Examples with SelectiveFileSystemAbstraction org.neo4j.graphdb.mockfs.SelectiveFileSystemAbstraction used on opensource projects

Example 6 with SelectiveFileSystemAbstraction

use of org.neo4j.graphdb.mockfs.SelectiveFileSystemAbstraction in project neo4j by neo4j.

the class DurableStateStorageIT method shouldProperlyRecoveryAfterCrashOnFileForceDuringWrite.

@Test
public void shouldProperlyRecoveryAfterCrashOnFileForceDuringWrite() throws Exception {
    EphemeralFileSystemAbstraction normalFSA = fileSystemRule.get();
    /*
         * Magic number warning. For a rotation threshold of 14, 990 operations on file A falls on a force() of the
         * current active file. This has been discovered via experimentation. The end result is that there is a
         * flush (but not write) a value. This should be recoverable. Interestingly, the failure semantics are a bit
         * unclear on what should happen to that value. We assume that exception during persistence requires recovery
         * to discover if the last argument made it to disk or not. Since we use an EFSA, force is not necessary and
         * the value that caused the failure is actually "persisted" and recovered.
         */
    AdversarialFileSystemAbstraction breakingFSA = new AdversarialFileSystemAbstraction(new MethodGuardedAdversary(new CountingAdversary(40, true), StoreChannel.class.getMethod("force", boolean.class)), normalFSA);
    SelectiveFileSystemAbstraction combinedFSA = new SelectiveFileSystemAbstraction(new File(new File(testDir.directory(), "long-state"), "long.a"), breakingFSA, normalFSA);
    long lastValue = 0;
    try (LongState persistedState = new LongState(combinedFSA, testDir.directory(), 14)) {
        while (// it will break from the Exception that AFS will throw
        true) {
            long tempValue = lastValue + 1;
            persistedState.setTheState(tempValue);
            lastValue = tempValue;
        }
    } catch (Exception expected) {
        // this stack trace should contain force()
        ensureStackTraceContainsExpectedMethod(expected.getStackTrace(), "force");
    }
    try (LongState restoredState = new LongState(normalFSA, testDir.directory(), 14)) {
        assertThat(restoredState.getTheState(), greaterThanOrEqualTo(lastValue));
    }
}