Clean-up: ust-consumer: replace manual metadata cache buffer allocation

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

diff --git a/src/common/consumer/consumer-metadata-cache.h b/src/common/consumer/consumer-metadata-cache.h
index 7dcf6976f3ada26eb4adf05beba86e710bc28752..b207cc79c233df23fb926aec7382b83094700a0d 100644 (file)
--- a/src/common/consumer/consumer-metadata-cache.h
+++ b/src/common/consumer/consumer-metadata-cache.h
@@ -1,41 +1,46 @@
 /*
- * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
- *                      David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
+ * Copyright (C) 2013 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.
+ * SPDX-License-Identifier: GPL-2.0-only
  *
- * 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/consumer.h>
+#include <common/dynamic-buffer.h>
 
-struct consumer_metadata_cache {
-       char *data;
-       uint64_t cache_alloc_size;
+enum consumer_metadata_cache_write_status {
+       CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR = -1,
+       /*
+        * New metadata content was appended to the cache successfully.
+        * Previously available content remains valid.
+        */
+       CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT = 0,
+       /*
+        * The new content pushed to the cache invalidated the content that
+        * was already present. The contents of the cache should be re-read.
+        */
+       CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED,
        /*
-        * Current version of the metadata cache.
+        * A metadata cache write can simply overwrite an already existing
+        * section of the cache (and it should be a write-through with identical
+        * data). From the caller's standpoint, there is no change to the state
+        * of the cache.
         */
+       CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE,
+};
+
+struct consumer_metadata_cache {
+       /* Current version of the metadata cache. */
        uint64_t version;
        /*
-        * 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.
+        * Size is the upper-limit of data written inside the buffer.
         * All cached data is contiguous.
         */
-       uint64_t max_offset;
+       struct lttng_dynamic_buffer contents;
        /*
         * Lock to update the metadata cache and push into the ring_buffer
         * (ustctl_write_metadata_to_channel).
@@ -45,9 +50,10 @@ struct consumer_metadata_cache {
        pthread_mutex_t lock;
 };
 
-int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
+enum consumer_metadata_cache_write_status
+consumer_metadata_cache_write(struct consumer_metadata_cache *cache,
                unsigned int offset, unsigned int len, uint64_t version,
-               char *data);
+               const 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,