PR25448: debuginfod: add transfer performance metrics

We now export metrics related to the time taken and data sent,
from which prometheus type tools can compute nice time series
with averages.

http_responses_duration_milliseconds_count{code="200"} 63
http_responses_duration_milliseconds_count{code="404"} 2
http_responses_duration_milliseconds_count{code="503"} 1
http_responses_duration_milliseconds_sum{code="200"} 66
http_responses_duration_milliseconds_sum{code="404"} 2
http_responses_duration_milliseconds_sum{code="503"} 0
http_responses_transfer_bytes_count{code="200"} 63
http_responses_transfer_bytes_count{code="404"} 2
http_responses_transfer_bytes_count{code="503"} 1
http_responses_transfer_bytes_sum{code="200"} 425177
http_responses_transfer_bytes_sum{code="404"} 18
http_responses_transfer_bytes_sum{code="503"} 37

Signed-off-by: Frank Ch. Eigler <fche@redhat.com>

2 files changed, 17 insertions, 0 deletions

diff --git a/debuginfod/ChangeLog b/debuginfod/ChangeLog
index 58ba85cf..989a9029 100644
--- a/debuginfod/ChangeLog
+++ b/debuginfod/ChangeLog
@@ -1,5 +1,10 @@
 2020-03-26  Frank Ch. Eigler <fche@redhat.com>
 
+	* debuginfod.cxx (handler_cb): Export two families of metrics for
+	prometheus traffic analysis: response times and data amounts.
+
+2020-03-26  Frank Ch. Eigler <fche@redhat.com>
+
 	* debuginfod.cxx (parse_opt): For -U, prefer dpkg-deb
 	after all if access(3)-able, fallback to bsdtar.
 
diff --git a/debuginfod/debuginfod.cxx b/debuginfod/debuginfod.cxx
index 9e8d5560..98491c2c 100644
--- a/debuginfod/debuginfod.cxx
+++ b/debuginfod/debuginfod.cxx
@@ -1767,6 +1767,7 @@ handler_cb (void * /*cls*/,
       inc_metric("http_responses_total","result","error");
       e.report(clog);
       http_code = e.code;
+      http_size = e.message.size();
       rc = e.mhd_send_response (connection);
     }
 
@@ -1778,6 +1779,17 @@ handler_cb (void * /*cls*/,
                  << ' ' << (int)(deltas*1000) << "ms"
                  << endl;
 
+  // related prometheus metrics
+  string http_code_str = to_string(http_code);
+  if (http_size >= 0)
+    add_metric("http_responses_transfer_bytes_sum","code",http_code_str,
+               http_size);
+  inc_metric("http_responses_transfer_bytes_count","code",http_code_str);
+
+  add_metric("http_responses_duration_milliseconds_sum","code",http_code_str,
+             deltas*1000); // prometheus prefers _seconds and floating point
+  inc_metric("http_responses_duration_milliseconds_count","code",http_code_str);
+
   return rc;
 }