profile: include time of build start

When using a serve end point, the analysis phase might take quite
long if serve has to actually build a delegated target or, at
least, has to synchronize artifacts with the remote end point.
Therefore, also record the time the build phase started (if building
is requested) as an additional time stamp in the profile.

4 files changed, 11 insertions, 0 deletions

diff --git a/share/man/just-profile.5.md b/share/man/just-profile.5.md
index 04c1e273..d3167b89 100644
--- a/share/man/just-profile.5.md
+++ b/share/man/just-profile.5.md
@@ -91,6 +91,9 @@ The profile file contains the following information.
 - For the key *`"start time"`* the start time of the invocation in
   seconds since the epoch.
 
+- For the key *`"build start time"`* the start time of the build phase (if
+  any) in seconds since the epoch.
+
 - For the key *`"stop time"`* the stop time of the invocation in seconds
   since the epoch.
 
diff --git a/src/buildtool/main/main.cpp b/src/buildtool/main/main.cpp
index 10abfa1a..3da6de93 100644
--- a/src/buildtool/main/main.cpp
+++ b/src/buildtool/main/main.cpp
@@ -1244,6 +1244,9 @@ auto main(int argc, char* argv[]) -> int {
                 analyse_result->id.ToShortString(
                     Evaluator::GetExpressionLogLimit()));
 
+            if (profile != nullptr) {
+                profile->StartBuild();
+            }
             auto build_result =
                 traverser.BuildAndStage(artifacts,
                                         runfiles,
diff --git a/src/buildtool/profile/profile.cpp b/src/buildtool/profile/profile.cpp
index 5ee9cd15..1d8a7b46 100644
--- a/src/buildtool/profile/profile.cpp
+++ b/src/buildtool/profile/profile.cpp
@@ -178,3 +178,7 @@ void Profile::SetRemoteExecutionConfig(RemoteExecutionConfig const& config) {
     remote["dispatch"] = dispatch;
     profile_["remote"] = remote;
 }
+
+void Profile::StartBuild() {
+    profile_["build start time"] = std::time(nullptr);
+}
diff --git a/src/buildtool/profile/profile.hpp b/src/buildtool/profile/profile.hpp
index 0db655fb..099ce2cc 100644
--- a/src/buildtool/profile/profile.hpp
+++ b/src/buildtool/profile/profile.hpp
@@ -46,6 +46,7 @@ class Profile {
                              IExecutionResponse::Ptr const& response,
                              std::string const& cwd);
     void NoteAnalysisError(std::string const& error_message);
+    void StartBuild();
 
   private:
     struct ActionData {