorded can be specified using the
+`--trace-event-categories` flag followed by a list of comma separated category names.
+By default the `node` and `v8` categories are enabled.
+
+```txt
+node --trace-events-enabled --trace-event-categories v8,node server.js
+```
+
+Running Node.js with tracing enabled will produce log files that can be opened
+in the [`chrome://tracing`](https://www.chromium.org/developers/how-tos/trace-event-profiling-tool)
+tab of Chrome.