src.ctf.lttng-live: handle `babeltrace.support-info` query object

This patch makes a `src.ctf.lttng-live` component class handle the
`babeltrace.support-info` query object. The query method replies a
weight of 0.75 (arbitrary, but it leaves some room for other component
classes to recognize this very specific URL format) when the input
string matches

    net://HOST[:PORT]/host/TGTHOST/SESSION

This makes it possible to create a conversion graph with a
`src.ctf.lttng-live` source like this:

    babeltrace2 net://localhost/host/qualinet/pour-un-travail-sans-retouche

Note that this will use the component's default "session not found"
action which is to continue, so the `src.ctf.lttng-live` message
iterator will never end. The legacy mode still works, however; when you
do:

    babeltrace2 -i lttng-live net://localhost/host/tgthost/session

the `convert` command adds the `session-not-found-action=end` parameter.

As such, when you do:

    babeltrace2 -i lttng-live net://localhost/host/tgthost

the `convert` command queries the `sessions` object to list the
available remote tracing sessions.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I73e38df1dfe9bed6d8e31015197a34945af026e5
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1944
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Simon Marchi <simon.marchi@efficios.com>

diff --git a/src/plugins/ctf/lttng-live/lttng-live.c b/src/plugins/ctf/lttng-live/lttng-live.c
index 1962aa2de3e4fdd9a25ac88bd1208a21d2fd4fc0..b804fbd505bdd5d77fe172fcee4d8fbdae47fb34 100644 (file)
--- a/src/plugins/ctf/lttng-live/lttng-live.c
+++ b/src/plugins/ctf/lttng-live/lttng-live.c
@@ -50,6 +50,7 @@
 
 #define MAX_QUERY_SIZE                     (256*1024)
 #define URL_PARAM                          "url"
+#define INPUTS_PARAM                       "inputs"
 #define SESS_NOT_FOUND_ACTION_PARAM        "session-not-found-action"
 #define SESS_NOT_FOUND_ACTION_CONTINUE_STR  "continue"
 #define SESS_NOT_FOUND_ACTION_FAIL_STR     "fail"
@@ -1599,6 +1600,81 @@ end:
        return status;
 }
 
+static
+bt_component_class_query_method_status lttng_live_query_support_info(
+               const bt_value *params, const bt_value **result,
+               bt_logging_level log_level)
+{
+       bt_component_class_query_method_status status =
+               BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_OK;
+       const bt_value *input_type_value;
+       const bt_value *input_value;
+       double weight = 0;
+       struct bt_common_lttng_live_url_parts parts = { 0 };
+
+       /* Used by the logging macros */
+       __attribute__((unused)) bt_self_component *self_comp = NULL;
+
+       *result = NULL;
+       input_type_value = bt_value_map_borrow_entry_value_const(params,
+               "type");
+       if (!input_type_value) {
+               BT_COMP_LOGE("Missing expected `type` parameter.");
+               goto error;
+       }
+
+       if (!bt_value_is_string(input_type_value)) {
+               BT_COMP_LOGE("`type` parameter is not a string value.");
+               goto error;
+       }
+
+       if (strcmp(bt_value_string_get(input_type_value), "string") != 0) {
+               /* We don't handle file system paths */
+               goto create_result;
+       }
+
+       input_value = bt_value_map_borrow_entry_value_const(params, "input");
+       if (!input_value) {
+               BT_COMP_LOGE("Missing expected `input` parameter.");
+               goto error;
+       }
+
+       if (!bt_value_is_string(input_value)) {
+               BT_COMP_LOGE("`input` parameter is not a string value.");
+               goto error;
+       }
+
+       parts = bt_common_parse_lttng_live_url(bt_value_string_get(input_value),
+               NULL, 0);
+       if (parts.session_name) {
+               /*
+                * Looks pretty much like an LTTng live URL: we got the
+                * session name part, which forms a complete URL.
+                */
+               weight = .75;
+       }
+
+create_result:
+       *result = bt_value_real_create_init(weight);
+       if (!*result) {
+               status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_MEMORY_ERROR;
+               goto error;
+       }
+
+       goto end;
+
+error:
+       if (status >= 0) {
+               status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
+       }
+
+       BT_ASSERT(!*result);
+
+end:
+       bt_common_destroy_lttng_live_url_parts(&parts);
+       return status;
+}
+
 BT_HIDDEN
 bt_component_class_query_method_status lttng_live_query(
                bt_self_component_class_source *comp_class,
@@ -1617,6 +1693,9 @@ bt_component_class_query_method_status lttng_live_query(
        if (strcmp(object, "sessions") == 0) {
                status = lttng_live_query_list_sessions(params, result,
                        log_level);
+       } else if (strcmp(object, "babeltrace.support-info") == 0) {
+               status = lttng_live_query_support_info(params, result,
+                       log_level);
        } else {
                BT_COMP_LOGI("Unknown query object `%s`", object);
                status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_UNKNOWN_OBJECT;
@@ -1675,7 +1754,9 @@ struct lttng_live_component *lttng_live_component_create(const bt_value *params,
                bt_logging_level log_level, bt_self_component *self_comp)
 {
        struct lttng_live_component *lttng_live;
-       const bt_value *value = NULL;
+       const bt_value *inputs_value;
+       const bt_value *url_value;
+       const bt_value *value;
        const char *url;
 
        lttng_live = g_new0(struct lttng_live_component, 1);
@@ -1687,13 +1768,36 @@ struct lttng_live_component *lttng_live_component_create(const bt_value *params,
        lttng_live->max_query_size = MAX_QUERY_SIZE;
        lttng_live->has_msg_iter = false;
 
-       value = bt_value_map_borrow_entry_value_const(params, URL_PARAM);
-       if (!value || !bt_value_is_string(value)) {
-               BT_COMP_LOGW("Mandatory `%s` parameter missing or not a string",
-                       URL_PARAM);
+       inputs_value = bt_value_map_borrow_entry_value_const(params,
+               INPUTS_PARAM);
+       if (!inputs_value) {
+               BT_COMP_LOGE("Mandatory `%s` parameter missing", INPUTS_PARAM);
+               goto error;
+       }
+
+       if (!bt_value_is_array(inputs_value)) {
+               BT_COMP_LOGE("`%s` parameter is required to be an array value",
+                       INPUTS_PARAM);
+               goto error;
+       }
+
+       if (bt_value_array_get_length(inputs_value) != 1) {
+               BT_COMP_LOGE("`%s` parameter's length is required to be 1",
+                       INPUTS_PARAM);
+               goto error;
+       }
+
+       url_value = bt_value_array_borrow_element_by_index_const(inputs_value,
+               0);
+       BT_ASSERT(url_value);
+
+       if (!bt_value_is_string(url_value)) {
+               BT_COMP_LOGE("First element of `%s` parameter is required to be a string value (URL)",
+                       INPUTS_PARAM);
                goto error;
        }
-       url = bt_value_string_get(value);
+
+       url = bt_value_string_get(url_value);
        lttng_live->params.url = g_string_new(url);
        if (!lttng_live->params.url) {
                goto error;
@@ -1701,8 +1805,13 @@ struct lttng_live_component *lttng_live_component_create(const bt_value *params,
 
        value = bt_value_map_borrow_entry_value_const(params,
                SESS_NOT_FOUND_ACTION_PARAM);
+       if (value) {
+               if (!bt_value_is_string(value)) {
+                       BT_COMP_LOGE("`%s` parameter is required to be a string value",
+                               SESS_NOT_FOUND_ACTION_PARAM);
+                       goto error;
+               }
 
-       if (value && bt_value_is_string(value)) {
                lttng_live->params.sess_not_found_act =
                        parse_session_not_found_action_param(value);
                if (lttng_live->params.sess_not_found_act == SESSION_NOT_FOUND_ACTION_UNKNOWN) {
@@ -1712,9 +1821,8 @@ struct lttng_live_component *lttng_live_component_create(const bt_value *params,
                        goto error;
                }
        } else {
-               BT_COMP_LOGW("Optional `%s` parameter is missing or "
-                       "not a string value. Defaulting to %s=\"%s\".",
-                       SESS_NOT_FOUND_ACTION_PARAM,
+               BT_COMP_LOGI("Optional `%s` parameter is missing: "
+                       "defaulting to `%s`.",
                        SESS_NOT_FOUND_ACTION_PARAM,
                        SESS_NOT_FOUND_ACTION_CONTINUE_STR);
                lttng_live->params.sess_not_found_act =