Fix: prevent calling adding the same trace recursively

[babeltrace.git] / formats / lttng-live / lttng-live-comm.c

diff --git a/formats/lttng-live/lttng-live-comm.c b/formats/lttng-live/lttng-live-comm.c
index 0e51c0c2ab5b1f2ab8519bb94e67e7305199e5b8..e08926380efab45e306a01ec59607012f51fbc90 100644 (file)
--- a/formats/lttng-live/lttng-live-comm.c
+++ b/formats/lttng-live/lttng-live-comm.c
@@ -1499,6 +1499,12 @@ int add_one_trace(struct lttng_live_ctx *ctx,
                ret = 0;
                goto end;
        }
+       /*
+        * add_one_trace can be called recursively if during the
+        * bt_context_add_trace call we need to fetch new streams, so we need to
+        * prevent a recursive call to process our current trace.
+        */
+       trace->in_use = 1;
 
        BT_INIT_LIST_HEAD(&mmap_list.head);
 
@@ -1561,7 +1567,6 @@ int add_one_trace(struct lttng_live_ctx *ctx,
        }
 
        trace->trace_id = ret;
-       trace->in_use = 1;
        printf_verbose("Trace now in use, id = %d\n", trace->trace_id);
 
        goto end;
@@ -1572,6 +1577,56 @@ end:
        return ret;
 }
 
+/*
+ * Make sure all the traces we know have a metadata stream or loop on
+ * ask_new_streams until it is done. This must be called before we call
+ * add_one_trace.
+ *
+ * Return 0 when all known traces have a metadata stream, a negative value
+ * on error.
+ */
+static
+int check_traces_metadata(struct lttng_live_ctx *ctx)
+{
+       int ret;
+       struct lttng_live_ctf_trace *trace;
+       GHashTableIter it;
+       gpointer key;
+       gpointer value;
+
+retry:
+       g_hash_table_iter_init(&it, ctx->session->ctf_traces);
+       while (g_hash_table_iter_next(&it, &key, &value)) {
+               trace = (struct lttng_live_ctf_trace *) value;
+               printf_verbose("Check trace %" PRIu64 " metadata\n", trace->ctf_trace_id);
+               while (!trace->metadata_stream) {
+                       printf_verbose("Waiting for metadata stream\n");
+                       if (lttng_live_should_quit()) {
+                               ret = 0;
+                               goto end;
+                       }
+                       ret = ask_new_streams(ctx);
+                       if (ret < 0) {
+                               goto end;
+                       } else if (ret == 0) {
+                               (void) poll(NULL, 0, ACTIVE_POLL_DELAY);
+                       } else {
+                               /*
+                                * If ask_new_stream got streams from a trace we did not know
+                                * about until now, we have to reinitialize the iterator.
+                                */
+                               goto retry;
+                       }
+               }
+       }
+
+       ret = 0;
+
+end:
+       printf_verbose("End check traces metadata\n");
+       return ret;
+}
+
 static
 int add_traces(struct lttng_live_ctx *ctx)
 {
@@ -1580,8 +1635,18 @@ int add_traces(struct lttng_live_ctx *ctx)
        GHashTableIter it;
        gpointer key;
        gpointer value;
+       unsigned int nr_traces;
 
        printf_verbose("Begin add traces\n");
+
+retry:
+       nr_traces = g_hash_table_size(ctx->session->ctf_traces);
+
+       ret = check_traces_metadata(ctx);
+       if (ret < 0) {
+               goto end;
+       }
+
        g_hash_table_iter_init(&it, ctx->session->ctf_traces);
        while (g_hash_table_iter_next(&it, &key, &value)) {
                trace = (struct lttng_live_ctf_trace *) value;
@@ -1589,6 +1654,15 @@ int add_traces(struct lttng_live_ctx *ctx)
                if (ret < 0) {
                        goto end;
                }
+               /*
+                * If a new trace got added while we were adding the trace, the
+                * iterator is invalid and we have to restart.
+                */
+               if (g_hash_table_size(ctx->session->ctf_traces) != nr_traces) {
+                       printf_verbose("New trace(s) added during add_one_trace()\n");
+                       printf_verbose("JORAJ: GREP HERE\n");
+                       goto retry;
+               }
        }
 
        ret = 0;