# Copyright 2015 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Test the locking library."""

import itertools
import multiprocessing
import os
import sys
import time

from chromite.lib import cros_test_lib
from chromite.lib import locking
from chromite.lib import osutils
from chromite.lib import parallel
from chromite.lib import process_util
from chromite.lib import timeout_util


LOCK_ACQUIRED = 5
LOCK_NOT_ACQUIRED = 6


class LockingTest(cros_test_lib.TempDirTestCase):
    """Test the Locking class."""

    def setUp(self):
        self.lock_file = os.path.join(self.tempdir, "lockfile")

    def _HelperSingleLockTest(self, blocking, shared, locktype):
        """Helper method to run a basic test with/without blocking/sharing."""
        self.assertNotExists(self.lock_file)

        lock = locking.FileLock(
            self.lock_file, blocking=blocking, locktype=locktype
        )
        self.assertFalse(lock.IsLocked())

        lock.write_lock()
        self.assertTrue(lock.IsLocked())
        self.assertExists(self.lock_file)

        # Acquiring the lock again should be safe.
        lock.lock(shared)
        self.assertTrue(lock.IsLocked())

        lock.close()
        self.assertFalse(lock.IsLocked())

        osutils.SafeUnlink(self.lock_file)

    def _HelperInsideProcess(
        self, blocking, shared, locktype=locking.LOCKF, blocking_timeout=None
    ):
        """Helper method that runs a basic test with/without blocking."""
        try:
            lock = locking.FileLock(
                self.lock_file,
                blocking=blocking,
                locktype=locktype,
                blocking_timeout=blocking_timeout,
            )
            with lock.lock(shared):
                pass
            sys.exit(LOCK_ACQUIRED)
        except locking.LockNotAcquiredError:
            sys.exit(LOCK_NOT_ACQUIRED)

    def _HelperStartProcess(
        self,
        blocking=False,
        shared=False,
        locktype=locking.LOCKF,
        blocking_timeout=None,
    ):
        """Create a process and invoke _HelperInsideProcess in it."""
        p = multiprocessing.Process(
            target=self._HelperInsideProcess,
            args=(blocking, shared, locktype, blocking_timeout),
        )
        p.start()

        # It's highly probably that p will have tried to grab the lock before
        # the timer expired, but not certain.
        time.sleep(0.1)

        return p

    def _HelperWithProcess(
        self, expected, blocking=False, shared=False, locktype=locking.LOCKF
    ):
        """Create a process and invoke _HelperInsideProcess in it."""
        p = multiprocessing.Process(
            target=self._HelperInsideProcess, args=(blocking, shared, locktype)
        )
        p.start()
        p.join()
        self.assertEqual(p.exitcode, expected)

    def testSingleLock(self):
        """Just test getting releasing a lock with options."""
        arg_list = [
            [True, False],  # blocking
            [True, False],  # shared
            [locking.FLOCK, locking.LOCKF],  # locking mechanism
        ]
        for args in itertools.product(*arg_list):
            self._HelperSingleLockTest(*args)

    def testDoubleLockWithFlock(self):
        """Tests that double locks do block with flock."""
        lock1 = locking.FileLock(
            self.lock_file, blocking=False, locktype=locking.FLOCK
        )
        lock2 = locking.FileLock(
            self.lock_file, blocking=False, locktype=locking.FLOCK
        )

        with lock1.write_lock():
            self.assertTrue(lock1.IsLocked())
            self.assertFalse(lock2.IsLocked())

            self.assertRaises(locking.LockNotAcquiredError, lock2.write_lock)
            self.assertTrue(lock1.IsLocked())
            self.assertFalse(lock2.IsLocked())

        self.assertFalse(lock1.IsLocked())
        self.assertFalse(lock2.IsLocked())

        lock2.unlock()
        self.assertFalse(lock1.IsLocked())
        self.assertFalse(lock2.IsLocked())

    def testDoubleLockTimeoutWithFlock(self):
        """Tests that double locking the same lock times out."""
        lock1 = locking.FileLock(
            self.lock_file,
            blocking=True,
            locktype=locking.FLOCK,
            blocking_timeout=1,
            verbose=True,
        )
        lock2 = locking.FileLock(
            self.lock_file,
            blocking=True,
            locktype=locking.FLOCK,
            blocking_timeout=1,
            verbose=True,
        )

        # Verify that if we grab the first lock, trying to use lock2
        # (on the same file) will throw an exception.
        with lock1.write_lock():
            self.assertTrue(lock1.IsLocked())
            self.assertFalse(lock2.IsLocked())

            self.assertRaises(timeout_util.TimeoutError, lock2.write_lock)
            self.assertTrue(lock1.IsLocked())

    def testDoubleLockWithLockf(self):
        """Tests that double locks don't block with lockf."""
        lock1 = locking.FileLock(
            self.lock_file, blocking=False, locktype=locking.LOCKF
        )
        lock2 = locking.FileLock(
            self.lock_file, blocking=False, locktype=locking.LOCKF
        )
        with lock1.write_lock():
            self.assertTrue(lock1.IsLocked())
            self.assertFalse(lock2.IsLocked())

            # With lockf, we can lock the same file twice in the same process.
            with lock2.write_lock():
                self.assertTrue(lock1.IsLocked())
                self.assertTrue(lock2.IsLocked())

        self.assertFalse(lock1.IsLocked())
        self.assertFalse(lock2.IsLocked())

    def testContextMgr(self):
        """Make sure we behave properly with 'with'."""
        # Create an instance, and use it in a with.
        prelock = locking.FileLock(self.lock_file)
        self._HelperWithProcess(expected=LOCK_ACQUIRED)

        with prelock.write_lock() as lock:
            # Assert the instance didn't change.
            self.assertIs(prelock, lock)
            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED)

        self._HelperWithProcess(expected=LOCK_ACQUIRED)

        # Construct the instance in the with expression.
        with locking.FileLock(self.lock_file).write_lock() as lock:
            self.assertIsInstance(lock, locking.FileLock)
            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED)

        self._HelperWithProcess(expected=LOCK_ACQUIRED)

    def testAcquireBeforeWith(self):
        """Sometimes you want to grab a lock and then return it into 'with'."""
        lock = locking.FileLock(self.lock_file, blocking=False)

        lock.write_lock()
        self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED)

        with lock:
            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED)

        self._HelperWithProcess(expected=LOCK_ACQUIRED)

    def testSingleProcessLock(self):
        """Test grabbing the same lock in processes with no conflicts."""
        arg_list = [
            [LOCK_ACQUIRED],
            [True, False],  # blocking
            [True, False],  # shared
            [locking.FLOCK, locking.LOCKF],  # locking mechanism
        ]
        for args in itertools.product(*arg_list):
            self._HelperWithProcess(*args)

    def testNonBlockingConflicts(self):
        """Test that we get a lock conflict for non-blocking locks."""
        with locking.FileLock(self.lock_file).write_lock():
            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED)

            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED, shared=True)

        # Can grab it after it's released.
        self._HelperWithProcess(expected=LOCK_ACQUIRED)

    def testSharedLocks(self):
        """Test lock conflict for blocking locks."""
        # Intial lock is NOT shared.
        with locking.FileLock(self.lock_file).write_lock():
            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED, shared=True)

        # Intial lock IS shared.
        with locking.FileLock(self.lock_file).read_lock():
            self._HelperWithProcess(expected=LOCK_ACQUIRED, shared=True)
            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED, shared=False)

    def testBlockingConflicts(self):
        """Test lock conflict for blocking locks."""
        # Intial lock is blocking, exclusive.
        with locking.FileLock(self.lock_file, blocking=True).write_lock():
            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED, blocking=False)

            p = self._HelperStartProcess(blocking=True, shared=False)

        # when the with clause exits, p should unblock and get the lock, setting
        # its exit code to sucess now.
        p.join()
        self.assertEqual(p.exitcode, LOCK_ACQUIRED)

        # Intial lock is NON blocking.
        with locking.FileLock(self.lock_file, blocking=False).write_lock():
            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED)

            p = self._HelperStartProcess(blocking=True, shared=False)

        # when the with clause exits, p should unblock and get the lock, setting
        # it's exit code to sucess now.
        p.join()
        self.assertEqual(p.exitcode, LOCK_ACQUIRED)

        # Intial lock is shared, blocking lock is exclusive.
        with locking.FileLock(self.lock_file, blocking=False).read_lock():
            self._HelperWithProcess(expected=LOCK_NOT_ACQUIRED)
            self._HelperWithProcess(expected=LOCK_ACQUIRED, shared=True)

            p = self._HelperStartProcess(blocking=True, shared=False)
            q = self._HelperStartProcess(blocking=True, shared=False)

        # when the with clause exits, p should unblock and get the lock, setting
        # it's exit code to sucess now.
        p.join()
        self.assertEqual(p.exitcode, LOCK_ACQUIRED)
        q.join()
        self.assertEqual(p.exitcode, LOCK_ACQUIRED)


class PortableLinkLockTest(cros_test_lib.TempDirTestCase):
    """Test locking.PortableLinkLock class."""

    def tearDown(self):
        """Looks for leaked files from the locking process."""
        leaked_files = os.listdir(self.tempdir)
        self.assertFalse(
            leaked_files,
            "Found unexpected leaked files from locking: %r" % leaked_files,
        )

    def testLockExclusivity(self):
        """Test that when we have a lock, someone else can't grab it."""
        lock_path = os.path.join(self.tempdir, "locked_file")
        with locking.PortableLinkLock(lock_path, max_retry=0):
            with self.assertRaises(locking.LockNotAcquiredError):
                with locking.PortableLinkLock(
                    lock_path, max_retry=5, sleep=0.1
                ):
                    self.fail("We acquired a lock twice?")

    def testCanUnlock(self):
        """Test that we release locks correctly."""
        lock_path = os.path.join(self.tempdir, "locked_file")
        with locking.PortableLinkLock(lock_path, max_retry=0):
            pass
        with locking.PortableLinkLock(lock_path, max_retry=0):
            pass


class PipeLockTest(cros_test_lib.TestCase):
    """Test locking.PipeLock class."""

    def testFdLeakage(self):
        """Make sure we don't leak any fds."""
        fds_before = os.listdir("/proc/self/fd/")
        lock = locking.PipeLock()
        fds_after = os.listdir("/proc/self/fd/")
        self.assertEqual(len(fds_before), len(fds_after) - 2)
        del lock
        fds_finished = os.listdir("/proc/self/fd/")
        self.assertEqual(fds_before, fds_finished)

    def testSimple(self):
        """Test we can Wait/Post."""
        # If this fails, we'd just hang :).
        with timeout_util.Timeout(30):
            lock = locking.PipeLock()
            lock.Post()
            lock.Post()
            lock.Wait()
            lock.Wait()
            del lock

    def testParallel(self):
        """Test interprocesses actually sync."""
        write_lock = locking.PipeLock()
        read_lock = locking.PipeLock()

        with osutils.TempDir() as tempdir:
            # Let the child create a file, but make sure the parent holds us
            # off. Then make the parent wait for the child to tell us it's done.
            flag_file = os.path.join(tempdir, "foo")

            pid = os.fork()
            if pid == 0:
                # Child.
                # pylint: disable=protected-access
                try:
                    write_lock.Wait()
                    del write_lock
                    osutils.Touch(flag_file)
                    read_lock.Post()
                    del read_lock
                except Exception:
                    os._exit(1)
                finally:
                    # No matter what happens, we must exit w/out running
                    # handlers.
                    os._exit(0)
            else:
                # Parent.
                time.sleep(0.5)
                self.assertNotExists(flag_file)
                write_lock.Post()
                del write_lock
                read_lock.Wait()
                del read_lock
                self.assertExists(flag_file)

                status = os.waitpid(pid, 0)[1]
                self.assertEqual(process_util.GetExitStatus(status), 0)

    def testParallelMany(self):
        """Same as testParallel, but with many more processes for stressing."""
        parallel.RunParallelSteps([self.testParallel] * 40)