add a class for logging builds (commands + timing)

1 files changed, 37 insertions, 0 deletions

diff --git a/src/build_log.h b/src/build_log.h
new file mode 100644
index 0000000..1d9463c
--- /dev/null
+++ b/src/build_log.h
@@ -0,0 +1,37 @@
+#include <map>
+#include <string>
+using namespace std;
+
+struct Edge;
+
+// Store a log of every command ran for every build.
+// It has a few uses:
+// 1) historical command lines for output files, so we know
+//    when we need to rebuild due to the command changing
+// 2) historical timing information
+// 3) maybe we can generate some sort of build overview output
+//    from it
+struct BuildLog {
+  bool OpenForWrite(const string& path, string* err);
+  void RecordCommand(Edge* edge, int time_ms);
+  void Close();
+
+  // Load the on-disk log.
+  bool Load(const string& path, string* err);
+
+  struct LogEntry {
+    string output;
+    string command;
+    int time_ms;
+    bool operator==(const LogEntry& o) {
+      return output == o.output && command == o.command && time_ms == o.time_ms;
+    }
+  };
+
+  // Lookup a previously-run command by its output path.
+  LogEntry* LookupByOutput(const string& path);
+
+  typedef map<string, LogEntry*> Log;
+  Log log_;
+  FILE* log_file_;
+};