acme: add log file in acme root directory

Reading /mnt/acme/log reports a log of window create,
put, and delete events, as they happen. It blocks until the
next event is available.

Example log output:

8 new /Users/rsc/foo.go
8 put /Users/rsc/foo.go
8 del /Users/rsc/foo.go

This lets acme-aware programs react to file writes, for example
compiling code, running a test, or updating an import block.

TBR=r
R=r
https://codereview.appspot.com/89560044

1 files changed, 2 insertions, 0 deletions

diff --git a/src/cmd/acme/acme.c b/src/cmd/acme/acme.c
index 1005bae9..c45bc28d 100644
--- a/src/cmd/acme/acme.c
+++ b/src/cmd/acme/acme.c
@@ -303,6 +303,7 @@ readfile(Column *c, char *s)
 	winresize(w, w->r, FALSE, TRUE);
 	textscrdraw(&w->body);
 	textsetselect(&w->tag, w->tag.file->b.nc, w->tag.file->b.nc);
+	xfidlog(w, "new");
 }
 
 char *ignotes[] = {
@@ -866,6 +867,7 @@ newwindowthread(void *v)
 		recvp(cnewwindow);
 		w = makenewwindow(nil);
 		winsettag(w);
+		xfidlog(w, "new");
 		sendp(cnewwindow, w);
 	}
 }