Fix: iterate manually over each live trace to add to catch errors

Instead of using g_hash_table_foreach, we now control the iteration over
the hash table, so we can handle properly the errors.
For now, if there is an error for any trace, we consider this a fatal
issue and exit.

We could allow the process to continue and only skip the problematic
traces, but we will wait until this becomes a real use-case.

Fixes: #827
Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/formats/lttng-live/lttng-live-comm.c b/formats/lttng-live/lttng-live-comm.c
index e473181578142a560d206ce09bc915266e9f8351..cbbeef2e77411e0fef0d5e0ac930e5a16bcf7c3c 100644 (file)
--- a/formats/lttng-live/lttng-live-comm.c
+++ b/formats/lttng-live/lttng-live-comm.c
@@ -70,7 +70,7 @@
 
 static void ctf_live_packet_seek(struct bt_stream_pos *stream_pos,
                size_t index, int whence);
-static void add_traces(gpointer key, gpointer value, gpointer user_data);
+static int add_traces(struct lttng_live_ctx *ctx);
 static int del_traces(gpointer key, gpointer value, gpointer user_data);
 static int get_new_metadata(struct lttng_live_ctx *ctx,
                struct lttng_live_viewer_stream *viewer_stream,
@@ -709,11 +709,14 @@ retry:
                if (rp.flags & LTTNG_VIEWER_FLAG_NEW_STREAM) {
                        printf_verbose("get_data_packet: new streams needed\n");
                        ret = ask_new_streams(ctx);
-                       if (ret < 0)
+                       if (ret < 0) {
                                goto error;
-                       else if (ret > 0)
-                               g_hash_table_foreach(ctx->session->ctf_traces,
-                                               add_traces, ctx->bt_ctx);
+                       } else if (ret > 0) {
+                               ret = add_traces(ctx);
+                               if (ret < 0) {
+                                       goto error;
+                               }
+                       }
                }
                if (rp.flags & (LTTNG_VIEWER_FLAG_NEW_METADATA
                                | LTTNG_VIEWER_FLAG_NEW_STREAM)) {
@@ -1031,11 +1034,14 @@ retry:
                if (rp->flags & LTTNG_VIEWER_FLAG_NEW_STREAM) {
                        printf_verbose("get_next_index: need new streams\n");
                        ret = ask_new_streams(ctx);
-                       if (ret < 0)
+                       if (ret < 0) {
                                goto error;
-                       else if (ret > 0)
-                               g_hash_table_foreach(ctx->session->ctf_traces,
-                                               add_traces, ctx->bt_ctx);
+                       } else if (ret > 0) {
+                               ret = add_traces(ctx);
+                               if (ret < 0) {
+                                       goto error;
+                               }
+                       }
                }
                break;
        case LTTNG_VIEWER_INDEX_RETRY:
@@ -1360,15 +1366,14 @@ int del_traces(gpointer key, gpointer value, gpointer user_data)
 }
 
 static
-void add_traces(gpointer key, gpointer value, gpointer user_data)
+int add_one_trace(struct lttng_live_ctx *ctx,
+               struct lttng_live_ctf_trace *trace)
 {
        int i, ret;
-       struct bt_context *bt_ctx = user_data;
-       struct lttng_live_ctf_trace *trace = value;
+       struct bt_context *bt_ctx = ctx->bt_ctx;
        struct lttng_live_viewer_stream *stream;
        struct bt_mmap_stream *new_mmap_stream;
        struct bt_mmap_stream_list mmap_list;
-       struct lttng_live_ctx *ctx = NULL;
        struct bt_trace_descriptor *td;
        struct bt_trace_handle *handle;
 
@@ -1381,14 +1386,15 @@ void add_traces(gpointer key, gpointer value, gpointer user_data)
         * times the same traces.
         * If a trace is already in the context, we just skip this function.
         */
-       if (trace->in_use)
-               return;
+       if (trace->in_use) {
+               ret = 0;
+               goto end;
+       }
 
        BT_INIT_LIST_HEAD(&mmap_list.head);
 
        for (i = 0; i < trace->streams->len; i++) {
                stream = g_ptr_array_index(trace->streams, i);
-               ctx = stream->session->ctx;
 
                if (!stream->metadata_flag) {
                        new_mmap_stream = zmalloc(sizeof(struct bt_mmap_stream));
@@ -1424,6 +1430,7 @@ void add_traces(gpointer key, gpointer value, gpointer user_data)
 
        if (!trace->metadata_fp) {
                fprintf(stderr, "[error] No metadata stream opened\n");
+               ret = -1;
                goto end_free;
        }
 
@@ -1431,6 +1438,7 @@ void add_traces(gpointer key, gpointer value, gpointer user_data)
                        ctf_live_packet_seek, &mmap_list, trace->metadata_fp);
        if (ret < 0) {
                fprintf(stderr, "[error] Error adding trace\n");
+               ret = -1;
                goto end_free;
        }
        trace->metadata_stream->metadata_len = 0;
@@ -1452,7 +1460,31 @@ void add_traces(gpointer key, gpointer value, gpointer user_data)
 end_free:
        bt_context_put(bt_ctx);
 end:
-       return;
+       return ret;
+}
+
+static
+int add_traces(struct lttng_live_ctx *ctx)
+{
+       int ret;
+       struct lttng_live_ctf_trace *trace;
+       GHashTableIter it;
+       gpointer key;
+       gpointer value;
+
+       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;
+               ret = add_one_trace(ctx, trace);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+
+       ret = 0;
+
+end:
+       return ret;
 }
 
 /*
@@ -1661,8 +1693,10 @@ int lttng_live_read(struct lttng_live_ctx *ctx)
                        }
                }
 
-               g_hash_table_foreach(ctx->session->ctf_traces, add_traces,
-                               ctx->bt_ctx);
+               ret = add_traces(ctx);
+               if (ret < 0) {
+                       goto end_free;
+               }
 
                begin_pos.type = BT_SEEK_BEGIN;
                iter = bt_ctf_iter_create(ctx->bt_ctx, &begin_pos, NULL);