mmap-based fixed-size record double-buffered logger

Change-Id: I760b482b9de457bbb17de817db7079b57d3f5ec1
Signed-off-by: Dave Barach <dave@barachs.net>

1 files changed, 99 insertions, 0 deletions

diff --git a/src/vppinfra/maplog.h b/src/vppinfra/maplog.h
new file mode 100644
index 00000000000..192dc22a71b
--- /dev/null
+++ b/src/vppinfra/maplog.h
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __included_maplog_h__
+#define __included_maplog_h__
+
+/** \file
+
+   mmap-based fixed-size record double-buffered logging
+*/
+
+#include <vppinfra/clib.h>
+#include <vppinfra/cache.h>
+#include <vppinfra/format.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+
+typedef struct
+{
+  /* rw: atomic ticket-counter, file index */
+  CLIB_CACHE_LINE_ALIGN_MARK (cacheline1);
+  volatile u64 next_record_index;
+  u64 file_size_in_records; /**< power of two */
+  u32 log2_file_size_in_records;
+  volatile u32 current_file_index;
+  volatile u32 flags;
+
+  /* ro: size parameters */
+    CLIB_CACHE_LINE_ALIGN_MARK (cacheline2);
+  u32 record_size_in_cachelines;
+
+  /* double-buffered mmap'ed logfiles */
+  volatile u8 *file_baseva[2];
+  u8 *filenames[2];
+  /* vector not c-string */
+  u8 *file_basename;
+} clib_maplog_main_t;
+
+int clib_maplog_init (clib_maplog_main_t * mm, char *file_basename,
+		      u64 file_size, u32 record_size_in_bytes);
+
+void clib_maplog_close (clib_maplog_main_t * mm);
+
+#define CLIB_MAPLOG_FLAG_INIT 	(1<<0)
+
+u8 *_clib_maplog_get_entry_slowpath (clib_maplog_main_t * mm,
+				     u64 my_record_index);
+
+static inline void *
+clib_maplog_get_entry (clib_maplog_main_t * mm)
+{
+  u64 my_record_index;
+  u8 *rv;
+
+  ASSERT (mm->flags & CLIB_MAPLOG_FLAG_INIT);
+
+  my_record_index = __sync_fetch_and_add (&mm->next_record_index, 1);
+
+  /* Time to unmap and create a new logfile? */
+  if (PREDICT_FALSE ((my_record_index & (mm->file_size_in_records - 1)) == 0))
+    {
+      /* Yes, but not the very first time... (;-)... */
+      if (my_record_index)
+	return _clib_maplog_get_entry_slowpath (mm, my_record_index);
+      /* FALLTHROUGH */
+    }
+
+  rv = (u8 *)
+    mm->file_baseva[(my_record_index >> mm->log2_file_size_in_records) & 1] +
+    (my_record_index & (mm->file_size_in_records - 1))
+    * mm->record_size_in_cachelines * CLIB_CACHE_LINE_BYTES;
+
+  return rv;
+}
+
+#endif /* __included_maplog_h__ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */