Added leased_concurrency to metrics and instrumented http connection manager and stream managers. (#392)

Author: JonathanHenson

include/aws/http/connection_manager.h

@@ -40,6 +40,8 @@ struct aws_http_manager_metrics {
     size_t available_concurrency;
     /* The number of requests that are awaiting concurrency to be made available from the HTTP manager. */
     size_t pending_concurrency_acquires;
+    /* The number of connections (http/1.1) or streams (for h2 via. stream manager) currently vended to user. */
+    size_t leased_concurrency;
 };
 
 /*

source/connection_manager.c

@@ -176,7 +176,7 @@ struct aws_http_connection_manager {
     /*
      * The number of all established, idle connections.  So
      * that we don't have compute the size of a linked list every time.
-     * It doesn't contribute to internal refcount as AWS_HCMCT_OPEN_CONNECTION inclues all idle connections as well.
+     * It doesn't contribute to internal refcount as AWS_HCMCT_OPEN_CONNECTION includes all idle connections as well.
      */
     size_t idle_connection_count;
 
@@ -1555,5 +1555,6 @@ void aws_http_connection_manager_fetch_metrics(
     AWS_FATAL_ASSERT(aws_mutex_lock((struct aws_mutex *)(void *)&manager->lock) == AWS_OP_SUCCESS);
     out_metrics->available_concurrency = manager->idle_connection_count;
     out_metrics->pending_concurrency_acquires = manager->pending_acquisition_count;
+    out_metrics->leased_concurrency = manager->internal_ref[AWS_HCMCT_VENDED_CONNECTION];
     AWS_FATAL_ASSERT(aws_mutex_unlock((struct aws_mutex *)(void *)&manager->lock) == AWS_OP_SUCCESS);
 }

source/http2_stream_manager.c

@@ -1231,6 +1231,7 @@ void aws_http2_stream_manager_fetch_metrics(
         out_metrics->pending_concurrency_acquires =
             stream_manager->synced_data.internal_refcount_stats[AWS_SMCT_PENDING_ACQUISITION];
         out_metrics->available_concurrency = all_available_streams_num;
+        out_metrics->leased_concurrency = stream_manager->synced_data.internal_refcount_stats[AWS_SMCT_OPEN_STREAM];
         s_unlock_synced_data((struct aws_http2_stream_manager *)(void *)stream_manager);
     } /* END CRITICAL SECTION */
 }

tests/test_stream_manager.c

@@ -893,6 +893,7 @@ TEST_CASE(h2_sm_mock_fetch_metric) {
     /* Acquired 1 stream, and we hold one connection, the max streams per connection is 2. */
     ASSERT_UINT_EQUALS(out_metrics.available_concurrency, 1);
     ASSERT_UINT_EQUALS(out_metrics.pending_concurrency_acquires, 0);
+    ASSERT_UINT_EQUALS(out_metrics.leased_concurrency, 1);
 
     ASSERT_SUCCESS(s_sm_stream_acquiring(1));
 
@@ -902,6 +903,7 @@ TEST_CASE(h2_sm_mock_fetch_metric) {
     aws_http2_stream_manager_fetch_metrics(s_tester.stream_manager, &out_metrics);
     ASSERT_UINT_EQUALS(out_metrics.available_concurrency, 0);
     ASSERT_UINT_EQUALS(out_metrics.pending_concurrency_acquires, 0);
+    ASSERT_UINT_EQUALS(out_metrics.leased_concurrency, 2);
 
     ASSERT_SUCCESS(s_sm_stream_acquiring(10));
     ASSERT_SUCCESS(s_wait_on_fake_connection_count(5));
@@ -910,6 +912,7 @@ TEST_CASE(h2_sm_mock_fetch_metric) {
     aws_http2_stream_manager_fetch_metrics(s_tester.stream_manager, &out_metrics);
     ASSERT_UINT_EQUALS(out_metrics.available_concurrency, 0);
     ASSERT_UINT_EQUALS(out_metrics.pending_concurrency_acquires, 2);
+    ASSERT_UINT_EQUALS(out_metrics.leased_concurrency, 10);
 
     ASSERT_SUCCESS(s_complete_all_fake_connection_streams());
     /* Still have two more streams that have not been completed */