pw_snapshot: Add timestamps to Snapshot proto

Adds a snapshot overlay for pw_chono TimePoint messages so snapshots can
capture information about when the snapshot occurred.

Change-Id: I50f02662420e7ecdcd4e4215d0d2528f8d79db11
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/42726
Pigweed-Auto-Submit: Armando Montanez <amontanez@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Reviewed-by: Keir Mierle <keir@google.com>
Reviewed-by: Ewout van Bekkum <ewout@google.com>

pw_chrono/chrono.proto

@@ -89,3 +89,13 @@ message TimePoint {
   int64 timestamp = 1;                   // Required
   ClockParameters clock_parameters = 2;  // Required
 }
+
+// The time of a snapshot capture. Supports multiple timestamps to
+// cover multiple time bases or clocks (e.g. time since boot, time
+// from epoch, etc).
+//
+// This is an overlay proto for Snapshot, see more details here:
+// https://pigweed.dev/pw_snapshot/proto_format.html#module-specific-data
+message SnapshotTimestamps {
+  repeated TimePoint timestamps = 22;
+}

pw_chrono/docs.rst

@@ -522,6 +522,11 @@ timestamps to be communicated in terms of the tick rate of a device, potentially
 providing significantly higher resolution. Logging, tracing, and system state
 snapshots are use cases that benefit from this additional resolution.
 
+This module provides an overlay proto (``pw.chrono.SnapshotTimestamps``) for
+usage with ``pw_snapshot`` to encourage capture of high resolution timestamps
+in device snapshots. Simplified capture utilies and host-side tooling to
+interpret this data are not yet provided by ``pw_chrono``.
+
 ---------------
 Software Timers
 ---------------

pw_cpu_exception_cortex_m/BUILD.bazel

@@ -85,6 +85,8 @@ pw_cc_library(
 proto_library(
     name = "cpu_state_protos",
     srcs = ["pw_cpu_exception_cortex_m_protos/cpu_state.proto"],
+    import_prefix = "pw_cpu_exception_cortex_m_protos",
+    strip_import_prefix = "//pw_cpu_exception_cortex_m/pw_cpu_exception_cortex_m_protos",
 )
 
 pw_cc_library(

pw_presubmit/py/pw_presubmit/pigweed_presubmit.py

@@ -356,7 +356,6 @@ def cmake_gcc(ctx: PresubmitContext):
     'pw_persistent_ram',
     'pw_presubmit',
     'pw_ring_buffer',
-    'pw_snapshot',
     'pw_software_update',
     'pw_spi',
     'pw_stm32cube_build',

pw_snapshot/BUILD.bazel

@@ -17,6 +17,7 @@ load(
     "pw_cc_library",
     "pw_cc_test",
 )
+load("//pw_protobuf_compiler:proto.bzl", "pw_proto_library")
 
 package(default_visibility = ["//visibility:public"])
 
@@ -32,7 +33,7 @@ pw_cc_library(
     ],
     includes = ["public"],
     deps = [
-        ":metadata_proto",
+        ":metadata_proto_cc",
         "//pw_bytes",
         "//pw_protobuf",
         "//pw_status",
@@ -44,24 +45,48 @@ proto_library(
     srcs = [
         "pw_snapshot_protos/snapshot_metadata.proto",
     ],
+    import_prefix = "pw_snapshot_metadata_proto",
+    strip_import_prefix = "//pw_snapshot/pw_snapshot_protos",
+    deps = [
+        "//pw_tokenizer:tokenizer_proto",
+    ],
 )
 
 proto_library(
     name = "snapshot_proto",
     srcs = [
         "pw_snapshot_protos/snapshot.proto",
     ],
+    import_prefix = "pw_snapshot_protos",
+    strip_import_prefix = "//pw_snapshot/pw_snapshot_protos",
     deps = [
         ":metadata_proto",
+        "//pw_chrono:chrono_proto",
+        "//pw_cpu_exception_cortex_m:cpu_state_protos",
+        "//pw_log:log_proto",
+        "//pw_thread:thread_proto",
     ],
 )
 
-# TODO(pwbug/366): pw_protobuf codegen doesn't work for Bazel yet.
-filegroup(
+pw_proto_library(
+    name = "metadata_proto_cc",
+    deps = [":snapshot_proto"],
+)
+
+pw_proto_library(
+    name = "snapshot_proto_cc",
+    deps = [":snapshot_proto"],
+)
+
+pw_cc_test(
     name = "cpp_compile_test",
     srcs = [
         "cpp_compile_test.cc",
     ],
+    deps = [
+        ":snapshot_proto_cc",
+        "//pw_unit_test",
+    ],
 )
 
 pw_cc_test(
@@ -70,7 +95,7 @@ pw_cc_test(
         "uuid_test.cc",
     ],
     deps = [
-        ":metadata_proto",
+        ":metadata_proto_cc",
         ":uuid",
         "//pw_bytes",
         "//pw_protobuf",

pw_snapshot/BUILD.gn

@@ -62,6 +62,7 @@ pw_proto_library("snapshot_proto") {
   sources = [ "pw_snapshot_protos/snapshot.proto" ]
   deps = [
     ":metadata_proto",
+    "$dir_pw_chrono:protos",
     "$dir_pw_cpu_exception_cortex_m:cpu_state_protos",
     "$dir_pw_log:protos",
     "$dir_pw_thread:protos",

pw_snapshot/CMakeLists.txt

@@ -58,9 +58,10 @@ pw_proto_library(pw_snapshot.snapshot_proto
   SOURCES
     pw_snapshot_protos/snapshot.proto
   DEPS
-    pw_snapshot.metadata_proto
+    pw_chrono.protos
     pw_cpu_exception_cortex_m.cpu_state_protos
     pw_log.protos
+    pw_snapshot.metadata_proto
     pw_thread.protos
 )
 

pw_snapshot/pw_snapshot_protos/snapshot.proto

@@ -18,6 +18,7 @@ package pw.snapshot;
 option java_package = "pw.snapshot.proto";
 option java_outer_classname = "Snapshot";
 
+import "pw_chrono/chrono.proto";
 import "pw_cpu_exception_cortex_m_protos/cpu_state.proto";
 import "pw_log/proto/log.proto";
 import "pw_thread_protos/thread.proto";
@@ -81,9 +82,14 @@ message Snapshot {
   // pw_trace_tokenized buffer format for stored data.
   bytes trace_data = 21;
 
+  // Timestamps that mark when this snapshot occurred. This field is repeated
+  // to accommodate wall-clock time, time since boot, and/or the raw system
+  // clock value.
+  repeated pw.chrono.TimePoint timestamps = 22;
+
   // RESERVED FOR PIGWEED. Downstream projects may NOT write to these fields.
   // Encodes to two bytes of tag overhead.
-  reserved 22 to 1031;
+  reserved 23 to 1031;
 
   // RESERVED FOR USERS. Encodes to two or more bytes of tag overhead.
   reserved 1032 to max;