Fix confusing smart console output from concurrent builds

Developers tend to blame the last printed line when a build takes too
long. Unfortunately, when building concurrently, the last printed line
may have actually finished a long time ago. Under the current system,
ninja does not update the status line to reflect what jobs are still
running. This change makes ninja always print the oldest still running job
instead. In other words, the likely build bottlenecks.

Patch from David Zarzycki, originally uploaded at #1320.

2 files changed, 14 insertions, 0 deletions

diff --git a/src/build.cc b/src/build.cc
index 0eda16b..c24d6a9 100644
--- a/src/build.cc
+++ b/src/build.cc
@@ -16,6 +16,7 @@
 
 #include <assert.h>
 #include <errno.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <functional>
@@ -130,6 +131,18 @@ void BuildStatus::BuildEdgeFinished(Edge* edge,
 
   if (!edge->use_console())
     PrintStatus(edge, kEdgeFinished);
+  if (printer_.is_smart_terminal()) {
+    int oldest_start = INT_MAX;
+    Edge* oldest = NULL;
+    for (i = running_edges_.begin(); i != running_edges_.end(); i++) {
+      if (i->second < oldest_start) {
+        oldest_start = i->second;
+        oldest = i->first;
+      }
+    }
+    if (oldest)
+      PrintStatus(oldest, kEdgeRunning);
+  }
 
   // Print the command that is spewing before printing its output.
   if (!success) {
diff --git a/src/build.h b/src/build.h
index 9b90e8a..ac7f951 100644
--- a/src/build.h
+++ b/src/build.h
@@ -222,6 +222,7 @@ struct BuildStatus {
 
   enum EdgeStatus {
     kEdgeStarted,
+    kEdgeRunning,
     kEdgeFinished,
   };