#!/usr/bin/env python
#
# Public Domain 2014-2016 MongoDB, Inc.
# Public Domain 2008-2014 WiredTiger, Inc.
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# test_nsnap04.py
#   Named snapshots: Create snapshot from running transaction

from suite_subprocess import suite_subprocess
from helper import simple_populate
import wiredtiger, wttest

class test_nsnap04(wttest.WiredTigerTestCase, suite_subprocess):
    tablename = 'test_nsnap04'
    uri = 'table:' + tablename
    nrows_per_itr = 10

    def check_named_snapshot(self, snapshot, expected):
        new_session = self.conn.open_session()
        c = new_session.open_cursor(self.uri)
        new_session.begin_transaction("snapshot=" + str(snapshot))
        count = 0
        for row in c:
            count += 1
        new_session.commit_transaction()
        # print "Checking snapshot %d, expect %d, found %d" % (snapshot, expected, count)
        self.assertEqual(count, expected)

    def test_named_snapshots(self):
        # Populate a table
        end = start = 0
        simple_populate(self, self.uri, 'key_format=i', 0)

        snapshots = []
        c = self.session.open_cursor(self.uri)
        for i in xrange(self.nrows_per_itr):
            c[i] = "some value"

        # Start a new transaction in a different session
        new_session = self.conn.open_session()
        new_session.begin_transaction("isolation=snapshot")
        new_c = new_session.open_cursor(self.uri)
        count = 0
        for row in new_c:
            count += 1
        new_session.snapshot("name=0")

        self.check_named_snapshot(0, self.nrows_per_itr)

        # Insert some more content using the original session.
        for i in xrange(self.nrows_per_itr):
            c[2 * self.nrows_per_itr + i] = "some value"

        self.check_named_snapshot(0, self.nrows_per_itr)
        new_session.close()
        # Update the named snapshot
        self.session.snapshot("name=0")
        self.check_named_snapshot(0, 2 * self.nrows_per_itr)

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