#!/usr/bin/env python
#
# Public Domain 2014-2018 MongoDB, Inc.
# Public Domain 2008-2014 WiredTiger, Inc.
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# test_truncate03.py
#       session level operations on tables

import wiredtiger, wttest
from wtdataset import SimpleDataSet

# A standalone test case that exercises address-deleted cells.
class test_truncate_address_deleted(wttest.WiredTigerTestCase):
    uri = 'file:test_truncate'

    # Use a small page size and lots of keys because we want to create lots
    # of individual pages in the file.
    nentries = 10000
    config = 'allocation_size=512,leaf_page_max=512'

    # address_deleted routine:
    #   Create an object that has a bunch of address-deleted cells on disk.
    #   Recover the object, and turn the address-deleted cells into free pages.
    def address_deleted(self):
        # Create the object, force it to disk, and verify the object.
        ds = SimpleDataSet(self, self.uri, self.nentries, config=self.config)
        ds.populate()
        self.reopen_conn()
        self.session.verify(self.uri)

        # Create a new session and start a transaction to force the upcoming
        # checkpoint operation to write address-deleted cells to disk.
        tmp_session = self.conn.open_session(None)
        tmp_session.begin_transaction("isolation=snapshot")

        # Truncate a big range of rows; the leaf pages aren't in memory, so
        # leaf page references will be deleted without being read.
        start = self.session.open_cursor(self.uri, None)
        start.set_key(ds.key(10))
        end = self.session.open_cursor(self.uri, None)
        end.set_key(ds.key(self.nentries - 10))
        self.session.truncate(None, start, end, None)
        self.assertEqual(start.close(), 0)
        self.assertEqual(end.close(), 0)

        # Checkpoint, forcing address-deleted cells to be written.
        self.session.checkpoint()

        # Crash/reopen the connection and verify the object.
        self.reopen_conn()
        self.session.verify(self.uri)

        # Open a cursor and update a record (to dirty the tree, else we won't
        # mark pages with address-deleted cells dirty), then walk the tree so
        # we get a good look at all the internal pages and the address-deleted
        # cells.
        cursor = self.session.open_cursor(self.uri, None)
        cursor.set_key(ds.key(5))
        cursor.set_value("changed value")
        self.assertEqual(cursor.update(), 0)
        cursor.reset()
        for key,val in cursor:
            continue
        self.assertEqual(cursor.close(), 0)

        # Checkpoint, freeing the pages.
        self.session.checkpoint()
        return ds

    # Test object creation, recovery, and conversion of address-deleted cells
    # into free pages.
    def test_truncate_address_deleted_free(self):
        # Create the object on disk.
        ds = self.address_deleted()

        # That's all just verify that worked.
        self.session.verify(self.uri)

    # Test object creation, recovery, and conversion of address-deleted cells
    # into free pages, but instead of verifying the final object, instantiate
    # empty pages by a reader after the underlying leaf pages are removed.
    def test_truncate_address_deleted_empty_page(self):
        # Create the object on disk.
        ds = self.address_deleted()

        # Open a cursor and update pages in the middle of the range, forcing
        # creation of empty pages (once the underlying leaf page is freed, we
        # have to magic up a page if we need it).  Confirm we can read/write
        # the value as well as write the page and get it back.
        cursor = self.session.open_cursor(self.uri, None)
        for i in range(3000, 7000, 137):
            k = ds.key(i)
            v = 'changed value: ' + str(i)
            cursor[k] = v
        for i in range(3000, 7000, 137):
            k = ds.key(i)
            v = 'changed value: ' + str(i)
            cursor.set_key(k)
            self.assertEqual(cursor.search(), 0)
            self.assertEqual(cursor.get_value(), v)
        self.assertEqual(cursor.close(), 0)

        self.session.checkpoint()
        self.reopen_conn()
        self.session.verify(self.uri)

        cursor = self.session.open_cursor(self.uri, None)
        for i in range(3000, 7000, 137):
            k = ds.key(i)
            v = 'changed value: ' + str(i)
            cursor.set_key(k)
            self.assertEqual(cursor.search(), 0)
            self.assertEqual(cursor.get_value(), v)
        self.assertEqual(cursor.close(), 0)

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