add perfetto with single .proto file, parts of it commented

we only want to encode data, and only part of it, so we can skip
some java-specific messages, as well as the whole Ftrace subsystem.

Makefile

@@ -14,6 +14,9 @@ test-autopromote:
 doc:
 	@dune build $(DUNE_OPTS) @doc
 
+genproto:
+	FORCE_GENPROTO=true dune build @lint --auto-promote
+
 WATCH?= @install @runtest
 watch:
 	dune build $(DUNE_OPTS) -w $(WATCH)

dune-project

@@ -94,4 +94,23 @@
  (tags
   (trace tracing fuchsia)))
 
+
+(package
+ (name trace-perfetto)
+ (synopsis
+  "A backend for trace based on perfetto's protobuf format")
+ (depends
+  (ocaml
+   (>= 4.08))
+  (trace
+   (= :version))
+  (mtime
+   (>= 2.0))
+  (thread-local-storage
+   (>= 0.2))
+  pbrt
+  dune)
+ (tags
+  (trace tracing perfetto)))
+
 ; See the complete stanza docs at https://dune.readthedocs.io/en/stable/dune-files.html#dune-project

src/perfetto/README.md

@@ -0,0 +1,6 @@
+
+## NOTES
+
+- to generate, `make genproto` in root directory. Pay attention to the version of `ocaml-protoc`.
+- we commented some parts that are not really relevant to reduce the size of the code.
+

src/perfetto/dune

@@ -0,0 +1,25 @@
+
+(library
+  (name trace_perfetto)
+  (public_name trace-perfetto)
+ (synopsis
+  "A high-performance backend for trace, emitting a Fuchsia trace into a file")
+ (libraries
+  trace.core
+  trace.private.util
+  trace.subscriber
+  thread-local-storage
+  mtime
+  mtime.clock.os
+  pbrt
+  ))
+
+(rule
+ (alias lint)
+ (mode promote)
+ (enabled_if %{env:FORCE_GENPROTO=false})
+ (targets perfetto_trace.ml perfetto_trace.mli)
+ (deps
+  (:file perfetto_trace.proto))
+ (action
+  (run ocaml-protoc %{file} --ml_out . --encode-only --pp --make --binary)))

trace-perfetto.opam

@@ -0,0 +1,36 @@
+# This file is generated by dune, edit dune-project instead
+opam-version: "2.0"
+version: "0.10"
+synopsis: "A backend for trace based on perfetto's protobuf format"
+maintainer: ["Simon Cruanes"]
+authors: ["Simon Cruanes"]
+license: "MIT"
+tags: ["trace" "tracing" "perfetto"]
+homepage: "https://github.com/c-cube/ocaml-trace"
+bug-reports: "https://github.com/c-cube/ocaml-trace/issues"
+depends: [
+  "ocaml" {>= "4.08"}
+  "trace" {= version}
+  "mtime" {>= "2.0"}
+  "thread-local-storage" {>= "0.2"}
+  "pbrt"
+  "dune" {>= "2.9"}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "--promote-install-files=false"
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+  ["dune" "install" "-p" name "--create-install-files" name]
+]
+dev-repo: "git+https://github.com/c-cube/ocaml-trace.git"