Metric for manager (#370)

Provide API to fetch metric for managers.

To support https://github.com/aws/aws-sdk-java-v2/blob/master/http-client-spi/src/main/java/software/amazon/awssdk/http/HttpMetric.java#L65

include/aws/http/connection_manager.h

@@ -25,6 +25,23 @@ typedef void(aws_http_connection_manager_on_connection_setup_fn)(
 
 typedef void(aws_http_connection_manager_shutdown_complete_fn)(void *user_data);
 
+/**
+ * Metrics for logging and debugging purpose.
+ */
+struct aws_http_manager_metrics {
+    /**
+     * The number of additional concurrent requests that can be supported by the HTTP manager without needing to
+     * establish additional connections to the target server.
+     *
+     * For connection manager, it equals to connections that's idle.
+     * For stream manager, it equals to the number of streams that are possible to be made without creating new
+     * connection, although the implementation can create new connection without fully filling it.
+     */
+    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;
+};
+
 /*
  * Connection manager configuration struct.
  *
@@ -143,6 +160,14 @@ int aws_http_connection_manager_release_connection(
     struct aws_http_connection_manager *manager,
     struct aws_http_connection *connection);
 
+/**
+ * Fetch the current manager metrics from connection manager.
+ */
+AWS_HTTP_API
+void aws_http_connection_manager_fetch_metrics(
+    const struct aws_http_connection_manager *manager,
+    struct aws_http_manager_metrics *out_metrics);
+
 AWS_EXTERN_C_END
 
 #endif /* AWS_HTTP_CONNECTION_MANAGER_H */

include/aws/http/http2_stream_manager.h

@@ -18,6 +18,7 @@ struct proxy_env_var_settings;
 struct aws_http2_setting;
 struct aws_http_make_request_options;
 struct aws_http_stream;
+struct aws_http_manager_metrics;
 
 /**
  * Always invoked asynchronously when the stream was created, successfully or not.
@@ -168,5 +169,16 @@ void aws_http2_stream_manager_acquire_stream(
     struct aws_http2_stream_manager *http2_stream_manager,
     const struct aws_http2_stream_manager_acquire_stream_options *acquire_stream_option);
 
+/**
+ * Fetch the current metrics from stream manager.
+ *
+ * @param http2_stream_manager
+ * @param out_metrics The metrics to be fetched
+ */
+AWS_HTTP_API
+void aws_http2_stream_manager_fetch_metrics(
+    const struct aws_http2_stream_manager *http2_stream_manager,
+    struct aws_http_manager_metrics *out_metrics);
+
 AWS_EXTERN_C_END
 #endif /* AWS_HTTP2_STREAM_MANAGER_H */

include/aws/http/private/random_access_set.h

@@ -64,16 +64,23 @@ int aws_random_access_set_remove(struct aws_random_access_set *set, const void *
  * Get the pointer to a random element from the data structure. Fails when the data structure is empty.
  */
 AWS_HTTP_API
-int aws_random_access_set_random_get_ptr(struct aws_random_access_set *set, void **out);
+int aws_random_access_set_random_get_ptr(const struct aws_random_access_set *set, void **out);
 
 AWS_HTTP_API
-size_t aws_random_access_set_get_size(struct aws_random_access_set *set);
+size_t aws_random_access_set_get_size(const struct aws_random_access_set *set);
 
 /**
  * Check the element exist in the data structure or not.
  */
 AWS_HTTP_API
-int aws_random_access_set_exist(struct aws_random_access_set *set, const void *element, bool *exist);
+int aws_random_access_set_exist(const struct aws_random_access_set *set, const void *element, bool *exist);
+
+/**
+ * Get the pointer to an element that currently stored at that index. It may change if operations like remove and add
+ * happens. Helpful for debugging and iterating through the whole set.
+ */
+AWS_HTTP_API
+int aws_random_access_set_random_get_ptr_index(const struct aws_random_access_set *set, void **out, size_t index);
 
 AWS_EXTERN_C_END
 #endif /* AWS_HTTP_RANDOM_ACCESS_SET_H */

source/connection_manager.c

@@ -1538,3 +1538,15 @@ static void s_cull_task(struct aws_task *task, void *arg, enum aws_task_status s
 
     s_schedule_connection_culling(manager);
 }
+
+void aws_http_connection_manager_fetch_metrics(
+    const struct aws_http_connection_manager *manager,
+    struct aws_http_manager_metrics *out_metrics) {
+    AWS_PRECONDITION(manager);
+    AWS_PRECONDITION(out_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;
+    AWS_FATAL_ASSERT(aws_mutex_unlock((struct aws_mutex *)(void *)&manager->lock) == AWS_OP_SUCCESS);
+}

source/http2_stream_manager.c

@@ -142,7 +142,7 @@ static struct aws_h2_sm_connection *s_get_best_sm_connection_from_set(struct aws
 
 /* helper function for building the transaction: Try to assign connection for a pending stream acquisition */
 /* *_synced should only be called with LOCK HELD or from another synced function */
-static void s_sm_try_assign_connection_to_pending_stream_acquisition(
+static void s_sm_try_assign_connection_to_pending_stream_acquisition_synced(
     struct aws_http2_stream_manager *stream_manager,
     struct aws_h2_sm_pending_stream_acquisition *pending_stream_acquisition) {
 
@@ -344,7 +344,7 @@ static void s_aws_http2_stream_manager_build_transaction_synced(struct aws_http2
                 aws_linked_list_pop_front(&stream_manager->synced_data.pending_stream_acquisitions);
             struct aws_h2_sm_pending_stream_acquisition *pending_stream_acquisition =
                 AWS_CONTAINER_OF(node, struct aws_h2_sm_pending_stream_acquisition, node);
-            s_sm_try_assign_connection_to_pending_stream_acquisition(stream_manager, pending_stream_acquisition);
+            s_sm_try_assign_connection_to_pending_stream_acquisition_synced(stream_manager, pending_stream_acquisition);
             if (pending_stream_acquisition->sm_connection == NULL) {
                 /* Cannot find any connection, push it back to the front and break the loop */
                 aws_linked_list_push_front(&stream_manager->synced_data.pending_stream_acquisitions, node);
@@ -994,3 +994,34 @@ void aws_http2_stream_manager_acquire_stream(
     } /* END CRITICAL SECTION */
     s_aws_http2_stream_manager_execute_transaction(&work);
 }
+
+static size_t s_get_available_streams_num_from_connection_set(const struct aws_random_access_set *set) {
+    size_t all_available_streams_num = 0;
+    size_t ideal_connection_num = aws_random_access_set_get_size(set);
+    for (size_t i = 0; i < ideal_connection_num; i++) {
+        struct aws_h2_sm_connection *sm_connection = NULL;
+        AWS_FATAL_ASSERT(aws_random_access_set_random_get_ptr_index(set, (void **)&sm_connection, i) == AWS_OP_SUCCESS);
+        uint32_t available_streams = sm_connection->max_concurrent_streams - sm_connection->num_streams_assigned;
+        all_available_streams_num += (size_t)available_streams;
+    }
+    return all_available_streams_num;
+}
+
+void aws_http2_stream_manager_fetch_metrics(
+    const struct aws_http2_stream_manager *stream_manager,
+    struct aws_http_manager_metrics *out_metrics) {
+    AWS_PRECONDITION(stream_manager);
+    AWS_PRECONDITION(out_metrics);
+    { /* BEGIN CRITICAL SECTION */
+        s_lock_synced_data((struct aws_http2_stream_manager *)(void *)stream_manager);
+        size_t all_available_streams_num = 0;
+        all_available_streams_num +=
+            s_get_available_streams_num_from_connection_set(&stream_manager->synced_data.ideal_available_set);
+        all_available_streams_num +=
+            s_get_available_streams_num_from_connection_set(&stream_manager->synced_data.nonideal_available_set);
+        out_metrics->pending_concurrency_acquires =
+            stream_manager->synced_data.internal_refcount_stats[AWS_SMCT_PENDING_ACQUISITION];
+        out_metrics->available_concurrency = all_available_streams_num;
+        s_unlock_synced_data((struct aws_http2_stream_manager *)(void *)stream_manager);
+    } /* END CRITICAL SECTION */
+}

source/random_access_set.c

@@ -150,7 +150,7 @@ int aws_random_access_set_remove(struct aws_random_access_set *set, const void *
     return AWS_OP_SUCCESS;
 }
 
-int aws_random_access_set_random_get_ptr(struct aws_random_access_set *set, void **out) {
+int aws_random_access_set_random_get_ptr(const struct aws_random_access_set *set, void **out) {
     AWS_PRECONDITION(set);
     AWS_PRECONDITION(out != NULL);
     size_t length = aws_array_list_length(&set->impl->list);
@@ -166,11 +166,11 @@ int aws_random_access_set_random_get_ptr(struct aws_random_access_set *set, void
     return aws_array_list_get_at(&set->impl->list, (void *)out, index);
 }
 
-size_t aws_random_access_set_get_size(struct aws_random_access_set *set) {
+size_t aws_random_access_set_get_size(const struct aws_random_access_set *set) {
     return aws_array_list_length(&set->impl->list);
 }
 
-int aws_random_access_set_exist(struct aws_random_access_set *set, const void *element, bool *exist) {
+int aws_random_access_set_exist(const struct aws_random_access_set *set, const void *element, bool *exist) {
     AWS_PRECONDITION(set);
     AWS_PRECONDITION(element);
     AWS_PRECONDITION(exist);
@@ -179,3 +179,9 @@ int aws_random_access_set_exist(struct aws_random_access_set *set, const void *e
     *exist = find != NULL;
     return re;
 }
+
+int aws_random_access_set_random_get_ptr_index(const struct aws_random_access_set *set, void **out, size_t index) {
+    AWS_PRECONDITION(set);
+    AWS_PRECONDITION(out != NULL);
+    return aws_array_list_get_at(&set->impl->list, (void *)out, index);
+}

tests/CMakeLists.txt

@@ -604,6 +604,7 @@ add_net_test_case(h2_sm_mock_multiple_connections)
 add_net_test_case(h2_sm_mock_bad_connection_acquired)
 add_net_test_case(h2_sm_mock_connections_closed_before_request_made)
 add_net_test_case(h2_sm_mock_max_concurrent_streams_remote)
+add_net_test_case(h2_sm_mock_fetch_metric)
 add_net_test_case(h2_sm_mock_complete_stream)
 add_net_test_case(h2_sm_mock_ideal_num_streams)
 add_net_test_case(h2_sm_mock_large_ideal_num_streams)

tests/test_stream_manager.c

@@ -823,6 +823,56 @@ TEST_CASE(h2_sm_mock_max_concurrent_streams_remote) {
     return s_tester_clean_up();
 }
 
+/* Test that the remote max concurrent streams setting hit */
+TEST_CASE(h2_sm_mock_fetch_metric) {
+    (void)ctx;
+    struct sm_tester_options options = {
+        .max_connections = 5,
+        .alloc = allocator,
+    };
+    ASSERT_SUCCESS(s_tester_init(&options));
+    s_override_cm_connect_function(s_aws_http_connection_manager_create_connection_sync_mock);
+    /* Set the remote max to be 2 */
+    s_tester.max_con_stream_remote = 2;
+    /* Acquire a stream to trigger */
+    ASSERT_SUCCESS(s_sm_stream_acquiring(1));
+    /* waiting for one fake connection made */
+    ASSERT_SUCCESS(s_wait_on_fake_connection_count(1));
+    s_drain_all_fake_connection_testing_channel();
+    ASSERT_SUCCESS(s_wait_on_streams_acquired_count(1));
+    struct aws_http_manager_metrics out_metrics;
+    AWS_ZERO_STRUCT(out_metrics);
+
+    aws_http2_stream_manager_fetch_metrics(s_tester.stream_manager, &out_metrics);
+    /* 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_SUCCESS(s_sm_stream_acquiring(1));
+
+    ASSERT_SUCCESS(s_wait_on_fake_connection_count(1));
+    s_drain_all_fake_connection_testing_channel();
+    ASSERT_SUCCESS(s_wait_on_streams_acquired_count(2));
+    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_SUCCESS(s_sm_stream_acquiring(10));
+    ASSERT_SUCCESS(s_wait_on_fake_connection_count(5));
+    s_drain_all_fake_connection_testing_channel();
+    ASSERT_SUCCESS(s_wait_on_streams_acquired_count(10));
+    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_SUCCESS(s_complete_all_fake_connection_streams());
+    /* Still have two more streams that have not been completed */
+    s_drain_all_fake_connection_testing_channel();
+    ASSERT_SUCCESS(s_complete_all_fake_connection_streams());
+
+    return s_tester_clean_up();
+}
+
 /* Test that the stream completed will free the connection for more streams */
 TEST_CASE(h2_sm_mock_complete_stream) {
     (void)ctx;