/*-
 * Public Domain 2014-2018 MongoDB, Inc.
 * Public Domain 2008-2014 WiredTiger, Inc.
 *
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * ex_stat.c
 *	This is an example demonstrating how to query database statistics.
 */
#include <test_util.h>

void get_stat(WT_CURSOR *cursor, int stat_field, uint64_t *valuep);
void print_cursor(WT_CURSOR *);
void print_database_stats(WT_SESSION *);
void print_derived_stats(WT_SESSION *);
void print_file_stats(WT_SESSION *);
void print_join_cursor_stats(WT_SESSION *);
void print_overflow_pages(WT_SESSION *);

static const char *home;

/*! [statistics display function] */
void
print_cursor(WT_CURSOR *cursor)
{
	const char *desc, *pvalue;
	uint64_t value;
	int ret;

	while ((ret = cursor->next(cursor)) == 0) {
		error_check(cursor->get_value(cursor, &desc, &pvalue, &value));
		if (value != 0)
			printf("%s=%s\n", desc, pvalue);
	}
	scan_end_check(ret == WT_NOTFOUND);
}
/*! [statistics display function] */

void
print_database_stats(WT_SESSION *session)
{
	WT_CURSOR *cursor;

	/*! [statistics database function] */
	error_check(session->open_cursor(
	    session, "statistics:", NULL, NULL, &cursor));

	print_cursor(cursor);
	error_check(cursor->close(cursor));
	/*! [statistics database function] */
}

void
print_file_stats(WT_SESSION *session)
{
	WT_CURSOR *cursor;

	/*! [statistics table function] */
	error_check(session->open_cursor(
	    session, "statistics:table:access", NULL, NULL, &cursor));

	print_cursor(cursor);
	error_check(cursor->close(cursor));
	/*! [statistics table function] */
}

void
print_join_cursor_stats(WT_SESSION *session)
{
	WT_CURSOR *idx_cursor, *join_cursor, *stat_cursor;

	error_check(session->create(
	    session, "index:access:idx", "columns=(v)"));
	error_check(session->open_cursor(
	    session, "index:access:idx", NULL, NULL, &idx_cursor));
	error_check(idx_cursor->next(idx_cursor));
	error_check(session->open_cursor(
	    session, "join:table:access", NULL, NULL, &join_cursor));
	error_check(session->join(
	    session, join_cursor, idx_cursor, "compare=gt"));
	print_cursor(join_cursor);

	/*! [statistics join cursor function] */
	error_check(session->open_cursor(session,
	    "statistics:join", join_cursor, NULL, &stat_cursor));

	print_cursor(stat_cursor);
	error_check(stat_cursor->close(stat_cursor));
	/*! [statistics join cursor function] */

	error_check(join_cursor->close(join_cursor));
	error_check(idx_cursor->close(idx_cursor));
}

void
print_overflow_pages(WT_SESSION *session)
{
	/*! [statistics retrieve by key] */
	WT_CURSOR *cursor;
	const char *desc, *pvalue;
	uint64_t value;

	error_check(session->open_cursor(session,
	    "statistics:table:access", NULL, NULL, &cursor));

	cursor->set_key(cursor, WT_STAT_DSRC_BTREE_OVERFLOW);
	error_check(cursor->search(cursor));
	error_check(cursor->get_value(cursor, &desc, &pvalue, &value));
	printf("%s=%s\n", desc, pvalue);

	error_check(cursor->close(cursor));
	/*! [statistics retrieve by key] */
}

/*! [statistics calculation helper function] */
void
get_stat(WT_CURSOR *cursor, int stat_field, uint64_t *valuep)
{
	const char *desc, *pvalue;

	cursor->set_key(cursor, stat_field);
	error_check(cursor->search(cursor));
	error_check(cursor->get_value(cursor, &desc, &pvalue, valuep));
}
/*! [statistics calculation helper function] */

void
print_derived_stats(WT_SESSION *session)
{
	WT_CURSOR *cursor;

	/*! [statistics calculate open table stats] */
	error_check(session->open_cursor(session,
	    "statistics:table:access", NULL, NULL, &cursor));
	/*! [statistics calculate open table stats] */

	{
	/*! [statistics calculate table fragmentation] */
	uint64_t ckpt_size, file_size, percent;
	get_stat(cursor, WT_STAT_DSRC_BLOCK_CHECKPOINT_SIZE, &ckpt_size);
	get_stat(cursor, WT_STAT_DSRC_BLOCK_SIZE, &file_size);

	percent = 0;
	if (file_size != 0)
		percent = 100 * ((file_size - ckpt_size) / file_size);
	printf("Table is %" PRIu64 "%% fragmented\n", percent);
	/*! [statistics calculate table fragmentation] */
	}

	{
	/*! [statistics calculate write amplification] */
	uint64_t app_insert, app_remove, app_update, fs_writes;

	get_stat(cursor, WT_STAT_DSRC_CURSOR_INSERT_BYTES, &app_insert);
	get_stat(cursor, WT_STAT_DSRC_CURSOR_REMOVE_BYTES, &app_remove);
	get_stat(cursor, WT_STAT_DSRC_CURSOR_UPDATE_BYTES, &app_update);

	get_stat(cursor, WT_STAT_DSRC_CACHE_BYTES_WRITE, &fs_writes);

	if (app_insert + app_remove + app_update != 0)
		printf("Write amplification is %.2lf\n",
		    (double)fs_writes / (app_insert + app_remove + app_update));
	/*! [statistics calculate write amplification] */
	}

	error_check(cursor->close(cursor));
}

int
main(int argc, char *argv[])
{
	WT_CONNECTION *conn;
	WT_CURSOR *cursor;
	WT_SESSION *session;

	home = example_setup(argc, argv);

	error_check(
	    wiredtiger_open(home, NULL, "create,statistics=(all)", &conn));
	error_check(conn->open_session(conn, NULL, NULL, &session));
	error_check(session->create(session,
	    "table:access", "key_format=S,value_format=S,columns=(k,v)"));

	error_check(session->open_cursor(
	    session, "table:access", NULL, NULL, &cursor));
	cursor->set_key(cursor, "key");
	cursor->set_value(cursor, "value");
	error_check(cursor->insert(cursor));
	error_check(cursor->close(cursor));

	error_check(session->checkpoint(session, NULL));

	print_database_stats(session);

	print_file_stats(session);

	print_join_cursor_stats(session);

	print_overflow_pages(session);

	print_derived_stats(session);

	error_check(conn->close(conn, NULL));

	return (EXIT_SUCCESS);
}
