MINOR: debug: Report the current tgid in "debug dev fd"

"debug dev fd" scans the FDs of the process as the calling thread sees
them, and reports the ones unknown to fdtab. With per-thread-group FD
tables, both that scan and the fdtab lookups only reflect the view of
the calling thread's group: the same command may report different FDs
depending on the thread that serves it. Let's print the current tgid in
a header line so the output states which view it shows.

diff --git a/src/debug.c b/src/debug.c
index 47c70437a428a50ffbd88a1db93b516854b59240..6e85ab3d5e3c0fa0eff3e068913928f8979a4a74 100644 (file)
--- a/src/debug.c
+++ b/src/debug.c
@@ -1970,6 +1970,7 @@ static int debug_parse_cli_trace(char **args, char *payload, struct appctx *appc
 /* CLI state for "debug dev fd" */
 struct dev_fd_ctx {
        int start_fd;
+       int hdr_done;
 };
 
 /* CLI parser for the "debug dev fd" command. The current FD to restart from is
@@ -2006,6 +2007,19 @@ static int debug_iohandler_fd(struct appctx *appctx)
 
        thread_isolate();
 
+       /* thread groups may have their own FD tables, and even their own view
+        * of the process's FDs, so let's always indicate which group the dump
+        * is seen from.
+        */
+       if (!ctx->hdr_done) {
+               chunk_printf(&trash, "# current tgid: %u\n", tgid);
+               if (applet_putchk(appctx, &trash) == -1) {
+                       ret = 0;
+                       goto leave;
+               }
+               ctx->hdr_done = 1;
+       }
+
        /* we have two inner loops here, one for the proxy, the other one for
         * the buffer.
         */
@@ -2163,6 +2177,7 @@ static int debug_iohandler_fd(struct appctx *appctx)
                }
        }
 
+ leave:
        thread_release();
        return ret;
 }