UST periodical metadata flush

[lttng-tools.git] / src / common / consumer-metadata-cache.h

diff --git a/src/common/consumer-metadata-cache.h b/src/common/consumer-metadata-cache.h
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+/*
+ * 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.
+ */
+
+#ifndef CONSUMER_METADATA_CACHE_H
+#define CONSUMER_METADATA_CACHE_H
+
+#include <common/consumer.h>
+
+struct consumer_metadata_cache {
+       char *data;
+       uint64_t cache_alloc_size;
+       /*
+        * How many bytes from the cache were already sent to the ring buffer.
+        */
+       uint64_t rb_pushed;
+       /*
+        * How many bytes are written in the buffer (excluding the wholes).
+        */
+       uint64_t total_bytes_written;
+       /*
+        * The upper-limit of data written inside the buffer.
+        *
+        * With the total_bytes_written it allows us to keep track of when the
+        * cache contains contiguous metadata ready to be sent to the RB.
+        * The metadata cache updates must not overlap.
+        */
+       uint64_t max_offset;
+       /*
+        * Lock to update the metadata cache and push into the ring_buffer
+        * (ustctl_write_metadata_to_channel).
+        */
+       pthread_mutex_t lock;
+};
+
+int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
+               unsigned int offset, unsigned int len, char *data);
+int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel);
+void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel);
+int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
+               uint64_t offset);
+
+#endif /* CONSUMER_METADATA_CACHE_H */