#!/usr/bin/env python
#
# Public Domain 2014-present MongoDB, Inc.
# Public Domain 2008-2014 WiredTiger, Inc.
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import os
import wiredtiger, wttest

# test_stat08.py
#    Session statistics for bytes read into the cache.
class test_stat08(wttest.WiredTigerTestCase):

    nentries = 350000
    conn_config = 'cache_size=10MB,statistics=(all)'
    entry_value = "abcde" * 40
    BYTES_READ = wiredtiger.stat.session.bytes_read
    READ_TIME = wiredtiger.stat.session.read_time
    session_stats = { BYTES_READ : "session: bytes read into cache",           \
        READ_TIME : "session: page read from disk to cache time (usecs)"}

    def check_stats(self, cur, k):
        #
        # Some Windows machines lack the time granularity to detect microseconds.
        # Skip the time check on Windows.
        #
        if os.name == "nt" and k is self.READ_TIME:
            return

        exp_desc = self.session_stats[k]
        cur.set_key(k)
        cur.search()
        [desc, pvalue, value] = cur.get_values()
        self.pr('  stat: \'%s\', \'%s\', \'%s\'' % (desc, pvalue, str(value)))
        self.assertEqual(desc, exp_desc )
        if k is self.BYTES_READ or k is self.READ_TIME:
            self.assertTrue(value > 0)

    def test_session_stats(self):
        self.session = self.conn.open_session()
        self.session.create("table:test_stat08",
                            "key_format=i,value_format=S")
        cursor =  self.session.open_cursor('table:test_stat08', None, None)
        # Write the entries.
        for i in range(0, self.nentries):
            cursor[i] = self.entry_value
        cursor.reset()

        # Read the entries.
        i = 0
        for key, value in cursor:
            i = i + 1
        cursor.reset()

        # Now check the session statistics for bytes read into the cache.
        stat_cur = self.session.open_cursor('statistics:session', None, None)
        for k in self.session_stats:
            self.check_stats(stat_cur, k)

        # Session stats cursor reset should set all the stats values to zero.
        stat_cur.reset()
        while stat_cur.next() == 0:
            [desc, pvalue, value] = stat_cur.get_values()
            self.assertTrue(value == 0)

if __name__ == '__main__':
    wttest.run()