Implement the relayd live features

[lttng-tools.git] / src / bin / lttng-relayd / ctf-trace.c

diff --git a/src/bin/lttng-relayd/ctf-trace.c b/src/bin/lttng-relayd/ctf-trace.c
new file mode 100644 (file)
index 0000000..adfbac3
--- /dev/null
+++ b/src/bin/lttng-relayd/ctf-trace.c
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
+ *                      David Goulet <dgoulet@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License, version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#define _GNU_SOURCE
+#include <assert.h>
+
+#include <common/common.h>
+#include <common/utils.h>
+
+#include "ctf-trace.h"
+
+static uint64_t last_relay_ctf_trace_id;
+
+/*
+ * Try to destroy a ctf_trace object meaning that the refcount is decremented
+ * and checked if down to 0 which will free it.
+ */
+void ctf_trace_try_destroy(struct ctf_trace *obj)
+{
+       unsigned long ret_ref;
+
+       if (!obj) {
+               return;
+       }
+
+       ret_ref = uatomic_add_return(&obj->refcount, -1);
+       assert(ret_ref >= 0);
+       if (ret_ref == 0) {
+               DBG("Freeing ctf_trace %" PRIu64, obj->id);
+               free(obj);
+       }
+}
+
+/*
+ * Create and return an allocated ctf_trace object. NULL on error.
+ */
+struct ctf_trace *ctf_trace_create(void)
+{
+       struct ctf_trace *obj;
+
+       obj = zmalloc(sizeof(*obj));
+       if (!obj) {
+               PERROR("ctf_trace alloc");
+               goto error;
+       }
+
+       obj->id = ++last_relay_ctf_trace_id;
+       DBG("Created ctf_trace %" PRIu64, obj->id);
+
+error:
+       return obj;
+}
+
+/*
+ * Check if we can assign the ctf_trace id and metadata stream to one or all
+ * the streams with the same path_name (our unique ID for ctf traces).
+ *
+ * The given stream MUST be new and NOT visible (in any hash table).
+ */
+void ctf_trace_assign(struct lttng_ht *ht, struct relay_stream *stream)
+{
+       struct lttng_ht_iter iter;
+       struct relay_stream *tmp_stream;
+
+       assert(ht);
+       assert(stream);
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct((void *) stream->path_name, lttng_ht_seed),
+                       ht->match_fct, (void *) stream->path_name,
+                       &iter.iter, tmp_stream, ctf_trace_node.node) {
+               if (stream->metadata_flag) {
+                       /*
+                        * The new stream is the metadata stream for this trace,
+                        * assign the ctf_trace pointer to all the streams in
+                        * this bucket.
+                        */
+                       pthread_mutex_lock(&tmp_stream->lock);
+                       tmp_stream->ctf_trace = stream->ctf_trace;
+                       uatomic_inc(&tmp_stream->ctf_trace->refcount);
+                       pthread_mutex_unlock(&tmp_stream->lock);
+                       DBG("Assigned ctf_trace %" PRIu64 " to stream %" PRIu64,
+                                       tmp_stream->ctf_trace->id, tmp_stream->stream_handle);
+               } else if (tmp_stream->ctf_trace) {
+                       /*
+                        * The ctf_trace already exists for this bucket,
+                        * just assign the pointer to the new stream and exit.
+                        */
+                       stream->ctf_trace = tmp_stream->ctf_trace;
+                       uatomic_inc(&stream->ctf_trace->refcount);
+                       DBG("Assigned ctf_trace %" PRIu64 " to stream %" PRIu64,
+                                       tmp_stream->ctf_trace->id, tmp_stream->stream_handle);
+                       goto end;
+               } else {
+                       /*
+                        * We don't know yet the ctf_trace ID (no metadata has been added),
+                        * so leave it there until the metadata stream arrives.
+                        */
+                       goto end;
+               }
+       }
+
+end:
+       rcu_read_unlock();
+       return;
+}
+