Bugfix/clear by tag on filesystem storage while files are already deleted

[skors]

This PR fixes the behavior on the special case that file content is read while tag file is deleted

More description in #44

@marc-mabe is this kind of try...catch solution you had in mind?

Merging this PR closes #44

[ghost]

This looks very error prone. I think it would be better to test if the file exists instead of parsing an exception message.

try {
    // ...
} catch (Exception\RuntimeException $e) {
    // ignore missing files because of possible raise conditions
    // e.g. another process already deleted that item
    if (!file_exists($pathname)) {
        continue;
    }
    throw $e;
}

[skors]

@DCMNMarc thanks, that was unclear to me.

[skors]

@DCMNMarc i've changed it. but wouldn't this behave same like you commented in #44 (comment) ?

[marc-mabe]

@skors Much thanks for this fix and unittest!

Today I had time play a little with it and was able to reduce the wait timings and removed the temporary file the tests still works (or fails) as expected.

This way the test should also fail if the process wait timings are not proper or even if something changed in the filesystem adapter which breaks the hack for delay unlink.

But I still doesn't understand why posix_kill(posix_getpid(), SIGTERM); is required.

Now it looks like the following:

    /**
     * @runInSeparateProcess
     */
    public function testClearByTagsWithoutLocking()
    {
        if (!function_exists('pcntl_fork') || !function_exists('posix_kill')) {
            $this->markTestSkipped('Missing pcntl_fork and/or posix_kill');
        }

        // create cache items
        $this->_storage->getOptions()->setDirLevel(0);
        $this->_storage->getOptions()->setFileLocking(false);
        $this->_storage->setItems([
            'a_key' => 'a_value',
            'b_key' => 'b_value',
            'other' => 'other',
        ]);
        $this->_storage->setTags('a_key', ['a_tag']);
        $this->_storage->setTags('b_key', ['a_tag']);

        $pidChild = pcntl_fork();
        if ($pidChild == -1) {
            $this->fail('pcntl_fork() failed');
        } elseif ($pidChild) {
            // The parent process
            // Slow down unlink function and start removing items.
            // Finally test if the item not matching the tag was removed by the child process.
            require __DIR__ . '/TestAsset/FilesystemDelayedUnlink.php';
            $this->_storage->clearByTags(['a_tag'], true);
            $this->assertFalse($this->_storage->hasItem('other'));
        } else {
            // The child process:
            // Wait to make sure the parent process has started determining files to unlink.
            // Than remove one of the items the parent process should remove and another item for testing.
            usleep(10000);
            $this->_storage->removeItems(['b_key', 'other']);
            posix_kill(posix_getpid(), SIGTERM);
        }
    }

    /**
     * @runInSeparateProcess
     */
    public function testClearByTagsWithLocking()
    {
        if (!function_exists('pcntl_fork') || !function_exists('posix_kill')) {
            $this->markTestSkipped('Missing pcntl_fork and/or posix_kill');
        }

        // create cache items
        $this->_storage->getOptions()->setDirLevel(0);
        $this->_storage->getOptions()->setFileLocking(true);
        $this->_storage->setItems([
            'a_key' => 'a_value',
            'b_key' => 'b_value',
            'other' => 'other',
        ]);
        $this->_storage->setTags('a_key', ['a_tag']);
        $this->_storage->setTags('b_key', ['a_tag']);

        $pidChild = pcntl_fork();
        if ($pidChild == -1) {
            $this->fail('pcntl_fork() failed');
        } elseif ($pidChild) {
            // The parent process
            // Slow down unlink function and start removing items.
            // Finally test if the item not matching the tag was removed by the child process.
            require __DIR__ . '/TestAsset/FilesystemDelayedUnlink.php';
            $this->_storage->clearByTags(['a_tag'], true);
            $this->assertFalse($this->_storage->hasItem('other'));
        } else {
            // The child process:
            // Wait to make sure the parent process has started determining files to unlink.
            // Than remove one of the items the parent process should remove and another item for testing.
            usleep(10000);
            $this->_storage->removeItems(['b_key', 'other']);
            posix_kill(posix_getpid(), SIGTERM);
        }
    }

[marc-mabe]

closed by bb8a75c

Thanks!