io-stats: Expose io-thread queue depths

Summary:
- This diff exposes the io-thread queue depths by sending a specialized getxattr() call down to the io-threads translator.
- Port of D3086477, D3094145, D3095505 to 3.8

Test Plan: Tested on devserver, will run prove tests. Valgrind + ASAN pass as well.

Reviewers: rwareing, kvigor

Subscribers: dld, moox, dph

Differential Revision: https://phabricator.fb.com/D3086477

Change-Id: Ia452a4fcdb9173a751c4cb48d739b25c235f6855
Reviewed-on: https://review.gluster.org/18143
Smoke: Gluster Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Shreyas Siravara <sshreyas@fb.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/xlators/performance/io-threads/src/io-threads.c b/xlators/performance/io-threads/src/io-threads.c
index 06ad0c2aae5..7f9dc5f82a8 100644
--- a/xlators/performance/io-threads/src/io-threads.c
+++ b/xlators/performance/io-threads/src/io-threads.c
@@ -278,6 +278,9 @@ iot_get_pri_meaning (iot_pri_t pri)
         case IOT_PRI_MAX:
                 name = "invalid";
                 break;
+        case IOT_PRI_UNSPEC:
+                name = "unspecified";
+                break;
         }
         return name;
 }
@@ -610,6 +613,34 @@ int
 iot_getxattr (call_frame_t *frame, xlator_t *this, loc_t *loc,
               const char *name, dict_t *xdata)
 {
+        iot_conf_t *conf = NULL;
+        dict_t     *depths = NULL;
+        int i = 0;
+
+        conf = this->private;
+
+        if (conf && name && strcmp (name, IO_THREADS_QUEUE_SIZE_KEY) == 0) {
+                // We explicitly do not want a reference count
+                // for this dict in this translator
+                depths = get_new_dict ();
+                if (!depths)
+                        goto unwind_special_getxattr;
+
+                for (i = 0; i < IOT_PRI_MAX; i++) {
+                        if (dict_set_int32 (depths,
+                                            (char *)fop_pri_to_string (i),
+                                            conf->queue_sizes[i]) != 0) {
+                                dict_destroy (depths);
+                                depths = NULL;
+                                goto unwind_special_getxattr;
+                        }
+                }
+
+unwind_special_getxattr:
+                STACK_UNWIND_STRICT (getxattr, frame, 0, 0, depths, xdata);
+                return 0;
+        }
+
         IOT_FOP (getxattr, frame, this, loc, name, xdata);
         return 0;
 }