sapling/eden/integration/takeover_test.py

#!/usr/bin/env python3
#
# Copyright (c) 2016-present, Facebook, Inc.
# All rights reserved.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree. An additional grant
# of patent rights can be found in the PATENTS file in the same directory.

import os
import resource
import sys
import threading
from pathlib import Path
from typing import Dict

from eden.cli.util import get_pid_using_lockfile
from facebook.eden.ttypes import FaultDefinition

from .lib import testcase


@testcase.eden_repo_test
class TakeoverTest(testcase.EdenRepoTest):
    pagesize: int
    page1: str
    page2: str
    commit1: str
    commit2: str

    def populate_repo(self) -> None:
        self.pagesize = resource.getpagesize()
        self.page1 = "1" * self.pagesize
        self.page2 = "2" * self.pagesize
        self.repo.write_file("tree/hello", self.page1 + self.page2)
        self.repo.write_file("tree/deleted", self.page1 + self.page2)
        self.repo.write_file("src/main.c", "hello world")
        self.commit1 = self.repo.commit("Initial commit.")

        self.repo.write_file("src/main.c", "hello world v2")
        self.repo.write_file("src/test/test1.py", "test1")
        self.repo.write_file("src/test/test2.py", "test2")
        self.commit2 = self.repo.commit("Initial commit.")

    def select_storage_engine(self) -> str:
        """ we need to persist data across restarts """
        return "sqlite"

    def edenfs_logging_settings(self) -> Dict[str, str]:
        if self._testMethodName == "test_takeover_with_io":
            # test_takeover_with_io causes lots of I/O, so do not enable
            # verbose logging of I/O operations in this test.
            return {}
        return {
            "eden.strace": "DBG7",
            "eden.fs.fuse": "DBG7",
            "eden.fs.inodes.InodeMap": "DBG6",
        }

    def do_takeover_test(self) -> None:
        hello = os.path.join(self.mount, "tree/hello")
        deleted = os.path.join(self.mount, "tree/deleted")
        deleted_local = os.path.join(self.mount, "deleted-local")

        # To test our handling of unlinked inodes, in addition
        # to unlinking something that is in the manifest we
        # need to check that we handle the case of a local
        # file being deleted to make sure that we cover both
        # code paths for FileInode.
        with open(deleted_local, "w") as dl:
            dl.write(self.page1)
            dl.write(self.page2)

        # We'd like to make sure that we do something reasonable
        # for directories that have been unlinked and that are
        # still referenced via a file descriptor.  Ideally we'd call
        # opendir() here and then readdir() it after we've performed
        # the graceful restart, but we can't directly call those
        # functions from python.  The approach used here is to
        # open a file descriptor to the directory and then try
        # to stat() it after the restart.  Since the directory
        # has to be empty in order to be unlinked, a readdir
        # from it wouldn't return any interesting results anyway.
        deleted_dir = os.path.join(self.mount, "deleted-dir")
        os.mkdir(deleted_dir)
        deleted_dir_fd = os.open(deleted_dir, 0)
        os.rmdir(deleted_dir)

        with open(hello, "r") as f, open(deleted, "r") as d, open(
            deleted_local, "r"
        ) as dl:
            # Read the first page only (rather than the whole file)
            # before we restart the process.
            # This is so that we can check that the kernel really
            # does call in to us for the second page and that we're
            # really servicing the read for the second page and that
            # it isn't just getting served from the kernel buffer cache
            self.assertEqual(self.page1, f.read(self.pagesize))

            # Let's make sure that unlinked inodes continue to
            # work appropriately too.  We've opened the file
            # handles and are holding them alive in `d` and `dl`,
            # so now let's unlink it from the filesystem
            os.unlink(deleted)
            os.unlink(deleted_local)

            print("=== beginning restart ===", file=sys.stderr)
            self.eden.graceful_restart()
            print("=== restart complete ===", file=sys.stderr)

            # Ensure that our file handle is still live across
            # the restart boundary
            f.seek(0)
            self.assertEqual(self.page1, f.read(self.pagesize))
            self.assertEqual(self.page2, f.read(self.pagesize))

            # We should be able to read from the `d` file handle
            # even though we deleted the file from the tree
            self.assertEqual(self.page1, d.read(self.pagesize))
            self.assertEqual(self.page2, d.read(self.pagesize))
            # Likewise for the `dl` file handle
            self.assertEqual(self.page1, dl.read(self.pagesize))
            self.assertEqual(self.page2, dl.read(self.pagesize))

        # Now check that the unlinked directory handle still seems
        # connected.  This is difficult to do directly in python;
        # the directory had to be empty in order to be removed
        # so even if we could read its directory entries there
        # wouldn't be anything to read.
        # Note that os.stat() will throw if the fd is deemed
        # bad either by the kernel or the eden instance,
        # so we're just calling it and discarding the return
        # value.
        os.stat(deleted_dir_fd)
        os.close(deleted_dir_fd)

        # Let's also test opening the same file up again,
        # just to make sure that that is still working after
        # the graceful restart.
        with open(hello, "r") as f:
            self.assertEqual(self.page1, f.read(self.pagesize))
            self.assertEqual(self.page2, f.read(self.pagesize))

    def test_takeover(self) -> None:
        return self.do_takeover_test()

    def test_takeover_after_diff_revisions(self) -> None:
        # Make a getScmStatusBetweenRevisions() call to Eden.
        # Previously this thrift call caused Eden to create temporary inode
        # objects outside of the normal root inode tree, and this would cause
        # Eden to crash when shutting down afterwards.
        with self.get_thrift_client() as client:
            client.getScmStatusBetweenRevisions(
                os.fsencode(self.mount),
                self.commit1.encode("utf-8"),
                self.commit2.encode("utf-8"),
            )

        return self.do_takeover_test()

    def test_takeover_with_io(self) -> None:
        num_threads = 4
        write_chunk_size = 1024 * 1024
        max_file_length = write_chunk_size * 100

        # TODO: Setting this higher than 1 currently makes it likely that
        # edenfs will crash during restart.
        # There are still some other bugs we need to track down in the restart
        # ordering.
        num_restarts = 1

        stop = threading.Event()
        bufs = [b"x" * write_chunk_size, b"y" * write_chunk_size]

        def do_io(thread_id: int, running_event: threading.Event) -> None:
            path = os.path.join(self.mount, "src", "test", "data%d.log" % thread_id)
            with open(path, "wb") as f:
                # Use raw file descriptors to avoid going through python's I/O
                # buffering code.
                fd = f.fileno()

                buf_idx = 0
                buf = bufs[buf_idx]
                offset = 0

                # Repeatedly write and rewrite the same file,
                # jalternating between two different data buffers.
                running_event.set()
                while True:
                    os.pwrite(fd, buf, offset)
                    if stop.is_set():
                        return
                    offset += len(buf)
                    if offset >= max_file_length:
                        buf_idx += 1
                        buf = bufs[buf_idx % len(bufs)]
                        offset = 0

        # Log the mount points device ID at the start of the test
        # (Just in case anything hangs and we need to abort the mount
        # using /sys/fs/fuse/connections/<dev>/)
        st = os.lstat(self.mount)
        print("=== eden mount device=%d ===" % st.st_dev, file=sys.stderr)

        # Start several threads doing I/O while we we perform a takeover
        threads = []
        try:
            running_events = []
            for n in range(num_threads):
                running = threading.Event()
                thread = threading.Thread(target=do_io, args=(n, running))
                thread.start()
                threads.append(thread)
                running_events.append(running)

            # Wait until all threads have started and are doing I/O
            for event in running_events:
                event.wait()

            # Restart edenfs
            for n in range(num_restarts):
                print("=== beginning restart %d ===" % n, file=sys.stderr)
                self.eden.graceful_restart()
                print("=== restart %d complete ===" % n, file=sys.stderr)
        finally:
            stop.set()
            for thread in threads:
                thread.join()

    def test_takeover_updates_process_id_in_lock_file(self) -> None:
        self.assertEqual(
            self.eden.get_pid_via_thrift(),
            get_pid_using_lockfile(Path(self.eden.eden_dir)),
        )
        self.eden.graceful_restart()
        self.assertEqual(
            self.eden.get_pid_via_thrift(),
            get_pid_using_lockfile(Path(self.eden.eden_dir)),
        )

    def test_takeover_preserves_inode_numbers_for_open_nonmaterialized_files(
        self
    ) -> None:
        hello = os.path.join(self.mount, "tree/hello")

        fd = os.open(hello, os.O_RDONLY)
        try:
            inode_number = os.fstat(fd).st_ino

            self.eden.graceful_restart()

            self.assertEqual(inode_number, os.fstat(fd).st_ino)
        finally:
            os.close(fd)

        fd = os.open(hello, os.O_RDONLY)
        try:
            self.assertEqual(inode_number, os.fstat(fd).st_ino)
        finally:
            os.close(fd)

    def test_contents_are_the_same_if_handle_is_held_open(self) -> None:
        with open(os.path.join(self.mount, "tree", "hello")) as c2_hello_file, open(
            os.path.join(self.mount, "src", "main.c")
        ) as c2_mainc_file:

            self.eden.graceful_restart()
            self.eden.run_cmd(
                "debug", "flush_cache", os.path.join("tree", "hello"), cwd=self.mount
            )
            self.eden.run_cmd(
                "debug", "flush_cache", os.path.join("src", "main.c"), cwd=self.mount
            )

            self.assertEqual(self.page1 + self.page2, c2_hello_file.read())
            self.assertEqual("hello world v2", c2_mainc_file.read())


@testcase.eden_repo_test
class TakeoverRocksDBStressTest(testcase.EdenRepoTest):
    enable_fault_injection: bool = True

    def populate_repo(self) -> None:
        self.repo.write_file("test-directory/file", "")
        self.commit1 = self.repo.commit("Initial commit.")

    def select_storage_engine(self) -> str:
        return "rocksdb"

    def test_takeover_with_tree_inode_loading_from_local_store(self) -> None:
        """
        Restart edenfs while a tree inode is being loaded asynchronously. Ensure
        restarting does not deadlock.
        """

        def load_test_directory_inode_from_local_store_asynchronously() -> None:
            """
            Make edenfs start loading "/test-directory" from the local store.

            To ensure that the local store is in use during takeover, load the tree
            inode using a prefetch.

            At the time of writing, os.listdir("foo") causes edenfs to prefetch
            the tree inodes of foo/*. Exploit this to load the tree inode for
            "/directory".

            Other options considered:

            * At the time of writing, if we load the tree inode using a FUSE
              request (e.g. os.stat), edenfs would wait for the FUSE request to
              finish before starting the inode shutdown procedure.

            * At the time of writing, 'edenfsctl prefetch' does not prefetch
              tree inodes asynchronously.
            """
            os.listdir(self.mount)

        graceful_restart_startup_time = 5.0

        with self.eden.get_thrift_client() as client:
            for key_class in ["local store get single", "local store get batch"]:
                client.injectFault(
                    FaultDefinition(
                        keyClass=key_class,
                        keyValueRegex=".*",
                        delayMilliseconds=int(graceful_restart_startup_time * 1000),
                        count=100,
                    )
                )

        load_test_directory_inode_from_local_store_asynchronously()
        self.eden.graceful_restart()